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Climate change, flooding, urbanisation and leptospirosis: Fuelling the fire?
Abstract
Flooding and heavy rainfall have been associated with numerous outbreaks of leptospirosis around the world. With global climate
change, extreme weather events such as cyclones and floods are expected to occur with increasing frequency and greater intensity
and may potentially result in an upsurge in the disease incidence as well as the magnitude of leptospirosis outbreaks. In
this paper, we examine mechanisms by which climate change can affect various ecological factors that are likely to drive an
increase in the overall incidence as well as the frequency of outbreaks of leptospirosis. We will discuss the geographical
areas that are most likely to be at risk of an increase in leptospirosis disease burden owing to the coexistence of climate
change hazard risk, environmental drivers of leptospirosis outbreaks, local socioeconomic circumstances, and social and demographic
trends. To reduce this disease burden, enhanced surveillance and further research is required to understand the environmental
drivers of infection, to build capacity in emergency response and to promote community adaptation to a changing climate.
... People in metropolitan areas are susceptible to leptospirosis when roadways flood after heavy rainfall [87,88]. There is a significant risk of infection for farmers in rural areas who labour in rice fields [89]. ...
... Different literature classifications of leptospirosis risk variables include behavioral, climatic, animal exposure, physical, environmental, and socioeconomic threats. Particularly in tropical and subtropical nations, climate change is expected to exacerbate extreme weather conditions and flooding, which could lead to an increase in the frequency of outbreaks [89]. According to research by Dhewantara [130], one of the elements supporting the emergence of leptospirosis' global dissemination is climate. ...
... Furthermore, misdiagnosis can cause significant delays in the application of therapies specific to a given disease, giving epidemics the opportunity to "escape." Following flooding, food-and water-borne diseases are frequent, and some of them might be challenging to distinguish clinically from leptospirosis [89]. ...
Leptospirosis is a potentially fatal and often ignored zoonotic illness caused by the genus Leptospira. The pathogen infects humans, animals, and ecosystems with diverse clinical signs and is estimated to be responsible for 60,000 mortalities, with over a million cases annually. It is common and poses a significant diagnostic problem in low-income tropical and subtropical countries. The incidence is seasonal; climate change, animal exposure, physical environment, and globalization are risk factors of leptospirosis. Rats are the primary reservoir species, while other mammals may potentially play a major role in the transmission of human illnesses. The high burden of pathogens on animals affects the livestock reproduction sector and impacts the socioeconomic burden. Human leptospirosis commercial vaccines are available in Japan, China, Cuba, and France. The pathogen’s ability to exist in the environment contributes to its growth in water and enables the maintenance and distribution of the bacteria globally. This situation reflects a higher impact on agriculture, human and animal health, and ecosystems, which need comprehensive management and a holistic approach, promoting different disciplines and joint-work initiatives toward controlling and treating leptospirosis. Therefore, this book chapter is aimed at highlighting the leptospirosis disease epidemiology, its global health effects, the risk factors, and the challenges in leptospirosis disease control and prevention.
... Esses municípios foram estabelecidos às margens de rios, que eram as principais vias de transporte, comércio e abastecimento de água na época de seu surgimento. Com o passar dos anos, houve aumento na densidade populacional e crescimento urbano desordenado, especialmente ao longo das margens dos rios [13][14][15] . ...
... Nessas localidades, é comum encontrar crescimento urbano desordenado, infraestrutura precária, acúmulo de lixo, presença de animais sinantrópicos e ocorrência frequente de enchentes 13,15 . Esses fatores tendem a contribuir para o aumento da incidência de leptospirose 14,[16][17][18] . ...
... A relação entre leptospirose e enchentes é conhecida há bastante tempo 19 . O surgimento da leptospirose está intimamente ligado à exposição a condições ecológicas que facilitam a transmissão 14 anos, em 37 ocorreram enchentes de porte pequeno, médio, grande ou extraordinário 13,20 . Identificou-se um aglomerado espaçotemporal de alto risco em Porto Acre, Rio Branco e Bujari no período de 2013 a 2015, apresentando RR para leptospirose de 9,51 vezes em comparação com os demais municípios durante esse período. ...
Objective: To identify clusters of high and low risk for the occurrence of leptospirosis in space and space-time in Acre, between 2001 and 2022, as well as to characterize temporal trends and epidemiological profiles of the disease in the state.
Methods: An ecological study of cases mandatorily reported by health services in Brazil. For the analysis of clusters in space and space-time, the SaTScan software was used, which calculated the relative risks (RR). Additionally, temporal trends were obtained using Prais-Winsten linear regression and epidemiological profiles estimated by incidences by sex and age group.
Results: A high-risk spatial cluster was identified in Rio Branco, Bujari, and Porto Acre (RR=2.94), occurring mainly between 2013 and 2015, according to the space-time cluster (RR=9.51). The municipality of Cruzeiro do Sul also showed a high-risk spatial cluster (RR=1.31). This municipality and contiguous municipalities showed an increasing temporal trend in cases, while the other municipalities in the state showed a stationary temporal trend. The disease mainly affected men between 20 and 59 years old, followed by young people aged 10 to 19 years. However, the RR of leptospirosis in older women was 2.1 times higher than in older men (95%CI 1.6-2.9).
Conclusion: The findings indicated that leptospirosis, although endemic in the state, had a more significant incidence in certain municipalities and years. Therefore, it is necessary to act with greater or lesser intensity in specific locations and periods, both for the prevention and control of the disease.
Keywords: Spatial analysis; Spatiotemporal analysis; Amazonian ecosystem; Leptopira
... These municipalities were established on the banks of rivers, which were the main routes for transportation, trade, and water supply at the time of their emergence. Over the years, there has been an increase in population density and disorderly urban growth, especially along the riverbanks [13][14][15] . ...
... In these locations, it is common to find disorderly urban growth, poor infrastructure, accumulation of garbage, presence of synanthropic animals, and frequent occurrence of floods 13,15 . These factors tend to contribute to the increased incidence of leptospirosis 14,[16][17][18] . ...
... The relationship between leptospirosis and floods has been known for a long time 19 . The emergence of leptospirosis is closely linked to exposure to ecological conditions that facilitate transmission 14 . In Rio Branco, in the last 49 years, there have been 37 small, medium, large, or extraordinary floods 13,20 . ...
Objective: To identify clusters of high and low risk for the occurrence of leptospirosis in space and space-time in Acre, between 2001 and 2022, as well as to characterize temporal trends and epidemiological profiles of the disease in the state.
Methods: An ecological study of cases mandatorily reported by health services in Brazil. For the analysis of clusters in space and space-time, the SaTScan software was used, which calculated the relative risks (RR). Additionally, temporal trends were obtained using Prais-Winsten linear regression and epidemiological profiles estimated by incidences by sex and age group.
Results: A high-risk spatial cluster was identified in Rio Branco, Bujari, and Porto Acre (RR=2.94), occurring mainly between 2013 and 2015, according to the space-time cluster (RR=9.51). The municipality of Cruzeiro do Sul also showed a high-risk spatial cluster (RR=1.31). This municipality and contiguous municipalities showed an increasing temporal trend in cases, while the other municipalities in the state showed a stationary temporal trend. The disease mainly affected men between 20 and 59 years old, followed by young people aged 10 to 19 years. However, the RR of leptospirosis in older women was 2.1 times higher than in older men (95%CI 1.6-2.9).
Conclusion: The findings indicated that leptospirosis, although endemic in the state, had a more significant incidence in certain municipalities and years. Therefore, it is necessary to act with greater or lesser intensity in specific locations and periods, both for the prevention and control of the disease.
Keywords: Spatial analysis; Spatiotemporal analysis; Amazonian ecosystem; Leptopira
... Leptospires are excreted via animal urine into the environment, where humans may become infected through contact with infected animals or contaminated soil and water [2]. An increasing number of leptospirosis outbreaks have been reported around the world, particularly following heavy rainfall and flooding [3]. ...
... Poverty was another important driver of infection in remote Pacific Islands, which aligns with findings from other resourcelimited settings in Asia and South America [54]. Low socioeconomic areas are associated with more intimate contact with animals and poor sanitation and hygiene [3]. Furthermore, untreated household water supply systems were independently associated with infections, which may be due to high rates of bacterial contamination in these water sources [55]. ...
... In the Pacific Islands, the highest risk of infection was in the one-to-two-month period following heavy rainfall events [24,42]. Short periods of intense rainfall result in the accumulation of leptospires in soil and water at the surface level [55] whilst simultaneously contaminating water supply systems and displacing people from their homes and animals from their habitats, transiently increasing human-animal interactions [3]. ...
Leptospirosis is a bacterial zoonosis that poses an increasing global public health risk. Pacific Island communities are highly vulnerable to leptospirosis outbreaks, yet the local drivers of infection remain poorly understood. We conducted a systematic review to identify the drivers of human Leptospira infection in the Pacific Islands. There were 42 included studies from which findings were synthesized descriptively. In tropical Pacific Islands, infections were a product of sociodemographic factors such as male gender/sex, age 20 to 60 years, Indigenous ethnicity, and poverty; lifestyle factors such as swimming, gardening, and open skin wounds; and environmental factors, including seasonality, heavy rainfall, and exposure to rodents, cattle, and pigs. Possible mitigation strategies in these islands include strengthening disease reporting standards at a regional level; improving water security, rodent control, and piggery management at a community level; and information campaigns to target individual-level drivers of infection. By contrast, in New Zealand, exposures were predominantly occupational, with infections occurring in meat and farm workers. Accordingly, interventions could include adjustments to occupational practices and promoting the uptake of animal vaccinations. Given the complexity of disease transmission and future challenges posed by climate change, further action is required for leptospirosis control in the Pacific Islands.
... Human infection primarily occurs through contact with water, mud, or soil contaminated with the urine of animals shedding the bacteria [2,3]. Increased leptospirosis cases have been documented after heavy rains and floods in tropical countries, including Brazil [4][5][6][7][8][9][10]. ...
... The relationship between rainfall and leptospirosis incidence has been well documented worldwide [4,49,50]. While many studies have reported leptospirosis outbreaks after floods, most lack estimates of the extent of the increase. ...
Leptospirosis is a well-known disease that frequently occurs after floods. At the beginning of May 2024, a catastrophic flood occurred in the state of Rio Grande do Sul, Brazil, affecting two million people and leading to a state of calamity. Given the State’s high pre-flood leptospirosis rates, the disease became a major concern for decision-makers. This study aimed to estimate the rise in leptospirosis cases after the flood, assess the changes in case patterns before and after the disaster, and document the response of the state health surveillance center to the outbreak. We estimated the increase during the flood period (May to July 2024) by comparing it with the same period in the previous year as baseline. During the first three months of the catastrophic event, 6273 suspected cases of leptospirosis were reported to the surveillance system, and 958 cases were confirmed. The number of confirmed cases during the flood was 10.3-fold higher than the baseline. Spearman’s rank-order correlation coefficient was 0.77 (p-value < 0.0001) for the association of Health Regions regarding the rank in incidence rates of confirmed cases in the flood period and the proportion of the population with households flooded. Thirty deaths (three females) were confirmed, a 6.0-fold rise compared with 2023. The state responders carried out many activities, including epidemiological surveillance and the dissemination of information. Among the challenges faced was the lack of evidence in the literature supporting recommendations for antibiotic chemoprophylaxis for rescue personnel. Another difficulty concerned performing gold-standard laboratory diagnostic tests to confirm the enormous number of suspected cases reported during this catastrophe. Despite implementing many actions to mitigate its impact, leptospirosis remained a major challenge during the event. These findings may provide valuable insights for decision-makers facing similar situations in massive climate disasters.
... The warm, humid climate of the tropics, combined with heavy precipitation, creates ideal conditions for the survival and transmission of Leptospira spp. The rainy season, particularly during monsoons, hurricanes and other major weather events, often coincides with increased cases and outbreaks [31][32][33][34][35][36], as heavy rains facilitate the dispersal of leptospires from soil into surface waters [3,4,31,[37][38][39][40]. Flooding amplifies the risk by exposing individuals to contaminated water, leading to large-scale outbreaks across high-and low-resource areas in rural and urban settings. ...
... The Intergovernmental Panel on Climate Change predicts that rising global temperatures and more frequent extreme precipitation events will increase the burden of waterborne zoonotic diseases such as leptospirosis in many regions and could potentially expand the areas where infections are prevalent [43]. Climate-driven models demonstrate that both temperature and precipitation are highly predictive of the seasonal dynamics of leptospirosis in tropical regions, with some areas potentially experiencing increased incidence because of climate change [35,44,45]. Modeling also suggests that the burden of leptospirosis is significantly underappreciated in some areas [45]. ...
Leptospirosis is a globally distributed zoonotic disease transmitted from animal reservoirs to humans. It is particularly common in tropical regions of Africa, Asia, and Central and South America during heavy rainfall when bacterial spirochetes are released from soil into areas of flooding. Despite causing over 1 million severe cases, 58,900 deaths, and 2.9 million disability-adjusted life-years annually—exceeding established neglected tropical diseases (NTDs)—leptospirosis remains underrecognized as an NTD. It affects occupational groups like farmers due to high prevalence in livestock and is spread by rodents in urban settings with poor sanitation and infrastructure. Although effectively treated with inexpensive antibiotics, neglect of leptospirosis research and development has led to a lack of awareness and unavailability of preventive and diagnostic approaches. This review covers the geographic prevalence, disproportionate impacts on marginalized communities, and opportunities for improving social, economic, and healthcare burdens for patients with leptospirosis.
... Leptospirosis is an acute febrile disease whose contamination occurs through direct contact of the wounded skin and membranes with infected animal urine or indirectly through contact with contaminated water, soil, food, and vegetation (Bharti et al. 2003). Thus, numerous cases of leptospirosis after floods are observed around the world (Ahern et al. 2005;de Freitas et al. 2014;Guimarães et al. 2014;Kawaguchi et al. 2008;Ko et al. 1999;Lau et al. 2010;Londe et al. 2016;Miyazato et al. 2013;Morshed et al. 1994;Mwachui et al. 2015;Reis et al. 2008;Vanasco et al. 2008). ...
