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This study was undertaken to evaluate the current status of shistosomiasis in the Nkolmébanga region (Lékié) of Cameroon, previously determined to be a mixed zone harboring both Schistosoma mansoni and S. intercalatum. Study involved both malacology with collection and identification of freshwater snails in four waterpools and parasitology with collection and analysis of stools from schoolchildren. Five species of freshwater snails were identified including two that were intermediate host of Schistosomes, i.e., Biomphalaria pfeifferi and Bulinus forskalii. Only B. pfeifferi species collected from the Momboh and Mbonsoh Rivers shed Schistosoma cercaria. A total of 347 schoolchildren were enrolled but only 200 provided stools for parasitological testing. There were 93 boys and 107 girls. Parisitology demonstrated S. intercalatum eggs in the stools of no children. S. mansoni eggs were identified in the stools of 10 children for a prevalence of 5%. Parasitic load ranged from 24 to 1104 eggs per gram of stool. In this study both malacologic and parasitological findings suggested that S. mansoni persists in Nkolmébanga region but that S. intercalatum has disappeared probably as a result of deforestation and urbanization.

A study on the compatibility between Schistosoma haematobium from three remote localities (Mourtourwa, Gounougou and Kékem) and four populations of Bulinus truncatus (Gounougou, Ngaoundéré, Bertoua and Kékem) and four populations of B. globosus (Mourtourwa, Ouroudoukoudje, Bafia and Yaoundé) was undertaken in order to estimate the risk of extension of urinary schistosomiasis in Cameroon. First generation of offspring from wild Bulinus was exposed to miracidia liberated by schistosome eggs extracted from patient urine. Between the 25th and the 60th day post-infestation the number of snails still alive, the number emitting cercariae and the prepatent period duration were noted. Results showed that all B. truncatus samples were susceptible to the three strains of parasite whereas only B. globosus of Mourtourwa and Ouroudoukoudje were susceptible to S. haematobium from Mourtourwa. The schistosome infection rate was then significantly higher in B. truncatus and the prepatent period significantly lower than in B. globosus. The compatibility characterised by a high infection rate and a low prepatent period was significantly better in homopatric couples than in allopatric combinations. The results suggested that B. truncatus might be potentially more implicated than B. globosus to the extension of the urinary bilharziasis in Cameroon.

A sero-epidemiological survey of school children was carried out in Kousseri, a focus for visceral leishmaniasis. Sero-immunological assays for the detection of anti-Leishmania antibodies were based on the indirect immunofluorescence assay test and counter-immunoelectrophoresis. 9 out of 223 school children tested positive for visceral leishmaniasis (seroprevalence rate of 4%). These 9 cases had no history of the disease. The data obtained confirm the endemicity of visceral leishmaniasis in this focus and call for extensive studies in order to determine the prevalence of the disease in the entire population as well as the main components of the transmission cycle.

Chloroquine is indicated for the first-line treatment of uncomplicated malaria in most African countries. However, the spread of chloroquine-resistant Plasmodium falciparum requires periodic monitoring. Between 1994 and 1999, we studied the evolution of chloroquine resistance in adults (aged15 years) and children aged 5-15 years by using tests of therapeutic efficacy and in vitro assays. Responses to the 14-day in vivo test were classified according to the new criteria established by the World Health Organization. The results of the semi-microtest and the microtest were expressed as the 50% inhibitory concentration (IC50), and the threshold level of resistance was set at IC50100 nM. The overall percentages of clinical and parasitological failures were 39.7% (31. 3% - 48.1%) and 48.8% (40.2% - 57.4%), respectively. Similarly, the percentage of isolates that were resistant in vitro was 52.5%. During the study, IC50 geometric mean varied between 84,6 nM and 149, 8 nM. The results of the in vitro assays agreed with those of tests of therapeutic efficacy (kappa coefficient = 0.69). The patients' chloroquine plasma levels were measured on day 0, day 3, day 7, and day 14. Drug measurement showed wide inter-individual variations and higher plasma levels in adults than in children. Some cases of therapeutic failure were associated with inadequate plasma levels of chloroquine. Our results confirm the high level of chloroquine resistance in Yaoundé and suggest that the use of an alternative antimalarial drug for the first-line treatment of uncomplicated malaria is warranted.

