Publications (23)154.54 Total impact
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Article: An extensive ultrasound and serologic study to investigate the prevalence of human cystic echinococcosis in northern Libya.
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ABSTRACT: A prevalence study of abdominal cystic echinococcosis (CE) was undertaken in the northwest, north-central, and northeast regions of Libya. A total of 36 villages along the coast were included, in which 20,220 people were screened by portable ultrasound. Three hundred thirty-nine (1.7%) were diagnosed with CE. There was no significant difference between CE prevalence rates in the three regions of Libya (mean = 1.6%); however, intervillage rates were variable, ranging from 0% to 4.5%. The prevalence of CE increased significantly with age (P < 0.0001) and females were significantly more affected (2%) than males (1.3%) (P < 0.0001). Cases of CE were distributed among 3.2% of housewives, 2.6% of farmers, 2.3% of male civil servants, 1.3% of female students, and 1.1% of male students. Housewives (P < 0.0001) and students (P < 0.0001) were significantly more at risk for CE. A statistically significant proportion (62% [210 of 339]) of CE cases kept dogs (P < 0.0001). Of the ultrasound-positive CE cases 69% (233 of 339) were antibody seropositive by ELISA using Echinococcus granulosus hydatid cyst fluid antigen B. Blood samples (n = 10,096) collected onto filter papers were taken randomly from ultrasound-negative people who entered the study, of which 11.2% were found to be seropositive. Seropositivity increased with age (P < 0.0001), with females exhibiting higher seroprevalence than males for all age groups (P < 0.0001). Seroprevalence was distributed occupationally among 17.3% of female students, 11.2% of male students, 8.3% of housewives, 7.3% of farmers, and 6.4% of male civil servants. Housewives and students were more likely to be seropositive (P < 0.0001). Forty-seven percent (526) of the seroreactors kept dogs. All liver hydatid cysts detected by ultrasound during community screening were classified according to morphology and size into six types. Type I (17.5% of all cases) were small univesicular cysts less than 50 mm in diameter with no laminations or daughter cysts. Type II (34%) were univesicular cysts with only laminations. Type IIIa (8.5%) were univesicular cysts with the appearance of laminations and daughter cysts. Type IIIb (13%) were univesicular with laminations and less prominent daughter cysts. Type IV (5.6%) presented as a solid mass. Type V were degenerated calcified or partially calcified cysts (13.2%). Type VI presented as multiple cysts (8% of all cases). The CE cases that exhibited Types II, IIIa, IIIb, IV or VI cysts showed the highest seropositivity (86%, 96%, 95%, 100%, and 96%, respectively), while Types I and V were the least seroreactive (38% and 22%, respectively). Cases of CE occurred in 311 families, with 93% having only one member as a CE case while 7% of the families had two or more cases. However, 25% of the ultrasound-negative persons belonging to families with an index CE case were seropositive for antibodies to Echinococcus. These results confirm the importance of human CE in Libya. They also confirm the usefulness of ultrasound combined with serology as a mass screening approach for CE in north African communities.The American journal of tropical medicine and hygiene 03/1999; 60(3):462-8. · 2.59 Impact Factor -
Article: The potential of vervet monkeys (Cercopithecus aethiops) and baboons (Papio anubis) as models for the study of the immunology of Echinococcus granulosus infections.
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ABSTRACT: Nine vervet monkeys and nine baboons were infected with eggs of Echinococcus granulosus per os. Six of the vervets and one of the baboons possessed hydatid cysts at autopsy, 15-28 months post-infection. The sequential IgG response to hydatid fluid and protoscolex antigens showed considerable inter-animal variation. Infected vervets and baboons became seropositive after an average of 8 months post-infection. Considerable fluctuation in the IgG response was observed, particularly to the hydatid fluid antigen which, in humans, may contribute to the existence of a significant proportion of seronegative individuals. Vervets, in particular, may be useful to study immunological events associated with exposure, development and resolution of hydatid disease in outbred human populations.Parasitology 07/1993; 106 ( Pt 5):511-7. · 2.96 Impact Factor -
Article: A large focus of alveolar echinococcosis in central China.