... Additionally, the total population rate had a significant effect for the month of the disaster and the immediately subsequent month. These results for leptospirosis corroborate other studies investigating disasters worldwide (Ahern et al. 2005;Kawaguchi et al. 2008;Lau et al. 2010;Morshed et al. 1994;Mwachui et al. 2015) and in Brazil (de Freitas et al. 2012;Guimarães et al. 2014;Londe et al. 2016;Miyazato et al. 2013;Reis et al. 2008). The increase in leptospirosis cases following a catastrophe is expected, as, according to the World Health Organization (2005), this disease is one of the few with the potential to become epidemic in cases of extreme events. ...
The Northeast region of Brazil is characterized by long periods of drought. However, the region is also frequently affected by floods. The socioeconomic characteristics of the locality make the population more vulnerable to the impacts of these disasters. Therefore, the aim of this article is to investigate the short to long‐term impacts of hydrological disasters in northeastern Brazil on morbidity and mortality rates, by age groups. For this purpose, the difference‐in‐differences method proposed by Callaway and Sant'Anna was applied to a monthly panel data spanning the period from 2000 to 2012. The results indicate that in the short term there is an increase in the mortality rate associated with drowning. In the medium term, there are effects particularly on morbidity rates, with emphasis on leptospirosis and acute respiratory diseases. For the long‐term diseases analyzed, no effects of hydrological disasters were observed.
... Flooding increases the risk of infectious and non-communicable diseases, including leptospirosis [2,3], hepatitis [4], mental illness and heart problems [5]. Leptospirosis has been recognized as an infection of intensifying global public health concern and particularly in the Global South [6], yet it remains a neglected tropical disease [7]. ...
... Many cities are designed and built in proximity with water bodies because the resources these environments provide are essential for population livelihood, particularly during city formation [20] However, several anthropic activities that promote contact with these sites lead to changes in the biological cycles of disease vectors, hosts and reservoirs, as well as in the ways humans are exposed to them [21]. In Brazil, the growing urbanization in large cities contributes to leptospirosis outbreaks because the concentration of human habitat generates residues that can serve as refuge and provide resources for rodents [3]. In addition, the increase in urban sprawling and paved roads and streets cause soil impermeability and prevent or hinder the infiltration of rainwater, resulting in flooding and a greater number of infected people [20,22]. ...
Leptospirosis is an epidemic disease caused by bacteria of the Leptospira genus. Its risk is closely associated with inadequate sanitation and flooding, a common public health challenge in large urban centers together with urban environmental modifications, and socio-economic factors. This retrospective observational research investigated the association between three contextual factors (drainage, soil impermeability and social vulnerability) and the distribution of leptospirosis cases in Campinas city, São Paulo, Brazil. We hypothesized that the number of cases will increase in areas that are impermeable and in proximity to drainage systems (rivers and canals) as well as where social vulnerability is high. We investigated the links between infection and the environment based on 54 autochthonous cases that reported having had contact with flood water or mud. Spatial statistics were used to map disease distribution and investigate the relationship between leptospirosis cases and contextual factors. Our results indicate that leptospirosis occurs in areas of greater social vulnerability, near drainage systems and in the most waterproofed urban areas, with the highest risk at 200 m from drainage systems. This study demonstrated that leptospirosis risk remains highly determined by living and working conditions. These findings support targeted strategies to deliver effective prevention, treatment and control interventions in highly populated urban areas of the Global South. Furthermore, combining local contextual environmental information with spatial analysis produces meaningful data in terms of guiding health public policy and spatial planning and provides more precise parameters for future epidemiological models and prevention actions.
Author summary
This study explores the links between environmental and contextual factors that influence the post-flood risk of leptospirosis transmission to humans in Campinas, São Paulo, Brazil. Leptospirosis is an infectious disease caused by the Leptospira bacteria. We investigated how drainage systems, impermeable soil area, and social vulnerability contribute to disease distribution, using spatial statistics to map spatial conditions for 54 cases linked to flood water exposure. Our findings highlight how environmental and socio-economic factors intersect to influence public health, shedding light on the role of urban planning and drainage infrastructure in the transmission risk of infectious diseases. This interdisciplinary approach underscores the importance of considering social and environmental contexts when developing public health strategies, aligning with broader global efforts to address diseases linked to urbanization and environmental changes. Our study advances the understanding of how spatial data and environmental factors can guide more precise parameters for epidemiological models, offering insights into disease control interventions. We discuss the role of prevention, flood management, and equitable infrastructure in safeguarding public health, emphasizing how the environment shapes health risks. This research provides practical recommendations for helping decision-makers prioritize areas for intervention to reduce the burden of leptospirosis, particularly in vulnerable communities.
... La leptospirosis es una zoonosis de distribución mundial 31,70 . Su ciclo comprende una compleja interacción entre poblaciones humanas, reservorios animales, en especial pequeños marsupiales y roedores, y el ambiente en el que convi-ven 1,30 . Factores ambientales como climas cálidos y húmedos, determinan una mayor supervivencia de Leptospira spp. ...
... Considerando que los Estudios de infección por patógenos zoonóticos en la interfase humano -animal -ecosistema distintos grados de perturbación ambiental podrían determinar patrones epidemiológicos distintos para la presentación de Leptospira spp. 66,30 , se consideró a la RECS un ambiente relevante para el estudio de la epidemiología de un agente zoonótico multihospedador como Leptospira spp., así como de la distribución de sus reservorios animales. ...
... In 2015, it was estimated that there were over 1 million annual cases of leptospirosis worldwide with ~60000 deaths and the loss of 2.9 million disability-adjusted life years [1][2][3]. With urban expansion and, potentially, the impact of anthropogenic climate change, the global incidence of leptospirosis is expected to rise [4,5]. ...
Abstract
The case-fatality rate of severe leptospirosis can exceed 50%. This retrospective cohort study examined 111 individuals with laboratory-confirmed leptospirosis admitted to Cairns Hospital, a referral hospital in tropical Australia, between January 2015 and June 2024. We examined the patients’ demographic, clinical, laboratory and imaging findings at presentation and correlated them with disease course. Severe disease was defined as the presence of pulmonary haemorrhage or a requirement for intensive care unit (ICU) admission. The patients’ median (interquartile range) age was 38 (24-55) years; 85/111 (77%) were transferred from another health facility. Only 13/111 (12%) had any comorbidities. There were 63/111 (57%) with severe disease, including 56/111 (50%) requiring ICU admission. Overall, 56/111 (50%) required vasopressor support, 18/111 (16%) required renal replacement therapy, 14/111 (13%) required mechanical ventilation and 2/111 (2%) required extracorporeal membrane oxygenation. Older age – but not comorbidity – was associated with the presence of severe disease. Hypotension, respiratory involvement, renal involvement and myocardial injury – but not liver involvement – frequently heralded a requirement for ICU care. Every patient in the cohort survived to hospital discharge. Leptospirosis can cause multi-organ failure in otherwise well young people in tropical Australia; however, outcomes are usually excellent in the country’s well-resourced health system.
... A leptospirose é uma zoonose de ocorrência mundial, de ampla distribuição, com significativo impacto social, econômico e sanitário 1 Trata-se, ainda, de importante problema de saúde pública no Brasil, devido à alta incidência nas populações que vivem em aglomerações urbanas sem adequada infraestrutura sanitária e com altas infestações de roedores 3 . Estes fatores, associados às estações chuvosas e às inundações, induzem a disseminação e a persistência da leptospira no ambiente e predispõem ao contato com águas contaminadas, as quais facilitam a ocorrência de surtos da doença [2][3][4] . ...
O objetivo do estudo é analisar a tendência temporal da incidência de leptospirose, de acordo com índices pluviométricos na Região da Grande Florianópolis, conforme sazonalidade - 2005 a 2015. Trata-se de estudo ecológico de séries temporais, com dados de leptospirose, índices pluviométricos e população. Foram analisadas taxas de incidência de leptospirose, excesso relativo da incidência, coeficiente de correlação de Pearson (r), coeficiente angular (), a partir do ajuste da regressão linear, com nível de significância de 5%. Apresenta distribuição dos casos de leptospirose, índices pluviométricos e razão casos/índices pluviométricos, estratificados por mês de ocorrência. Foram registrados 1.001 casos de leptospirose, média mensal de 83 casos, com variação de 43, nos meses de agosto, a 146, nos meses de fevereiro. A taxa média de leptospirose foi 8,24/100 mil habitantes. O índice pluviométrico médio foi 154,83 mm, os índices mais baixos ocorreram nos meses de junho, média de 99,48 mm, e, os mais elevados nos meses de janeiro, média de 226,16 mm. Uma correlação positiva entre taxas de leptospirose e níveis pluviométricos, ao longo do período, janeiro a dezembro (r=0,64; p=0,003), aponta para associação temporal positiva entre quantidade de chuva e casos da doença. A doença ocorreu o ano todo e apresentou nítida sazonalidade no período de outubro a março.
... However, the efficiency of these prevention measures encounters significant challenges due to the rising of global temperatures and the increasing frequency of extreme weather events such as heavy rainfall and flooding. 48,49 The significant climatic changes provide conditions that favour survival and transmission of Leptospira. The rise in global temperature could expand the geographic range of Leptospira, introducing the pathogen into new regions and escalating outbreaks in tropical and subtropical areas. ...
... Penggunaan lahan merupakan faktor lingkungan penting dalam dinamika kesehatan manusia. [3]. ...
Land use is an important environmental factor in the dynamics of human health. In the case of leptospirosis, environmental transmission cycles are caused by rat transition, environmental changes and populations at risk. Utilization of GIS-based spatial analysis may help detecting distribution patterns of leptospirosis cases, allocating resources and planning effective control and surveillance programs in endemic areas. This study aims to analyze the spatial distribution of leptospirosis based on land use and stream flow in Bantul District, 2010-2018. This ecological study was conducted in Bantul District, Yogyakarta for 9 years. Spatial analysis overlays processed data on leptospirosis cases per village and land use maps of 2016 using QGIS 3.0. Spatial distribution of 12 of high leptospirosis villages (18-35 cases) are in residential areas, tributaries, croplands, irrigated fields, rain-fed rice fields, and plantations. Those villages was crossed by major river basin which is potentially as transmission media of leptospirosis cases after heavy rainfall. It is suggested to increase the Early Awareness and Alert (EAA) system by active surveillance of early case finding from the government and endemic villagers.
... We did not find an association between precipitation and incidence of human leptospirosis, in contrast to several studies that observed an increased leptospirosis incidence with more precipitation, although these studies were performed in tropical climates [6][7][8][26][27][28]. Additionally, some studies in tropical climates showed a correlation between flooding due to heavy rainfall and leptospirosis [32]. ...
Background
The incidence of leptospirosis, a zoonotic infection transmitted mainly by rodents, has increased in humans over the past decade in the Netherlands. Previous studies, mostly from countries with tropical climates, suggest that temperature and rainfall influence leptospirosis incidence.
Aim
We aimed to identify factors that could explain the increasing leptospirosis incidence in the Netherlands, including temperature and precipitation.
Methods
Epidemiological data of leptospirosis cases notified from 2005 to 2023 to the national surveillance system were analysed to identify changes over the years. Negative binomial regression models were used to assess associations between weather variables and leptospirosis incidence.
Results
From 2005 to 2023, 1,164 cases were notified. The annual number of cases increased 2.7-fold in the period of 2019–2023 compared with 2005–2009, and the number of autochthonous cases 4.1-fold. Data from 1,158 cases were included in the analyses, and 596 (51.5%) of these cases were autochthonous. Most cases were male (n = 927; 80.1%), needed hospital treatment (n = 861; 74.4%) and acquired the infection through contact with surface water and/or soil (n = 611, 72.6%). Higher mean winter (incidence rate ratio (IRR) = 1.27; 95% confidence interval (CI): 1.18–1.36) and summer (IRR = 1.38; 95% CI: 1.18–1.61) temperatures were significantly associated with increased leptospirosis incidence.
Conclusion
Leptospirosis incidence has increased over the past decades and may continue to increase due to climate change. Prevention should aim at advising the appropriate preventive measures to avoid exposure to Leptospira and increasing awareness about leptospirosis among clinicians to allow for timely diagnosis and treatment.
... In other studies, these bacteria were detected at the beginning of the rainy season after low to moderate and moderate rainfall. While researchers believe that its prevalence in rodents is associated with rainfall [45], there is no substantial evidence to confirm an association between Leptospira circulation and rainfall. Several previous studies have suggested that the Leptospira infection risk also strongly depends on socio-environmental conditions [19,21]. ...
Leptospirosis is a bacterial zoonosis caused by pathogenic species from the genus Leptospira. Infection mostly occurs through indirect contact with environmental water contaminated with the urine of reservoir animals. Information on the circulation of leptospirosis in West Africa, as well as its potential reservoir hosts, is limited. Therefore, we carried out trapping surveys in the Guinean forest in November 2022, and samples were collected from 42 micromammals. The animals were both morphologically and genetically identified. The lungs and kidneys were screened for Leptospira using Lfb1-gene-targeting real-time PCR, and positive samples were genotyped based on the polymorphic Lfb1 gene. Leptospira species were detected in the kidneys of three micromammals: Mastomys natalensis, Lophuromys sikapusi, and Rattus rattus. Leptospira borgpetersenii was identified in Rattus rattus and Mastomys natalensis that were captured in two different villages. The phylogenetic analysis indicated that this subspecies had previously been detected in one patient in Mayotte, but the reservoir was not identified. A new subspecies of Leptospira kirschneri was isolated in Lophuromys sikapusi from the same village as the Mastomys natalensis positive for L. borgpetersenii. The high diversity of both the reservoirs and Leptospira species in the Guinean forest indicates that we should study other natural regions and reinforce communities’ awareness of Leptospira infection risks in Guinea.