The spread of chloroquine resistance or its stabilization at a high level calls for a change in the therapeutic strategy, including a possible replacement of chloroquine. We assessed and compared the efficacy of amodiaquine and sulfadoxine-pyrimethamine in Yaoundé. Of 140 adults and children5 years enrolled in the study, 59 in the amodiaquine and 58 in the sulfadoxine-pyrimethamine treatment group were followed until day 14. The efficacy of amodiaquine was 100%, whereas 12.1% of the patients treated with sulfadoxine-pyrimethamine responded with an early treatment failure. Side effects in both treatment groups were mild and did not require any specific treatment. We did in vitro drug assays for monodesethylamodiaquine (active metabolite of amodiaquine) and pyrimethamine and measured plasma levels of monodesethylamodiaquine, sulfadoxine, and pyrimethamine. Unlike amodiaquine, the results of the in vitro drug sensitivity test for pyrimethamine were not concordant with the clinical response. A wide inter-individual variation in the plasma drug levels was observed. Unlike chloroquine, the mean plasma concentrations did not vary with age. There was no significant difference in the plasma concentrations of sulfadoxine and pyrimethamine between patients responding with an adequate clinical response and those responding with treatment failure. Amodiaquine has several advantages over sulfadoxine-pyrimethamine combination and may be considered to be an effective drug in an endemic zone with a moderate level of chloroquine resistance.

Severe forms of malaria in children are responsible for 1 million deaths yearly in young children in hyperendemic areas. The main objective of this study was to identify and compare common manifestations of different forms of severe malaria and to evaluate the prognosis for hospital treatment in an endemic area. 271 files of children admitted into hospital between March 1991 and September 1996 were analysed. These children were confirmed to have Plasmodium falciparum in their peripheral blood. 78 patients (29%) had the severe form of malaria. 43 patients (53%) were under 5 years of age. The 5 severe types identified were characterized by very high temperatures 28 cases (36%), cerebral malaria 20 cases (26%), prostration and weakness 15 cases (19%), severe anaemia 14 cases (18%) and haemoglobinuria 1 case (1.3%). Cerebral malaria and severe anaemia were more common in children under 5 years old. The average parasitemia was 16,366 +/- 1390 parasites per microlitre. Clearance of parasitemia was obtained on day 3 in almost all cases; 6 patients with very high temperatures presented neither sign of visceral complications nor convulsions. The average period in coma for cases of cerebral malaria was 1.7 days; 12 anaemic patients were transfused. There were no deaths. No abnormality was found on physical examination after an average hospitalisation of 5.3 days. An early diagnosis and adequate treatment of severe forms of malaria in children by qualified personnel will usually result in a favourable prognosis in our area.

This randomized, non-comparative clinical trial without placebo was carried out to assess the efficacy and tolerance of artesunate for treatment of acute Plasmodium ovale malarial attacks. Thirty Cameroonese patients were included. All presented acute Plasmodium ovale malarial attacks with parasitemia in excess of 500 asexual forms per mm3. Four days after treatment with artesunate, all 30 patients were asymptomatic with no parasitemia. Reduction rates were 93.9 p. 100 for asexual forms and 75.4 p. 100 for gametocytes. Parasite clearance was achieved within 38.8 hours and fever disappeared within 36.6 hours. Tolerance was excellent in 29 patients. The remaining patient briefly complained of mild vertigo. A transient decrease in reticulocyte levels was observed in one patient initially presenting anemia. Artesunate appears to achieve rapid and complete resolution of acute Plasmodium ovale malarial attacks. Since artesunate eliminates both asexual forms and gametocytes, it also acts on transmission by limiting the duration of survival of asexual forms.

