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An epidemiological and ecological study of human alveolar echinococcosis transmission in south Gansu, China
Abstract
Human alveolar echinococcosis (AE) is usually a rare, highly pathogenic zoonotic disease, transmitted across the northern hemisphere between fox and rodent hosts. In China the first cases were described in 1965; however very few epidemiological studies have been undertaken since. Following identification in 1991 of a serious focus of human AE in south Gansu province, detailed village-based community and ecological studies were carried out between 1994 and 1997. Hepatic ultrasound mass screening with serological testing (five tests) identified 84/2482 new AE cases (3%). An overall prevalence of 4.1% (135/3331) was recorded for the area when previous cases were also included. Based on a seropositive result only, without an ultrasound scan indication, no additional AE cases were identified. Of the evolutive AE cases, 96% were seropositive in at least one test, while up 15-20% of individuals who exhibited hepatic calcified lesions and 12-15% exhibiting hepatic nodular lesions were seropositive for specific Em2 or Em18 antibodies. Village (n=31) human AE prevalence rates varied from 0 to 15.8%. Questionnaire analysis indicated that total number of dogs owned over a period was a risk factor (P<0.006), but not a history of red fox hunting (P>0.6). Rodent ecology studies revealed an association between density indices of voles (Microtus limnophilus) and village AE prevalence rates, on the one hand, and village landscape characterised by a ratio of scrub/grassland to total area above 50% (P<0.005). Long-term transmission of Echinococcus multilocularis and risk of zoonotic infection of south Gansu farmers may be related ultimately to a process of deforestation driven by agriculture. This in turn probably results in creation of optimal peri-domestic habitats for rodents that serve as intermediate host species (such as M. limnophilus) and subsequent development of a peri-domestic cycle involving dogs.
... In China, the incidence of AE was 257 cases in Ningxia, 88 cases in Xinjiang, 71 cases in Gansu, 49 cases in Sichuan, 37 cases in Qinghai, 1 case in Heilongjiang Tibet provinces in 1992 (12). In recent years, over 350 AE cases have been detected in the Gansu region alone. ...
... Several other studies have found that dogs and cats are significant risk factors for AE, although results have been mixed (33,34). The number of dogs owned over time and the degree of dog contact were the most relevant risk factors in a Chinese study of the Gansu-Han population with over 2,500 participants, including 86 individuals with AE (12). ...
... However, the feasibility of implementing such controls throughout wide swathes of AE-prevalent areas, such as the Tibetan plateau, is debatable. Although dog interaction has been identified as a risk factor for transmission to humans (12) and dogs are particularly vulnerable to infection with this parasite (37), periodic treatment of dogs will not disrupt the transmission cycle and will have considerably less impact on long-term transmission rates to humans (38, 39). Other studies suggest that improved control of food or water supplies that may be contaminated with parasite eggs is another way to reduce disease burden. ...
Background
Human alveolar echinococcosis (AE) is a neglected zoonotic disease. Prevalence of AE in humans is reported in Pakistan as a result of poor economic and sanitary conditions, close proximity to wildlife and limited knowledge of AE. Studies on the prevalence and transmission of AE have been limited, especially for rural Pakistan. The study objectives were to identify knowledge, attitudes and practices relating to AE, to determine awareness of the disease, and to identify knowledge about possible risk factors of infections involving the landscape epidemiological attributes of rural villages in Hunza, one of the districts of Gilgit-Baltistan, a region of Pakistan that borders China.
Methods
A community-based cross-sectional study was conducted among the general population of Hunza to establish the level of awareness, knowledge, attitudes, practices, landscape epidemiology, and disease management and control relating to AE in rural areas of Hunza. Data were collected by questionnaire.
Results
A total of 387 questionnaires was received. Statistical analysis showed that the population's knowledge about the disease was poor. The attitudes and practices of the participants indicated that their risk of infection was low. Knowledge of landscape epidemiology of the disease was poor but knowledge about AE disease management was good. The attitudes of residents toward disease treatment and control strategies were positive, although the overall knowledge of participants about prevention of infection was poor.
Conclusion
Knowledge of AE is poor among the residents of Hunza, Pakistan. Our study demands continued and strengthened awareness of the changes to lifestyle and practices associated with AE, not only in the study locality but throughout other areas of Pakistan.
... However distribution of baits containing praziquantel can have significant impacts on vulpine prevalence of E. multilocularis, but is difficult to maintain over long periods and large geographic areas [16]. Contact with dog definitive hosts can be a major risk factor for human AE infection in communities where dogs live in close vicinity to humans, for example on St Lawrence Island in the Bering sea [17] and rural areas of China [5,18]. ...
... Three years later, between 1994 and 1997, a much larger study was undertaken in Zhang county and the neighbouring Puma district (Min county), in which 2482 persons were voluntarily screened in 1994-6 by portable ultrasound in their villages (n = 31). That program detected 84 AE cases (3.4% prevalence, but increasing to 4.1% when AE cases identified in the 1991 survey were included) with a mean age of 38.7 years (range 12-70 years) [18]. Village human AE prevalences varied from 0% to >10% and 9 villages had AE prevalences >5%, with main risk factors for an AE case being: female >20 years old, landscape-type around village of domicile (ie.>50% scrub/grassland), presence of free-roaming/scavenging dogs, the number/ history of dog ownership and dog carer [18]. ...
... That program detected 84 AE cases (3.4% prevalence, but increasing to 4.1% when AE cases identified in the 1991 survey were included) with a mean age of 38.7 years (range 12-70 years) [18]. Village human AE prevalences varied from 0% to >10% and 9 villages had AE prevalences >5%, with main risk factors for an AE case being: female >20 years old, landscape-type around village of domicile (ie.>50% scrub/grassland), presence of free-roaming/scavenging dogs, the number/ history of dog ownership and dog carer [18]. In addition small mammal species assemblages were investigated in depth, and two dominant susceptible host species (Microtus limnophilus and Cricetulus longicaudatus) with potential for pluriannual population increases, were shown to occur in the high risk scrub/grassland habitats [4,26]. ...
Background
Human alveolar echinococcosis caused by infection with Echinococcus multilocularis is one of the most potentially pathogenic helminthic zoonoses. Transmission occurs involving wildlife cycles typically between fox and small mammal intermediate hosts. In the late 1980s/early 1990s a large focus of human AE was identified in poor upland agricultural communities in south Gansu Province, China. More detailed investigations in 1994–97 expanded community screening and identified key risk factors of dog ownership and landscape type around villages that could support susceptible rodent populations. A crash of the dog population (susceptible domestic definitive host) in the early 1990s appeared to stop transmission.
Methodology/Findings
We subsequently undertook follow-up eco-epidemiological studies based on human population screening and dog survey, in 2005/6 and in 2014/15. Our observations show a decrease in human AE prevalence, especially marked in the 11–30 year old age category. In 2015, although the dog population had recovered and in addition, forest protection and the reforestation of some areas may have favoured red fox (wild definitive host) population growth, there was no evidence of infection in owned dogs.
Conclusions/Significance
Those observations suggest that over decades socio-ecological changes resulted in a cascade of factors that exacerbated and then interrupted parasite emergence, with probable elimination of peri-domestic transmission of E. multilocularis in this area, despite the relative proximity of large active transmission foci on the eastern Tibetan Plateau. This study case exemplifies how anthropogenic land use and behavioural changes can modify emergence events and the transmission of endemic zoonotic parasite infections, and subsequently the importance of considering processes over the long-term in a systems approach in order to understand pathogen and disease distribution.
... In 1991 portable ultrasound was used to successfully screen for hepatic AE disease in poor Han upland (2000-2500 m altitude) agricultural villages in south Gansu Province situated approximately 300 km from the eastern edge of the Tibetan Plateau (Craig et al., , 2000. Mass screening for echinococcosis using portable ultrasound in Tibetan communities however presented greater difficulties than for most other regions of China. ...
... That difference may be due to more chance of seasonal environmental contamination by E. granulosus eggs in dog faeces in winter township settlements used by semi-nomadic herdsmen (Moss et al., 2013;Wang et al., 2016) (see also Section 3.2). Dogs are an excellent host for both E. granulosus (Gemmell et al., 1986) and E. multilocularis (Kapel et al., 2006); therefore zoonotic risk for CE and AE will tend to increase with dog ownership and numbers of dogs owned over longer periods (Craig et al., 2000;Wang et al., 2016). Several studies show a greater risk of CE and AE for Tibetan females especially > 25 years of age, which is probably related to more dog contact as the primary dog carer and also greater contact with dog faeces contaminated environments around households and villages. ...
... granulosus and also for AE/E. multilocularis to humans in Tibetan communities and in some other parts of China (Craig et al., 2000;. Therefore, the Chinese National Echinococcosis Control programme adopted deworming dogs (using praziquantel) as the most substantial control measure (Ministry of Health China, 2006). ...
Since the mid-1990s detailed studies and field investigations on the Tibetan Plateau have revealed human echinococcosis to be an under-reported major public health problem, particularly in the dominant pastoral communities in the eastern and central regions. Human prevalence surveys showed that cystic echinococcosis (CE, caused by Echinococcus granulosus) and alveolar echinococcosis (AE, caused by Echinococcus multilocularis) are co-endemic with higher burdens of each disease than other endemic world regions. Epidemiological investigations identified some major risk factors for human CE and AE including dog ownership, husbandry practices and landscape features. Dogs appear to be the major zoonotic reservoir for both E. granulosus and E. multilocularis, but the latter is also transmitted in complex wildlife cycles. Small mammal assemblages especially of vole and pika species thrive on the Plateau and contribute to patterns of E. multilocularis transmission which are influenced by landscape characteristics and anthropogenic factors. Tibetan foxes are a principal definitive host for both E. multilocularis and E. shiquicus. In 2006 a national echinococcosis control programme was initiated in Tibetan communities in northwest Sichuan Province and rolled out to all of western China by 2010, and included improved surveillance (and treatment access) of human disease and regular deworming of dogs with annual copro-testing. Control of echinococcosis in Tibetan pastoral communities poses a difficult challenge for delivery and sustainability.
... Domestic dogs are susceptible to infection with both parasites, and are currently regarded as significant hosts for E. granulosus and E. multilocularis (Moss et al., 2013;Rausch, 1995). In Gansu Province and the eastern Tibetan plateau, PR China, particularly, domestic dogs have been identified as the main transmission source of both parasites to the local human population (Craig et al., 2000;Wang et al., 2010). Comprehensive reviews of the life cycles of E. granulosus and E. multilocularis, clinical manifestations of human echinococcoses, diagnosis, treatment, prevention and control are available Kern et al., 2017;Romig et al., 2017). ...
... Then, a blood sample from the ear lobe was collected from participants for specific antibody testing by enzyme linked immunosorbent assay (ELISA) using E. granulosus cyst fluid antigen B and E. multilocularis crude protoscolex extract (Craig et al., 1992;Yang et al., 2008). EgB and EmP ELISA sensitivity is >85% for CE and >90% for AE, respectively (Bartholomot et al., 2002;Craig et al., 1992;Craig et al., 2000). Specificity is from 70% to 100% for CE (Carmena et al., 2006) and 87% for AE (Bartholomot et al., 2002). ...
... The project also advocates for desertification control and prohibition of enclo-sures for grazing practices (Wang et al., 2007). Studies conducted in other echinococcosis-endemic regions, where landscape transformation processes have taken place, indicate that some types of land cover change may have had an impact on the transmission patterns of E. multilocularis and, consequently, the risk of infection has increased for animals and humans (Craig et al., 2000;Giraudoux et al., 1998;Giraudoux et al., 2003). This study demonstrated similarities in the spatial distribution of the predicted seroprevalence of E. granulosus among schoolchildren and infection in domestic dogs in the four counties in 2012-2013. ...
The geographical distribution of Echinococcus spp. infections in Ningxia Hui Autonomous Region (NHAR) has been reported to be expanding in response to environmental change. The aim of the present study was to predict and compare the spatial distribution of human seropositivity for Echinococcus granulosus and Echinococcus multilocularis and infections with these parasites in dogs in four counties in the south of NHAR to identify communities where targeted prevention and control efforts are required. Predicted seroprevalence of E. granulosus in schoolchildren and E. granulosus infections in dogs concurred spatially, whereas predicted seroprevalence of E. multilocularis in schoolchildren and E. multilocularis infections in dogs differed spatially. Enhanced vegetation index was significantly associated with E. multilocularis seropositivity among schoolchildren, and infections with E. granulosus and E. multilocularis in dogs. A positive association was also found between dog infection with E. granulosus and cultivated land, and a negative association between human seropositivity for E. granulosus and bare-land/artificial surfaces. The findings of this study support the importance of land cover and climatic variables in determining habitat suitability for Echinococcus spp. infections, and suggest that definitive hosts other than dogs (e.g. foxes) are important in defining the geographical risk of human seropositivity for E. multilocularis in NHAR.
... The Chinese government is implementing a series of extensive landscape regeneration projects to restore the country's degraded ecological landscape [19,20]. Studies conducted in various echinococcosis-endemic regions have documented that land cover transformations are related to higher population densities of key intermediate hosts for E. multilocularis, which has increased the risk of human AE infection [21][22][23][24][25][26][27][28]. Hence, research also needs to be conducted to better describe the ecological processes that may lead to variations in the transmission patterns of E. granulosus and E. multilocularis based on shifting environmental factors [29]. ...
... Participants were also asked to provide a small blood sample from the ear lobe for specific antibody testing by enzyme linked immunosorbent assay (ELISA) using E. granulosus cyst fluid antigen B (EgB) and E. multilocularis crude protoscolex extract (EmP) [38]. Sensitivity of EgB and EmP ELISA is > 85% for CE and > 90% for AE, respectively [23,38,39]. Specificity ranges from 70 to 100% for CE [40] and 87% for AE [39]. ...
... Spatially explicit statistical models were constructed previously to predict the spatial distribution of infection with E. multilocularis among the non-student population in Xiji County in 2002-2003 [27]. That model showed that the landscape features associated with an increased AE risk in Xiji County differed from previous observations in Zhang County in the neighbouring Gansu Province [21,23]. Unlike the findings in Zhang County, where grassland/shrubland favoured the creation of optimal peri-domestic habitats for E. multilocularis intermediate host species, and the development of a peri-domestic cycles involving dogs [21,23], in Xiji County, abundance of reforested lowland pastures was correlated with higher prevalence of human AE risk. ...
Background:
Human echinococcoses are parasitic helminth infections that constitute a serious public health concern in several regions across the world. Cystic (CE) and alveolar echinococcosis (AE) in China represent a high proportion of the total global burden of these infections. This study was conducted to predict the spatial distribution of human seropositivity for Echinococcus species in Xiji County, Ningxia Hui Autonomous Region (NHAR), with the aim of identifying communities where targeted prevention and control efforts are required.