... Although vapor pressure (representing specific humidity) is a prerequisite for precipitation, their moderate correlation (Pearson's r = 0.3786, Fig. S2) suggests independent mechanisms of influence. While numerous studies have documented rainfall's role in leptospirosis risk across various countries [46][47][48], vapor pressure's influence has remained largely unexplored. Despite being the most significant climatic factor, vapor pressure ranked only fifth overall in our SHAP analysis, suggesting either a limited impact of annual climatic trends or a unique characteristic of leptospirosis epidemiology in Thailand. ...
Leptospirosis poses a significant public health challenge in Thailand, driven by a complex mix of environmental and socioeconomic factors. This study develops an XGBoost machine learning model to predict leptospirosis outbreak risk at the provincial level in Thailand, integrating climatic, socioeconomic, and agricultural features. Using national surveillance data from 2007-2022, the model was trained to classify provinces as high or low risk based on the median incidence rate. The model’s predictive performance was validated for the years 2018-2022, spanning pre-COVID-19, COVID-19, and post-COVID-19 periods. SHapley Additive exPlanation (SHAP) analysis was employed to identify key predictive factors. The optimized XGBoost model achieved high predictive accuracy for the pre-pandemic (AUC=0.93) and post-pandemic (AUC= 0.95) testing periods. SHAP analysis revealed rice production factors, household size, and specific climatic variables as the strongest predictors of leptospirosis risk. However, model performance declined during the COVID-19 pandemic (2020-2021), suggesting surveillance disruption and potential underreporting. This study demonstrates the utility of machine learning for predicting leptospirosis risk in Thailand and highlights the complex interplay of environmental and socioeconomic factors in driving outbreaks. The adaptable modeling framework provides a foundation for developing early warning systems and targeted interventions to reduce the burden of this neglected tropical disease.
Author summary
Leptospirosis, a disease caused by Leptospira bacteria, poses a significant public health challenge in Thailand. The bacteria thrive in contaminated environments, particularly those associated with rice farming. In this study, we developed a machine learning model to predict the risk of leptospirosis outbreaks in Thailand based on climatic, socioeconomic, and agricultural factors. Our analysis revealed that rice production practices, household size, and specific climatic variables were the strongest predictors of leptospirosis risk. We also observed a reduction in model performance during the COVID-19 pandemic, suggesting surveillance disruptions and potential underreporting. These findings highlight and explain the complex interplay of environmental and socioeconomic factors in driving leptospirosis outbreaks. Our adaptable modeling framework provides a foundation for developing early warning systems and targeted interventions to reduce the burden of this often-overlooked tropical disease. Better understanding the factors that contribute to leptospirosis risk can guide responses to protecting vulnerable populations and improving public health outcomes in Thailand and beyond in times of socio-environmental changes.
... It is also known by various synonyms, including Weil's disease, Weil-Vasiliev disease, Swineherd's disease, rice-field fever, waterborne fever, nanukayami fever, cane-cutter fever, swamp fever, mud fever, Stuttgart disease, and Canicola [3] . It is sensitive to climate conditions [4]. It is primarily transmitted through contact with water, soil, or food contaminated by the urine of infected animals [5]. ...
Leptospirosis, a zoonotic bacterial infection caused by Leptospira species, significantly impacts both human and animal populations, particularly in tropical and subtropical regions. Transmission typically occurs through contact with contaminated water or soil, with rodents, livestock, and other animals serving as key reservoirs. Despite its prevalence, leptospirosis remains underreported due to diagnostic challenges, complex transmission dynamics, and insufficient surveillance systems. This paper proposes the establishment of a Global One Health Coordination Committee to address these issues, focusing on improving the understanding of transmission pathways, developing accessible and accurate diagnostic tools, and strengthening surveillance efforts. By integrating insights from human, animal, and environmental health sectors, this committee would facilitate global data sharing, prioritize research funding, and support public health initiatives. Such a collaborative framework is essential for mitigating leptospirosis’ global health burden and fostering sustainable preventative measures across diverse ecological and socio-economic contexts.
... Regular monitoring and treatment of water sources can help to reduce bacterial loads. Chlorination, filtration, and other water purification methods are effective at removing Leptospira from drinking water supplies and recreational water bodies [113]. Additionally, controlling flooding and runoff is crucial, as these conditions can spread Leptospira through contaminated water across urban and rural areas. ...
Leptospirosis is a significant zoonotic disease that poses a global public health challenge, particularly in warm, humid regions. The aim of this review paper is to critically synthesize existing literature on interventions for leptospirosis at the interfaces of humans, animals, and the environment. It also emphasizes the importance of interdisciplinary collaboration and integrated approaches to effectively address the complex challenges posed by this infectious disease. The authors conducted a systematic scoping review following the PRISMA-ScR guidelines and analyzed 344 studies that met the inclusion criteria. The paper highlights advancements in diagnostic techniques, treatment, and vaccine development. It also emphasizes the significance of health governance frameworks that support risk communication, surveillance, policy development, and community engagement. Various health interventions related to each interface are discussed, and the paper concludes with a discussion regarding One Health approach to interventions, which highlights the key targets, including pathogen characteristics and transmission. This paper proposes a framework for leptospirosis interventions across the human-animal-environment interfaces, which may serve as a guide for policymakers and scientists in understanding the gaps and less explored aspects of intervening in leptospirosis.
... Farmers are exposed to leptospire-contaminated environments during rice transplanting, field management, and rice harvesting, which corresponds to the demographic characteristics showing that farmers (74%) and males (nearly 70%) account for the majority of cases. Additionally, most southern regions in China have climatic conditions favourable for leptospire survival, with a high diversity of host animals and a high bacterial carriage rate in endemic areas, leading to the long-term persistence of natural foci [50]. One study systematically reviewed the Leptospira positivity rates in rodents in China, showing that southern PLADs (Guangxi: 35.29%; ...
Background
Leptospirosis, a zoonotic disease caused by pathogenic species of the genus Leptospira , is an important public health concern globally. Leptospirosis has been notifiable under statute in China since 1955, and its epidemiological characteristics have evolved during near 70 years. This study aimed to describe the spatial and temporal patterns and demographic characteristics of leptospirosis from 1955 to 2022 in China, and explore the possible factors that influence leptospirosis transmission risk.
Methods
Wavelet time series analysis, global Moran’s I coefficients, space–time scanning statistics, and so on were used to analyze temporal, seasonal, geographic, and demographic trends in leptospirosis using reported national surveillance data from Chinese mainland from 1955 to 2022. Additionally, a Bayesian spatiotemporal model was used in a preliminary analysis to explore potential factors associated with leptospirosis occurrence.
Results
Between 1955 and 2022, China reported 25,236,601 leptospirosis cases, with 91% occurring from July to October. The annual incidence rate peaked at 38.28/100,000 during outbreaks in the 1960s–1980s but stabilized at a low level (0.07/100,000) between 2005 and 2022, with over 99% of cases in southern China. Clustering increased over time, being greatest during the period 2015–2022 (Moran’s I = 0.41, P < 0.01). Space-time cluster analysis indicated that the most likely clusters were in northern provincial-level administrative divisions (PLADs) from 1955 to 1984, in southern PLADs from 1985 to 2022. The main identified risk factors of leptospirosis occurrence were annual average precipitation (3.68, 95% CI: 2.50 to 5.12), GDP per capita (-3.70, 95% CI: − 5.97 to − 1.41), and the total power of agricultural machinery (− 2.51, 95% CI: − 3.85 to − 1.17).
Conclusions
Over past 70 years, leptospirosis in China has occurred as significant outbreaks but has ultimately declined to stable, low levels of occurrence. However, a clear north–south disparity persists, with tropical and subtropical regions in southern China remaining high-risk areas. The nearly 70-year dataset underscores the complex interplay of climate and socioeconomic factors influencing the disease’s occurrence. Targeted prevention and control measures are critical to prevent outbreaks, especially in regions prone to extreme climatic events like heavy rainfall and floods, which may signal the resurgence of leptospirosis.
... For instance, CC can potentially modify the habitats and behaviours of disease-carrying vectors and reservoirs like sandflies and rodents, leading to an expansion in their population size and geographical range [14]. Seasonal variations can also impact the population and behaviour of these species and people's exposure to them [24]. Two examples of zoonotic diseases influenced by CC and seasonal variations are leishmaniasis and Leptospirosis. ...
Climate change (CC) is increasingly recognised as a critical driver in the emergence and re-emergence of infectious diseases. The relationship between CC and infectious diseases is complex and multifaceted, encompassing changes in temperature, precipitation patterns, and extreme weather events. This study describes the role of CC in the emergence and re-emergence of infectious diseases, emphasising zoonoses. It used a mixed methodology, including an initial literature contextualisation and a bibliometric analysis, to identify key thematic research areas related to CC and zoonotic diseases and show their connections. The research relied on the Scopus database for the identification of relevant source literature and focused the search query on publications in English. VOSviewer was used to discover clear thematic clusters that illustrate what research areas have been addressed in the literature and how they are interlinked. In addition, the research selected and analysed twelve literature-supported studies to investigate the relevance of the zoonoses involved in infectious disease emergence and re-emergence linked to CC impacts. Many pathogens and their vectors, such as mosquitoes, ticks, and rodents, are sensitive to temperature and moisture. CC can expand or shift the geographical distribution of these vectors, bringing diseases to new areas. Warmer temperatures may allow mosquitoes that transmit diseases like malaria and dengue fever to survive and reproduce in regions that were previously too cold. Also, extreme events such as floods, droughts, and hurricanes can lead to immediate increases in waterborne and vector-borne diseases (VBD) by facilitating the spread of pathogens. There is a need to better understand the connections between CC and zoonoses. To address the challenges posed by zoonoses linked to CC, international organizations like the WHO should coordinate a global response to provide clear guidance. Governments must integrate CC and zoonoses into national health policies, ensuring that health frameworks address these interconnected risks. Funding should be allocated for research on the root causes of CC and for strengthening defenses, particularly in developing countries with fragile health systems. Additionally, enhanced communication, education, and training for healthcare professionals about the links between CC and zoonoses are essential for raising awareness and promoting proactive measures.
... Anicteric infection covers approximately 80-90% of leptospira infections (Levett 2001). It consists of an incubation period of 1 to 2 weeks with a range of 2 to 30 days after which characteristic clinical signs begin to appear (Lau et al. 2010). It is present in the environment and enters the body through cuts, abrasions, or contact with mucous membranes. ...
Leptospirosis is a waterborne zoonotic melody faced globally by both animals and humans. Based on the emergence and losses caused by leptospirosis, it is a recurring and neglected disease of public health importance all over the globe. Lack of public awareness and negligence on a massive scale combined with expeditious and unplanned urbanization in developing countries cause the re-emergence of this disease under unsanitary conditions. As most wild and domestic animals can be the carriers of the pathogen causing this acute febrile illness, everyone is at risk of getting infected including all the healthcare professionals, pet owners, farmers, workers and volunteers at animal daycare centres and shelters for stray animals, fishermen, sanitary workers, rodent catchers, sewage cleaners, etc. The clinical signs and symptoms include a variety of flu-like to acute kidney failure in severe or untreated cases. Typical cases of leptospirosis depict signs like pneumonia, pulmonary haemorrhages and jaundice but many cases are reported worldwide with very rare and uncommon clinical manifestations. This chapter will cover all the possible aspects of dog-mediated leptospirosis from the morphology of the pathogen, its transmission, occurrence, clinical signs, diagnosis and prevention of this disease.
... It is also known by various synonyms, including Weil's disease, Weil-Vasiliev disease, Swineherd's disease, rice-field fever, waterborne fever, nanukayami fever, cane-cutter fever, swamp fever, mud fever, Stuttgart disease, and Canicola [3] . It is sensitive to climate conditions [4]. It is primarily transmitted through contact with water, soil, or food contaminated by the urine of infected animals [5]. ...
Leptospirosis, a zoonotic bacterial infection caused by Leptospira species, significantly impacts both human and animal populations, particularly in tropical and subtropical regions. Transmission typically occurs through contact with contaminated water or soil, with rodents, livestock, and other animals serving as key reservoirs. Despite its prevalence, leptospirosis remains underreported due to diagnostic challenges, complex transmission dynamics, and insufficient surveillance systems. This paper proposes the establishment of a Global One Health Coordination Committee to address these issues, focusing on improving the understanding of transmission pathways, developing accessible and accurate diagnostic tools, and strengthening surveillance efforts. By integrating insights from human, animal, and environmental health sectors, this committee would facilitate global data sharing, prioritize research funding, and support public health initiatives. Such a collab-orative framework is essential for mitigating leptospirosis' global health burden and fostering sustainable preventative measures across diverse ecological and socioeconomic contexts.
... Climate change impacts on human exposure to pathogen hazards tend to occur primarily through shifts in human and animal (domestic and wildlife) movement, or through human response to climate change impacts such as agricultural production systems, and individual socio-economic status and activities [87]. For example, shifts in temperature and precipitation can alter the range of certain wildlife species and vectors, increasing human exposure to infectious agents not typically present in a given region, as has been observed for both zoonotic diseases and vector-borne diseases in the case of rodent-borne diseases (e.g., Leptospira sp.) and zoonotic diseases in bushmeat hunters [88]. ...