Onchocerciasis, also known as "river blindness", presents a plenum of clinical manifestations which vary from one individual to another, and from one area to another. This large spectrum of clinical manifestations of the disease is an indication of the complexity of the pathogenesis of onchocerciasis and suggests that many interacting factors might influence the clinical features of the disease. The present study has focused on the heterogenicity of the host immune response as a plausible explanation for differences in clinical manifestations of the infection. Host genetic factors, namely HLA genes, might play an important role in determining the nature of the immune response mounted against the parasite Onchocerca volvulus, and thus the development of different manifestations of the infection. Genetic diversity of onchocerciasis was assessed in different endemic foci in Cameroon. In order to investigate the possibility that the Major Histocompatibility Complex (MHC) genes might be associated with the different clinical types of onchocerciasis, 146 subjects living in three endemic areas of Cameroon were studied. They were classified in four groups: A (asymptomatic subjects), P (putatively immune subjects) L (patients with localised disease) and G (patients with generalised disease). The four groups differed in the distribution of HLA class II alleles as determined by Direct Heteroduplex Analysis. On the one hand, allele HLA-DQA1*0501 appeared to be associated with protection against severe onchocerciasis; on the other, allele HLA-DQB1*0201 might play an important role in the severe form of the disease.

Cerebral malaria is one of the major and deadly complications of malaria. In Cameroon, recent reports indicate that severe cases of malaria are increasingly more prevalent, particularly in children. The present study aims at describing the clinical presentation and laboratory findings of cerebral malaria in children in Yaounde. All patients admitted in the paediatric ward of Yaounde Central Hospital with malaria, who presented neurological signs and were tested positive for Plasmodium in their peripheral blood were recruited into the study. 36 cases were enrolled in all, making up 2.7% of all admissions. The patients' median age was 4.5 years. 52.8% were on malaria prophylaxis. Convulsions and coma with preceding hyperthermia were present in more than 90% of the patients. Blood parasites level median was 1.3% on admission. One patient had hypoglycaemia on admission and two others had it later on after admission; 16.7% had neurological sequels at discharge and two children died (5.6%). Delay in diagnosis and initiation of treatment with quinine adversely affected the prognosis of cerebral malaria in the study group.

The present study was designed to assess the health risk of the future hydroelectric dam of Memve'ele with reference to vector-borne diseases. Entomological and malacological surveys were carried out in the project area. The main vectors collected were Anopheles gambiae and An. nili for malaria; Simulium damnosum for onchocerciasis; Glossina palpalis for trypanosomiasis; Chrysops dimidiata and C. silacea for loasis. No snail host of schistosome was reported. The risk of introduction of the diseases they transmit are discussed.

The appearance of Symmers' periportal fibrosis (SPF) is considered a major event in the natural history of Schistosoma mansoni infection, because of the risk of portal hypertension and subsequent intestinal hemorrhage. Ultrasonography has been found useful in the assessment of this lesion. We undertook the present study to determine the prevalence of SPF in Nkolbisson (near Yaoundé), where previous studies had shown Schistosoma mansoni infection to be endemic.147 patients more than 15 years old (mean age: 32 years) were prospectively studied during a 3 month period. 107 subjects (51 male, and 56 female) were excreting Schistosoma mansoni eggs in the stools (mean egg output = 336 egg/g), and 40 controls had a negative stool exam. A medical history, a physical examination, and an abdominal ultrasound examination were performed on each subject. The degree of SPF was graded according to Homeida's scale.39 Subjects (24 male, 15 female) with positive stool examination had SPF giving a prevalence rate of 37%, while it was found to be 5% for controls. 28 patients had mild fibrosis (grade I), 7 patients had moderate fibrosis (grade II), and 4 patients had severe fibrosis (grade III). Higher prevalence rates of SPF were associated with longer duration of infection and very high egg outputs (1,000 egg/g). The positive predictive value of hepatomegaly or splenomegaly for the presence of SPF was 0.52, and the negative predictive value 0.69.We conclude that SPF affects a significant proportion of infected patients and ultrasonography is a valuable tool in the study of this lesion in our patients.