Methods:
Bayesian geostatistical models with environmental and demographic covariates were developed to predict spatial variation in the risk of human seropositivity for Echinococcus granulosus (the cause of CE) and E. multilocularis (the cause of AE). Data were collected from three cross-sectional surveys of school children conducted in Xiji County in 2002-2003, 2006-2007 and 2012-2013. Environmental data were derived from high-resolution satellite images and meteorological data.
Results:
The overall seroprevalence of E. granulosus and E. multilocularis was 33.4 and 12.2%, respectively, across the three surveys. Seropositivity for E. granulosus was significantly associated with summer and winter precipitation, landscape fragmentation variables and the extent of areas covered by forest, shrubland, water and bareland/artificial surfaces. Seropositivity for E. multilocularis was significantly associated with summer and winter precipitations, landscape fragmentation variables and the extent of shrubland and water bodies. Spatial correlation occurred over greater distances for E. granulosus than for E. multilocularis. The predictive maps showed that the risk of seropositivity for E. granulosus expanded across Xiji during the three surveys, while the risk of seropositivity for E. multilocularis became more confined in communities located in the south.
Conclusions:
The identification of high-risk areas for seropositivity for these parasites, and a better understanding of the role of the environment in determining the transmission dynamics of Echinococcus spp. may help to guide and monitor improvements in human echinococcosis control strategies by allowing targeted allocation of resources.
... The remaining 6 publications were unsuitable for meta-analysis as no OR for individual risk factors could be extracted. Of the 17 publications, data were separately extracted from case-control (n = 6) [19][20][21][22][23][24] and cross-sectional studies (n = 11) [10,[25][26][27][28][29][30][31][32][33][34] (S2 Table; S1 Flow Diagram). No cohort studies were identified. ...
... Of the 6 case-control studies, 3 were allocated an 8-star rating [19,22,23] and the other 3 studies received a 9 [20], 4 [24] and a 2-star score [21]. Within the 11 cross-sectional studies, 5 received a 8-star rating [10,26,[28][29][30], 3 a 6-star rating [25,33,34], 2 a 7-star rating [31,32] and 1 a 9-star score [27]. ...
... Meta-analyses performed on eleven cross-sectional studies corresponding to thirteen substudies revealed thirteen PRFs. Most studies originated from endemic areas in the People's Republic of China, namely, Ningxia Hui autonomous region (n = 2) [29,34], Sichuan province (n = 4) [10,25,26,33], Gansu province (n = 2) [30,31], Qinghai province (n = 1) [28], Sichuan and Qinghai provinces (n = 1) [27] and one from Europe (Germany) [32]. All studies were community-based ultrasonography surveys. ...
Background
Human alveolar echinococcosis (AE) is a severe zoonotic disease caused by the metacestode stage of Echinococcus multilocularis. AE is commonly associated with a long incubation period that may last for more than ten years. The objective of this systematic literature review was to identify and summarize the current knowledge on statistically relevant potential risk factors (PRFs) associated with AE in humans.
Methodology/Principal findings
Six bibliographic databases were searched, generating a total of 1,009 publications. Following the removal of duplicate records and the exclusion of papers that failed to meet the criteria of a previously agreed a priori protocol, 23 publications were retained; however, 6 of these did not contain data in a format that allowed their inclusion in the meta-analysis. The remaining 17 publications (6 case-control and 11 cross-sectional studies) were meta-analysed to investigate associations between AE and PRFs. Pooled odds ratios (OR) were used as a measure of effect and separately analysed for case-control and cross-sectional studies. In the case-control studies, the following PRFs for human AE showed higher odds of outcome: “dog ownership”, “cat ownership”, “have a kitchen garden”, “occupation: farmer”, “haymaking in meadows not adjacent to water”, “went to forests for vocational reasons”, “chewed grass” and “hunting / handling foxes”. In the cross-sectional studies, the following PRFs showed higher odds of outcome: “dog ownership”, “play with dogs”, “gender: female”, “age over 20 years”, “ethnic group: Tibetan”, “low income”, “source of drinking water other than well or tap”, “occupation: herding” and “low education”. Our meta-analysis confirmed that the chance of AE transmission through ingestion of food and water contaminated with E. multilocularis eggs exists, but showed also that food- and water-borne PRFs do not significantly increase the risk of infection.
Conclusions/significance
This systematic review analysed international peer-reviewed articles that have over the years contributed to our current understanding of the epidemiology of human AE. The identification of potential risk factors may help researchers and decision makers improve surveillance and/or preventive measures that aim at decreasing human infection with E. multilocularis. More primary studies are needed to confirm potential risk factors and their role in the epidemiology of human AE.
... In Kyrgyzstan, the number of AE cases is negatively associated with 10-year lag mean annual temperature (Paternoster et al., 2021). Human AE prevalence in farmers in Gansu province is related to the ratio of area of scrub/grassland in China (Craig et al., 2000). ...
... Many studies have the same finding that human AE incidence is significantly positively correlated with altitude (Craig et al., 2019;Giraudoux et al., 2013;Yin et al., 2022). Some features of grassland (mainly alpine meadow) are also found significantly related to human AE incidence, such as the area of grassland , the ratio of grassland (Craig et al., 2000;Giraudoux et al., 2013), the proximity of villages to grassland . These are similar to our finding and ours provide a landscape perspective on the effect of grassland on human AE incidence. ...
Human alveolar echinococcosis (AE) is a lethal helminthic infection caused by the tapeworms Echinococcus multilocularis. The Qinghai-Tibet Plateau has the greatest endemicity of human AE globally, but the natural risk factors and its impact mechanism are still unclear. Generalized linear models and generalized additive models are used to select key linear and non-linear environmental factors associated with cases of AE. The interactive effect between different factors is identified using concurvity test. From fifty-nine variables analyzed, four key factors and one interaction term were identified associated with AE. Considering interaction terms between climatic and geographical landscape factors can significantly improve model fitting. Minimum winter precipitation, percentage of grassland cover, and minimum elevation have significant positive linear relationship with human AE incidence. The relationship between maximum summer precipitation and human AE is non-linear with high AE incidence associated with moderate precipitation. The interaction term of maximum summer precipitation and number of patches of grassland on human AE indicates that human AE incidence is highest when both factors were high. The climatic and landscape risk factors together are associated with the local transmission of human AE in Qinghai-Tibet Plateau. This study provides a scientific basis for human intervention in AE from fine-scale ecological environment.
... Eight studies tested the effect of the proportion of grasslands in the landscape on the infection in humans ( [35,[86][87][88][89][90][91][92]; group 11). The study from Qian et al. [93] was not included in this group as it focused on a slightly different exposure (i.e. the proportion of fenced pastures) in order to assess the effect of overgrazing on dog infection through modification of intermediate host populations. ...
... However, the impossibility to obtain robust and fine-scale land-use data over several decades in the study region (China) prevents the authors from drawing any definitive conclusion. The less valid studies [35,86,[88][89][90] reported a positive correlation between echinococcosis incidence or prevalence and the proportion of grassland in the landscape, but none of them accounted for the latency period of the disease. Thus, results from these studies should be taken with much caution. ...
Background
The control and prevention of vector-borne and zoonotic diseases is often based on the reduction of host or vector populations, involving but not limited to preventative culling and use of insecticides. Yet, destructive interventions such as these have shown several limitations including ineffectiveness on arthropods and negative impacts on ecosystems. An alternative strategy would be to rely on the natural ecosystem functions and their careful management to regulate such diseases. The goal of our work was to evaluate existing scientific evidence on potential links between ecosystem components/functions and 14 vector-borne and zoonotic diseases impacting human health and answer the question: “What evidence exists on the impact of specific ecosystem components and functions on infectious diseases?”.
Methods
We searched for scientific articles published in English and French and screened them in a 3-round process (title, abstract and full-text). Articles were retained, without any geographical limitation, if they matched the following eligibility criteria: an exposure/intervention linked to changes in biological communities, habitats, or landscapes; an outcome consisting of any measure of infection in vector, animal or human hosts; and the presence of a comparator, in time and/or in space. The results are presented as a systematic map, followed by a narrative review where the amount of papers allowed for synthesis.
Results
Searches in 5 scientific publication databases allowed to retrieve 9723 unique articles, among which 207 were retained after the screening process. The amount of relevant literature was highly variable depending on diseases, and the types of exposures also varied greatly among studies focusing on the same disease. A hundred articles presented in the map were unique in their “disease x exposure” combination and thus not eligible for further narrative description. The remaining 107 articles were organized in 34 “disease x exposure” groups, encompassing 9 out of the 14 initial diseases. The groups were composed of 2 to 16 articles and were examined to provide a description of the current state of knowledge for those diseases.
Conclusion
Studies investigating the interaction between infectious diseases and ecosystems components and functions are still very scarce, and certain diseases are much more studied than others. Out of 14 diseases, 8 generated less than 10 relevant articles, while 2 diseases (Lyme disease and West Nile disease) represented 44% of all relevant studies. Although several vector-borne diseases included in the review represent a major health issue in the world, such as malaria or dengue, they have been exclusively studied under the prism of land-use, and we were unable to find relevant studies that tested the regulatory role of animal biodiversity-related functions. The role of predation in the regulation of vector and host populations has rarely been studied, with the exception of schistosomiasis. The dilution and amplification effects were addressed in several studies focusing on the composition of ecological communities. This map is a first step and could be upgraded in order to guide future research projects with the aim to conduct meta-analysis and build a robust evidence base to inform decision-making.
... The reported AE cases in Gansu province were concentrated in south Gansu. A large focus of human AE was confirmed by mass US screening in the survey during 1994-1997 in south Gansu, showing a 3.4% prevalence 10 . Furthermore, liver US scan identified nine AE and one CE from 362 participants in west Gansu, demonstrating a AE and CE co-epidemic area 13 . ...
... They spent most of their time around tents and houses, where dogs and/or dog feces were present. Similarly, higher risk among females was also reported in Tibetan communities of Sichuan and Gansu province 10,30 . The age distribution in this survey demonstrated that the prevalence increased with age. ...
Echinococcosis is endemic in pastoral regions of south, west and mid-Gansu province, China. The present study aimed to determine the prevalence of echinococcosis in east Gansu, and analyze its associated risk factors. A cross-sectional survey was conducted in 2011 in 12 villages of Xiaonangou township, Huan County in east Gansu province by ultrasound abdominal scan and auxiliary serotest, and a prevalence surveillance study from 2008 to 2014 was performed in one villages by ultrasonography screening. Questionnaire information analysis indicates that the risk factors are in association with the gender, age, and education level. The cross-sectional survey found a cystic echinococcosis prevalence of 2.21% (107/4837). Higher prevalence was seen in females ( χ ² = 4.198, P < 0.05), older ages (> 60 years) ( χ ² trend = 96.30, P < 0.05), and illiterates ( χ ² = 90.101, P < 0.05). Prevalence surveillance showed changing profile of 3.35% in 2011 to 0.88% (1/113) in 2014.
... In Zhang County, Gansu Province, a study revealed that the process of land cover change that occurred in this endemic area affected the transmission dynamics of the parasite. There, the increase in grassland/shrubland that followed a process of deforestation favoured the creation of peri-domestic habitats of intermediate host species, and the development of peridomestic cycles involving dogs [13,82]. Similarly, the percentage of area covered by grassland and E. multilocularis infection in humans and foxes had a positive relationship in Eastern France [13,83,84]. ...
... Infection with E. multilocularis has also been detected in wolves (Canis lupus) and corsac foxes (Vulpes corsac) in other parts of the P.R. China [82]. ...
Background:
Human cystic (CE) and alveolar (AE) echinococcoses are zoonotic parasitic diseases that can be influenced by environmental variability and change through effects on the parasites, animal intermediate and definitive hosts, and human populations. We aimed to assess and quantify the spatiotemporal patterns of human echinococcoses in Ningxia Hui Autonomous Region (NHAR), China between January 1994 and December 2013, and examine associations between these infections and indicators of environmental variability and change, including large-scale landscape regeneration undertaken by the Chinese authorities.
Methods:
Data on the number of human echinococcosis cases were obtained from a hospital-based retrospective survey conducted in NHAR for the period 1 January 1994 through 31 December 2013. High-resolution imagery from Landsat 4/5-TM and 8-OLI was used to create single date land cover maps. Meteorological data were also collected for the period January 1980 to December 2013 to derive time series of bioclimatic variables. A Bayesian spatio-temporal conditional autoregressive model was used to quantify the relationship between annual cases of CE and AE and environmental variables.
Results:
Annual CE incidence demonstrated a negative temporal trend and was positively associated with winter mean temperature at a 10-year lag. There was also a significant, nonlinear effect of annual mean temperature at 13-year lag. The findings also revealed a negative association between AE incidence with temporal moving averages of bareland/artificial surface coverage and annual mean temperature calculated for the period 11-15 years before diagnosis and winter mean temperature for the period 0-4 years. Unlike CE risk, the selected environmental covariates accounted for some of the spatial variation in the risk of AE.
Conclusions:
The present study contributes towards efforts to understand the role of environmental factors in determining the spatial heterogeneity of human echinococcoses. The identification of areas with high incidence of CE and AE may assist in the development and refinement of interventions for these diseases, and enhanced environmental change risk assessment.
... Domestic dogs (Canis lupus familiaris) and cats (Felis catus) may uncommonly harbor the tapeworm (synanthropic cycle) [87,88]. However, domestic dogs may be the dominant definitive hosts in the peri-domestic cycle in high endemic zones of southern and western China created by deforestation driven by agriculture [71,72,[89][90][91]. The population of dogs (Canis lupus familiaris) has grown multifold in Kashmir, as the law prohibits killing, poisoning, or rendering useless any animal in the society [92][93][94]. ...