Climate change is having unprecedented impacts on human health, including increasing infectious disease risk. Despite this, health systems across the world are currently not prepared for novel disease scenarios anticipated with climate change. While the need for health systems to develop climate change adaptation strategies has been stressed in the past, there is no clear consensus on how this can be achieved, especially in rural areas in low- and middle-income countries that experience high disease burdens and climate change impacts simultaneously. Here, we highlight the need to put health systems in the context of climate change and demonstrate how this can be achieved by taking into account all aspects of infectious disease risk (i.e., pathogen hazards, and exposure and vulnerability to these pathogen hazards). The framework focuses on rural communities in East Africa since communities in this region experience climate change impacts, present specific vulnerabilities and exposure to climate-related hazards, and have regular exposure to a high burden of infectious diseases. Implementing the outlined approach can help make health systems climate adapted and avoid slowing momentum towards achieving global health grand challenge targets.
... The quality of life of urban residents has been broadly studied across multiple domains, from sociology to urban studies, associated with public health and wellbeing (Marans and Stimson, 2011b;Pacione, 2003;Marans and Stimson, 2011a;Jaroszewicz et al., 2023;Alfaro-Navarro et al., 2024). However, cities today are facing urban challenges in diverse ways, for example, such as unequal access to public facilities and unaffordable housing due to extensive urbanisation (Zhang, 2016;While and Whitehead, 2013;Castells-Quintana and Royuela, 2015;Ziogas et al., 2023;Hu et al., 2023;Yin et al., 2023), as well as the essential to adapt to climate change and build resilience against natural events and resource fluctuations (Godfrey and Julien, 2005;Lau et al., 2010;Maheshwari et al., 2020;Aboagye and Sharifi, 2024). The growing interest in the quality of human life in both academia and practice confirms its multitude of important benefits and longterm value (Samavati and Veenhoven, 2024;Syamili et al., 2023;Patino et al., 2023). ...
Urban comfort is a means of measuring the dynamic quality of urban life as an outcome of the interaction between humans and urban environments, capturing spatio-temporal phenomena in cities. We design a multidimensional urban comfort framework encompassing 44 features, to comprehensively represent urban living environments, based on 3D urban morphology, socio-economic features, human perception, and environmental factors. We develop a graph-based approach to measure urban comfort through an index and explain its driving forces by exploiting spatial relationships between urban comfort and surrounding features. Explainable artificial intelligence (XAI) is leveraged to interpret feature importance and inherent complexity in urban contexts, advancing conventional methods that are limited to linear relationships. We implement the framework in Amsterdam, generating a city-wide comfort index. Compared to the baseline random forest model, our graph-based approach demonstrates competitive performance in measuring the urban comfort index, achieving an MAE of 1.03, an RMSE of 2.04, and an R-squared value of 93.6\%. Meanwhile, we visualise how the urban comfort index changes across quarters, examining the spatio-temporal dynamics at the neighbourhood level.
Furthermore, we employ XAI to explain the positive and negative impacts of urban features by categorising neighbourhoods into high and low-comfort groups, indicating the varied contributions of urban features. Exploring the usability of the urban comfort index, we simulate various urban strategies in a neighbourhood of interest benefiting from urban digital twins (e.g.\ improving air quality to mitigate its negative impact on urban comfort). The urban comfort study demonstrates the potential to address information gaps by incorporating multidimensional features in cities, thereby providing insights into understanding and interpreting local comfort. It can further serve as an instrument to inform neighbourhood design, suggest feasible strategies, and indicate far-reaching implications for urban health and wellbeing.
... Therefore, coastal risk mapping highlights areas of major concern and, combined with the adoption of the 100 m setback zone as an exposure zone, raises complex spatial planning issues in terms of socio-economic pressures, which are likely to increase further in the future due to climate change. As climate change is expected to intensify coastal squeeze in the short term, high potential impact areas will face significant climate risks associated with sea level rise (SLR) (Holt 2012;Lau et al. 2010). Assessing the links between socioeconomic pressures and SLR impacts is crucial for effective adaptation policymaking. ...
Beaches play a pivotal role in supporting the socio-economic sector, particularly within the 'Sun, Sea, and Sand' (3S) tourism model. Valued for their ecosystem services, these coastal landforms are among the most dynamic and vulnerable environments, facing significant pressure from various climate challenges, which is further intensified by extensive anthropic exploitation. Their sustainable use is intrinsically linked to balancing the 3Ps: Planet, People, and Profit. To address the need for protection and sustainable utilization of coastal areas, the European Union has introduced the Protocol on Integrated Coastal Zone Management (ICZM) in the Mediterranean, specifically recommending in Article 8(2) the establishment of a setback buffer zone where permanent constructions are prohibited. This paper explores the application of risk mapping in the context of coastal setback policies, focusing on their effectiveness in managing beach retreat and adapting to climate change, particularly rising sea levels. The study examines selected beach areas in Peloponnese, Greece, influenced by various socio-economic factors. Through this analysis, the paper aims to contribute to the discourse on coastal management strategies that balance environmental sustainability with socio-economic benefits.
... Fog and smog have a substantial impact on animal health, which is a main feature of the dairy farming industry (Abbas et al. 2019). Thus, floods and excessive rain are associated with multiple leptospirosis epidemics (Lau et al. 2010). Additionally, salinity issues contribute to various skin diseases in the livestock sector (Hughes, 2008). ...
Livestock plays a crucial part in the global food chain; however, its production and supply could be jeopardized due to climate change-related risks. Therefore, this study gathered information regarding adverse climatic livestock production, adaptation, and mitigation strategies to the hazards' impact, finding research opportunities, and suggesting ideas for policymaking. The impact of increased temperature, altered rainfall, drought, flood, riverbank erosion, salinity, natural calamities like cyclones, etc. on livestock production was reviewed and reported in this article. They are responsible for reducing the availability and quality of fodder and water, declining livestock growth and reproduction, spreading diseases, and posing a threat to animal genetic resources. On the other hand, Bangladesh is anticipated to descend under water as a result of sea level rise resulting in a saline incursion into cropland and freshwater, drastically affecting crop and livestock production, especially in coastal regions. The impact of the hazards can be reduced through following some mitigation and adaptation strategies such as adopting and improving local breeds, practicing mixed farming systems, embracing climate smart livestock management systems, providing insurances for the losses to farmers, and so on. Feeding practices can be altered during flood by providing tree leaves, UMB, unconventional feeds. In conclusion, this review provided a compiled knowledge of climate change affecting livestock production, identifies the research gaps and suggests further research opportunities in this sector. Bangladesh Journal of Animal Science 52 (1): 1-14, March 2023
... Community-level exposure to livestock, especially pigs and cows, also seems to be a strong predictor of the risk of leptospirosis infection (Lau et al. 2017 ). Flooding events, exacerbated by climate change, further propagate the spread of pathogenic Leptospira through contaminated water and soil, heightening the risk of infection for both humans and animals (e.g., Lau et al. 2010 ). Socio-economics and poor living conditions have also been linked to higher risk of infection (Lau et al. 2016 ). ...
Islands play a central role in understanding the ecological and evolutionary processes that shape life but are rarely used to untangle the processes that shape human, animal, and environmental health. Islands, with their discrete human and animal populations, and often well-studied ecological networks, serve as ideal natural laboratories for exploring the complex relationships that shape health across biomes. Relatively long coastlines and, in some cases, low lying topography also make islands sentinels for climate change. In this article, we examine the potential of islands as valuable laboratories and research locations for understanding the One Health nexus. By delving into the challenges faced in island settings, we provide valuable insights for researchers and policymakers aiming to globally promote and apply One Health principles. Ultimately, recognizing the interconnected health of humans, animals, and the environment on islands contributes to efforts aimed at promoting global health and sustainability.
... It is highly prevalent in the tropics, reaching over one million cases of infection per year worldwide (Costa et al., 2015;Rajapakse, 2022). Because of global climate change, heavy rains and flooding have been associated with several leptospirosis epidemics (Lau et al., 2010). Symptoms range from asymptomatic to mild febrile to severe acute infection, potentially leading to organ failure and death. ...
Introduction
Leptospirosis is a global zoonosis that affects more than one million people per year, with a lethality rate of approximately 15%. Chemokines are crucial in the immune response against Leptospira, recruiting leukocytes to the site of infection and regulating immune activity. In previous studies, we have shown that CCL2, CXCL5, and CCL8 are involved in the leptospirosis process, although the mechanisms are not understood.
Methods
In this study, we present the frequency of Leptospira serovars in human samples. We then evaluated the profile of various chemokines in sera from patients diagnosed with leptospirosis, assessing the possible correlation between them. Moreover, we evaluated the changes in the chemokine profile on different days after the first symptoms. The frequency of the Leptospira serovars in human samples is presented.
Results and discussion
The main findings were that CCL5, CXCL5, and CXCL9 are highly expressed during leptospirosis, indicating a special role of these molecules in the immunity and pathogenesis of the disease. The correlation analysis of detected chemokines CXCL11, CXCL9, CCL3, and CCL2 helps to clarify the role of each cytokine in leptospirosis. The possible use of CCL5 as a biomarker for complementary diagnosis of the disease is suggested.
... Waterborne transmission is the most important mode of transmission and outbreaks are as such often linked to floods. Increased thaw and water run-off as well as more frequent extreme (Seguro and Andrade, 2013) (Andersen-Ranberg et al., 2016;Hartskeerl et al., 2011;Lau et al., 2010;Minette, 1983) (Revich et al., 2012;Tokarevich and Stoyanova, 2011;Zakharova et al., 2020) (Bradley et al., 2005;Prescott et al., 2002; Lepto-seroprevalence among Greenlanders: unpubl. Mat., Prof Anders Koch and Emilie A.-Ranberg) (Lévesque et al., 1995;Revich et al., 2012) (continued on next page) weather events will therefore increase the risk of infection. ...
... Existió una significancia entre casos de Leptospirosis y la precipitación en el Ecuador para el período 1994-2013. Estos resultados pueden ser comparados con Lau et al. (2010); Wynwood et al. (2014); Arias-Monsalve y Builes-Jaramillo (2019). En el Ecuador, la humedad persistente y las precipitaciones regulares durante la época de lluvia son las mejores condiciones para la diseminación de la Leptospirosis. ...
Este estudio de revisión bibliográfica se centra en la leptospirosis canina con la finalidad de evaluar la relación entre precipitación y leptospirosis, identificar la región más afectada y justificar estudios adicionales mediante un metaanálisis. La metodología incluye el análisis de relación entre precipitación y casos de leptospirosis (1994-2013), la exploración de la incidencia por regiones en Ecuador mediante análisis de correspondencia y un metaanálisis global de la interacción entre factores ambientales de 106 artículos de distintas bases de datos. Los resultados muestran una relación exponencial significativa entre leptospirosis y precipitación en Ecuador, destacando la importancia de las condiciones climáticas en la evaluación de riesgos. La región costa, especialmente Manabí, es la más afectada, con una sólida asociación entre leptospirosis y varios hospederos (perros, cerdos, ratas y múltiples animales). El metaanálisis subraya la importancia de factores como inundaciones, suelos y eventos de lluvia, que representan el 52.4% de la variación en la literatura analizada. En contraste, otros elementos carecen de relevancia, lo que indica la necesidad de priorizar investigaciones y estrategias específicas. En conclusión, se proporciona una visión integral de la leptospirosis canina, destacando la importancia de factores climáticos y ambientales para desarrollar estrategias efectivas de prevención y control en Ecuador.
... Extreme rainfall and flooding, high temperatures, overcrowding, poor sanitation, inadequate health care systems, poverty, and a high presence of rats and other animal reservoirs have been associated with outbreaks of leptospirosis [241][242][243][244][245][246][247][248]. ...
Environmental disasters are extreme environmental processes such as earthquakes, volcanic eruptions, landslides, tsunamis, floods, cyclones, storms, wildfires and droughts that are the consequences of the climate crisis due to human intervention in the environment. Their effects on human health have alarmed the global scientific community. Among them, autoimmune diseases, a heterogeneous group of disorders, have increased dramatically in many parts of the world, likely as a result of changes in our exposure to environmental factors. However, only a limited number of studies have attempted to discover and analyze the complex association between environmental disasters and autoimmune diseases. This narrative review has therefore tried to fill this gap. First of all, the activation pathways of autoimmunity after environmental disasters have been analyzed. It has also been shown that wildfires, earthquakes, desert dust storms and volcanic eruptions may damage human health and induce autoimmune responses to inhaled PM2.5, mainly through oxidative stress pathways, increased pro-inflammatory cytokines and epithelial barrier damage. In addition, it has been shown that heat stress, in addition to increasing pro-inflammatory cytokines, may also disrupt the intestinal barrier, thereby increasing its permeability to toxins and pathogens or inducing epigenetic changes. In addition, toxic volcanic elements may accelerate the progressive destruction of myelin, which may potentially trigger multiple sclerosis. The complex and diverse mechanisms by which vector-borne, water-, food-, and rodent-borne diseases that often follow environmental diseases may also trigger autoimmune responses have also been described. In addition, the association between post-disaster stress and the onset or worsening of autoimmune disease has been demonstrated. Given all of the above, the rapid restoration of post-disaster health services to mitigate the flare-up of autoimmune conditions is critical.
... In Tanzania, especially Unguja Island, there have been few reports of leptospirosis despite the reports of the leptospirosis burden worldwide [13,18]. Like those in other developing countries, slaughterhouses in Unguja feature poor sanitation, inappropriate waste disposal, and sewage, which promotes the spread of rodents and poses a danger of Leptospira infection to slaughter facility personnel [19]. This study assessed the Leptospira infection and carrier status of rodents captured around the slaughterhouses in Unguja Island, stressing the possible hazards to animals and people. ...