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ABSTRACT: Human alveolar echinococcosis (AE) is a rare and highly pathogenic helminthic zoonosis due to infection with the intermediate stage of the small fox tapeworm, Echinococcus multilocularis. Parasite transmission is restricted to northern latitudes, including central and north China, from where few clinical and no detailed community studies have been reported. In August, 1991, 65 (5%) of 1312 people residing in three rural communes of Zhang County, Gansu Province, China were diagnosed as having hepatic AE after mass ultrasound scanning with serological back-up. This represents one of the highest prevalence rates of AE ever recorded. It is also the first time that mass ultrasound scanning and serology have been used together in an AE endemic region. The region was selected one year earlier, when a preliminary serosurvey on 606 unselected people in the same locality resulted in an 8.8% serum antibody positive rate with a 76% rate of confirmation of hepatic AE in 37 individuals who could be followed up in 1991. Seropositivity rates varied for villages between 0 and 20.5%. Overall, females (7.8%) had a significantly greater risk of infection than males (2.5%), especially in the 31-50 age group, a difference which may be related to contact with dogs and dog faeces over many years. Age-specific prevalence of AE increased from 0% in the under 5-year group to 8.2% in those aged 31-50. The youngest case was 11 years and the mean age of diagnosis was 40 years. Adult tapeworms of E multilocularis were identified from the small intestines of 10% of domestic dogs. Sylvatic animal hosts of the parasite have not yet been identified. The high prevalence of human AE in this region of central China is most probably due to semi-domestic transmission of E multilocularis between wild rodents and dogs, together with the poverty and poor hygiene in these rural communities.The Lancet 11/1992; 340(8823):826-31. · 38.28 Impact Factor -
Article: Prevalence of human hydatid disease in northwestern Libya: a cross-sectional ultrasound study.
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ABSTRACT: A total of 4103 people were screened in an ultrasound survey of the prevalence of hydatid disease (Echinococcus granulosus) in five areas of northwestern Libya; hydatid cysts were seen in 57 (1.4%), an overall prevalence of approximately 2.0% when adjusted for the likelihood of the occurrence of cysts in other sites in the body. All ultrasound-positive cases were confirmed by dot-blot ELISA. The prevalence of hydatid cysts increased with age, and differed between the sexes except in the five to 14 age group. All diagnosed cases, even those with large cysts, were asymptomatic. This study demonstrates the value of ultrasonography for screening field populations for hydatid disease. The technique was well received locally, facilitating the rapid collection of prevalence data from all ages and both sexes. Libyan people keep guard dogs, but there is little direct human:dog contact. Many people own a single dog, invariably kept outside and often chained up. Stray dogs are common, roaming the countryside to scavenge sheep carcases etc., and such dogs could be the main reservoir of E. granulosus in Libya. Because of the minimal direct human:dog contact, transmission of hydatid disease in Libya is probably indirect by ingestion of eggs from contaminated vegetables or drinking water.Annals of Tropical Medicine and Parasitology 09/1992; 86(4):381-6. · 1.43 Impact Factor -
Article: Release and survival of Echinococcus eggs in different environments in Turkana, and their possible impact on the incidence of hydatidosis in man and livestock.
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ABSTRACT: In Turkana, Kenya, a prevalence of hydatidosis of nearly 10% has been recorded among the pastoralists yet their livestock have a much lower prevalence of the disease. The present study investigated the release from dogs and subsequent survival of Echinococcus eggs in Turkana huts, water-holes and in the semi-arid environment. The results were compared with the survival of eggs of Taenia hydatigena and T. saginata. The study was repeated under the cooler and moister conditions found in Maasailand where livestock have a greater incidence of hydatid disease than in Turkana but where the incidence in man is ten times lower. The average number of Echinococcus eggs per proglottid is 823. Nine percent of these remain in proglottids 15 minutes after release from a dog and the released eggs lose their viability in less than two, 48 and 300 hours in the sun, huts and water in Turkana respectively: the major influencing factor being temperature. The greater survival of eggs in the houses, coupled with the fact that dogs congregate for most of the day in the small houses facilitating a close man:dog contact, provide ideal conditions for the transmission of the parasite to man. The hostile environmental conditions and lack of contact between dogs and livestock contributes to the lower infection rate in livestock. Conversely in Maasailand, Echinococcus eggs survive in the environment for longer than three weeks and in addition, dogs are used for herding. This partly explains the higher infection rate among Maasai livestock but the low human infection rate remains arcane and requires further study.(ABSTRACT TRUNCATED AT 250 WORDS)Journal of Helminthology 04/1991; 65(1):55-61. · 1.38 Impact Factor -
Article: Hydatid disease in the Turkana District of Kenya, VII: analysis of the infection pressure between definitive and intermediate hosts of Echinococcus granulosus, 1979-1988.