A prospective study on 110 patients with echinococcosis at Dr. Khuroo’s Medical Clinic, Srinagar, Kashmir, India, from March 2019 to April 2024 identified 12 cases (4 males, 8 females; mean age of 46.58 ± 11.97 years) of Alveolar echinococcosis (AE). Two patients were detected through ultrasound examinations carried out for unrelated causes; one presented with features of liver abscess, and nine had pain in the right upper quadrant for a mean period of 2.2 ± 1.79 years. All had the liver as the primary organ involved, with 15 tumor masses of a mean maximum diameter of 9.22 ± 3.21 cm and volume of 426 ± 374.61 cm3. Tumors placed centrally had invaded vessels and the biliary tract in eight patients, and those placed peripherally had invaded the liver capsule and adjacent organs in nine patients. Histologic examination of liver biopsies or resected organs revealed necrotic lesions, calcifications, and granulomatous inflammation with slender, thin-walled vesicles of bizarre configuration that stained strongly eosinophilic with periodic acid Schiff. Two patients had segmental liver resections; one was treated with liver aspiration, while the other nine with advanced disease received chemotherapy with albendazole along with praziquantel. Patients showed clinical improvement on a median follow-up of 12 months (range 1 to 60 months); however, MRI T2-weighted images and 18F-FDG-PET-CECT scans in two patients showed active disease on follow-up at one and five years, respectively. A systematic review detected 146 cases of AE in India from 1980 to April 2024. Twenty cases were from foreign countries, mostly from Central Asian republics, and 118 (93.65%) of the remaining 126 Indian patients were permanent residents of Kashmir Valley. The disease affected a population of 79,197 residing in 22 villages from 5 border districts of the valley. These villages were either high in or adjacent to the Himalayan mountain range. Disease prevalence in the affected population was 146.47/105 (males 131.53/105 and females 163.18/105) and the incidence was 12.41/105/year (males 11.16/105/year and females 13.81/105/year). Possible causes of the emergence of AE are discussed, and future directions for research to face this challenge arebeen identified.
... With the process of deforestation, the increase of grasslands or shrubs is conducive to the creation of near domestic habitats for small mammals and the development of near domestic cycles involving dogs. The distribution of small mammals in Gansu Province is also due to the short-term increase of grasslands and shrubs after deforestation [27,35]. In eastern France, voles and vole population outbreaks have been reported in areas where cultivated land has been converted to permanent grassland [28]. ...
Background
Echinococcosis is a natural focal, highly prevalent disease in China. Factors influencing the spread of echinococcosis are not only related to personal exposure but also closely related to the environment itself. The purpose of this study was to explore the influence of environmental factors on the prevalence of human echinococcosis and to provide a reference for prevention and control of echinococcosis in the future.
Methods
Data were collected from 370 endemic counties in China in 2018. By downloading Modis, DEM and other remote-sensing images in 2018. Data on environmental factors, i.e., elevation, land surface temperature (LST) and normalized difference vegetation index (NDVI) were collected. Rank correlation analysis was conducted between each environmental factor and the prevalence of echinococcosis at the county level. Negative binomial regression was used to analyze the impact of environmental factors on the prevalence of human echinococcosis at the county level.
Results
According to rank correlation analysis, the prevalence of human echinococcosis in each county was positively correlated with elevation, negatively correlated with LST, and negatively correlated with NDVI in May, June and July. Negative binomial regression showed that the prevalence of human echinococcosis was negatively correlated with annual LST and summer NDVI, and positively correlated with average elevation and dog infection rate. The prevalence of human cystic echinococcosis was inversely correlated with the annual average LST, and positively correlated with both the average elevation and the prevalence rate of domestic animals. The prevalence of human alveolar echinococcosis was positively correlated with both NDVI in autumn and average elevation, and negatively correlated with NDVI in winter.
Conclusion
The prevalence of echinococcosis in the population is affected by environmental factors. Environmental risk assessment and prediction can be conducted in order to rationally allocate health resources and improve both prevention and control efficiency of echinococcosis.
... Although protoscoleces are not always well proliferated in AE patients, Em18 prepared from protoscoleces is a good marker for identification of AE and approximately 90% of AE cases are easily detectable by an Em18immunoblot (Craig et al., 2000). This is due to the fact that Em18 is shared between protoscoleces and microvesicles ( fig. 1). ...
Rats are known to be relatively resistant to infection with Echinococcus multilocularis. However, when rats are inoculated with the parasite tissues, E. multilocularis proliferates slowly at first but after 6 months the cysts increase in size considerably and contain large numbers of protoscoleces. As rats survive for 18 months or longer, approximately 100 ml of packed protoscoleces can be produced from each rat. A comparison of the antigenicity of the protoscoleces and microvesicles by immunoblot methods showed that both Em18 and Em16 are shared components between both protoscoleces and microvesicles, although the latter have some additional antigenic components. In antigens prepared from protoscoleces, the banding patterns around Em18 were much simpler than those from microvesicles. Therefore, for serodiagnosis of E. multilocularis, antigens should be carefully prepared from protoscoleces rather than microvesicles from the rat.
... Generally, both E. granulosus sensu lato and E. multilocularis have multi-host systems that are influenced by environmental factors such as the number of host species, habitats, density, predator-prey relationships, and egg survival [10][11][12][13][14][15][16]. ...
Background
In the normal life cycle of the parasite ( Echinococcus multilocularis ) that causes alveolar echinococcosis, domestic and wild carnivores act as definitive hosts, and rodents act as intermediate hosts. The presented study contributes to the research on the distribution and transmission pattern of E. multilocularis in China having identified sheep as an unusual intermediate host taking part in the domestic transmission of alveolar echinococcosis in Gansu Province, China.
Methods
From 2020 to 2021, nine whitish different cyst-like were collected from the liver of sheep in Gansu Province for examination. A near complete mitochondrial ( mt ) genome and selected nuclear genes were amplified from the cyst-like lesion for identification. To confirm the status of the specimen, comparative analysis with reference sequences, phylogenetic analysis, and network analysis were performed.
Results
The isolates displayed ≥ 98.87% similarity to E . multilocularis NADH dehydrogenase sub-unit 1 ( nad 1) (894 bp) reference sequences deposited in GenBank. Furthermore, amplification of the nad 4 and nad 2 genes also confirmed all nine samples as E . multilocularis with > 99.30% similarity. Additionally, three nuclear genes, pepck (1545 bp), elp-exons VII and VIII (566 bp), and elp-exon IX (256 bp), were successfully amplified and sequenced for one of the isolates with 98.42% similarity, confirming the isolates were correctly identified as E. multilocularis . Network analysis also correctly placed the isolates with other E. multilocularis .
Conclusions
As a result of the discovery of E. multilocularis in an unusual intermediate host, which is considered to have the highest zoonotic potential, the result clearly demonstrated the necessity for expanded surveillance in the area.
Graphical Abstract
... This was caused mainly by traditional feeding of dogs during the periods of animal slaughtering as a consequence of close relationships of stray dogs and citizens. [14,15,16,17] Especially important factor of veterinary control related to Echinococcosisis is anithelminthic procedure which is an obligate activity according to the current legislative. ...
... Unexpectedly, sheep density was observed to be negatively correlated with CE in our study, possibly attributable to the move of slaughtering operations from the home to slaughterhouses in areas of high sheep density, which decreases the risk of echinococcosis infection to some extent. For AE, our analysis showed that high rodent density and prevalence contributed to high disease prevalence, which is consistent with the findings of previous studies [33]. In addition, although some researchers have revealed that contact with stray dogs and wild animals was a risk factor for AE [19], unexpectedly, our results showed no significant relationship between Canidae density and AE; this may be the result of using low-resolution data of Canidae density converted from shapefiles. ...
Background
Human cystic and alveolar echinococcosis are neglected tropical diseases that WHO has prioritized for control in recent years. Both diseases impose substantial burdens on public health and the socio-economy in China. In this study, which is based on the national echinococcosis survey from 2012 to 2016, we aim to describe the spatial prevalence and demographic characteristics of cystic and alveolar echinococcosis infections in humans and assess the impact of environmental, biological and social factors on both types of the disease.
Methods
We computed the sex-, age group-, occupation- and education level-specific prevalences of cystic and alveolar echinococcosis at national and sub-national levels. We mapped the geographical distribution of echinococcosis prevalence at the province, city and county levels. Finally, by analyzing the county-level echinococcosis cases combined with a range of associated environmental, biological and social factors, we identified and quantified the potential risk factors for echinococcosis using a generalized linear model.
Results
A total of 1,150,723 residents were selected and included in the national echinococcosis survey between 2012 and 2016, of whom 4161 and 1055 tested positive for cystic and alveolar echinococcosis, respectively. Female gender, older age, occupation at herdsman, occupation as religious worker and illiteracy were identified as risk factors for both types of echinococcosis. The prevalence of echinococcosis was found to vary geographically, with areas of high endemicity observed in the Tibetan Plateau region. Cystic echinococcosis prevalence was positively correlated with cattle density, cattle prevalence, dog density, dog prevalence, number of livestock slaughtered, elevation and grass area, and negatively associated with temperature and gross domestic product (GDP). Alveolar echinococcosis prevalence was positively correlated with precipitation, level of awareness, elevation, rodent density and rodent prevalence, and negatively correlated with forest area, temperature and GDP. Our results also implied that drinking water sources are significantly associated with both diseases.
Conclusions
The results of this study provide a comprehensive understanding of geographical patterns, demographic characteristics and risk factors of cystic and alveolar echinococcosis in China. This important information will contribute towards developing targeted prevention measures and controlling diseases from the public health perspective.
Graphical Abstract
... These embryonated eggs can remain alive and contagious for months in favorable environments with high humidity and low temperature. Canine existence was thought to be critical for cystic echinococcosis transmission (Wang et , and many other studies also indicated that dog-related risk factors were primarily significant (Craig et al., 2000). Seropositivity in children may or may not be associated to the progression of hydatid cyst types, as an initial exposure can result in progressive abscesses, abortive lesions, or spontaneous cure. ...
seroprevalence and risk factors of human cystic echinococcosis in central and North Kashmir, india 21 ___________________________________________________________________________Andrabi et al. abstract Cystic echinococcosis (CE) is a dreadful zoonotic neglected disease that affects public health globally. The infection is highly endemic in northern India (Kashmir valley). The present survey based study was done to know the seroprevalence of cystic echinococcosis infection among residents of north and central Kashmir valley and to identify risk variables linked to this infection. In addition to collecting 462 serum samples (244 males and 218 females), a questionnaire was also filled out for each participant utilizing systematic random sampling from June to November 2019 in 16 villages and 6 districts. Using a commercial enzyme-linked immunosorbent assay (ELISA) kit, the samples were tested for immunoglobulin G. Of the 462 serum samples obtained, 33 (7.14 percent) were found to be positive. Results showed that age group, gender, contact with dogs, occupation, and literacy rate were significantly related with the rate of seroprevalence of cystic echinococcosis infection in Central and North Kashmir. Statistics showed that the observations were significant (P< 0.05). Children, men, and those who were uneducated had considerably greater rates of seropositivity for this infection.
... Furthermore, Tibetan herdsmen families keep at least one dog and pastoralists and Buddhist monks always have large numbers of ownerless stray dogs to stay [27]. Previous investigations have shown that owned dogs were the main transmission factor for both CE and AE on the Qinghai-Tibet Plateau [28,29]. Other components that maintain the high level of transmission in the Qinghai-Tibet Plateau are the lack of preventive measures, limited awareness of disease transmission, and traditional way of life, exposing people to the parasite [30,31]. ...
Background
Echinococcosis is a zoonotic parasitic disease caused by larval stages of cestodes belonging to the genus Echinococcus. The infection affects people’s health and safety as well as agropastoral sector. In China, human echinococcosis is a major public health burden, especially in western China. Echinococcosis affects people health as well as agricultural and pastoral economy. Therefore, it is important to understand the prevalence status and spatial distribution of human echinococcosis in order to advance our knowledge of basic information for prevention and control measures reinforcement.
Methods
Report data on echinococcosis were collected in 370 counties in China in 2018 and were used to assess prevalence and spatial distribution. SPSS 21.0 was used to obtain the prevalence rate for CE and AE. For statistical analyses and mapping, all data were processed using SPSS 21.0 and ArcGIS 10.4, respectively. Chi-square test and Exact probability method were used to assess spatial autocorrelation and spatial clustering.
Results
A total of 47,278 cases of echinococcosis were recorded in 2018 in 370 endemic counties in China. The prevalence rate of human echinococcosis was 10.57 per 10,000. Analysis of the disease prevalence showed obvious spatial positive autocorrelation in globle spatial autocorrelation with two aggregation modes in local spatial autocorrelation, namely high-high and low-high aggregation areas. The high-high gathering areas were mainly concentrated in northern Tibet, western Qinghai, and Ganzi in the Tibetan Autonomous Region and in Sichuan. The low-high clusters were concentrated in Gamba, Kangma and Yadong counties of Tibet. In addition, spatial scanning analysis revealed two spatial clusters. One type of spatial clusters included 71 counties in Tibet Autonomous Region, 22 counties in Qinghai, 11 counties in Sichuan, three counties in Xinjiang Uygur Autonomous Region, two counties in Yunnan, and one county in Gansu. In the second category, six types of spatial clusters were observed in the counties of Xinjiang Uygur Autonomous Region, and the Qinghai, Gansu, and Sichuan Provinces.
Conclusion
This study showed a serious prevalence of human echinococcosis with obvious spatial aggregation of the disease prevalence in China. The Qinghai-Tibet Plateau is the "hot spot" area of human echinococcosis in China. Findings from this study indicate that there is an urgent need of joint strategies to strengthen efforts for the prevention and control of echinococcosis in China, especially in the Qinghai-Tibet Plateau.
... Human AE, compared to CE, has a longer asymptomatic period (5-20 years). It is imperative to notice that its mortality rate in untreated or inappropriately treated patients exceeded 90% within 10 to 15 years [6]. Given serious medical, social, and economic consequences in those underpopulated regions, echinococcosis has been listed as one of the 17 neglected tropical diseases (NTDs) by the World Health Organization (WHO) awaiting control or elimination by 2050 [7]. ...
Echinococcosis, caused by genus Echinococcus, is the most pathogenic zoonotic parasitic disease in the world. In Tibet of the People’s Republic of China, echinococcosis refers principally to two types of severe zoonosis, cystic echinococcosis (CE) and alveolar echinococcosis (AE), which place a serious burden on public health and economy in the local community. However, research on the spatial epidemiology of echinococcosis remains inadequate in Tibet, China. Based on the recorded human echinococcosis data, maps of the spatial distribution of human CE and AE prevalence in Tibet were produced at city level and county level respectively, which show that the prevalence of echinococcosis in northern and western Tibet was much higher than that in other regions. We employ a geographical detector to explore the influencing factors for causing CE and AE while sorting information on the maps of disease prevalence and environment factors (e.g. terrain, population, and yak population). The results of our analysis showed that biological factors have the most impact on the prevalence of echinococcosis, of which the yak population contributes the most for CE, while the dog population contributes the most for AE. In addition, the interaction between various factors, as we found out, might further explain the disease prevalence, which indicated that the echinococcosis prevalence is not simply affected by one single factor, but by multiple factors that are correlated with each other complicatedly. Our results will provide an important reference for the evaluation of the echinococcosis risk, control projects, and prevention programs in Tibet.