The aim of this study was to investigate endoscopically and histologically rectal mucosa complications in bilharzia patients. Coprology using KATO's technique was carried out in 1406 school children aged 4 to 18 years. 134 (9.53%) were infested. Among the infested school children and the sample population, a random selection of 80 school children (40 infested and 40 of sample population) was made, in whom rectoscopy and biopsy of rectal mucosa were carried out. The lesions found were classified on endoscopic and histologic basis. The prevalence of the disease 9.53% appears to be in constant regression. Inflammatory lesions are more common in bilharzia patients. Histology facilitated the unveiling of a specific rectitis in 72.5% bilharzia patients and 12.5% of the sample population. This study confirm the effectiveness of the several bilharzia eradication campaigns carried out in the Nkolbisson area. Rectoscopy with biopsy of the rectal mucosa should be reserved to symptomatic patients, in whom many coprologies have turned out negative.

This study from a series of 80 patients showed that the prevalence rate of malaria increased from 8% before to 15% after surgery in the tropics. The difference was not significant (p0.05). The conclusion is that patients should be investigated for malaria parasites before any major surgery; in case of a non infectious post-operative fever, antimalarial drugs should be prescribed only to patients with a positive thick film.

This study confirms the efficiency of bilharzia eradication campaigns at Nkolbisson. The authors recommend rectal mucosa biopsy of symptomatic patients in whom several investigations have turned out negative.

In this preliminary study, we discuss 9 cases of Candidosis diagnosed during a 6 month period in 32 AIDS patients hospitalized in three health Centers in Yaoundé. Most of the patients presented with buccal candidosis and/or dysphagia. Of the 18 strains grown, 17 (94%) are Candida albicans.

The data obtained in the survey carried out in the villages of the Mandara mountains are as follows. P. falciparum is the only species of Plasmodium which has been found in the area. The parasitic rate in children 2 to 9 years of age is 40.8 p. 100 and the spleen rate 35.6 p. 100. The immunofluorescent test performed with an homologous P. falciparum antigen is positive in 37.7 p. 100 of the children of this class of age. The thick drop shows parasites in 25 p. 100 of the newborn children. The parasitic load rated by number of blood cells harboring parasites is high in young children, then diminishing in adults while the antibodies increased. Malaria cases are more numerous at the end of the rainy season but a new spell of the disease is also noticed at the beginning of the year while the outside temperature is especially high. Malaria, now mesoendemic in the study area, seems to decrease as far as parasite and spleen rates are concerned in comparison with the rates obtained in the Mandara mountains 20 years ago. This seems to be a consequence of an increase in the intake of chloroquine by the inhabitants.

The aim of the study is to establish the prevalence of loaiasis, dipetalonemiasis, tetrapetalonemiasis, with particular emphasis on T. streptocerca infection. Eight small villages located close to Douala in the mangrove area of the Wouri estuary are visited and 788 dermic scarification prints stained with Böhmer hematoxylin are examined. Microfilariae belonging to the species L. loa are found in 11,2 p. 100 of the prints, D. perstans mirofilariae are found in 23,2 p. 100 and T. streptocerca in 6,9 p. 100. The prevalence of filariasis and the parasitic load are higher in male than in female. The older the inhabitants are, the more heavily infected they are found. Except for pruritus and craw-craw associating a filarial infection with characteristic symptoms seems to be difficult in this study.

At Loum, S. intercalatum infection still occurs in its pure form. The infection, however, is regressing while S. haematobium and hybrid forms between the two species are developing. A single oral dose of 2-cyclo-hexylcarbonyl-1,2,3,6,7,11b-hexahydro-4H-pyrazino[2,1-a]isoquinolin-4-o ne(praziquantel, EMBAY 8440, Biltricide), 40 mg/kg body weight, is a very effective treatment of the disease. Forty days after treatment eggs no longer occurred in the faeces of ten children voiding S. intercalatum eggs in their stools before they were cured. Five children voiding hybrid bilharzia eggs in their urine were no longer passing eggs after treatment.