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ABSTRACT: The rate of acquisition of Echinococcus granulosus and Taenia hydatigena was examined in dogs treated with praziquantel in northwestern Turkana District of Kenya. An attempt was also made to assess the effect of drought on the prevalence of E. granulosus. The infection pressure to dogs with the cestodes was shown to be high, and the prevalence returned to pretreatment levels within six months. The unreliability of arecoline purging in prevalence studies of dog cestodes is shown by mathematical contrast to the results of autopsy. Arecoline purge may underestimate the real prevalence by 10-fold. Dosing intervals in hydatid control programmes utilizing mass dog-purging to estimate re-infection rates should therefore take this factor into consideration. It is proposed that a mass dog-dosing schedule in Turkana, using praziquantel, should take into consideration the short prepatent period of E. granulosus, the financial constraints, and the slaughter practices in the area. During the prolonged droughts which occur approximately every 10 years, the programme will be adjusted accordingly to cater for the initial increase in infection intensity to dogs.Annals of Tropical Medicine and Parasitology 09/1990; 84(4):361-8. · 1.43 Impact Factor -
Article: Assessment of a serological test for the detection of Echinococcus granulosus infection in dogs in Kenya.
Acta Tropica 06/1990; 47(4):245-8. · 2.72 Impact Factor -
Article: Observations on human echinococcosis (hydatidosis) and evaluation of transmission factors in the Maasai of northern Tanzania.
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ABSTRACT: An attempt was made to estimate the prevalence of hydatid disease amongst the Maasai people of northern Tanzania and to examine the factors which would contribute to the transmission of the disease in this region. Retrospective review of hospital records revealed an annual surgical rate of hydatid disease for 1977 through 1986 of 11 per 100,000 people. Ten (1%) of 959 people screened by ultrasound scanning had hydatid cyst-like echoes, giving a prevalence estimation of 1.4%. Thirty per cent of positive ultrasound cases were also positive in an ELISA antibody test. Three of four dogs necropsied and two of six dogs purged were found to harbour patent Echinococcus infections. Quantitative man:dog contact studies, examination of soil and water samples for Echinococcus eggs and comparison of the anti-Echinococcus antibody responders revealed that there are few marked differences in exposure to infection between the Maasai and the Turkana, who have a much higher prevalence of hydatidosis and perhaps the highest prevalence in the world. Hypotheses to explain the differences in the infection rate between these two groups of pastoralists who share a similar traditional lifestyle are presented. The Maasai, like the Turkana, had no knowledge of hydatid disease, and it is suggested that the best way to control the disease in Maasailand would be by proven dog control measures, supported by a suitable, more durable, educational programme.Annals of Tropical Medicine and Parasitology 11/1989; 83(5):489-97. · 1.43 Impact Factor -
Article: Hydatid disease in the Turkana district of Kenya. VI. Man:dog contact and its role in the transmission and control of hydatidosis amongst the Turkana.
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ABSTRACT: Despite a hostile environment unsuited to parasite transmission, Turkana district in northwestern Kenya has the highest incidence of hydatid disease in the world. The prevalence of the disease varies ten-fold, being higher in the north than the south of the district. This study examined whether differences in man:dog contact and specific activities of dogs enhanced the transmission of Echinococcus granulosus eggs to man. A total of 24,541 observation-minutes were completed, studying 31 dogs from 20 manyattas in six locations throughout Turkana district, and in one location in neighbouring Pokot. Correlations were found between the time a dog spent in a manyatta and whether dogs were allowed to clean children, scavenge from cooking utensils and defecate within the home area. The amount of time a dog spent in a manyatta depended upon the availability of water, food and shade. The study also revealed that it is difficult to change the Turkana's behaviour and attitudes towards their dogs, despite continuous education. Therefore, in an area where home slaughter is practised, dosing of dogs with a suitable taeniacide will for many years to come remain an important component in the hydatid control programme being carried out in Turkana.Annals of Tropical Medicine and Parasitology 09/1988; 82(4):343-56. · 1.43 Impact Factor -
Article: Sodium hypochlorite as an ovicide for Echinococcus.