... Based on previous ecological studies on AE and CE [9][10][11]14,[16][17][18][19][20][21][22][23], we derived 190 geospatial variables on potential environmental and climatic risk factors for CE and AE from different satellite-based remote-sensing data sources. These data sources included the Giovanni online data system of the National Aeronautics and Space Administration (NASA) Goddard Earth Sciences Data and Information Services Center [24], the WorldPop data portal [25,26], Earthstat [27], and WorldClim 2.0 Beta version 1 [28]. ...
Background
Cystic and alveolar echinococcosis (CE and AE) are neglected tropical diseases caused by Echinococcus granulosus sensu lato and E. multilocularis, and are emerging zoonoses in Kyrgyzstan. In this country, the spatial distribution of CE and AE surgical incidence in 2014-2016 showed marked heterogeneity across communities, suggesting the presence of ecological determinants underlying CE and AE distributions.
Methodology/Principal findings
For this reason, in this study we assessed potential associations between community-level confirmed primary CE (no.=2359) or AE (no.=546) cases in 2014-2016 in Kyrgyzstan and environmental and climatic variables derived from satellite-remote sensing datasets using conditional autoregressive models. We also mapped CE and AE relative risk. The number of AE cases was negatively associated with 10-year lag mean annual temperature. Although this time lag should not be considered as an exact measurement but with associated uncertainty, it is consistent with the estimated 10–15-year latency following AE infection. No associations were detected for CE. We also identified several communities at risk for CE or AE where no disease cases were reported in the study period.
Conclusions/Significance
Our findings support the hypothesis that CE is linked to an anthropogenic cycle and is less affected by environmental risk factors compared to AE, which is believed to result from spillover from a wild life cycle. As CE was not affected by factors we investigated, hence control should not have a geographical focus. In contrast, AE risk areas identified in this study without reported AE cases should be targeted for active disease surveillance in humans. This active surveillance would confirm or exclude AE transmission which might not be reported with the present passive surveillance system. These areas should also be targeted for ecological investigations in the animal hosts.
... Seven risk factors were recognized among the studies including AE, and a meta-analysis was executed on nine cross-sectional studies[8, 25,31,32,35,[39][40][41]43]. The results of the meta-analysis and forest plots are summarized in Table 2 ...
Background
Echinococcosis is a severe zoonotic disease that imposes a substantial burden on human life. Numerous studies on echinococcosis have involved a variety of risk factors, and it is difficult to evaluate the key risk factors. The objectives of this meta-analysis are to summarize available data on the prevalence of human echinococcosis and identify the key risk factors for echinococcosis.
Methods
Relevant studies were comprehensively searched in the PubMed, EMBASE, Web of Science, Cochrane, Chinese National Knowledge Infrastructure (CNKI), Chongqing VIP Information (VIP), Wanfang and SinoMed databases from database inception until August 22, 2020. A random-effects model was used to estimate the pooled odds ratio (OR) and 95% confidence interval (CI) by integrating the OR values of each risk factor. The I² and Q statistics were calculated to evaluate the heterogeneity, and potential sources of heterogeneity were identified using sensitivity analysis and subgroup analysis. Publication bias was estimated by funnel plots and Egger’s test.
Results
A total of 1026 studies were identified through the database search, of which 26 were eligible for this meta-analysis. In total, 23 and 9 of the 26 studies were cystic echinococcosis (CE) and alveolar echinococcosis (AE) studies, respectively (6 papers included both AE and CE). The pooled prevalence of echinococcosis was 5.52% (95% CI: 5.47%-5.58%). Ethnicity (OR = 2.93, 95% CI: 1.81–4.75; I² = 0), being a herder (OR = 2.66, 95%CI95% CI: 2.25–3.14; I² = 8%), not washing hands before meals (OR = 2.40, 95% CI: 1.34–4.28; I² = 82.8%) and being female (OR = 1.45, 95% CI: 1.26–1.66; I² = 33.9%) were risk factors for AE. The top five risk factors for CE were ethnicity (OR = 3.18, 95% CI: 1.55–6.52; I² = 79.2%), nomadism (OR = 2.71, 95% CI: 1.65–4.47; I² = 55.8%), drinking nonboiled water (OR = 2.47, 95% CI: 1.36–4.47; I² = 85.7), feeding viscera to dogs (OR = 2.35, 95% CI: 1.89–2.91; I² = 21.5%), and being a herder (OR = 2.19, 95% CI: 1.67–2.86; I² = 85.1%). The study design-specific subgroup analysis showed that the heterogeneity of CE risk factors decreased to varying degrees.
Conclusions
Specific characteristics (i.e., ethnicity and herder status) and behaviors (i.e., not washing hands before meals and feeding viscera to dogs ) are possible risk factors for echinococcosis. This study provided remarkable insight for future prevention and control of echinococcosis.
... Echinococcosis has been considered as a serious threat to public health in China, particularly in TAR. Dog is the primary definitive host for E. granulosus and a major host for E. multilocularis if infected by ingesting small mammalian with metacestodes infection [9][10][11][12]. Due to their close relationship with humans, dogs are considered as the main risk to human echinococcosis [13][14][15]. ...
Abstract Background Echinococcosis is highly endemic in western and northern China. Tibet Autonomous Region (TAR) is the most serious prevalent area. Linzhi is located in southeastern part of TAR. Dogs are the primary infection source for the transmission of echinococcosis to humans. A control and prevention campaign based on dog management has been implemented in the past three years. This study aims to evaluate the effects of dog management on the infection rate of dogs. Methods Data of dog population, registration and de-worming of seven counties/district in Linzhi between 2017 and 2019 were obtained from the annual prevention and control report. Domestic dog fecal samples were collected from each endemic town of seven counties/district in Linzhi in 2019 to determine the infection of domestic dogs using coproantigen enzyme-linked immunosorbent assay (ELISA). Data analysis was processed using SPSS statistics to compare dog infection rate between 2016 and 2019 by chi-square test, and maps were mapped using ArcGIS. Results In Linzhi, domestic dog population has decreased from 17 407 in 2017 to 12 663 in 2019, while the registration rate has increased from 75.9% in 2017 to 98.6% in 2019. Similarly, stray dog population has decreased from 14 336 in 2017 to 11 837 in 2019, while sheltered rate has increased from 84.6% in 2017 to 96.6% in 2019. Dog de-worming frequency has increased from 4 times per annum in 2017 to 12 times in 2019, indicating that approximately every dog was dewormed monthly. A total of 2715 dog fecal samples were collected for coproantigen ELISA assay. The dog infection rate was 2.8% (77/2715) in 2019, which was significantly lower than 7.3% (45/618) in 2016 (P
... Dog is the main de nitive host for E. granulosus and a major host for E. multilocularis if infected by ingesting small mammalian with metacestodes infection [9][10][11][12]. Dogs are considered as the main risk to humans echinococcosis due to their close relationship with human [13][14][15]. ...
Background Echinococcosis is highly endemic in western and northern China, Tibet Autonomous Region ( TAR) is the most serious prevalent area . Linzhi is located in southeastern part of TAR. Dogs are the main infection source for the transmission of echinococcosis to humans. A control and prevention campaign based on dog management has been conducted in the past three years. This study is to evaluate the effects of dog management on infection rate of dogs.
Methods Data of dog population, registration and de-worming of seven counties/district in Linzhi were collected from the annual prevention and control report. Domestic dog fecal samples were collected from each endemic town of seven counties/district in Linzhi in 2019 to determine the infection of domestic dogs using coproantigen ELISA. Data analysis was processed using SPSS statistics to compare dog infection rate between 2016 and 2019 by chi-square test, and maps were mapped using ArcGIS.
Results In Linzhi, domestic dog population has decreased from 17407 in 2017, 16512 in 2018, to 12663 in 2019, while the registration rate has increased from 75.9% in 2017, 95.5% in 2018, to 98.6% in 2019. Similarly, stray dog population has decreased from 14336 in 2017, 13067 in 2018, to 11837 in 2019, while sheltered rate has increased from 84.6% in 2017, 92.3% in 2018, to 96.6% in 2019. Dog de-worming frequency has increased from four times per annum in 2017 to 12 times in 2019, indicating that approximately every dog was dewormed monthly. A total number of 2715 dog fecal samples were collected for coproantigen ELISA assay. The dog infection rate was 2.8% (77/2715) in 2019, which was significantly lower than7.3% (45/618) in 2016 (P<0.05).
Conclusions Increased dog registration, decreased dog population, and increased dog de-worming frequency contributed to significantly decreased dog infection rate in Linzhi, TAR. Control and prevention campaign based on dog management can significantly decrease dog infection with Echinococcus spp in echinococcosis endemic areas.
... Dog is the main de nitive host for E. granulosus and a major host for E. multilocularis if infected by ingesting small mammalian with metacestodes infection [9][10][11][12]. Dogs are considered as the main risk to humans echinococcosisdue to their close relationship with human [13][14][15]. ...
Background Echinococcosis is highly endemic in western and northern China, Tibet Autonomous Region （TAR）is one of the most serious prevalent areas where the prevalence of echinococcosis in 2016 was 1.66% in humans and dog infection rate was 7.30%. Linzhi is located in southeastern part of TAR where the prevalence of echinococcosis in 2016 was 1.55% in humans and in dog infection rate was 7.28%.Dogs are the main infection source for the transmission of echinococcosis to humans. A control and prevention campaignbased on dog management has been conductedin the past three years. This study is toevaluate the effects of dog management on infection rate of dogs.
Methods Data of dog population, registration and de-worming of 7 counties/district in Linzhi from 2017 to 2019 were collected. Domestic dog fecal samples were collected from each endemic town of7 counties/district in Linzhiin 2019 to determine the infection of dogsusing coproantigen ELISA. Data analysis was processed using SPSS statistics to compare dog infection rate between 2016 and 2019 by chi-square test, and maps were mapped using ArcGIS.
Results In Linzhi, domestic dog population decreased from 17407 in 2017, 16512 in 2018, to 12663 in 2019, whilethe registration rate increased from 75.92% in 2017, 95.48% in 2018, to 98.64% in 2019. Similarly, stray dog populationdecreased from 14336 in 2017, 13067 in 2018, to 11837 in 2019, while sheltered rateincreased from 84.63% in 2017, 92.32% in 2018, to 96.63% in 2019.Dog de-worming frequency increased from 4 times per annum in 2017 to 12 times in 2019, indicating almost every dog was dewormed monthly. A total of 2715 dog fecal samples were collected for coproantigen ELISA assay. The dog infection rate was 2.84% (77/2715) in 2019, which was significantly lower than7.28% (45/618) in 2016 (P＜0.05).
Conclusion Increased dog registration, decreased dog population and increased dog de-worming frequency contributed to significantly decreased dog infection rate in Linzhi, TAR. Control and prevention campaign based on dog management can significantly decrease dog infection with Echinococcus spp in echinococcosis endemic areas.
... After an international team began epidemiological investigations in 2000, it was revealed that risk of human AE was associated with the occurrence of peri-domestic cycles of E. multilocularis involving owned dogs, stray dogs and small mammals in the region. However, no statistical association was found with hunting foxes or contact with fox skin products (Craig et al., 2000(Craig et al., , 2019Wang et al., 2001Wang et al., , 2014Moss et al., 2013). The situation was broadly similar to that described on St. Lawrence Island, Alaska (USA) in the 1970s, where small mammals (northern voles, Microtus oeconomus) and dogs enabled occurrence of a peri-domestic cycle of E. multilocularis and a high incidence of human AE (Rausch et al., 1990). ...
Human alveolar echinococcosis (AE) is considered a neglected zoonotic disease by the World Health Organization (WHO). The causative pathogen, Echinococcus multilocularis, lives as an adult tapeworm in the intestinal tract of canines. AE was identified as an emerging public health issue in Tibetan communities of Shiqu County 20 years ago. On St. Lawrence Island, Alaska (USA), in the 1980s peri-domestic transmission of E. multilocularis was controlled by regular deworming of owned dogs over a 10-year period. In Tibetan communities, on the Tibetan Plateau, control of E. multilocularis transmission is challenging due to the continental setting, complex epidemiology, disease ecology, geography, and socio-cultural factors. However, a control programme based on deworming owned dogs using praziquental (PZQ) has been carried out since 2006. Assessment was conducted in townships where baseline data were available 10 years prior. Purging of dogs by oral administration of arecoline was used to measure E. multilocularis prevalence, trapping small mammals around communities was employed to assess the change in infection of pikas and voles, and analysis of human AE abdominal ultrasound-based data was used to understand the change in prevalence in the past decade. In all three evaluated townships, the E. multilocularis prevalence in owned dogs was significantly (P < 0.01) reduced from 7.23% (25/346) during 2000-2003 to 0.55% (1/181) in 2016. Human AE ultrasound-based prevalence (adjusted for age and sex) in five evaluated townships decreased significantly (P < 0.01) from 6.25% (200/3,198) during 2000-2002 to 3.67% (706/19,247) during 2015-2017. The 2016 prevalence of E. multilocularis metacestodes in small mammal intermediate hosts was not significantly different from the prevalence in 2008. The control programme was effective in reducing E. multilocularis infection in owned dogs and human AE prevalence, but did not significantly impact infection in wildlife intermediate hosts.
... In China, the prevalence scope of echinococcosis to both animals and humans in alpine meadows, pastoral areas and agro pastoral regions, such as Xinjiang, Ningxia, Sichuan, Tibet, Gansu, Qinghai and Inner Mongolia, are very extensive in cold weather, drought and less rain (see [5,8,11,21,22,24,29]). Scientists have done a lot of research on echinococcosis. ...
In this paper, based on the transmission mechanism of echinococ-cosis in China, we propose a discrete-time dynamical model for the transmission of echinococcosis. The research results indicate that transmission dynamics of this discrete-time model are determined by basic reproduction number R 0. It is shown that when R 0 ≤ 1 then the disease-free equilibrium is globally asymptotically stable and when R 0 > 1 then the model is permanent while the disease-free equilibrium is unstable. Finally, on the basis of the theoretical results established in this paper, we come up with some specific measures to control the transmission of echinococcosis.
... Dog is the primary de nitive host for E. granulosus and also a major host for E. multilocularis if infected by ingesting small mammalian infected with metacestodes [9][10][11][12]. Dogs are considered as the main risk to humans CE due to close relationship with people [13][14][15]. ...
Background
Echinococcosis is highly endemic in western and northern China，Tibet Autonomous Region （TAR）is one of the most serious prevalent area with the prevalence of echinococcosis in humans was 1.66% and in dog was 7.30% in 2016. Linzhi is located in southeastern part of TAR with the prevalence of echinococcosis in humans was 1.55% and in dog was 7.28% in 2016.，Dogs are the main infection source for the transmission of echinococcosis to humans. A control and prevention campaignbased on dog management has been undertaken in the past three years. This study is toevaluate the effects of dog management on prevalence of echinococcosis in dogs.