Background: Leptospira infection is an invasion of animal or human body with the pathogenic spirochete bacteria of the genus Leptospira resulting to a disease called leptospirosis. This study aimed to investigate Leptospira infection and the carrier status of rodents caught near slaughterhouses at Unguja Island, Tanzania. Methods: This cross-sectional study was conducted from January to April 2022 at Unguja Island to determine the seroprevalence of Leptospira infection in rodents captured in and around the slaughterhouse’s compounds. A total of 302 sera samples from four slaughterhouses were tested for anti-leptospiral antibodies using microscopic agglutination test (MAT) with a panel of 5 Leptospira serovars: Pomona, Lora, Hebdomadis, Grippotyphosa and Sokoine; and were considered positive at MAT titer ≥1:20. Chi-square test and the Fisher exact test were used to assess the statistical association between variables at a p value of < 0.05. Results: The overall seroprevalence of Leptospira infection in rodents was 10.6% (32/302). Individual rodent species had seroprevalence of 8.5% for Mus musculus, 0.0% for Mastomys natalensis, 20.8% for Rattus norvegicus, 9.3% for Rattus rattus and Cricetomys gambianus at 12.5%. However, the apparent seroprevalence in the individual slaughter facilities was 15.0% (15/100) Kinyasini, 10.4% (5/48) Mfenesini, 9.3% (5/54) Kisakasaka, and 7.0% (7/100) Muwanda. Conclusion: With over ten percent of rodents testing positive for Leptospira infection, it is crucial to implement rodent control measures to prevent the spread of the disease to those working in or around the slaughterhouses in Unguja Island.
... are spreading to areas previously free of these diseases, representing a major public health challenge. Leptospirosis, transmitted through contact with contaminated water, has become more prevalent in areas subject to flooding [12]. Covid-19 has also highlighted how climate change can influence the spread of infectious diseases, exacerbating environmental conditions that facilitate viral transmission [13,14]. ...
... These conditions could give rise to possible hotspots of contamination, promoting the establishment and development of rodent populations (Battersby et al. 2002). For example, nonhermetic constructions allow rodents to enter dwellings, while unpaved streets, broken pipes, and the absence of proper storm sewers (with missing catch basins or broken manholes) facilitate the invasion and dispersal of rodents throughout the urban environment, thereby increasing the risk of exposure to vector-borne and zoonotic pathogens (Costa et al. 2017;Panty May 2016, Lau et al. 2010. Under this scenario, urbanization works that include infrastructural improvements -such as enhancing sidewalks, providing potable water supply and satisfactory sewage connectionsmust be prioritized to improve the quality of life of the residents. ...
Rats are a problem in cities worldwide, particularly in low-income neighborhoods. Urbanization works (e.g. construction, excavations, demolition, etc.) in these neighborhoods must be a priority to improve the quality of life of their residents. The disturbances generated by these works can destroy the habitats of rodents, forcing them to seek new shelters in nearby areas, such as homes and human structures, taking advantage of rubble and construction materials that offer ideal conditions for their survival. However, limited research has focused on how infrastructural works affect the dispersion of rodents to surrounding areas. The current study aimed to evaluate the effectiveness of a rodent control program implemented during infrastructural works and its effect on the spatiotemporal dynamics of rodent population in a low-income neighborhood in Buenos Aires, Argentina. For three months, multiple infrastructural works were carried out in the neighborhood. Rodent control measures and estimation of rodent activity were carried out jointly by installing chemical box stations and contact glue traps throughout the neighborhood. We carried out a generalized additive mixed model to assess spatiotemporal changes and identify factors influencing rodent activity during the infrastructural intervention. Our results revealed that the proximity to construction works affected rodent activity, with higher infestations closer to work sites. However, after the initial 30-day period, rodent activity increased with distance. Also, remote sites located more than 150 m away exhibited a constant level of rodent activity throughout the entire study period. The findings suggest that rodent control strategies should prioritize control interventions within a 150-meter radius for at least the first month following the commencement of construction works. This ecological knowledge contributes to form a robust framework for evidence-based rat management in urban environments and provides valuable insights for urban planners, pest control professionals, and public health authorities.
... Leptospirosis accounts for more than one million human cases and 60,000 deaths per year worldwide (6), and incidence rates are likely underestimated (7,8). Recent occurrences of extreme climatic events are anticipated to exacerbate its global burden (9). ...
Leptospirosis, caused by pathogenic bacteria from the genus Leptospira, is a global zoonosis responsible for more than one million human cases and 60,000 deaths annually. The disease also affects many domestic animal species. Historically, genetic manipulation of Leptospira has been difficult to perform, resulting in limited knowledge on pathogenic mechanisms of disease and the identification of virulence factors. The application of CRISPR/Cas9 and its variations have helped fill these gaps but the generation of knockout mutants remains challenging because double-strand breaks (DSBs) inflicted by Cas9 nuclease are lethal to Leptospira cells. The novel CRISPR prime editing (PE) strategy is the first precise genome-editing technology that allows deletions, insertions, and base substitutions without introducing DSBs. This revolutionary technique utilizes a nickase Cas9 that cleaves a single strand of DNA, coupled with an engineered reverse transcriptase and a modified single-guide RNA (termed prime editing guide RNA) containing an extended 3′ end with the desired edits. We demonstrate the application of CRISPR-PE in both saprophytic and pathogenic Leptospira from multiple species and serovars by introducing deletions or insertions into target DNA with a remarkable precision of just one nucleotide. Additionally, we demonstrate the ability to genetically manipulate Leptospira borgpetersenii, a prevalent pathogenic species of humans, domestic cattle, and wildlife animals. Rapid plasmid loss by mutated strains in liquid culture allows for the generation of knockout strains without selective markers, which can be readily used to elucidate virulence factors and develop optimized bacterin and/or live vaccines against leptospirosis.
IMPORTANCE
Leptospirosis is a geographically widespread bacterial zoonosis. Genetic manipulation of pathogenic Leptospira spp. has been laborious and difficult to perform, limiting our ability to understand how leptospires cause disease. The application of the CRISPR/Cas9 system to Leptospira enhanced our ability to generate knockdown and knockout mutants; however, the latter remains challenging. Here, we demonstrate the application of the CRISPR prime editing technique in Leptospira, allowing the generation of knockout mutants in several pathogenic species, with mutations comprising just a single nucleotide resolution. Notably, we generated a mutant in the Leptospira borgpetersenii background, a prevalent pathogenic species of humans and cattle. Our application of this method opens new avenues for studying pathogenic mechanisms of Leptospira and the identification of virulence factors across multiple species. These methods can also be used to facilitate the generation of marker-less knockout strains for updated and improved bacterin and/or live vaccines.
The flood exposure in India exacerbates childhood malnutrition, particularly in the vulnerable regions of India. Presently, India is facing a dual burden of natural disasters and malnutrition, especially in the vulnerable regions that are exposed to floods. Many studies have been focused on micro-level or regional-level analyses. The present study is uniquely examining the association between flood exposure and malnutrition at a national scale. The
study investigated the impacts of flood exposure on childhood malnutrition, using the Composite Index of Anthropometric Failure (CIAF) to assess stunting, wasting, and underweight among children under five years age group. The present study is based on the analyses of data from the National Family Health Survey (NFHS-5, 2019–2021) and Central Water Commission (CWC) reports. The data were analyzed across flood-affected regions
in India and categorized by the frequency of flood events (i.e., non-flooded; 1–2 times flooded; and three times flooded events). The analysis reveals a significant increase in malnutrition rates with higher flood exposure in regions experiencing three flood events, 38 percent of children were stunted, 20 percent were wasted, and 35.7 percent were underweight as compared to non-flooded areas. Factors such as low birth weight, maternal edu
cation, sanitation facilities, and household infrastructure intensified malnutrition outcomes. The major findings of the study suggested that repeated flooding events aggravate food insecurity and increase vulnerability to child malnutrition. This study not only highlights the compounded effects of flood exposure and socio-economic disparities on CIAF malnutrition but also offers policy-relevant insights. The results of the study highlight the urgent need for targeted interventions, including developing disaster-resilient infrastructure, educational programs for mothers, and enhanced access to sanitation and healthcare in flood-affected regions in India
Background
Leptospirosis is an endemic disease in countries with tropical climates such as South America, Southern Asia, and Southeast Asia. There has been an increase in leptospirosis incidence in Malaysia from 1.45 to 25.94 cases per 100,000 population between 2005 and 2014. With increasing incidence in Selangor, Malaysia, and frequent climate change dynamics, a study on the disease hotspot areas and their association with the hydroclimatic factors could enhance disease surveillance and public health interventions.
Methods
This ecological cross-sectional study utilised a geographic information system (GIS) and remote sensing techniques to analyse the spatiotemporal distribution of leptospirosis in Selangor from 2011 to 2019. Laboratory-confirmed leptospirosis cases ( n = 1,045) were obtained from the Selangor State Health Department. Using ArcGIS Pro, spatial autocorrelation analysis (Moran’s I) and Getis-Ord Gi* (hotspot analysis) was conducted to identify hotspots based on the monthly aggregated cases for each subdistrict. Satellite-derived rainfall and land surface temperature (LST) data were acquired from NASA’s Giovanni EarthData website and processed into monthly averages. These data were integrated into ArcGIS Pro as thematic layers. Machine learning algorithms, including support vector machine (SVM), Random Forest (RF), and light gradient boosting machine (LGBM) were employed to develop predictive models for leptospirosis hotspot areas. Model performance was then evaluated using cross-validation and metrics such as accuracy, precision, sensitivity, and F1-score.
Results
Moran’s I analysis revealed a primarily random distribution of cases across Selangor, with only 20 out of 103 observed having a clustered distribution. Meanwhile, hotspot areas were mainly scattered in subdistricts throughout Selangor with clustering in the central region. Machine learning analysis revealed that the LGBM algorithm had the best performance scores compared to having a cross-validation score of 0.61, a precision score of 0.16, and an F1-score of 0.23. The feature importance score indicated river water level and rainfall contributes most to the model.
Conclusions
This GIS-based study identified a primarily sporadic occurrence of leptospirosis in Selangor with minimal spatial clustering. The LGBM algorithm effectively predicted leptospirosis hotspots based on the analysed hydroclimatic factors. The integration of GIS and machine learning offers a promising framework for disease surveillance, facilitating targeted public health interventions in areas at high risk for leptospirosis.
Animals and humans have lived alongside and interacted with one another for
millennia and yet little is understood of such interactions. Although the majority of such interactions have a positive impact on humans, not all are positive or beneficial to humans with some of them leading to disease transmission to humans.
The objectives of this research were to 1) identify how dogs interact with humans
across and their implications for conservation in developing landscapes such as rural Madagascar, 2) investigate the geographic count variation in leptospiral occurrence using a set of animal-host, environmental and socioeconomic regressors across Florida, and 3) Further, consider the risk factors responsible for the transmission of possible zoonotic diseases and describe their direct and indirect costs to individuals in a village in Madagascar.
Results support the hypothesis that some interactions between humans and animals
can have adverse effects on humans by causing the transmission of several zoonotic diseases (zoonoses) such as leptospirosis, plague, Severe Acute Respiratory Syndrome (SARS), Zika, etc. Such interactions between humans and animals might increase due to expanding human and animal populations and their increased contact.
BACKGROUND
Leptospirosis is among transfusion transmissible infections but is not screened routinely among blood donors and is endemic in Southern India. The presence of carrier state and the donors being asymptomatic may lead to transfusion transmission in the absence of screening. We aimed to study the prevalence of leptospirosis among blood donors and to assess the need to implement screening strategies for its detection.
METHODS
A prospective observational study was conducted among blood donors using Purposive sampling to select donors for the study. The samples collected for routine transfusion transmissible infections screening were used to screen for Ig M antibodies to leptospira infection by Enzyme linked immunosorbent assay (ELISA) method. Samples that were reactive twice were true positive. These donors were contacted telephonically to enquire if they developed any symptoms of the infection.
RESULTS
A total of 3576 came for blood donation during the study period of which 124 participated in the study. Among the 124 donors screened, a total of seven samples (5.64%) samples were found to be reactive for IgM Leptospira antibodies. The mean age of the donors that were found to be reactive was 27.5 years (SD: 3.15, Range: 20-45 years) with a male to female ratio of 6:1. All these donors were asymptomatic before or after seven days and 2 weeks of blood donation.
CONCLUSION
Approximately six out of 100 donors screened were positive for IgM antibodies of Leptospira without any symptoms. As there is a risk of transmission via blood transfusion, regular screening may be needed at least in areas of high prevalence.
A leptospirose é uma doença infecciosa que afeta diversos mamíferos, incluindo gatos domésticos (Felis catus), causada pela bactéria gram-negativa do gênero Leptospira. Esta bactéria apresenta potencial zoonótico e tem a capacidade de permanecer viável por meses na água e em solos úmidos, sendo transmitida indiretamente por água e solos contaminados ou diretamente pela urina. Roedores, são reservatórios e disseminadores potenciais. Em gatos, a infecção por Leptospira spp. é menos estudada comparado a outras espécies. Gatos infectados, especialmente os com sistema imunológico comprometido, podem apresentar sinais clínicos associados a distúrbios renais e hepáticos. Os principais fatores de risco incluem a persistência do agente no ambiente, sazonalidade e o elevado grau de variação antigênica e a capacidade de sobrevivência da bactéria. Gatos errantes têm maior probabilidade de entrar em contato com a Leptospira spp. devido à exposição a ambientes contaminados e ao hábito de caça de roedores. Este estudo revisou a literatura relacionada à leptospirose em gatos, discutindo aspectos epidemiológicos, clínicos, diagnósticos e terapêuticos da leptospirose.