Annals of Tropical Medicine and Parasitology 05/1988; 82(2):211-3. · 1.43 Impact Factor -
Article: Immunodetection of Echinococcus eggs from naturally infected dogs and from environmental contamination sites in settlements in Turkana, Kenya.
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ABSTRACT: A species-specific indirect immunofluorescence test using an anti-Echinococcus oncosphere monoclonal antibody (EgOH6-4E5) was applied to identify Echinococcus oncospheres released from taeniid eggs collected in environmental soil and water samples, and from perianal or faecal samples of naturally infected dogs, in northern Turkana, Kenya. The specificity of immunodetection of Echinococcus eggs by specific fluorescence of Echinococcus oncospheres from naturally infected dogs was 100% when compared to Taenia hydatigena infections, and a sensitivity of 73% was obtained in the detection of dogs infected with Echinococcus using perianal Scotch tape swabs. Taeniid eggs were recovered from various soil samples inside Turkana manyattas (settlements) and from waterhole samples. Some oncospheres obtained from taeniid eggs recovered from all sampled areas, but particularly from inside Turkana huts (akai) and from water samples from open waterholes used by the people and their livestock, reacted positively with the Echinococcus 4E5 monoclonal antibody. The potential importance of contamination of such sites with Echinococcus eggs is discussed in relation to the transmission of echinococcosis in this hyperendemic region of northern Kenya.Transactions of the Royal Society of Tropical Medicine and Hygiene 02/1988; 82(2):268-74. · 2.16 Impact Factor -
Article: Portable ultrasound scanner versus serology in screening for hydatid cysts in a nomadic population.
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ABSTRACT: 3553 nomads in Turkana, a remote area of north-west Kenya, were screened for hydatid cysts by a portable ultrasound scanner and by serology. 198 (5.6%) proved to have liver or upper abdominal cysts. In the group screened by both techniques (2644) 174 (6.6%) cases of hydatidosis were detected by ultrasonography and 76 (2.9%) by serology. Ultrasonography gave immediate results and was less expensive and more acceptable and educationally valuable to the people. This non-invasive rapid technique also provided important clinical information about the cysts. The prevalence data thus obtained will contribute to the surveillance of a hydatid control programme.The Lancet 09/1987; 2(8553):259-61. · 38.28 Impact Factor -
Article: Cyst growth and spontaneous cure in hydatid disease.
The Lancet 05/1986; 1(8485):861. · 38.28 Impact Factor -
Article: Hepatitis delta virus infection in Kenya. Its geographic and tribal distribution.
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ABSTRACT: In 1982-1984, an epidemiologic survey of the prevalence of hepatitis B virus surface antigen (HBsAg) in circulating blood (HBs-antigenemia) and of hepatitis delta virus infection was performed in Kenya. The distributions of hepatitis B virus and the delta virus were shown to be very variable. In southern Kenya, only two of 202 sera from HBsAg-positive individuals with no known liver disease and none from 123 HBsAg-positive patients with hepatitis B-related liver disease were positive for delta antibody. In contrast, in northern Kenya, there was an overall prevalence of delta antibody in healthy individuals of 31%. The distribution of delta infection is discussed in relation to lifestyle, ethnic group, and geographic area.American Journal of Epidemiology 04/1986; 123(3):416-23. · 5.22 Impact Factor -
Article: Hydatid disease: research and control in Turkana, IV. The pilot control programme.
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ABSTRACT: A pilot programme to control hydatid disease in north-west Turkana district was started in October 1983 with an intensive educational campaign. This was followed by control and treatment of the dog population to reduce the prevalence of Echinococcus granulosus, thereby reducing the infective pressure on man. Surveillance is by mass annual sero-epidemiological and ultrascan surveys of the nomadic Turkana within the control region and by arecoline purging of the dogs. Some of the recent advances in research on hydatid disease in subject areas such as immunodiagnosis, chemotherapy and epidemiology have been incorporated into the present programme, and their relevance to this and other similar programmes is discussed.Transactions of the Royal Society of Tropical Medicine and Hygiene 02/1986; 80(2):196-200. · 2.16 Impact Factor -
Article: The identification of eggs of Echinococcus by immunofluorescence using a specific anti-oncospheral monoclonal antibody.