Methods
Data of dog population, registration and de-worming of 7 counties/district in Linzhi from 2017 to 2019 were collected. Domestic dog fecal samples were collected from each endemic town of7 counties/district in Linzhi in 2019 to determine infection of dog using coproantigen ELISA. Data analysis was processed using SPSS statistics to compare dog infection rate between 2016 and 2019 by chi-square test, and maps were mapped using ArcGIS.
Results
In Linzhi, domestic dog population with 17407, 16512, 12663 decreased and the registration rate with 5.92%, 95.48%, 98.64% increased each year from 2017 to 2019. Similarly, stray dog population with 14336, 13067, 11837 decreased while sheltered rate with 84.63%, 92.32% 96.63% increased year by year. Dog de-worming frequency increased from 4 times per annum in 2017 to 12 times in 2019, almost every dog was dewormed monthly. A total of 2715 dog fecal samples were collected for coproantigen ELISA assay. The dog infection rate was 2.84% (77/2715) in 2019, which significantly lower than 2016 with 7.28% (45/618) (P＜0.05).
Conclusion
Increased dog registration, decreased dog population and increased dog de-worming frequency contributed to significantly decreased dog infection rate in Linzhi, TAR. Control and prevention campaign based on dog management can significantly decrease dog infection with Echinococcus spp in echinococcosis endemic areas but needs strictly implementation.
... Tilkilerin enfeksiyonun yayılmasında en önemli sonkonak olduğu bilinmekle birlikte, rakun köpekleri ile etrafa saçılan yumurta miktarının tilkilere yakın olduğu, evcil köpeklerin ise kedilerden daha uygun bir sonkonak olduğu kaydedilmiştir (7). Bununla birlikte, dünyada insan AE olgularının en fazla görüldüğü yer olan, Çin'in doğusundaki Tibet Ovası'nda, köpekler insanlara bulaşta önemli rol oynamaktadır (8,9). Sonkonak karnivorların dışkısı ile doğaya atılan yumurtalar dayanıklıdır, çevre şartlarına göre değişmekle birlikte bir yıldan fazla canlı kalabilirler. ...
Echinococcus multilocularis, a heteroxen and zoonotic parasite, is found in the intestine of carnivores, particularly foxes. Adult cestodes are regarded apathogenic in definitive hosts, while metacestode, the alveolar form, is high pathogenic for intermediate hosts. The alveolar cyst causes a maling tumor-like lesions with infiltrative, proliferative and destructive character which locates in the liver primarily, then metastasizes to other organs. If it is not treated in intermediate hosts it causes irreversible symtoms and death after located in vital organs such as liver, lungs, brain. Humans are infected by oral uptake of the viable eggs, accidentally. Because its life-cycle depends on relationship between hunter and hunting, endemic areas of the parasite are limited. The cestoda is found only in the Northern Hemisphere, while some countries are regarded high-endemic, such as Turkey. However, there is a few study on epidemiology of the parasite in Turkey, except human cases. In the review, data on the distribution of E. multilocularis in definitive and intermediate hosts in the world are presented, and the situation of the parasite in Turkey has been evaluated in detail.
... Cases of human disease do not necessarily occur in all endemic areas. The different rates of parasitic infection observed in the wildlife compared with the spread of human AE rest on various factors, such as host-dependant transmission patterns, landscape characteristics such as grass lands, local socioeconomic conditions including awareness of the disease within the public health system and general population [9][10][11]. A further deciding factor is thought to be the considerable variation in the intraspecific human pathogenicity of the parasite and the human host susceptibility [2]. ...
Purpose
Human alveolar echinococcosis (AE) is a potentially lethal zoonosis caused by the cestode Echinococcus multilocularis. The aim of this systematic review is to establish a comprehensive global AE literature overview taking into account the epidemiologically relevant AE research of the twenty-first century.
Methods
We systematically searched the global literature published from 2001 through 2018 via MEDLINE, EMBASE, the Russian databases eLIBRARY.RU, CyberLeninka, the Chinese databases CNKI, VIP, Journals.research.ac.ir (Farsi language-based), Jordan E-Library (Arab language-based) and supplementary Google Scholar, in accordance with the PRISMA guidelines. QGIS software was used for the mapping of the affected countries.
Results
We have listed 154 relevant publications in the final literature synopsis in consideration of our quality assessment. Including non-autochthonous cases, human AE was reported in 36 countries within the northern hemisphere from 2001 to 2018. The first publication of AE in Tajikistan, Pakistan, South Korea, Belgium, the Netherlands, Slovakia, Hungary, Lithuania, Latvia, Slovenia and Morocco occurred in this century; further first cases in Taiwan, Thailand, and Denmark were considered to be non-autochthonous by the authors. The highest total case numbers (n ≥ 100 in a single article) were reported in France, Germany, Switzerland, Poland, and Lithuania, including China and Kyrgyzstan with by far the highest prevalence figures.
Conclusions
Our paper emphasises the increasing spread of reported cases and the rise in its numbers in the literature of the twenty-first century, especially in western, northern and eastern Europe, as well as in central Asia. Epidemiological studies on human infections are lacking in many parts of the world.
... This was shown in a recently published study in which case-control and cross-sectional studies were compared and no connection between hunting and AE Echinococcosis was proven (37). In south Gansu, China, a large number of AE cases was diagnosed using serological screening and ultrasonography, and hunting had no effect as a risk factor (38). A total of 23,321 people were examined in three published serological screening studies in Austria (21,39,40). ...
The Austrian province of Tyrol belongs to the areas where the alveolar echinococcosis (AE) caused by the fox tapeworm Echinococcus multilocularis (E. multilocularis) is highly endemic. In Central Europe and since 2011 in Austria, a growing incidence of human cases of AE has been observed, presumably linked with increasing fox populations infected by the fox tapeworm E. multilocularis. Hunting and the related activities put hunters in a high-risk group, and they are considered particularly vulnerable for the contraction of an AE. In light of this risk and the increased number of AE cases made public in Austria, the objective of the study was to investigate the prevalence of AE in hunters and to provide a possible connection to the incidence increase. In 2015 and 2016, we examined 813 serums of active hunters from all nine districts of Tyrol and serologically tested them for E. multilocularis antibodies. Twenty-one (2.58%) positive results in ELISA were detected via Western blot (WB), and only one (0.12%) serum showed a low positive reaction. No lesion in the liver parenchyma could be detected by abdominal ultrasonography in this patient so far, but the risk of developing alveolar echinococcosis remains for this WB-positive hunter. Risk factor analysis of these 813 hunters revealed that 697 (85.7%) hunted red foxes regularly and 332 (40.8%) of those skinned them as well. Three hundred and eighteen (39.1%) out of the 813 hunters were owners of hunting dogs; 89 (10.9%) and 243 (29.9%) were owners of non-hunting dogs and cats, respectively. Our results indicate that hunters do not have a greater risk of infection with E. multilocularis compared to non-hunters in Austria. The cause of the unexpected increase in AE cases in Austria remains unclear.
... A neglected zoonotic disease, HAE is responsible for a significant burden of human disease across continental Asia, and is expanding in the prevalence and range in Europe, North America, and Asia [4][5][6]. In China and central Asia, HAE prevalence humans can exceed 10% locally [7][8][9] even though geographical patterns are highly variable, as elsewhere in the world [10]. The reasons for this variability are unknown. ...
1) Background: Echinococcus multilocularis (Em), a highly pathogenic parasitic tapeworm, is responsible for a significant burden of human disease. In this study, optical and time-series Synthetic Aperture Radar (SAR) data is used synergistically to model key land cover characteristics driving the spatial distributions of two small mammal intermediate host species, Ellobius tancrei and Microtus gregalis, which facilitate Em transmission in a highly endemic area of Kyrgyzstan. (2) Methods: A series of land cover maps are derived from (a) single-date Landsat Operational Land Imager (OLI) imagery, (b) time-series Sentinel-1 SAR data, and (c) Landsat OLI and time-series Sentinel-1 SAR data in combination. Small mammal distributions are analyzed in relation to the surrounding land cover class coverage using random forests, before being applied predictively over broader areas. A comparison of models derived from the three land cover maps are made, assessing their potential for use in cloud-prone areas. (3) Results: Classification accuracies demonstrated the combined OLI-SAR classification to be of highest accuracy, with the single-date OLI and time-series SAR derived classifications of equivalent quality. Random forest analysis identified statistically significant positive relationships between E. tancrei density and agricultural land, and between M. gregalis density and water and bushes. Predictive application of random forest models identified hotspots of high relative density of E. tancrei and M. gregalis across the broader study area. (4) Conclusions: This offers valuable information to improve the targeting of limited-resource disease control activities to disrupt disease transmission in this area. Time-series SAR derived land cover maps are shown to be of equivalent quality to those generated from single-date optical imagery, which enables application of these methods in cloud-affected areas where, previously, this was not possible due to the sparsity of cloud-free optical imagery.
... Domestic dogs, and other suitable carnivores, are the usual definitive hosts of E. granulosus, whilst a number of ungulate species (goats, sheep, pigs, cattle, etc.) can act as intermediate hosts [1,2]. Domestic dogs can also serve as definitive hosts of E. multilocularis if they become infected through the ingestion of small mammalian species (mainly rodents) infected with metacestodes, thus perpetuating a synanthropic cycle [3,4]. Dogs become infected with E. granulosus after ingesting offal harbouring hydatid cysts containing viable protoscoleces. ...
Abstract Background Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are highly endemic in Xiji County of Ningxia Hui Autonomous Region (NHAR) in China where the control campaign based on dog de-worming with praziquantel has been undertaken over preceding decades. This study is to determine the current prevalence of Echinococcus granulosus and E. multilocularis in domestic dogs and monitor the echinococcosis transmission dynamics. Methods Study villages were selected using landscape patterns (Geographic Information System, GIS) for Echinococcus transmission “hot spots”, combined with hospital records identifying risk areas for AE and CE. A survey of 750 domestic dogs, including copro-sampling and owner questionnaires, from 25 selected villages, was undertaken in 2012. A copro-multiplex PCR assay was used for the specific diagnosis of E. granulosus and E. multilocularis in the dogs. Data analysis, using IBM SPSS Statistics, was undertaken, to compare the prevalence of the two Echinococcus spp. in dogs between four geographical areas of Xiji by the χ 2 test. Univariate analysis of the combinations of outcomes from the questionnaire and copro-PCR assay data was carried out to determine the significant risk factors for dog infection. Results The highest de-worming rate of 84.0% was found in the northwest area of Xiji County, and significant differences (P 0.05) in the prevalence of E. granulosus in dogs from the northwest, southwest, northeast, and southeast of Xiji, but there were significant differences (P
... The parasite Echinococcus multilocularis, the causative agent of zoonotic alveolar echinococcosis (AE), represents an emerging and worrisome health concern in the Northern hemisphere with an epidemiology that highly contrasts among areas with dispersed endemic foci. The cycle mainly involves red foxes (Vulpes vulpes) as definitive hosts, which are maintained in a sylvatic life cycle in Europe, whereas the synanthropic cycle involves mainly dogs in China and Alaska; these animals might have a predominant role in human transmission (Craig et al., 2000;Giraudoux et al., 2013;Jenkins et al., 2013). A large panel of small mammal species can be intermediate hosts (Romig et al., 2017). ...
In zoonotic infections, the relationships between animals and humans lead to parasitic disease with severity that ranges from mild symptoms to life-threatening conditions. In cities and their surrounding areas, this statement is truer with the overcrowding of the protagonists of the parasites' life cycle. The present study aims to investigate the distribution of a parasite, Echinococcus multilocularis, which is the causative agent of alveolar echinococcosis, using copro-sampling in historically endemic rural settlements of the eastern part of France and in newly endemic areas including urban parks and settlements surrounding Paris. Based on 2741 morphologically identified and geolocalized copro-samples, the density of fox faeces was generally higher in the surrounding settlements, except for one rural area where the faeces were at larger density downtown in the winter. Fox faeces are rare but present in urban parks. Dog faeces are concentrated in the park entrances and in the centre of the settlements. DNA was extracted for 1530 samples that were collected and identified from fox, dog, cat, stone marten and badger carnivore hosts. Echinococcus multilocularis diagnosis and host faecal tests were performed using real-time PCR. We failed to detect the parasite in the surroundings of Paris, but the parasite was found in the foxes, dogs and cats in the rural settlements and their surroundings in the historically endemic area. A spatial structuring of the carnivore stool distribution was highlighted in the present study with high densities of carnivore stools among human occupied areas within some potentially high-risk locations.
... Although hospital reports (especially from Europe but also from low-income countries) do not show big differences in terms of gender perhaps because men are more likely to undergo hospital treatment than women, in most of the highly endemic areas where mass screenings have been performed women are more infected than men, both for CE and AE. This may be only due to behavioral factors (such as caring for dogs, which was often correlated to woman susceptibility in risk factor analyses) (Craig et al., 2000); specific hormonal factors may also be evoked. Pregnant women have been reported at risk of metastatic dissemination of AE ; this might be due to the relative state of immune tolerance which develops in this condition; however, no systematic studies have been published. ...
Introduction
Echinococcosis is a widespread zoonotic disease caused by tapeworms of the Echinococcus genus, manifesting in mature or larval forms. Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are the primary types affecting humans, linked, respectively, to Echinococcus granulosus and Echinococcus multilocularis. This study is a systematic review and meta-analysis of the risk factors associated with CE and AE in humans.
Methods
Relevant English publications were found through a thorough search of eligible databases. The inclusion criteria focused on cross-sectional and case–control studies investigating risk factors for human echinococcosis. Collected data included author, country, study design, demographics, sample size, literacy, occupation, drinking water source, dog ownership, and hand hygiene.
Results
A total of 1,594 studies were found in the initial search, with only 36 papers (involving 1,207,436 cases) meeting the inclusion criteria. Most of the study population (99.35%) showed no echinococcosis infection, while 0.65% were infected. Of the infected cases, 77.92% had CE, while 22.08% had AE. Among 629,996 (52.18%) females, 4,830 (0.76%) were infected, compared to 2,968 (0.52%) infections among 565,872 (46.86%) males (p < 0.001). Rural areas, low education levels, agricultural/livestock workers, dog owners, water sources, and poor hand hygiene were all significantly associated with the infection (p < 0.05).
Conclusion
Echinococcosis remains a global health concern, particularly among rural residents, those with lower education, agricultural workers, and dog owners. Targeted public health measures, including improved hygiene practices and access to clean water, are essential to reducing its impact.