While inventoring the local malacological fauna and evaluating the density of species acting as intermediate hosts of human schistosomes it has been shown that Bulinus truncatus is predominant in the study area. Bulinus globosus is scarcely encountered. Biomphalaria pfeifferi is only found in the Mayo Guerleo, in irrigation canals and draining ditches. But B. globosus and B. pfeifferi have not yet invaded the recent aquatic network and are not found in the lake nor in the newly created irrigation systems. Snails shedding cercariae of S. haematobium and S. mansoni have been collected in the area. Bulinus forskalii is found in all types of permanent of temporary waterbodies but S. intercalatum has not yet been reported from North-Cameroon. Lymnaea natalensis, the intermediate host of Fasciola gigantica, is found in the lake and in the canals, in the Mayo Guerleo and in the Toupasko pool. The rice field does not form by itself a favorable environment for snails to develop in it. Spots where transmission occurare more often in the area the secondary of tertiary irrigation canals and the brains. The ditches obstructed by plants are the places where the snails are developing best. Bulinus spp. are found in large numbers in the lowest parts of the aquatic network and they accumulate there to survive drought conditions in the mud. The recently built irrigation systems are not massively invaded by the snails yet and the prevalence of bilharziasis in the area correspond to the distribution of the intermediate hosts of schistosomes and to the density of the snails populations.

The effect of the bancroftian filariasis on the health of the inhabitants are minimal in the study area, where the prevalence of the disease (nocturnal microfilaremia) is 0.4% only. But skin snips harboring Onchocerca microfilariae are seen in 12.1% of the sample studied. Onchocerciasis skin lesions, low visual acuity and blindness are often seen in the villages where the prevalence is high, among inhabitants more than 40 years of age. Simulium damnosum is seldom seen in the area, except in the large streams and rivers like the mayo Tsanaga and the mayo Djingliya. Larvae and nymphae of this species hardly succeed in developing on the overspelling of the small dams, this being due more to a discontinuous run of the water in the overspilling than to a to high speed of the water.

The map of the Mandara Mountains dracuntiasis focus showing the wells and water bodies, which are the transmission sites of the disease in the study area, shows that the focus is relatively well limited. The drilling of new wells, the protection of existing water bodies used for human consumption, the health education project and the treatment of water by temephos lead to ascertain that the number of Guinea worm cases seen is decreasing every year in the area where the project is meticulously performed. These encouraging results show that it is now possible to eliminate the Guinea worm from North Cameroon by extending the operations in progress to the comprehensive surface of the focus, including the remote areas in mountains and the satellite foci in the plain along the Nigerian border.

The prevalence of intestinal helminthiasis is measured by means of stool examinations. In Bafia eggs are passed in the feces of 69.1% of the inhabitants for Ascaris lumbricoides, 70.1 % for Trichuris trichiura, 59.6 % for Necator americanus and 14.8% for Enterobius vermicularis. A small focus of intestinal bilharziasis exists in Bafia and eggs of Schistosoma mansoni are found in the feces of 18.6% of the persons studied. Biomphalaria pfeifferi is the intermediate host of the parasite and transmission occurs in the town itself, in the fish-culture pool and in the rivers Guen and Rutop.

The examination of the thick drops shows malaria parasites in 20,8% of the slides in Minkama and Nalassi: 95,7% of those slides are positive for P. falciparum and 4,3% for P. malariae. The parasite rate, representing the percentage of children up to 9 years of age showing parasites in their blood, is 42,2%. Using the immunofluorescent test, antibodies are found in 43,7% of the blood samples in the study area. In the hospital, 51% of the patients with malaria are 0 to 4 years old children. The clinical symptoms observed are, in a decreasing frequency, fever, vomiting and diarrhoea, myalgia, arthralgia and asthenia, convulsions, delirious or coma. They are no obvious correlations concerning the rain-gauging data and the monthly number of malaria cases admitted at the hospital in this Cameroonian rainforest area.