This study focuses on the prevention of dengue and leptospirosis in vulnerable populations in the riverside area of the city of Santa Fe, Argentina, comparing the effectiveness of vector and reservoir control strategies through participatory interventions with a community approach, compared to traditional vertical strategies in riverside areas of Santa Fe. In the face of the hegemonic sanitary and medical model, it is necessary to provide more knowledge on the effectiveness of other possible forms of prevention, based on critical, socio-ecological, participatory models and approaches, which occur at the local scale, in the territories inhabited by the community. The methodology of the study comprised a quali-quantitative, randomized, controlled community trial with local community action. Two representative zones were selected from riverside sectors of Santa Fe, which share similar socioeconomic indices. In one area, participatory interventions were applied based on participatory action research, Citizen Science, and SEPA (Sociabilization of Evidence for Action) approaches. Simultaneously, and as a control, vertical and centralized prevention mechanisms were applied in the other zone. In order to make comparisons of effectiveness, a characterization of the socio-environmental, sanitary, vector and reservoir conditions, and knowledge, attitudes and practices regarding these diseases was carried out in both zones, at pre- and post-intervention times.In exploratory analyses of the data collected, significant rates of change were found between both zones post-intervention, and a significant effect of the participatory interventions for response variables of health importance in dengue. Sampling for leptospirosis remains to be done
In the past decade, leptospirosis has emerged as a globally important infectious disease. It occurs in urban environments of industrialised and developing countries, as well as in rural regions worldwide. Mortality remains significant, related both to delays in diagnosis due to lack of infrastructure and adequate clinical suspicion, and to other poorly understood reasons that may include inherent pathogenicity of some leptospiral strains or genetically determined host immunopathological responses. Pulmonary haemorrhage is recognised increasingly as a major, often lethal, manifestation of leptospirosis, the pathogenesis of which remains unclear. The completion of the genome sequence of Leptospira interrogans serovar lai, and other continuing leptospiral genome sequencing projects, promise to guide future work on the disease. Mainstays of treatment are still tetracyclines and beta-lactam/cephalosporins. No vaccine is available. Prevention is largely dependent on sanitation measures that may be difficult to implement, especially in developing countries.
Self-organising systems adapt to environmental change, and this ability modulates the relationship between specific exposures and outcomes. Vulnerability can be thought of as the sensitivity of the system to multiple exposures, taking into account the system’s ability to adapt. This paper describes 5 causes of vulnerability to climate change in the Asia Pacific region: destructive growth, poverty, political rigidity, dependency and isolation. Impoverished populations are always at greater risk because they have fewer choices. However, rapid increases in population size, density of settlement and use of natural resources may also compromise responsiveness by damaging the buffering capacity of ecological systems against environmental adversity. Public health depends on a responsive social order. Political rigidity may have contributed to recent, severe impacts of climate-related disasters in parts of Asia. Dependency (such as reliance on others for information) is a potent cause of vulnerability because it justifies fatalism. Geographically isolated countries are tied firmly to international fortunes by the increased mobility of people and goods. In these modern circumstances remoteness may be a liability. Vulnerability to climate change will be shaped by many factors, but effects on health will undoubtedly be most severe in populations that are already marginal. For these populations, climate change is one further cause of ‘over-load’. The problem of human-induced climate change is global in extent and is long term, but that should not deter policy-makers—measures taken to reduce the future impact of climate change will bring other benefits sooner.
Overwhelming evidence shows that climate change presents growing threats to public health security - from extreme weather-related disasters to wider spread of such vector-borne diseases as malaria and dengue. The impacts of climate on human health will not be evenly distributed around the world. The Third Assessment Report (Intergovernmental Panel on Climate Change-2001) concluded that vulnerability to climate change is a function of exposure, sensitivity, and adaptive capacity. Developing country populations, particularly in small island states, arid and high mountain zones, and in densely populated coastal areas are considered to be particularly vulnerable. India is a large developing country, with the Great Himalayas, the world's third largest ice mass in the north, 7500 km long, and densely populated coast line in the south. Nearly 700 million of her over one billion population living in rural areas directly depends on climate-sensitive sectors (agriculture, forests, and fisheries) and natural resources (such as water, biodiversity, mangroves, coastal zones, grasslands) for their subsistence and livelihoods. Heat wave, floods (land and coastal), and draughts occur commonly. Malaria, malnutrition, and diarrhea are major public health problems. Any further increase, as projected in weather-related disasters and related health effects, may cripple the already inadequate public health infrastructure in the country. Hence, there is an urgent need to respond to the situation. Response options to protect health from effects of climate change include mitigation as well as adaptation. Both can complement each other and together can significantly reduce the risks of climate change.
Leptospirosis is a zoonotic disease that has emerged as an important cause of morbidity and mortality among impoverished populations. One hundred years after the discovery of the causative spirochaetal agent, little is understood about Leptospira spp. pathogenesis, which in turn has hampered the development of new intervention strategies to address this neglected disease. However, the recent availability of complete genome sequences for Leptospira spp. and the discovery of genetic tools for their transformation have led to important insights into the biology of these pathogens and their pathogenesis. We discuss the life cycle of the bacterium, the recent advances in our understanding and the implications for the future prevention of leptospirosis.
Leptospirosis is a worldwide zoonotic infection that has been recognized for decades, but the problem of the disease has not been fully addressed, particularly in resource-poor, developing countries, where the major burden of the disease occurs. This paper presents an overview of the current situation of leptospirosis in the region. It describes the current trends in the epidemiology of leptospirosis, the existing surveillance systems, and presents the existing prevention and control programs in the Asia Pacific region.
Data on leptospirosis in each member country were sought from official national organizations, international public health organizations, online articles and the scientific literature. Papers were reviewed and relevant data were extracted.
Leptospirosis is highly prevalent in the Asia Pacific region. Infections in developed countries arise mainly from occupational exposure, travel to endemic areas, recreational activities, or importation of domestic and wild animals, whereas outbreaks in developing countries are most frequently related to normal daily activities, over-crowding, poor sanitation and climatic conditions.
In the Asia Pacific region, predominantly in developing countries, leptospirosis is largely a water-borne disease. Unless interventions to minimize exposure are aggressively implemented, the current global climate change will further aggravate the extent of the disease problem. Although trends indicate successful control of leptospirosis in some areas, there is no clear evidence that the disease has decreased in the last decade. The efficiency of surveillance systems and data collection varies significantly among the countries and areas within the region, leading to incomplete information in some instances. Thus, an accurate reflection of the true burden of the disease remains unknown.
Leptospirosis outbreaks occur frequently in North and South Andaman Islands but not in Middle Andaman. In 2002, an outbreak appeared in Middle Andaman for the first time. Although a study on risk factors was conducted in North Andaman, it used seropositivity to define leptospirosis. Since seropositivity might not indicate current leptospiral infection and as no study on risk factors was conducted in Middle Andaman, we carried out this study to identify the risk factors during the outbreak.
A suspected outbreak of leptospirosis occurred in Rangat of Middle Andaman during October - November 2002. Suspected cases were screened for leptospirosis using microscopic agglutination test (MAT). Fifty two patients confirmed to have leptospirosis based on rising titres in MAT on paired sera, and 104 age, sex and neighbourhood seronegative matched controls, were included in the study. A conditional multiple regression by backward elimination process was carried out with acute leptospirosis as the dependent factor and various environmental, occupational and behavioural factors as independent factors. A stratified analysis was also carried out.
The presence of cattle in the house, drinking stream water, contact with garbage, walking barefoot and standing in water while working were identified as significant factors associated with leptospirosis. Stratified analysis showed a dose response relationship between number of cattle in the house and the risk of leptospiral infection suugesting that cattle could be a source of infection.
Identification of the potential risk factors would help understand the transmission dynamics of the disease and formulate public health interventions.
Between August and November 2006, a population-based case control study was conducted to identify the probable risk factors for leptospirosis during flooding in Surat city.
Sixty-two laboratory confirmed cases out of 129 suspected cases, and 253 age and sex matched fever and healthy controls were interviewed with the help of predesigned questionnaire. The association of risk factors with acquiring leptospirosis was assessed by adjusted OR with the help of logistic regression model to control confounders.
By univariate analysis, factors identified were, walking barefoot (OR = 10.34, 95% CI 5.09-21.31, P <0.05).
Prompt and vigilant fever surveillance activities in pre-monsoon preparedness plan, intensive IEC messages, rodent control programs and improvement of environmental sanitary conditions may help to greatly reduce the incidence of leptospirosis.
There is scarce data on the burden of leptospirosis and its epidemiological characteristics in Argentina. This study aimed to evaluate distribution of leptospirosis cases and identify risk factors for the disease during national laboratory-based surveillance. From January 1999 to December 2005, 812 suspected cases were referred to the national reference laboratory, of which 182 and 463 had respectively, laboratory confirmed and unconfirmed diagnosis of leptospirosis. The diagnosis of leptospirosis was discarded in 167 cases. The most prevalent presumptive infecting serogroup was Icterohaemorrhagie followed by Pomona, Ballum and Canicola. The majority of cases occurred during the worm and rainy months. Confirmed cases were predominantly adults and males, who presented with fever, headache and myalgias. Severe clinical manifestations included jaundice and acute renal insufficiency. Conjunctival suffusion, a hallmark clinical sign of leptospirosis, was found in 55% of confirmed cases, and 43% of the cases with discarded diagnosis (p=0.036). After multivariate analyses, age >30 years (OR=2.16; 1.05-4.41), occupation in a rural setting (OR=3.41; 1.45-8.06), contact with contaminated surface water (OR=2.17; 1.01-4.68), and contact with floods (OR=4.49; 1.17-17.25) were significantly associated with leptospirosis. In conclusion, although activities associated with rural occupations remain important risk factors in Argentina, exposures occurring during flooding events have emerged to be the major risk factor for leptospirosis.
An automated enzyme-linked immunosorbent assay detecting specific immunoglobulin M in infections with Leptospira interrogans serovar hardjo was evaluated on 69 patients. The test was sensitive and simple to perform, requiring a single dilution of test serum, with data expressed as units of antibody activity interpolated from a reference serum pool.
In October 1995, epidemic “hemorrhagic fever,” without jaundice or renal manifestations was reported in rural Nicaragua following
heavy flooding; 2259 residents were evaluated for nonmalarial febrile illnesses (cumulative incidence, 6.1%) and 15 (0.7%)
died with pulmonary hemorrhage. A case-control study found that case-patients were more likely than controls to have ever
walked in creeks (matched odds ratio [MOR], 15.0; 95% confidence interval [CI], 1.7–132.3), have household rodents (MOR, 10.4;
95% CI, 1.1 -97.1), or own dogs with titers ≥400 to Leptospira species (MOR, 23.4; 95% CI, 3.6–∞). Twenty-six of 51 case-patients had serologic or postmortem evidence of acute leptospirosis.
Leptospira species were isolated from case-patients and potential animal reservoirs. This leptospirosis epidemic likely resulted from
exposure to flood waters contaminated by urine from infected animals, particularly dogs. Leptospirosis should be included
in the differential diagnosis for nonmalarial febrile illness, particularly during periods of flooding or when pulmonary hemorrhage
occurs.
Leptospirosis has rarely been reported in Puerto Rico, although in the period from 1948 to 1952, 208 cases of leptospirosis and an island-wide seroprevalence of antibody to Leptospira of 14% were documented. In Puerto Rico in October 1996, following rainfall and a period of flooding generated by Hurricane Hortense, serum specimens of 4 patients with suspected dengue fever that were negative for dengue tested positive for Leptospira-specific IgM antibodies in a dipstick assay. Subsequently, we used an island-wide dengue laboratory-based surveillance system to determine the increase in leptospirosis after hurricane-generated floods. All anti-dengue IgM-negative patients (n = 142) with disease onset from August 8 to October 6, 1996 from prehurricane and posthurricane groups were investigated for leptospirosis. Laboratory-confirmed leptospirosis cases were defined as microscopic agglutination test titers > or = 1 :400 to 1 or more serovars, or positive immunohistochemistry in autopsy tissues. Four (6%) of 72 prehurricane and 17 (24%) of 70 posthurricane patients had laboratory-confirmed cases of leptospirosis (relative risk [RR] = 4.4, 95% confidence interval [CI] = 1.6-12.4). The mean age of case-patients was 34 years (range = 13-64). Eighteen (86%) of 21 confirmed case-patients were males, including one patient who died (31 years old). Patients were located in 18 (38%) of 48 municipalities that submitted serum samples. Clinical features significantly associated with leptospirosis were eye pain (RR = 1.5, 95% CI = 1.3-1.9), joint pain (RR = 1.4, 95% CI = 1.1-1.6), diarrhea (RR = 1.7, 95% CI = 1.2-2.5), and jaundice (RR = 3.3, 95% CI = 1.5-7.2). This study demonstrates the utility of a dengue laboratory-based surveillance system for the detection of an increase of leptospirosis, which most likely would have gone unrecognized. Leptospirosis is treatable with antibacterial agents; knowledge of this diagnosis may significantly reduce morbidity and mortality.
The relationship between serologically confirmed cases of leptospirosis and the amount of rainfall in greater Florianôpolis, in southern Brazil, was studied retrospectively for the period 1991 to 1996. Maximum daily and total monthly rainfall for present and previous months were statistically significant predictors of the number of cases of leptospirosis in Poisson regression models. However, daily maximum rainfall data showed a much better model fit than total monthly rainfall. For each millimeter increase in maximum daily rainfall for the month above the average for the period studied, there was an increase of 0.55% in the number of leptospirosis cases relative to the period average. For the past month's daily maximum, this increase was 0.21%. Maximum daily rainfall during the month is a sensitive indicator of large amounts of rain falling in a brief period of time. This may cause flash floods and, thus, disseminate pathogenic Leptospira among the human population, particularly in densely populated areas with large rodent populations and without adequate drainage. This situation is typical for the association of tropical rainstorms and the spread of leptospirosis among slum dwellers.
An assay device for the rapid detection ofLeptospira-specific immunoglobulin M (IgM) antibodies in human sera is presented. The sensitivity (85.8%) and specificity (93.6%) of
the assay compared well (91.9% agreement) with those of an IgM enzyme-linked immunosorbent assay routinely used in the serodiagnosis
of leptospirosis. The sensitivity of the assay varied with the stage of the disease. The assay uses stabilized components
and is simply performed by the addition of serum and sample fluid to the sample well of the assay device. The assay is read
after 10 min, and a positive result is obtained when staining of the test line is observed.