Global change is expected to have complex effects on the distribution and transmission patterns of zoonotic parasites. Modelling habitat suitability for parasites with complex life cycles is essential to further our understanding of how disease systems respond to environmental changes, and to make spatial predictions of their future distributions. However, the limited availability of high quality occurrence data with high spatial resolution often constrains these investigations. Using 449 reliable occurrence records for Echinococcus multilocularis from across Europe published over the last 35 years, we modelled habitat suitability for this parasite, the aetiological agent of alveolar echinococcosis, in order to describe its environmental niche, predict its current and future distribution under three global change scenarios, and quantify the probability of occurrence for each European country. Using a machine learning approach , we developed large-scale (25 × 25 km) species distribution models based on seven sets of predictors, each set representing a distinct biological hypothesis supported by current knowledge of the autecology of the parasite. The best-supported hypothesis included climatic, orographic and land-use/land-cover variables such as the temperature of the coldest quarter, forest cover, urban cover and the precipitation seasonality. Future projections suggested the appearance of highly suitable areas for E. multilocularis towards northern latitudes and in the whole Alpine region under all scenarios, while decreases in habitat suitability were predicted for central Europe. Our spatially explicit predictions of habitat suitability shed light on the complex responses of parasites to ongoing global changes.
Echinococcus multilocularis is a cestode parasite that circulates in a lifecycle alternating larval and adult forms. The human disease is named alveolar echinococcosis, because of the “alveolar” structure of the parasitic pseudotumor caused by the development of the E. multilocularis larva. In the Jura Massif, under the direction of Pierre Delattre, INRA researchers sampled local small mammal populations from 1979 to 1996 in order to understand the causation of grassland vole outbreaks and their decline phases. The parasite was found in several rodent species over that period. This chapter presents the results obtained over decades in the Jura socioecosystem using this multidisciplinary approach, and examines how this research has been successfully applied to other transmission systems in Asia, mainly in western China and also in southern Kyrgyzstan. Echinococcus multilocularis 's prevalence on a landscape scale rarely exceeds one per thousand in a vole population, even in highly endemic areas.
Background
Echinococcosis is a severe zoonotic disease that imposes a substantial burden on human life. This meta-analysis aimed to summarize available data on the prevalence of human echinococcosis and identify the key risk factors for echinococcosis in the Chinese general population.
Methods
Relevant studies were comprehensively searched in the PubMed, EMBASE, Web of Science, Cochrane, Chinese National Knowledge Infrastructure (CNKI), Chongqing VIP Information (VIP), Wanfang and SinoMed databases until August 22, 2020. A random-effects model was used to estimate the pooled odds ratio (OR) and 95% confidence interval (95% CI). The I² and Q statistics were calculated to evaluate the heterogeneity, and potential sources of heterogeneity were identified using sensitivity analysis and subgroup analysis. Publication bias was estimated by funnel plots and Egger's test.
Results
A total of 1026 studies were identified through the database search, of which 26 were eligible for this meta-analysis. The pooled prevalence of AE and CE were 2.88% and 5.66%, respectively. Ethnicity (OR = 2.93, 95% CI: 1.81–4.75; I² = 0), herdsman occupation (OR = 2.66, 95% CI: 2.25–3.14; I² = 8.0%), not washing hands before meals (OR = 2.40, 95% CI: 1.34–4.28; I² = 82.8%) and being female (OR = 1.45, 95% CI: 1.26–1.66; I² = 33.9%) were risk factors for AE. The top five risk factors for CE were ethnicity (OR = 3.18, 95% CI: 1.55–6.52; I² = 79.2%), nomadism (OR = 2.71, 95% CI: 1.65–4.47; I² = 55.8%), drinking nonboiled water (OR = 2.47, 95% CI: 1.36–4.47; I² = 85.7), feeding viscera to dogs (OR = 2.35, 95% CI: 1.89–2.91; I² = 21.5%), and herdsman occupation (OR = 2.19, 95% CI: 1.67–2.86; I² = 85.1%).
Conclusions
This study generalized articles that have contributed to our current understanding of the epidemic of human echinococcosis (AE and CE) in China over the years. The results support that the ethnicity and dog-related factors are major risk factors for both CE and AE. The identification of echinococcosis risk factors may aid researchers and policymakers in improving surveillance and preventive measures aimed at reducing Echinococcus granulosus and Echinococcus multilocularis infection in humans.
Purpose of review:
Infection with the larval (metacestode) stage of Echinococcus multilocularis causes alveolar echinococcosis (AE), a serious hepatic disorder. The parasite has increased its infection extensity in wildlife and domestic dogs, mainly due to urbanization and spatial extension of wildlife hosts in Europe, Asia as well as North America, resulting in emerging infection risk for humans.
Recent findings:
In hyperendemic areas such as Kyrgyzstan and China, ecological and socioeconomic changes have been associated with the unpredictable increase of AE cases. In North America, the appearance of the European-like genotype is of concern. In Europe, the annual increase of human case numbers reached a plateau even in hyperendemic situations. Therefore, we conclude that most of the exposed individuals are resistant to parasite invasion and/or to disease development. Thus, AE develops in a few healthy individuals, but preferentially in immunosuppressed patients.
Summary:
In the future, improved diagnostic strategies will allow more precise estimations of transmission routes including the role of food, water and direct dog contact, which should yield improved public health recommendations. Finally, understanding protective innate and acquired immune mechanisms as well as parasite-driven immune-evasion processes will be essential to develop curative therapies in nonoperable patients and, futuristically, appropriate vaccines.
Echinococcoses are serious zoonotic diseases in China's vast, western and north-western pastoral areas that has one of the highest prevalence in the world. The two most common forms, cystic echinococcosis (CE) and alveolar echinococcosis (AE), are co-epidemic in some areas causing a grave threat to people's health and economic development. Echinococcus spp. are transmitted through domestic, sylvatic and mixed cycles involving many kinds of host. Successful transmission requires a favourable environment for the growth of the parasites and survival of their eggs, while the unique customs and religious beliefs in the endemic areas pose a challenge to the prevention and control of these parasites. Based on previous epidemiological studies, this paper reviews the particular factors affecting the transmission of Echinococcus parasites in China, with a focus on biological (parasite genotype and the species, age, sex and density of hosts), environmental (landscape and climate) and social (age, gender, ethnicity, education, occupation, life style, cultural customs, living conditions and hygiene practices of humans in the endemic areas). These three factors interact with each other and jointly determine the parasites’ transmission intensity, the study of which supports the formulation of the strategies and measures that are significant for control of these infections.
Alveolar echinococcosis (AE) is a zoonosis caused by Echinococcus multilocularis, a heteroxenous parasite belonging to Cestodes. AE is currently considered an important public health issue, but epidemiological and notably molecular data from several endemic countries, including Pakistan, are sparse. Here we report the first detection of Echinococcus multilocularis in wildlife from Pakistan after real-time PCR and sequencing confirmation in the faecal samples of three foxes from northern Kaghan and Siran regions. The apparent occurrence is estimated at 2.9% (95% CI 0.9-12.4). In order to go further in the epidemiological investigations on E. multilocularis and due to the potential presence of other Echinococcus species, we suggest the need for further epidemiological surveys targeting E. multilocularis and E. granulosus sensu lato isolates from humans and intermediate hosts as well as definitive hosts from wildlife in Pakistan.
Background:
Human alveolar echinococcosis (HAE), caused by the larvae of Echinococcus multilocularis, is a severe parasitic disease that is a major public health concern. New HAE cases in China account for 91% of the global HAE burden every year. Although there are a few studies and systematic reviews (SRs) on the prevalence of HAE in China, trends in the prevalence have not been estimated. This study aims to describe the overall variation in the trend of HAE prevalence in China, and provide evidence for preventive measures in the future.
Methods:
Thirty-five eligible studies were retrieved from PubMed, Web of Science, EMBASE, CNKI, Wanfang Data, and VIP, and included in the SR and meta-analysis. An adjusted Agency for Healthcare Research and Quality checklist was used to evaluate study quality. The arcsine transformation was used to adjust the individual reported prevalence, and the pooled HAE prevalence was calculated. Heterogeneity was evaluated using the chi-square test and I2 statistic. Forest plots were generated for the meta-analysis, and publication bias of the studies was assessed using the Egger's test and funnel plots. We conducted subgroup analyses, sensitivity analyses, and meta-regression analyses to analyze the source of heterogeneity and factors potentially influencing the prevalence of HAE.
Results:
The meta-analysis indicated that the pooled HAE prevalence in China was 0.96% (95% CI: 0.71 to 1.25%). Factors potentially influencing HAE prevalence were female sex (OR = 1.60, 95% CI: 1.35 to 1.91, P<0.01), being ≥30 years old (OR = 4.72, 95% CI: 2.29 to 9.75, P<0.01), and being farmers and/or herdsmen (OR = 2.54, 95% CI: 1.60 to 4.02, P<0.01). The results of the meta-regression analysis (R2 = 38.11%, P < 0.01) indicated that HAE prevalence is on a downward trend.
Conclusions:
HAE prevalence has decreased over time and maintained low levels after 2005 in China. This decline was influenced by the utilization of One Health strategies as intervention measures. Therefore, these One Health strategies should be used as references to formulate future programs for HAE control. More high-quality epidemiological investigations and surveillance programs should be conducted in order to improve HAE control in the future.
Background
A substantial proportion of echinococcosis transmission to humans via contamination of food has been assumed. However, the relative importance of food as a transmission vehicle has previously been estimated through expert opinion rather than empirical data.
Objective
To find and evaluate empirical data that could be used to estimate the source attribution of echinococcosis, in particular the proportion that is transmitted through contaminated food.
Methods
A systematic review was undertaken to identify reports on the risk factors for human cystic (CE) and alveolar (AE) echinococcosis. Data bases searched included PubMed, Scopus, Web of Knowledge, Cab Direct, Science Direct, Google Scholar, eLIBRARY.RU, CyberLeninka, CNKI and VIP. Search terms included Echinococc*, hydatid, epidemiology, logistic regression, risk factors, odds ratio, relative risk, risk factors. Reports, including grey literature where available, that had suitable data were selected and data were extracted. The main pathways of transmission were hypothesised to be contact with the definitive host, contaminated water, contaminated food and contaminated environment (other than food). For each study the attributable fraction for these potential sources of infection was calculated from the data presented. A meta-analysis was then undertaken to obtain pooled estimates for the relative contribution of these transmission pathways.
Results
Data from 28 cross-sectional studies and 14 case-control studies were extracted. There was strong evidence for transmission by direct contact with dogs for both CE and AE. The estimated attributable fractions were 26.1% (CI 13.8%-39.6%) and 34.4% (CI 20.7% -48.2%) respectively. Transmission through contaminated water was estimated to be responsible for approximately 29.4% (CI 12.1%-51.7%) for CE and 24.8% (CI 10.6% to 42.6%) for AE. Contaminated food may be responsible for approximately 23.4% of CE cases (CI 2.1%-47.3%). Globally, there was insufficient evidence to conclude AE can be transmitted by food, although case control studies from low human incidence areas suggested that possibly 32.5% (CI 10.0%-53.2%) could be transmitted by food. There was also insufficient evidence that direct contact with foxes was a significant source of human disease. There were no suitable studies with a risk of environmental contact reported, but the residual attributable fraction thatwould likely include this pathway was approximately 21.1% for CE and 11.1% for AE.
Conclusions
The results support the hypothesis that dog contact and drinking contaminated water are major pathways of transmission of both CE and AE. For contaminated food, the results are less consistent, but suggest that it is an important transmission pathway and provide better evidence than expert elicitations as previously used.
Background: Human alveolar echinococcosis (HAE), caused by the larvae of Echinococcus multilocularis，is a severe parasitic disease that is a major public health concern. New HAE cases in China account for 91% of the global HAE burden every year. Although there are a few studies and systematic reviews (SRs) on the prevalence of HAE in China, trends in the prevalence have not been estimated. This study aims to describe the overall variation in the trend of HAE prevalence in China, and provide evidence for preventive measures in the future.
Methods: Thirty-five eligible studies were retrieved from PubMed, Web of Science, EMBASE, CNKI, Wanfang Data, and VIP, and included in the SR and meta-analysis. An adjusted Agency for Healthcare Research and Quality checklist was used to evaluate study quality. The arcsine transformation was used to adjust the individual reported prevalence, and the pooled HAE prevalence was calculated. Heterogeneity was evaluated using the chi-square test and I² statistic. Forest plots were generated for the meta-analysis, and publication bias of the studies was assessed using the Egger’s test and funnel plots. We conducted subgroup analyses, sensitivity analyses, and meta-regression analyses to analyze the source of heterogeneity and factors potentially influencing the prevalence of HAE.
Results: The meta-analysis indicated that the pooled HAE prevalence in China was 0.96% (95% CI: 0.71 to 1.25%). Factors potentially influencing HAE prevalence were female sex (OR=1.60, 95% CI: 1.35 to 1.91, P＜0.01), being ≥30 years old (OR=4.72, 95% CI: 2.29 to 9.75, P＜0.01), and being farmers and/or herdsmen (OR=2.54, 95% CI: 1.60 to 4.02, P＜0.01). The results of the meta-regression analysis (R²=38.11%, P < 0.01) indicated that HAE prevalence is on a downward trend.
Conclusions: HAE prevalence has decreased over time and maintained low levels after 2005 in China. This decline was influenced by the utilization of One Health strategies as intervention measures. Therefore, these One Health strategies should be used as references to formulate future programs for HAE control. More high-quality epidemiological investigations and surveillance programs should be conducted in order to improve HAE control in the future.
Background Human alveolar echinococcosis (HAE) is a severe parasitic disease that is a major public health concern. A review has indicated that new HAE cases in China account for 91% of the global HAE burden every year. Although there are a few studies and systematic reviews (SRs) on the prevalence of HAE in China, trends in the prevalence have not been estimated. Therefore, this study aims to describe the overall variation in the trend of HAE prevalence, and provide evidence for preventive measures in the future.
Methods Thirty-five eligible studies were retrieved from PubMed, Web of Science, EMBASE, CNKI, Wanfang Data, and VIP, and included in the SR and meta-analysis. An adjusted Agency for Healthcare Research and Quality checklist was used to evaluate study quality. We used the arcsine transformation to adjust the individual reported prevalences and also calculated the pooled HAE prevalence. We evaluated heterogeneity using the chi-square test and I 2 statistic, as well as random-effects models and fixed-effects models. We generated forest plots for the meta-analysis results and assessed publication bias of the studies using the Egger’s test and funnel plots. We conducted subgroup analyses, sensitivity analyses, and meta-regression analyses to analyze the source of heterogeneity and factors potentially influencing the prevalence of HAE.
Results The meta-analysis indicated that the pooled HAE prevalence in China was 0.96% (95% CI: 0.71 to 1.25%). Factors potentially influencing HAE prevalence are female sex (OR=1.60, 95% CI: 1.35 to 1.91), being ≥30 years of age (OR=4.72, 95% CI: 2.29 to 9.75), and being farmers and/or herdsmen (OR=2.54, 95% CI: 1.60 to 4.02). The results of the meta-regression analysis (R 2 =38.11%, P < 0.01) indicated that HAE prevalence is on a downward trend.