In Eseka and Edea bilharziasis caused by S. intercalatum is transmitted by B. forskali, the only intermediate host of human schistosomes found in the area. The prevalence of the disease is obtained by calculating the percentage of inhabitants voiding eggs in their stools in the districts of the towns located in the neighbourhood of Bulinus-containing streams and ponds. The prevalence is low, 5,6% in Eseka and 4,9% in Edea. The size and the number of waterbodies where transmission occurs is small. Rectoscopy showed that rectal and sigmoid lesions are frequently seen. Clinical manifestations are abdominal pain, diarrhoea, dysentery, tenesmus, appearance of blood in the stools. Hepatomegaly and splenomegaly occur sometimes. A single dose of 2-cyclohexylcarbonyl-1,2,3,6,7,11b-hexahydro-4H-pyrazino[2,1-a] isoquinolin-4-one (praziquantel, EMBAY 8440, Biltricide) is effective in the treatment of the disease.

Prevalence of intestinal helminthiasis: 970 stool specimens are examined in Doualare and 999 in Doursongo (Maroua) North Cameroon. In this sample eggs of T. saginata are seen in 14.0% of the specimens, eggs of A. lumbricoides in 5.1%, N. americanus in 5.8% and S. mansoni in 2.1%. Eggs of T. trichiura, S. stercoralis and H. nana are found in less than 2% of the specimens. Stool examinations are performed in Doursongo before and after treatment with mebendazole: 94.1% of the inhabitants with A. lumbricoides eggs in their stools are free of this parasite after treatment, with T. trichiura 83.3% are cured.

In the Mandara Mountains, where small dams have been erected, people living in the Tala Mokolo district eliminate some S. haematobium eggs in 31,4% of urines samples, and some S. mansoni eggs in 38,1% of stools samples. Evaluated from hemagglutination test, bilharziosis prevalence reaches 55,7%. Male subjects are more frequently affected than female subjects, particularly as for as intestinal bilharziosis is concerned. Urinary bilharziosis prevalence or intestinal bilharziosis prevalence are subject to proximity of small water reservoirs mostly infested either by Bulinus globosus or Biomphalaria pfeifferi. These small water reservoirs are mainly "mayo" head-bays.

Paragonimiasis does not occur only in the South West Province of Cameroon. Four foci exist in the country. They are the well known focus in the Mount Kupe area, the Mbam focus, the Nyong focus and the Ntem focus. All of them are located in the rainforest within the distribution area of Potadoma. This disease, characterized by the presence of eggs in sputum and feces, has often been confused with tuberculosis. In the villages where paragonimiasis is diagnosed by means of parasitological techniques circulating antibodies, revealed with a P. westermani antigen (ELISA), are often found in blood specimens taken from inhabitants. Teen agers suffer the most from the disease and females more often than males. Women and children are traditionally concerned with crabs fishing and they eat them after partly raw. Crabs of the genus Sudanautes contain the infective metacercariae. Paragonimiasis is enzootic and the civet cat V. civetta seems to be the main natural definitive host in Cameroon. Niclofolan given orally in a single dose of 2 mg/kg body weight showed a 100% cure rate. Side reactions are mild and transient.

The results of the malaria investigation carried out in April 1981 in the irrigated regions of the Logone Valley show that Plasmodium falciparum is the only species o. the genus Plasmodium to be found there. In terms of parasitaemia in blood, the prevalence of malaria is highest in the 5 to 9 year-old age group, whereas fluorescent antibodies are to be found progressively greater quantities as subjects grow older. From the age of 40, 95% of the inhabitants of the region present circulating antibodies in the blood. Plasmodial index of children from 2 to 9 years of age is equal to only 8.5% at the end of the dry season, whereas the spleen index, which is 34.8%, would suggest that malaria is meso-endemic in the region. With regard to the different sites studied, there is no significant difference in the values of the spleen or plasmodial indexes, either next to, or away from surface water. The malaria death rate is highest during the rainy months of August, September and October. The significant rise in the death rate during March corresponds to the concomitant rise in temperature. Entomological studies performed on the species of anophelines resting in the houses, which are gathered in the morning after a pulverization of insecticide, reveal that the dominant anopheline species in June is Anopheles gambiae, a species which, in the rainy season, abounds at water sites which are frequently temporary. On the other hand, in April, the dominant species is Anopheles funestus, which it would seem, develops easily during the dry season in those waterbodies which are artificially maintained all year round in the irrigated areas.