Freshwater resources are a high-priority issue in the Pacific region. Water shortage is a serious problem in many small island states, and many depend heavily on rainwater as the source of their water. Lack of safe water supplies is an important factor in diarrheal illness. There have been no previous studies looking specifically at the relationship between climate variability and diarrhea in the Pacific region. We carried out two related studies to explore the potential relationship between climate variability and the incidence of diarrhea in the Pacific Islands. In the first study, we examined the average annual rates of diarrhea in adults, as well as temperature and water availability from 1986 to 1994 for 18 Pacific Island countries. There was a positive association between annual average temperature and the rate of diarrhea reports, and a negative association between water availability and diarrhea rates. In the second study, we examined diarrhea notifications in Fiji in relation to estimates of temperature and rainfall, using Poisson regression analysis of monthly data for 1978-1998. There were positive associations between diarrhea reports and temperature and between diarrhea reports and extremes of rainfall. These results are consistent with previous research and suggest that global climate change is likely to exacerbate diarrheal illness in many Pacific Island countries.
Diseases such as plague, typhus, malaria, yellow fever, and dengue fever, transmitted between humans by blood-feeding arthropods, were once common in the United States. Many of these diseases are no longer present, mainly because of changes in land use, agricultural methods, residential patterns, human behavior, and vector control. However, diseases that may be transmitted to humans from wild birds or mammals (zoonoses) continue to circulate in nature in many parts of the country. Most vector-borne diseases exhibit a distinct seasonal pattern, which clearly suggests that they are weather sensitive. Rainfall, temperature, and other weather variables affect in many ways both the vectors and the pathogens they transmit. For example, high temperatures can increase or reduce survival rate, depending on the vector, its behavior, ecology, and many other factors. Thus, the probability of transmission may or may not be increased by higher temperatures. The tremendous growth in international travel increases the risk of importation of vector-borne diseases, some of which can be transmitted locally under suitable circumstances at the right time of the year. But demographic and sociologic factors also play a critical role in determining disease incidence, and it is unlikely that these diseases will cause major epidemics in the United States if the public health infrastructure is maintained and improved.
The environmental context in which a leptospirosis outbreak took place during the summer of 1996 in the Rio de Janeiro Western Region was examined by using spatial analysis of leptospirosis cases merged with socio-demographic data using Geographic Information System (GIS). Risk areas were mapped based on flood and solid waste accumulation information for the region. Incidence rates were calculated for each area by the division of number of cases per total population in the specific areas. Higher rates were observed for census tracts inside the flood risk area and in the vicinities of waste accumulation sites. These findings are in agreement with the expected risk of leptospirosis, evidencing the role of environmental and collective factors in the determination of the disease.
The objective was to describe the current epidemiology and trends in New Zealand human leptospirosis, using descriptive epidemiology of laboratory surveillance and disease notification data, 1990-8. The annual incidence of human leptospirosis in New Zealand 1990-8 was 44 per 100,000. Incidence was highest among meat processing workers (163.5/100,000), livestock farm workers (91.7), and forestry-related workers (24.1). The most commonly detected serovars were Leptospira borgpetersenii serovar (sv.) hardjo (hardjobovis) (46.1%), L. interrogans sv. pomona (24.4%) and L. borgpetersenii sv. ballum (11.9%). The annual incidence of leptospirosis declined from 5.7/100,000 in 1990-2 to 2.9/100,000 in 1996-8. Incidence of L. borgpetersenii sv. hardjo and L. interrogans sv. pomona infection declined, while incidence of L. borgpetersenii sv. ballum infection increased. The incidence of human leptospirosis in New Zealand remains high for a temperate developed country. Increasing L. borgpetersenii sv. ballum case numbers suggest changing transmission patterns via direct or indirect exposure to contaminated surface water. Targeted and evaluated disease control programmes should be renewed.
Leptospirosis is an important cause of fever in the rural tropics. Since 1996, there has been a marked increase in the incidence of leptospirosis in northeastern Thailand. Although leptospirosis generally is susceptible to antibiotics, there is no consensus regarding the optimal treatment for severe leptospirosis.
An open-label, randomized comparison of parenteral cefotaxime, penicillin G sodium (hereafter known as "penicillin G"), and doxycycline for the treatment of suspected severe leptospirosis was conducted. The study involved 540 patients admitted to 4 hospitals in northeastern Thailand.
A total of 264 patients (48.9%) had leptospirosis confirmed by serologic testing or culture. The overall mortality rate was 5%. There were no significant differences between the antibiotics with regard to associated mortality, defervescence, or time to resolution of abnormal findings of laboratory tests either among all study participants or among the subgroup of patients with confirmed leptospirosis. A total of 132 patients had rickettsial infection diagnosed, and, for these patients, treatment with doxycycline was superior to treatment with penicillin G.
Doxycycline or cefotaxime is a satisfactory alternative to penicillin G for the treatment of severe leptospirosis.
The complementary concepts QALYs and DALYs combine years of life and quality of life in a single measure.1–3 In Arnesen and Nord’s words: “QALYs are years of healthy life lived; DALYs are years of healthy life lost. Both approaches multiply the number of years (x axis) by the quality of those years (y axis). QALYs use “utility weights” of health states; DALYs use “disability weights” to reflect the burden of the same states. If the utility of deafness is …
Epidemiologic trends of human leptospirosis in Germany were investigated by analyzing national surveillance data from 1962 to 2003 and by conducting a questionnaire-based survey from 1997 to 2000. After a steady decrease of leptospirosis incidence from 1962 to 1997, surveillance data indicate an increase in disease incidence to 0.06 per 100,000 (1998-2003). Of 102 laboratory-confirmed cases in humans from 1997 to 2000, 30% were related to occupational exposures. Recreational exposures were reported in 30% (including traveling abroad in 16%), whereas residential exposure accounted for 37% of the cases. Direct contact with animals, mostly rats and dogs, was observed in 31% of the cases. We conclude that recent changes in transmission patterns of leptospirosis, partially caused by an expanding rat population and the resurgence of canine leptospirosis, may facilitate the spread of the disease in temperate countries like Germany. Preventive measures should be adapted to the changing epidemiology of leptospirosis.
Studies have shown that the urbanization of a catchment can drastically
change the flood characteristics of a river. Published results are
synthesized to show the general relationship between the increase in
flood flows following urbanization and both the percentage of the basin
paved and the flood recurrence interval. In general, (1) floods with a
return period of a year or longer are not affected by a 5% paving of
their catchment, (2) small floods may be increased by 10 times by
urbanization, (3) floods with a return period of 100 yr may be doubled
in size by a 30% paving of the basin, and (4) the effect of urbanization
declines, in relative terms, as flood recurrence intervals increase.
Climate change will affect the health of urban populations. It represents a range of environmental hazards and will affect populations where the current burden of climate-sensitive disease is high — such as the urban poor in low- and middle-income countries. Understanding the current impact of weather and climate variability on the health of urban populations is the first step towards assessing future impacts. In this paper, we have reviewed the scientific evidence for the effects of temperature, rainfall and extreme events on human health, in particular the impacts of heat waves and floods. The methods for assessing the risks of climate change are undergoing development, and there is a need to shift the focus from global and regional to local studies. Sectoral approaches to climate change impact assessments often ignore the effects on health. There is a need to better describe the risks to health from extreme weather events as well as improve the effectiveness of public health interventions. Improving the resilience of cities to climate change also requires improvements in the urban infrastructure, but such improvements may not be achieved quickly enough to avoid an increased burden of disease due to global climate change.
The increase observed in 1987 (443 cases) gives evidence of the actuality of leptospirosis in France ; the incidence of occupational diseases remains important but 60 % of cases originate from aquatic recreational activities. Icterohaemorrhagiae serovar prevails but serotypic spectrum is wide (17 serovars). Accordingly, clinical pictures are very polymorphic, neurologic forms are at least as frequent as classical triad “jaundice — febrile syndrome — renal failure”. In French Overseas Territories (Reunion, New Caledonia), leptospirosis in sometimes a public health problem. Lastly, the authors specify the conditions of a rational use of biological diagnosis in order to obtain a better evaluation of leptospirosis in France.
To develop improved estimates of (1) flooding due to storm surges, and (2) wetland losses due to accelerated sea-level rise, the work of Hoozemans et al. (1993) is extended to a dynamic analysis. It considers the effects of several simultaneously changing factors, including: (1) global sea-level rise and subsidence; (2) increasing coastal population; and (3) improving standards of flood defence (using GNP/capita as an “ability-to-pay” parameter). The global sea-level rise scenarios are derived from two General Circulation Model (GCM) experiments of the Hadley Centre: (1) the HadCM2 greenhouse gas only ensemble experiment and (2) the more recent HadCM3 greenhouse gas only experiment. In all cases there is a global rise in sea level of about 38 cm from 1990 to the 2080s. No other climate change is considered. Relative to an evolving reference scenario without sea-level rise, this analysis suggests that the number of people flooded by storm surge in a typical year will be more than five times higher due to sea-level rise by the 2080s. Many of these people will experience annual or more frequent flooding, suggesting that the increase in flood frequency will be more than nuisance level and some response (increased protection, migration, etc.) will be required. In absolute terms, the areas most vulnerable to flooding are the southern Mediterranean, Africa, and most particularly, South and South-east Asia where there is a concentration of low-lying populated deltas. However, the Caribbean, the Indian Ocean islands and the Pacific Ocean small islands may experience the largest relative increase in flood risk. By the 2080s, sea-level rise could cause the loss of up to 22% of the world's coastal wetlands. When combined with other losses due to direct human action, up to 70% of the world's coastal wetlands could be lost by the 2080s, although there is considerable uncertainty. Therefore, sea-level rise would reinforce other adverse trends of wetland loss. The largest losses due to sea-level rise will be around the Mediterranean and Baltic and to a lesser extent on the Atlantic coast of Central and North America and the smaller islands of the Caribbean. Collectively, these results show that a relatively small global rise in sea level could have significant adverse impacts if there is no adaptive response. Given the “commitment to sea-level rise” irrespective of any realistic future emissions policy, there is a need to start strategic planning of appropriate responses now. Given that coastal flooding and wetland loss are already important problems, such planning could have immediate benefits.
This review presents a theory and prototype for a neural controller called INFANT that learns sensory-motor coordination from its own experience. Three adaptive abilities are discussed: locating stationary targets with movable sensors; grasping arbitrarily positioned and oriented targets in 3D space with multijoint arms, and positioning an unforeseen payload with accurate and stable movements despite unknown sensor feedback delay. INFANT adapts to unforeseen changes in the geometry of the physical motor system, the internal dynamics of the control circuits and to the location, orientation, shape, weight, and size of objects. It learns to accurately grasp an elongated object with almost no information about the geometry of the physical sensory-motor system. This neural controller relies on the self-consistency between sensory and motor signals to achieve unsupervised learning. It is designed to be generalized for coordinating any number of sensory inputs with limbs of any number of joints. The principle theme of the review is how various geometries of interacting topographic neural fields can satisfy the constraints of adaptive behavior in complete sensory-motor circuits.
The study was designed to find out the epidemic characteristics of leptospriosis and to develop effective intervention measures. The effects of floods on leptospriosis in some areas along Yangzi river and Huai river in Anhui province was also analysed.
Study on serum epidemiology of leptospriosis was carried out from serous samples collected from native residents and animal hosts including isolation of pathogens at different phases (before,middle and after) and different monitoring spots,during the floods.
Infection rate with leptospriosis pathogen among native residents was 13.49% during the flood-period,much higher than 2.18% at post-flood (chi2 = 22.78, P < 0.01) stage, in the flood-affected areas along Yangzi river in 1998. The average rates of infection were 2.48% and 5.35% in affected and unaffected areas along Huai river respectively, in 2003.
There was full evidence that floods causing the epidemics of leptospriosis. However, the transmission of leptospriosis among people would depend on affecting factors as scales of floods, lasting time, coincidence between flood happening and epidemic season, immuno-protection level against leptospriosis among people and so on to a great extent. Factors as the magnitude of pathogens carried by various kinds of infectious sources were also important determinants affecting the nature, being epidemic or pandemic of leptospriosis. It was suggested that active surveillance network on the sources of infection and risk factors of leptospriosis should be developed for the control and prevention of the disease, in the flood-hit areas.
Long-term health impacts in communities that have experienced natural disasters are often overlooked. Recovery from natural disasters is often a long, drawn-out process. Recovery plans need to address these interruptions in the return to pre-disaster functioning and make provisions for addressing ongoing health problems. The following review will examine illness patterns that may arise, directly or indirectly, in the months and years following a disaster event. The objectives of the review are: (i) to identify the burden of long-term community ill-health following natural disaster events; (ii) to evaluate current gaps in the ongoing process of health monitoring for populations affected by disaster; (iii) to review approaches that would provide ongoing surveillance of physical and psychosocial ill-health.
The World Health Organization/Food and Agriculture Organization Collaborating Center for Reference and Research on Leptospirosis, Western Pacific Region, is part of Queensland Health Scientific Services, Queensland Health. In 1999 there was a marked increase in human leptospirosis notifications in North Queensland. Australia, over the period of January to May. There were 216 notifications for the state of Queensland in 1999, compared with 108 in 1998 and 64 in 1997. By April 1999, the Reference Laboratory and Queensland Health's Tropical Public Health Unit (TPHU), Cairns, had reported an outbreak of leptospirosis in North Queensland. Notifications reported for the North Queensland Health districts of Cairns, Tablelands and Innisfail were the highest, with the majority involving workers in the banana industry. The outbreak resulted from infections with a number of serovars, mostly attributed to serovars australis and zanoni. Sixty leptospiral isolates were obtained from human cases in North Queensland during the outbreak. The hospitalization rate was in excess of 50%. The Queensland Health's TPHU has implemented a program to educate target industries and the community on the risks and prevention strategies associated with leptospirosis.