Conclusions HAE prevalence has decreased over time and maintained low levels after 2005 in China. This decline was influenced by the utilization of One Health strategies as intervention measures. Therefore, these One Health strategies should be used as references to formulate future programs for HAE control. More high-quality epidemiological investigations and surveillance programs ought to be conducted in order to improve HAE control in the future.
Human alveolar echinococcosis (AE) is a highly pathogenic zoonotic parasitic disease caused by Echinococcus multilocularis. An ultrasound study in southern Kyrgyzstan during 2012 revealed a prevalence of 4.2% probable or confirmed AE and an additional 2.2% possible AE, representing an emerging situation. The risk for probable or confirmed AE was significantly higher in dog owners. © 2018, Centers for Disease Control and Prevention (CDC). All rights reserved.
Pour l’amélioration de la lutte contre la tuberculose à Madagascar, nous avons décidé de mener des études sur l’analyse de la diversité et la distribution des génotypes de BK y circulant au cours du temps et dans l’espace afin de connaitre le mode de transmission de la TB et les sources potentielles de la TB malgache. Plus spécifiquement il s’agit premièrement, d’étudier la diversité génétique et la distribution des génotypes des BK dans le pays pour évaluer le niveau de transmission de la maladie et d’essayer de retracer les sources potentielles d’importation de la TB malgache ; deuxièmement, étudier la diversité de la souche endémique de Madagascar, le SIT109, afin de voir le niveau de transmission d’une souche à l’intérieur de l’île ainsi que son niveau d’évolution ; et troisièmement, identifier les zones de transmission de la TB par combinaison d’analyse spatiale et de génotypage en commençant par une étude pilote dans la capitale.Pour réaliser cela, 1014 souches représentatives de Madagascar isolés de 2005 à 2007 ont été typés par le spoligotypage. Les génotypes définis ont servi pour l’estimation de la transmission de la TB et l’identification des sources potentielles de la TB ; ensuite, 156 BK endémiques de Madagascar portant l’identité SIT109 ont été typés par la méthode des MIRU-VNTR (« Mycobacterial Interspersed Repetitive Units – Variable Number of Tandem Repeat ») afin d’étudier leur diversité, leur niveau d’évolution et le niveau de distribution de la TB au niveau d’une seule souche et enfin, 523 patients ont été recrutés à Antananarivo en 2013 afin de typer par le spoligotypage leur BK, d’identifier à partir de leur génotype ceux qui sont potentiellement associés à des cas de transmission récente et d’analyser leur clusterisation spatiale par la méthode de Kulldorff.Les résultats nous ont montré une grande diversité génétique des BK circulant dans le pays avec une prédomination de deux lignées de BK qui sont les souches « East african Indian » et « Tuscan » ; une distribution particulière des BK dans la capitale par rapport aux autres provinces ; des similitudes particulières des BK circulant avec des pays comme les USA, la France, l’Italie, le Danemark, l’Arabie Saoudite ou encore le Pays Bas ; une grande diversité des souches SIT109 ainsi que leur distribution dans tout le pays ; ainsi que quatre clusters spatiaux de cas de TB associé à la transmission récente dans la capitale.Cette étude nous a permis de déterminer que la transmission de la TB à Madagascar est toujours très active et se fait à très grande échelle, une petite part de la TB à Madagascar a pu être importée par les populations d’origines mais la majorité des cas actuels provient d’importation assez récente de BK de plusieurs régions du monde. Douze Fokontany de la capitale correspondent à des zones à risque de transmission de la TB et méritent une attention particulière aux responsables de la lutte contre la TB à Madagascar et enfin la méthode combinant génotypage et analyse spatiale permet la détection de ces zones à risque et pourrait servir pour le « Programme National de Lutte contre la Tuberculose » d’outil d’aide à la décision pour les stratégies de lutte contre la TB dans tout Madagascar.
Background and aim: Echinococcosis as a zoonosis disease is one of the most important parasitic helminth that is affected by many risk factors such as the environmental factors. Thus, we predicted the regional vulnerability to Echinococcosis based on environmental factors using a fuzzy inference system (FIS) in Lorestan Province.
Methods: Our study was cross-sectional study on 200 patients from Lorestan Province (west of Iran) who underwent surgery for hydatidosis between October 2005 and November 2014. In order to model the vulnerability to Echinococcosis, first we determined the effective environmental variables. In the next step, the FIS was designed and implemented using MATLAB v.2012 software. Thus, definition and determination of linguistic variables, linguistic values, and their range were performed based on expert knowledge. Then, the membership functions of inputs (environmental variables) and output (vulnerability to Echinococcosis) were defined. A fuzzy rules base was formed. Also, the defuzzification of output was done using a centroid defuzzification function. To test the accuracy of the predictive model, we calculated the AUC (to this purpose, we used four different thresholds, 5%, 10%, 15%, and 20%) using IDRISI Selva v.17.0 software.
Results: Based on the results of this study, Aligoudarz and Koohdasht counties were identified as a highest and lowest risk area in Lorestan, respectively. The results showed that a predictive model was more efficient than a random model (AUC>0.5). Also, potential vulnerable areas cover 78.29% at threshold of 5%, 60.72% at threshold of 10%, 43.54% at threshold of 15%, and 39.82% at threshold of 20% of the study area.
Conclusion: According to the success of this research, we emphasized the necessity of attention to fuzzy approach to model vulnerability to hydatidosis. This approach can provide a practical economic basis for making informed preventive services decisions and the allocation of health resources.
Small mammals were surveyed along a deforestation gradient in southern Gansu, China (2300-2600 m altitude), a high endemicity area for human alveolar echinococcosis. Rodent distribution was assessed using removal trapping in six habitat types from timbered forest to farmland and villages, by index transects, and by the collection of specimens by local people. Species captured were 2 shrews: Anourosorex squamipes, Sorex sinalis; 12 rodents: Eozapus setchuanus, Microtus limnophilus, Cricetulus longicaudatus, Tscherskia triton, Apodemus agrarius, Apodemus draco, Apodemus peninsulae, Micromys minutus, Mus musculus, Rattus norvegicus, Niviventer confucianus, Myospalax fontanieri; and 1 lagomorph Ochotona thibetana. On the basis of trap success four rodent assemblages were recognized. Species richness decreases after deforestation, especially in the intermediate stage (scrubland-grassland).
This paper aims to answer the following question: are the fluctuations of abundance of Common Vole (Microtus arvalis) specific to different types of landscapes? The research was carried out in landscapes where grassland was dominant. The sampling method was based upon a partition in both landscape types and landscape units. Tracking of vole indices was used to evaluate their relative abundance. Six landscape transects were sampled during two successive years. Results show that population variation and diffusion of demographic states are closely related to landscape types. The possible causes of this are discussed. The landscape units can be used as global variables to assess outbreak risk and landscape design can be used to prevent them.
Sera from 17 166 blood donors living in 10 cantons of northern Switzerland in an area endemic for Echinococcus multilocularis were investigated by serological survey for alveolar echinococcosis (AE). A highly species-specific antigen (Em2) and a commonly
used E. granulosus hydatid fluid antigen (EgHF) were compared for their suitability in seroepidemiology. EgHF showed a degree of nonspecificity
which did not allow direct detection of AE cases. Antibody reaction with Em2 resulted in the detection of 2 asymptomatic clinical
cases of AE (seroprevalence 0·01%) within this population of blood donors. A further 4 persons were positive in Em2-ELISA.
These 4 persons had negative imaging studies and will be followed serologically and clinically.
A study of voles (Arvicolidae, Rodentia) from Gansu (China) designed to identify a potential host of Echinococcus multilocularis, responsible for human alveolar echinococcosis, leads to a general analysis of Microtus limnophilus population karyotypes, M1 of M. oeconomus populations from all of Eurasia and of M. limnophilus of Mongolia. The Microtus of Gansu belonging to the nominal subspecies M. limnophilus limnophilus (2n = 38; NF = 58) differs markedly in size and shape of M1 from the M. limnophilus of Mongolia, which must therefore be considered as a new subspecies M. limnophilus of malygini nov. ssp. (2n = 38; NF = 60) and the M. oeconomus of Mongolia should be ranked as M. oeconomus kharanurensis nov. ssp. (2n = 30; NF = 60).
The inhabitants of a rural community in southwestern Germany were examined for alveolar echinococcosis (AE). The study was prompted by the recent increase of the prevalence of the parasite in foxes and the increase of fox populations: in the study area, 75% of the foxes carried Echinococcus multilocularis. The human population was screened using hepatic ultrasound and serology. All participants were interviewed for demographic and potential risk factors. Of 2,560 participants, one was identified with active AE, while 3 others had suspicious liver lesions. Another 9 participants were seropositive for specific antibodies without detectable lesions. Demographic and behavioral factors were not correlated with active or suspected cases nor with seropositivity. If the prevalence of 40/100,000 (95% confidence interval = 15-295/100,000) for active cases would be representative for the rural population in high endemicity areas, the current number of AE cases in southwestern Germany is considerably higher than previously suspected.
Several papers on hydatidosis are reviewed. The importance of Echinococcus granulosus infection in Iraq is established, distribution of cases according to districts in Iraq for the last 9 yr is demonstrated and difficulties in collecting complete and correct statistical data are outlined. Transmission of echinococcosis and its prevalence in animals is discussed, and prevention of human infection, prophylactic measures against canine reinfection and eradication of canine infection are described.
This study investigates the effect of land use, and landscape composition and structure on the population dynamics of fossorial water vole (Arvicola terrestris scherman Shaw). Water vole populations were monitored from 1989 to 1994 in the Doubs department, France, by using index methods. Land use patterns were studied based on agriculture and forestry data from the French Ministry of Agriculture collected in 1956, 1970, 1979 and 1988. Grassland quality and landscape structure were studied based on field transects, combined with the assessment of landscape structure from maps at 1:25,000 scale. Outbreaks of water vole populations occurred as a wave, spreading from epicentres over more than 2500 km2. The propagation speed was in excess of 10 km/yr. On a regional level (n × 10 km) and over 5 years and more, density variation patterns of water vole were linked to the ratio of ploughed land and of permanent grassland to farmland. At a sectional scale (n × 1 km), forests and uncultivated lands had a dampening effect both on the outbreaks and on their duration. The evolution of farmlands from 1956 to 1988 was apparently the major cause of increase in density variations of water vole. Therefore, land use and landscape management could be a way to control water vole outbreaks, and their effects are discussed.
Durch Untersuchungen an wildlebenden Tieren der Schwäbischen Alb und durch Infektionsversuche im Laboratorium konnte der Lebenszyklus des europäischen Alveolarechkiococcus aufgeklärt werden. Als natürliche Wirte des Bandwurmstadiums wurden Füchse, und als natürliche Träger des alveolären Larvenstadiums Feldmäuse ermittelt. Infektionen des Menschen können außer von Füchsen auch von Hunden und Katzen ausgehen, die befallene Mäuse gefressen haben. Die Untersuchung des Bandwurmstadiums ergab, daß eine vom gewöhnlichen Echinococcus granulosus verschiedene Art vorliegt, für die als zoologischer Name die alte Bezeichnung Echinococcus multilocularis Leuckart, 1863, vorgeschlagen wird.
Summary
Investigations on wild animals in the Swabian Alb, coupled with animal experiments, succeeded in elucidating the life cycle of the European polycystic echinococcus. Foxes were found to be the natural hosts during the tapeworm stage, whilst field mice acted as the natural carriers during the larval stage of this echinococcus. The infection is transmitted to human beings not only by foxes, but also by dogs who have fed on infected field mice. Investigations of the tapeworm-stage proved that the echinococcus belonged to a different species from the common echinococcus granulosus; the name “echinococcus multilocularis” Leuckart, 1863, is suggested.
Resumen
Sobre el ciclo de desarrollo y la filiación de especie del equinococo alveolar europeo
Mediante investigaciones en animales salvajes de Suabia y mediante intentos de infección en el laboratorio pudo esclarecerse el ciclo vital del equinococo alveolar europeo. Como huésped natural del estadio de tenia se descubrió la zorra y como portadores naturales del estadio de larva alveolar los ratones de campo. La infección del hombre puede provenir no sólo de zorras sino también de perros que hayan comido ratones infectados. La investigación sobre el estadio de tenia dió por resultado que existe una especie distinta de equinococo granuloso para el que ha sido propuesto como nombre zoológico el de Echinococcus multilocularis, Leuckart, 1863.
Various observed patterns of common vole (Microtus arvalis) population kinetics have been classified into five types according to two criteria: the time period of changes in abundance (season or year) and the presence or absence of local extinction. Some types may be subdivided into categories depending on the duration of population fluctuations. They can be ordinate along a gradient correlated to the importance of permanent grassland in farmland and we suggest that this correlation is mainly due to the fact that a major predator (Mustela nivalis) can use grassy landscape elements as refuges and easily disrupt population kinetics from low abundance and smooth variations to large amplitude cycles with pullulation periods. Thus major shifts in land use patterns towards a dominance of grassland can enhance the abundance of a pest species such as the common vole. Local extinctions and recolonization as observed in type IV are characteristics of metapopulation. Further field data of local vole populations will be very useful in the development of predictive models.
Human alveolar echinococcosis (AE) is a rare and highly pathogenic helminthic zoonosis due to infection with the intermediate stage of the small fox tapeworm, Echinococcus multilocularis. Parasite transmission is restricted to northern latitudes, including central and north China, from where few clinical and no detailed community studies have been reported. In August, 1991, 65 (5%) of 1312 people residing in three rural communes of Zhang County, Gansu Province, China were diagnosed as having hepatic AE after mass ultrasound scanning with serological back-up. This represents one of the highest prevalence rates of AE ever recorded. It is also the first time that mass ultrasound scanning and serology have been used together in an AE endemic region. The region was selected one year earlier, when a preliminary serosurvey on 606 unselected people in the same locality resulted in an 8.8% serum antibody positive rate with a 76% rate of confirmation of hepatic AE in 37 individuals who could be followed up in 1991. Seropositivity rates varied for villages between 0 and 20.5%. Overall, females (7.8%) had a significantly greater risk of infection than males (2.5%), especially in the 31-50 age group, a difference which may be related to contact with dogs and dog faeces over many years. Age-specific prevalence of AE increased from 0% in the under 5-year group to 8.2% in those aged 31-50. The youngest case was 11 years and the mean age of diagnosis was 40 years. Adult tapeworms of E multilocularis were identified from the small intestines of 10% of domestic dogs. Sylvatic animal hosts of the parasite have not yet been identified. The high prevalence of human AE in this region of central China is most probably due to semi-domestic transmission of E multilocularis between wild rodents and dogs, together with the poverty and poor hygiene in these rural communities.