The stools of 35 patients with S. intercalatum bilharziasis are examined 48 hours, 45 days and 6 months after treatment, using praziquantel, a new trematodicide drug, in an individual single dose of 40 mg/kg body weight. The number of eggs per gram of faeces is not significantly reduced 2 days after treatment. After 45 days however eggs are only to be found in the stool of one patient among the 25 treated persons who were seen for control. Six months later 23 persons were examined again and 3 stools specimens were found positive, this being possibly due to reinfection. The drug has been well tolerated, except for minor side effects such as headache, nausea and abdominal discomfort.

Prevalence of intestinal helminthiasis: 999 stool specimens are examined in 9 villages located in the valley of the Guerleo River. In this sample eggs of N. americanus are seen in 20.4% of the specimens, eggs of S. mansoni in 2.6%, T. trichiura in 2.0%, T. saginata in 1.4%, A. lumbricoides in 1.1% and H. nana in 0.6%. The prevalence of bilharziasis measured by means of the hemagglutination test using a S. mansoni antigen is 28.5% in the villages. It should be noticed that urinary bilharziasis too is frequently seen in the area. In the village of Madalam , where intestinal bilharziasis as the highest prevalence, B. pfeifferi are numerous in the Guerleo River close to the village.

Schistosomiasis is still a public health problem in Cameroon. Urinary form caused by S. haematobium is the most widespread and is transmitted to humans by snails which serve as intermediate host. Bulinus truncatus and B. globosus being the most important. In an attempt to explain the observed diversity in the functioning of urinary schistosomiasis focy, a genetic study of B. truncatus and B. globosus population's structure was conducted using microsatellite markers.In B. truncatus populations, genetic diversity at some loci is relatively high but no heterozygotes were observed, probably due to a very high rate of self-fertilization. A strong genetic structure was observed between populations, it may results from the combined actions of self-fertilization, genetic drift, and low migration rate.In B. globosus populations, the level of variability is lower, but some loci have a high genetic diversity. Heterozygotes are present in law proportion such that all populations are in Hardy-Weinberg disequilibrium. A significant positive correlation was observed between geographic and genetic distances. While the distant population's pairs are structured, the close ones are not.Population structure is strong in B. truncatus and average in B. globosus. This could be at the origin of the differential development in Bulinus populations and may explain the observed diversity in patterns of urinary schistosomiasis transmission in the endemic foci in Cameroon., Les schistosomoses constituent encore un problème de santé publique au Cameroun. La forme urinaire due à S. haematobium est la plus répandue et est transmise à l'homme par des mollusques hôtes intermédiaires dont les plus importants sont Bulinus truncatus et B. globosus. Pour tenter d'expliquer la diversité observée dans le fonctionnement des foyers de schistosomoses urinaires, une étude de la structure génétique des populations de B. truncatus et de B. globosus a été menée en utilisant le polymorphisme de plusieurs loci microsatellites.Dans les populations de B. truncatus, la diversité génétique à certains loci est relativement élevée mais aucun hétérozygote n'a été observé, expliqué probablement par un taux d'autofécondation très élevé. Une forte structuration génétique a été observée entre les populations, pouvant résulter des actions combinées de l'autofécondation, de la dérive génétique et d'un faible taux de migration.Dans les populations de B. globosus, le niveau de variabilité est plus faible mais certains loci ont une diversité génétique élevée. On note la présence des hétérozygotes mais en proportion insuffisante si bien que toutes les populations sont en déséquilibre de Hardy-Weinberg. Une corrélation positive et significative est observée entre les distances géographiques et génétiques si bien que les paires de populations éloignées sont structurées alors que les paires rapprochées ne le sont pas.La structuration des populations, forte chez B. truncatus et moyenne chez B. globosus a pu être à l'origine d'évolutions différentielles des populations de bulins, pouvant expliquer la diversité observée dans les schémas de transmission de la schistosomose urinaire dans les foyers de cette endémie au Cameroun.