A recent upsurge in leptospirosis in travellers has prompted the following review of the epidemiology of this infection in humans. The available data from the published literature as well as laboratory surveillance were examined to determine the possible causes of the apparent change in epidemiology.
A retrospective study to describe the epidemiology of human leptospirosis in Trinidad and Tobago during 1996-2007 was conducted. All confirmed cases of leptospirosis was analyzed according to age, sex, seasonality and geographic distribution. A total of 278 cases were recorded, with an average annual incidence rate of 1.84 per 100,000 population. Seventy-five percent of the cases occurred during the wet season, with the highest number of cases recorded in November. A positive correlation was found between number of cases and rainfall. Males constituted 80% of all cases, and the overall male:female ratio was 4.6:1. The total case fatality rate was 5.8%, with deaths among males four times more common than in females. Clinical leptospirosis was greatest in the 10-19 age group and lowest in the 0-9 age group. The total prevalence was 22 per 100,000 population, with the highest prevalence 41 per 100,000 recorded in the regional corporation of Sangre Grande and the lowest (6 per 100,000) in the city of Port of Spain. The lack of important information and active surveillance showed that the level of awareness of the disease is low in the country. The disease is still under-reported, and is considered to be of significant public health importance.
A leptospirosis epidemic affected New Caledonia during the first semester of 2008. A total of 135 cases were diagnosed with a relatively low fatality rate of 3.7%. Heavy rainfalls, related to La Niña, favoured this epidemic. The PCR, routinely used, confirmed 54% of the cases, and the microagglutination test 56%. Epidemiological and economical data on this epidemic are presented and discussed.
Epidémie de la leptospirose en Nouvelle-Calédonie: enjeux du diagnostic et charge de morbidité
Une épidémie de leptospirose a affecté la Nouvelle-Calédonie au cours du premier semestre de 2008. Un total de 135 cas ont été diagnostiqués avec un taux de létalité relativement faible de 3,7%. Des pluies abondantes liées à‘La Niña’ ont favorisé cette épidémie. La PCR utilisée en routine a confirmé 54% des cas et le test de microagglutination 56% des cas. Les données épidémiologiques et économiques sur cette épidémie sont présentées et discutées ici.
Brote de leptospirosis en Nueva Caledonia: cuestiones diagnósticas y carga de enfermedad
Una epidemia de leptospirosis afectó a Nueva Caledonia durante el primer semestre del 2008. Se diagnosticaron 135 casos con una tasa de fatalidad relativamente baja del 3.7%. Las lluvias torrenciales, relacionadas con La Niña, favorecieron esta epidemia. La PCR, utilizada rutinariamente, confirmó un 54% de los casos, y la prueba de microaglutinación un 56%. Se presentan y discuten los datos epidemiológicos y económicos sobre esta epidemia.
Thirteen patients with leptospirosis were identified, as confirmed by laboratory analysis during the last 5 years in our laboratory, who came from urban areas of Tokyo, Japan. All of the patients came into contact with rats before the onset of illness. Seventeen per cent of Norway rats captured in the inner cities of Tokyo carried leptospires in their kidneys. Most of these rat isolates were Leptospira interrogans serovar Copenhageni/Icterohaemorrhagiae. Antibodies against these serovars and their DNA were detected in the patients. This suggests that rats are important reservoirs of leptospirosis, and that rat-borne leptospires occur in urban areas of Tokyo.
Global changes, including an increase in trade and global warming, which act on the environment, are likely to impact on the evolution of pathogens and hence of diseases. To anticipate the risks created by this new situation, a French group of experts has developed a method for prioritising animal health risks. This is a two-phase method: the first step is to identify the diseases whose incidence or geographical distribution could be affected by the changes taking place, and the second step is to evaluate the risk of each of these diseases. As a result of this process, six priority diseases were selected: bluetongue, Rift Valley fever, West Nile fever, visceral leishmaniasis, leptospirosis and African horse sickness. The main recommendations were: to develop epidemiological surveillance, to increase knowledge of epidemiological cycles, to develop research into these diseases and to pool cross-border efforts to control them.
The effect of a 7-day course of intravenous penicillin (6 million units/day) on severe, advanced leptospirosis was examined in a randomised, placebo-controlled, double-blind trial involving 42 patients. Every measurable aspect of the disease was favourably affected by penicillin. Fever lasted more than twice as long in the placebo group (11.6 [SD 8.34] days vs 4.7 [4.19] days, p less than 0.005), and by the fourth day after starting penicillin more than half the treatment group, but only 1 of 19 in the placebo group, were afebrile (p less than 0.005). Creatinine rises persisted more than thrice as long in the patients receiving only placebo (8.3 [8.46] days vs 2.7 [1.90] days; p less than 0.01). Penicillin also shortened the hospital stay and prevented leptospiruria. Intravenous penicillin should be given to patients with severe leptospirosis, even if therapy can be begun only late in the course of their disease.
To study antibiotic efficacy, 29 patients with leptospirosis were treated in a randomized, double-blinded fashion with doxycycline, 100 mg orally twice a day, or placebo. Therapy was given for 7 days in a hospital, and patients were followed for 3 weeks afterwards. Duration of illness before therapy and severity of illness were the same in both groups. Doxycycline reduced the duration of illness by 2 days and favorably affected fever, malaise, headache, and myalgias. Treatment prevented leptospiruria and had no adverse effects. Doxycycline is effective in therapy for patients with leptospirosis.
We describe a series of 144 cases of leptospirosis diagnosed in 1989 in New Caledonia. The incidence rate was 90 per 100,000 person-years, with a specific mortality rate of 4% patients. Those affected (100 males, 44 females) were mainly aged 20 to 40 years. Incidence in rural areas (112 per 100,000 person-years) was seven times higher than in urban settlements. Two periods with higher incidence were noticed corresponding to highest rainfall. Twenty-nine of the cases occurred in individuals with professions commonly associated with leptospirosis. Contacts with rats, dogs and ditch or river water were the most frequently mentioned. The clinical expression of the disease was polymorphic: 60% of the patients had mild symptoms, 40% were acute forms including Weil's disease. Of 57 hospitalized, 23% were admitted with an initial diagnosis of dengue, and 37% with leptospirosis. Main clinical syndromes were: icterus and/or renal syndrome in 50% of patients, cardiac syndrome in 65%, acute myalgies in 58% and pulmonary syndrome in 50%. Although hemorrhages were uncommon (17%), 40% of the cases demonstrated thrombocytopenia (< 50,000/m3). Pancreatic involvement with hyperamylasemia was evidenced in 50% of cases. Twelve serogroups of Leptospira were implicated, Icterohaemorragiae predominated (41%), but was not associated with severe forms. In New Caledonia, like in all tropics, leptospirosis must be considered as an environmental diseases, professional activities being just an additional risk factor. Use of serology as a reliable tool for confirmation of cases in areas of high environmental contamination is discussed.
The potential health impacts of climate change are wide-ranging, from direct impacts at familiar local scales, through indirect effects occurring at the regional or ecosystem level, to long term effects on the sustainability of global systems. To assess these potential impacts, there is a need to broaden the scope of health impact assessment. Eco-epidemiology is emerging as a response to this need. Eco-epidemiology entails a shift in focus: from direct (toxicological) to indirect (ecological) mechanisms; and from effects occurring at 'human' temporal and geographical scales to those at regional and geophysical scales. We discuss the potential health impacts of climate change on each scale. At the global scale, interactions and feedbacks between systems are critical determinants of long term outcomes. From an eco-epidemiological perspective, the study of climate change becomes inseparable from the study of global change more generally.
A leptospirosis surveillance program was carried out for 12 months on the entire population of the Seychelles. Diagnosis was assessed by both microagglutination test and polymerase chain reaction (PCR) assay. In this population of 74,331, leptospirosis was clinically suspected in 125 subjects and confirmed in 75 patients (incidence of 101 per 100,000; 95% confidence interval = 79-126). Leptospirosis was more frequent in middle-aged males with environmental exposure. Eight serogroups were identified and Icterohaemorrhagiae (31%) and Hurstbridge (20%) were the most frequent. Hurstbridge, a recently identified new serogroup, was implicated in severe cases and death. Influenza-like forms accounted for 37% of the cases while jaundice, acute renal failure, and pulmonary hemorrhage occurred in 52%, 28%, and 19%, respectively. Death occurred in six patients and was related to pulmonary hemorrhage. The PCR result was positive after completion of treatment in eight patients, suggesting that the administered five-day course of penicillin may be inadequate to eradicate the bacteria.
In Western countries, leptospirosis is uncommon and mainly occurs in farmers and individuals indulging in water-related activities. In tropical countries, leptospirosis can be up to 1000 times more frequent and risk factors for this often severe disease may differ.
We conducted a one-year population-based matched case-control study to investigate the frequency and associated factors of leptospirosis in the entire population of Seychelles.
A total of 75 patients had definite acute leptospirosis based on microagglutination test (MAT) and polymerase chain reaction (PCR) assay (incidence: 101 per 100,000 per year; 95% confidence interval [CI]: 79-126). Among the controls, MAT was positive in 37% (past infection) and PCR assay in 9% (subclinical infection) of men aged 25-64 with manual occupation. Comparing cases and controls with negative MAT and PCR, leptospirosis was associated positively with walking barefoot around the home, washing in streams, gardening, activities in forests, alcohol consumption, rainfall, wet soil around the home, refuse around the home, rats visible around the home during day time, cats in the home, skin wounds and inversely with indoor occupation. The considered factors accounted for as much as 57% of the variance in predicting the disease.
These data indicate a high incidence of leptospirosis in Seychelles. This suggests that leptospires are likely to be ubiquitous and that effective leptospirosis control in tropical countries needs a multifactorial approach including major behaviour change by large segments of the general public.
Leptospirosis is a worldwide zoonotic infection with a much greater incidence in tropical regions and has now been identified as one of the emerging infectious diseases. The epidemiology of leptospirosis has been modified by changes in animal husbandry, climate, and human behavior. Resurgent interest in leptospirosis has resulted from large outbreaks that have received significant publicity. The development of simpler, rapid assays for diagnosis has been based largely on the recognition that early initiation of antibiotic therapy is important in acute disease but also on the need for assays which can be used more widely. In this review, the complex taxonomy of leptospires, previously based on serology and recently modified by a genotypic classification, is discussed, and the clinical and epidemiological value of molecular diagnosis and typing is also evaluated.
Two weeks after the cyclone during October-November 1999, several persons in Orissa suffered from a febrile illness with haemorrhagic manifestations. Serum samples from a few such patients tested positive for anti-leptospiral IgM antibodies. We conducted a study in four villages that were flooded after the cyclone to examine the possibility of leptospirosis being the cause of the outbreak.
One hundred forty-two persons living in four flooded villages in the Jaipur district of Orissa were interviewed for their disease history and possible risk factors after the cyclone. Blood samples were collected and tested for anti-leptospiral antibodies using the microscopic agglutination test, IgM ELISA and lepto-dipstick. Follow up samples were collected from those who had inconclusive results on the first test and the microscopic agglutination test was repeated on these samples.
Eighty-four of the 142 study subjects had suffered a febrile illness and 40 of them had positive results in one or more IgM-based tests and 28 had a positive microscopic agglutination test result as well. Thus, 19.2% of the study subjects (28/142) had serological evidence of symptomatic leptospiral infection after the cyclone. Also, 8.5% of the subjects had low levels of antibodies indicative of the level of background seroprevalence.
The results indicate that there was an outbreak of leptospirosis in the flooded villages and the attack rate was high. A carrier state might have existed in the animal population and the cyclone and floods changed the environment drastically making it conducive for transmission of infection. Large numbers of persons were continuously exposed to flood waters and this resulted in the outbreak.
The health effects of climate change will affect vulnerable low income populations first, and this review provides convincing evidence of the public health importance of monitoring hotspots of climate change and health.
A prospective, open-label, randomized trial at Khon Kaen Hospital (Thailand) was conducted from July 2000 through December
2001 to compare the clinical efficacies of ceftriaxone and sodium penicillin G for the treatment of severe leptospirosis.
A total of 173 patients with severe leptospirosis were randomly assigned to be treated with either intravenous ceftriaxone
(1 g daily for 7 days; n = 87) or intravenous sodium penicillin G (1.5 million U every 6 h for 7 days; n = 86). The primary outcome was time to fever resolution. Survival analysis demonstrated that the median duration of fever
was 3 days for both groups. Ten patients (5 in each group) died of leptospirosis infection. There were no statistically significant
differences in the duration of organ dysfunction. Ceftriaxone and sodium penicillin G were equally effective for the treatment
of severe leptospirosis. Once-daily administration and the extended spectrum of ceftriaxone against bacteria provide additional
benefits over intravenous penicillin.
Our review of the literature on leptospirosis in Vanatu turned up only one previous report describing 3 cases at the Central Port Vila Hospital in 1992. The purpose of this report is to describe 8 cases of leptospirosis in patients admitted to the North District Hospital on Espiritu Santo Island in 1997. There were 6 men and 2 women with a mean age of 45 +/- 16 years. At the onset of the disease patients presented fever, myalgia, and diarrhea. After an average of four days initial symptoms were followed by visceral involvement with severe jaundice in all cases. Kidney failure occurred in 6 cases and neurological manifestations in 5. Subconjunctival hemorrhage was observed in 2 cases. Laboratory studies demonstrated hyperleukocytosis in 6 cases and liver enzyme abnormalities in 6 cases. Three patients presented Weil syndrome. Microscopic agglutination testing performed more than a week after the onset of disease was positive at 1/800 in 6 cases and at 1/200 with typical clinical abnormalities and positive serum PCR in 2 cases. All patients responded favorably to antimicrobial therapy using penicillin IV and symptomatic treatment. The estimated incidence of leptospirosis in the North District of the Island of Espiritu Santo, in 1997 was 40/100,000 person-year but this was probably an underestimation because of unawareness of the disease, poor access to medical care, and underdiagnosis.