Evidence that the larval stage of Echinococcus multilocularis in humans is killed by chemotherapy is presented in a review of our 17-year experience with treatment of alveolar hydatid
disease in Alaska. The efficacy of chemotherapy was assessed with use of an in vivo assay of parasite viability by means of
inoculation of voles, immunohistochemical tests, and histopathologic findings. Of 14 tests performed for nine patients, 12
in vivo assays (86%) were negative after chemotherapy, while only two (17%) of 12 vole tests for seven untreated patients
were negative. Regression or arrest of growth of metastatic and primary hepatic lesions, together with their partial-to-complete
calcification and prolonged survival times has been observed among patients treated with the benzimidazole compounds. For
six who received appropriate chemotherapy, treatment has been discontinued for an average of 4.6 years (range, 3–7 years)
without an increase in lesion size or other evidence of reactivation.
Between 1986 and 1989, orthotopic liver transplantations were performed in our unit for 17 patients with incurable alveolar echinococcosis. Ten patients had hilar involvement (group I), and seven patients had posterior localization (five of them had chronic Budd-Chiari syndrome) (group II). The delay between diagnosis and the orthotopic liver transplantation was more than 48 mo in group Ia (six patients), less than 24 mo in group Ib (four patients) and less than 48 mo in group II. Previous operations were more common in group Ia than in group Ib and II. Five patients have died-four in group I and one in group II. The actuarial survival rate at 15 mo was 75%. Early reoperations were frequent (69%), mainly caused by rebleeding. Bacterial and fungal infections occurred only in group Ia (four cases) and group II (three cases). In eight patients (palliative group), residual foci of infected nonhepatic tissue occurred after surgery. The titer of specific antibodies decreased during the first 3 mo in all the patients but one. In patients with radical liver transplantation, the complete disappearance of specific antibodies occurred within 2 yr in four cases. In the remaining five patients, specific antibodies remained detectable, but no evidence of recurrence has been obtained up to now. In the palliative group, a peak of specific IgM occurred at 3 mo; an increase of specific IgG was observed later. The growth of residual parasitic foci was relatively slow, and all these patients remained asymptomatic with a mean follow-up of 19 mo. We conclude that orthotopic liver transplantation is feasible in incurable alveolar echinococcosis and could be proposed without delay to patients with parasitic Budd-Chiari syndrome or complicated secondary biliary cirrhosis. In the other cases, the best time to perform an orthotopic liver transplantation is more difficult to determine. Nevertheless, in the perspective of an orthotopic liver transplantation, the management of these patients has to change, and repetitive laparotomies for palliative surgical procedures have to be replaced by interventional radiology.
This paper reports the results of a 10-year field trial designed to reduce the risk of infection by Echinococcus multilocularis to residents of a village in a hyperendemic area (Savoonga, St. Lawrence Island). The objective was to prevent dispersal of infective eggs of the cestode within the village by means of monthly treatments of dogs with praziquantel. Northern voles, Microtus oeconomus, present in the village as commensals, served as an index of risk, as the incidence of infection in the voles provides information about the availability of eggs within the confines of the inhabited area. Voles were examined annually during early June before the population of overwintering voles was diluted by the first annual litters. The pretreatment infection-rate within the village was 29% (range 22-35%), and in control areas at some distance from the village for the entire study period it averaged 53% (284 infected voles from a sample of 533). Some fluctuation in incidence of infection in village voles occurred, apparently depending on the extent to which the residents kept their dogs chained and thus available for treatment. The success of the programme was demonstrated by the reduction in prevalence of infection to about 1% of voles in 1985, and an average infection rate during the last five years of the study of 5% (29 infected voles in a sample of 582). This 83% average reduction in the prevalence of the larval cestode within the village reflects a corresponding reduction in the risk of acquiring by the residents of the village. The method would be applicable for the control of E. multilocularis in most hyperendemic regions. Success depends, however, on elimination of unrestrained dogs and a precise schedule of treatment.
We studied 19 Eskimo patients with alveolar hydatid disease from the north-western coast of Alaska for risk factors for infection with Echinococcus multilocularis. Each case-patient was matched by age and sex with 2 unrelated controls who had no clinical or serologic evidence of infection with E. multilocularis and who resided in three villages endemic for alveolar hydatid disease. Behaviors thought to increase exposure to E. multilocularis and the chronologic occurrence of these behaviors in the participant's life were assessed by a standardized questionnaire. Case-patients were more likely than controls to have owned dogs for their entire lives (odds ratio 6.00, P less than 0.05), tethered their dogs near the house (odds ratio 8.50, P less than 0.05), and lived in houses built directly on the tundra rather than on gravel or a permanent foundation (odds ratio 11.00, P less than 0.01). Case-patients were not more likely to have owned sled dogs, trapped or skinned foxes, or engaged in other outdoor activities away from home. These findings suggest that controlling the parasite in the domestic dog population, as well as controlling the dog population itself, are important aspects of preventing alveolar hydatid disease in the northwestern Native Alaskan population.
Nine cases of asymptomatic alveolar hydatid disease (AHD) of the liver were diagnosed in 1985 among Eskimos from the endemic region of western Alaska. The patients were identified by screening with the enzyme-linked immunosorbent assay, using purified Echinococcus multilocularis antigen (Em2 ELISA). Five patients, and one diagnosed earlier (1979), were found to have lesions in which the larval E. multilocularis had died spontaneously at an early stage of infection. Viability was assessed histologically; by the avidin-biotin immunohistochemical method; and in vivo through intraperitoneal inoculation of membranes of the larval cestode into red-backed voles, Clethrionomys rutilus. The results were in agreement with the clinical impression, based on findings by computerized tomography and ultrasound scanning, and on the macroscopic appearance of the lesions, that the cestode was dead. Spontaneous death of E. multilocularis in humans has not been previously reported. The findings show that the Em2 ELISA may be positive in patients having lesions of AHD in which the etiologic agent is no longer viable.
Alveolar echinococcosis is considered to be the most dangerous endemic parasitic disease for man in Central Europe. In Germany, unlike the neighbouring countries of Switzerland, Austria and France, only limited data on the prevalence and incidence of echinococcosis are available. Therefore, a retrospective cross-sectional study was conducted in order to investigate the epidemiology of echinococcosis in Bavaria, one of the two southern states of Germany. A standardised questionnaire was sent to all hospitals in Bavaria requesting information about patients seen from 1985 to 1989. In a second step a team of reviewers was sent to all relevant hospitals for active case finding in hospital statistics and medical records. A total of 216 patients with echinococcosis were detected of whom 58 had alveolar echinococcosis. According to these data, the prevalence in Bavaria was calculated to be 0.5 per 100,000 inhabitants with peak values in the counties of Swabia (2.4) and Upper Bavaria (0.6). The annual mean incidence of newly diagnosed cases amounted to 0.03 per 100,000. The distribution of prevalence in man was closely correlated to the infection rates in foxes throughout Bavaria (p < 0.05). Farmers are the occupational group with the highest risk to acquire echinococcosis with a prevalence/odds ratio of 14.6 for Swabia and 8.8 for Upper Bavaria, when compared to the general rural population.
In a serologic survey for Echinococcus multilocularis infection, we screened sera from 7,884 subjects from the Doubs Departement in France, an area endemic for alveolar echinococcosis (AE) of the liver. An enzyme-linked immunosorbent assay (ELISA) with a highly species-specific antigen (Em2) and an E. multilocularis crude antigen (Emc) was used for screening. An evaluation of the cost/benefit relationship of this screening, followed by therapeutic management of patients, was made and compared with the actual cost of the follow-up and treatment of the disease in symptomatic cases in this endemic area. Antibody reactions to Em2 and/or Emc made possible the detection of eight asymptomatic clinical cases (seroprevalence averaging 1/1,000), with typical lesions of active AE revealed by abdominal ultrasonography and computed tomography. All were seropositive using the Emc ELISA but two were seronegative using the Em2 ELISA. In five additional seropositive cases, the radiologic investigations revealed small calcified lesions similar to the lesions of abortive AE previously found in Alaska. The cost of this serologic screening program per screened subject and per diagnosed case averaged 50.00 French Francs (FF) (U.S. 10,909.00), respectively. The cost of diagnosis, follow-up and treatment of the patients was 5,086.00 FF (U.S. 1,288.00) per patient per month for patients with symptomatic AE. This survey indicates a high prevalence of AE in the target area; it confirms the long latency period of the larval growth in human AE and shows that abortive AE is present in Europe. The use of both the Emc and Em2 ELISAs seems to be better than using the Em2 ELISA alone. The cost of the hospitalization and treatment of the eight screened patients would appear to be relatively high. Even though two of them were asymptomatic, they had very severe forms of the disease. In fact, the total cost was much lower than the actual cost of the disease when diagnosed from clinical symptoms.
Western blot analysis was carried out using crude antigens of Echinococcus multilocularis and 33 serum samples from the People's Republic of China to differentiate patients with alveolar hydatid disease (AHD) with active lesions from those with inactive lesions, those with other parasitoses including cystic hydatid disease (CHD), and healthy persons. This analysis was based on the detection of antibody responses against two polypeptides, Em18 and Em16, which appeared to be species specific and good indices for the differentiation of AHD with active lesions from AHD with inactive lesions. Twenty-one of the 33 samples showed antibody responses against Em18 and/or Em16. Fifteen were antibody-positive for both Em18 and Em16, five were antibody-positive for Em18 only, and one was antibody-positive for Em16 only. Of the subjects from which the 33 samples were obtained, 12 patients had AHD with active lesions, two had AHD, but their lesions were resolved by surgical resections, 14 had CHD with active lesions, and five were apparently healthy people. Western blot analysis confirmed all 14 cases of AHD, three of the 14 cases of CHD, and showed that one of the five apparently healthy individuals had a positive serologic response for AHD. This apparently healthy person with a positive serologic response for AHD by Western blot analysis was found to be positive for the disease on re-examination. Thus, Western blot analysis based on the antibody responses against Em18 and Em16, especially against Em18, was extremely reliable for the detection of AHD with active lesions, although it failed to differentiate two of the 14 patients with CHD.(ABSTRACT TRUNCATED AT 250 WORDS)
Echinococcus multilocularis was identified in a coyote in Indiana in January 1990. Subsequently, 300 wild canids (red foxes, gray foxes, coyotes) were collected from Indiana, Ohio, Illinois, Michigan, and Kentucky and examined for this parasite. Of these, 41 (13.7%) were infected with E. multilocularis. Infected animals were from northern and central Indiana, northwestern Ohio, and east-central Illinois. Twenty-nine of 162 (17.9%) animals from northern and central Indiana were positive, versus 0 of 83 from southern Indiana. Infected animals from northern and central Indiana included 16 of 71 (22.5%) red foxes and 13 of 70 (18.6%) coyotes. In Ohio, 6 of 22 (27.3%) red foxes were infected, and in Illinois, 6 of 17 (35.3%) coyotes were positive. Mean intensity of infection for red foxes was 372 worms (range, 2-3, 640), and for coyotes, 6,579 worms (range, 1-52,000). These findings constitute new state and distribution records for E. multilocularis and a significant range extension for this parasite species in central North America.
This chapter focuses on the public health importance of taeniid cestode zoonoses especially cystic echinococcosis, alveolar echinococcosis and T. solium cysticercosis. The chapter addresses the problem of neurocysticercosis and epilepsy in developing countries particularly Latin America and its public health consequences in the USA and elsewhere. E. multilocularis, which is the cause of one of the most pathogenic of all human parasitic infections, appears to be spreading in parts of western Europe, USA, and Japan. The remarkable development in the past 20 years or so of high resolution imaging technologies, such as computerized tomography (CT) scan and ultrasound have enabled precision detection of taeniid larval cystic infection in humans. Coupled with improvements in immunodiagnostic test sensitivity and antigen specificity, diagnosis of cestode zoonoses is now more accurate than ever before. Although further developments in immunodiagnosis are required, laboratory tests have provided improved capability for screening populations in both epidemiological and community studies. Parallel and recent development of genus specific coproantigen tests for human taeniasis and canine echinococcosis have also provided major new tools for epidemiological and surveillance programs.
An immunoblot study to confirm the species-specificity of the diagnostic antigens Em18 and Em16 of Echinococcus multilocularis protoscolex extract showed that both antigens cross-reacted with sera from cystic echinococcosis (CE) patients. The 18 kDa component was detectable by 75% of the sera from active alveolar echinococcosis (AE) patients, while only 31% detected Em16. Western blot analysis also showed that AE sera recognized a band in the 18 kDa region of E. granulosus protoscolex extract, which was different from the 16/17 kDa subunit of antigen B. The results suggested that Em18 antigen is present in E. granulosus as well as E. multilocularis, and that some CE patients may have serum antibody against this antigen.
Hydatid disease, caused by the larval form of a tapeworm, Echinococcus granulosus (Batsch, 1786), is of circumpolar distribution, but has not previously been considered to be of much public health significance in North America. It is the purpose of this paper to present observations on this disease in Alaska, with special reference to its transmission to humans.
The 'small fox tapeworm' Echinococcus multilocularis has recently become a matter of intense interest in Germany. A long-term increase of its prevalence in foxes has been noted in the well-known endemic areas in Southern Germany, and reports on the occurrence of the parasite in other parts of the country suggest that the parasite is actually much more widespread than previously thought. As nearly all of the relevant studies are published in the German language in a veterinary journal and in the hunting press, accessibility to the information is limited. Richard Lucius and Brigit Bilger here describe the situation, and discuss the possible reasons and consequences.
Life cycle patterns and geographic distribution of Echinococcus species
- Rausch
Rausch, R.L., 1995. Life cycle patterns and geographic distri-bution of Echinococcus species. In: Thompson, R.C.A., Lymbery, A.J. (Eds.), Echinococcus and Hydatid Disease. CAB International, Wallingford, pp. 89 – 134.
First clinical report of alveolar hydatid disease in China
- Yao
Yao, P., 1965. First clinical report of alveolar hydatid disease in China. Chin. J. Surg. 13, 461..
Epidemiology and control of hydatid disease
- P M Schantz
- J Chai
- P S Craig
- J Eckert
- D J Jenkins
- C N L Macpherson
- A Thakur
Schantz, P.M., Chai, J., Craig, P.S., Eckert, J., Jenkins, D.J., Macpherson, C.N.L., Thakur, A.., 1995. Epidemiology and control of hydatid disease. In: Thompson, R.C.A., Lymbery, A.J. (Eds.), Echinococcus and Hydatid Disease. CAB Inter-national, Wallingford, pp. 89 – 134.