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ABSTRACT: A relatively simple and specific test has been developed to distinguish eggs of Echinococcus from those of other morphologically identical taeniid species. A specific anti-Echinococcus oncosphere monoclonal antibody was produced which binds in an indirect immunofluorescence test to egg-derived oncospheres of E. granulosus but not to those of other taeniid species, such as Taenia hydatigena, T. saginata, T. pisiformis, T. ovis, T. multiceps, or T. taeniaeformis. Specific fluorescence was obtained with oncospheres of E. granulosus derived from either hatch/activated viable eggs using artificial intestinal fluid or from hypochlorite/detergent treated eggs. The potential use of this test in the study of the transmission of Echinococcus in Turkana, Kenya, is discussed.The American journal of tropical medicine and hygiene 02/1986; 35(1):152-8. · 2.59 Impact Factor -
Article: Hydatid disease in the Turkana District of Kenya, IV. The prevalence of Echinococcus granulosus infections in dogs, and observations on the role of the dog in the lifestyle of the Turkana.
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ABSTRACT: The prevalence of Echinococcus granulosus in dogs in the Turkana District of Kenya was 39.4% of 695 examined. Of these, 98 (35.8%) had heavy Echinococcus worm burdens (10(3)-5 X 10(4) ), while 54 (19.7%) and 122 (44.5%) had medium (201-1000) and light (1-200) burdens. The possible sources of these infections are discussed. The prevalence rate differed in various parts of the district, ranging from 63.5% in the northwest, where the highest incidence of human hydatidosis also occurs, to nil along the shores of Lake Turkana. Infection rates of 32.0% and 16.7% were recorded at Lokitaung (north-east) and Lodwar (central), while in the south 48.9% of dogs harboured Echinococcus. This latter figure is surprising as the area has a low incidence of human hydatidosis. The Turkana keep a large number of dogs, and the reasons for this and the social role of the dog in the district is discussed. No difference in susceptibility was found between Turkana-type dogs and those of mixed breeds from Nairobi when they were experimentally infected with hydatid protoscolices from man, camels, cattle, sheep and goats. However, it proved difficult to infect the Turkana-type of dogs with viable protoscolices of cattle origin. The reasons for this and its epidemiological implications remain unclear. It is suggested that droughts, which affect Turkana every six to ten years, may play an important role in the perpetuation of hydatid disease in the area.Annals of Tropical Medicine and Parasitology 03/1985; 79(1):51-61. · 1.43 Impact Factor -
Article: Epidemiology of hydatid disease in Kenya: a study of the domestic intermediate hosts in Masailand.
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ABSTRACT: The results are given of a study on the epidemiological significance of cattle, sheep and goats in maintaining the life-cycle of Echinococcus granulosus in Masailand, Kenya. A total of 134 (8.9%) of 1499 cattle, 146 (8.1%) of 1798 sheep and 144 (7.1%) of 2020 goats slaughtered in abattoirs in Masailand were found to harbour hydatid cysts. The frequency distribution of the hydatid cysts in each intermediate host species was over-dispersed. Of 729 cattle cysts examined 71 (9.7%) were fertile (cyst contained protoscoleces) with an average viability of 71%, 507 (69.5%) were sterile and 151 (20.7%) were calcified. Out of 810 sheep and 451 goat cysts examined 571 (70.5%) and 213 (47.0%) were fertile with respective viabilities of 88% and 86% and 143 (17.7%) and 194 (43.0%) were sterile leaving 96 (11.6%) and 45 (10.0%) sheep and goat cysts which were calcified. The greater fertility of the sheep and, to a lesser extent, goat cysts coupled with the reported greater infectivity of sheep and goat than cattle material to dogs and the common Masai practice of slaughtering sheep and goats at home, indicates that, at present, sheep and goats are the most important intermediate hosts for the maintenance of the domestic life-cycle of E. granulosus in Masailand. The incidence of hydatidosis in donkeys and the relationship of the domestic cycle to the wildlife cycle operating in the same area is unknown and requires further study.Transactions of the Royal Society of Tropical Medicine and Hygiene 02/1985; 79(2):209-17. · 2.16 Impact Factor -
Article: Perspective on options for the implementation of a pilot hydatidosis control programme in the Turkana District of Kenya.
East African medical journal 08/1984; 61(7):513-23. -
Article: An Echinococcus pilot control programme for north-west Turkana, Kenya.
Annals of Tropical Medicine and Parasitology 07/1984; 78(3):188-92. · 1.43 Impact Factor
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1988
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Oxford College
Oxford, OH, USA -
Liverpool School of Tropical Medicine
Liverpool, ENG, United Kingdom
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