[The current epidemiological situation of cysticercosis in Madagascar]. / Situation épidémiologique actuelle de la cysticercose à Madagascar.

Being associated to fecal-oral transmission, cysticercosis is contracted either by auto-infection or by ingestion of food contaminated with eggs from the pork tape worm (Taenia solium). In the stomach, the larvae named cysticercus (Cysticercus cellulosae) hatches from the eggs and invades the host through the mucosa membrane. Human cysticercosis occurs in highly prevalent proportions in many developing countries including Madagascar where hygiene conditions are deplicable. Serology tests applicable to epidemiological surveillance of cysticercosis and associated pathology in the Malagasy population have been developed: an enzyme-linked immunosorbent assay (ELISA) for screening purpose, and an enzyme-linked immunoelectrotransfer blot assay (EITB) for confirmative testing. Two specific bands (13 and 14 kDa) have been identified as significant markers of the cysticercus in an active (vesicle) stage of the infection when cestocidal treatment is strongly indicated. The same bands may on the other hand be absent at early (cyste) as well as late (calcified) stages of the infection. Series of studies, including 4,375 serum samples, have been undertaken from 1994 until 1999 aiming at determinating the cysticercosis sero-prevalence in different provinces of Madagascar. It was confirmed that cysticercosis is highly frequent on the island, and that there exists a marked variation in the prevalence from 7 to 21% between the different provinces: less than 10% in coastal regions (Mahajanga and Toamasina) increasing to 20% in central regions (Ihosy, Ambositra and Mahasolo). It has also been observed that cysticercosis may occur in individuals at any age, and that it is equally distributed in urban as in rural areas. However, it is more frequently detected in women than in men. Madagascar is an endemic country for cysticercosis, which causes major and severe disease with implications in the public health sector. A national control program is, therefore, urgently warranted.

[Validation of questionnaire methods to identify Schistosoma haematobium bilharziasis hyperendemic zones in Madagascar]. / Validation de la méthode du questionnaire pour identifier les zones hyperendémiques de la bilharziose à Schistosoma haematobium à Madagascar.

Schistosomiasis is a major public health problem in Madagascar. The aim of the national control program is to reduce the morbidity in hyperendemic areas. A prospective study has been conducted in Morombe and Ampanihy to elaborate a simple method to identify Shistosoma haematobium hyperendemic communities. The study included 1,373 children from 5 to 15 years old in 17 primary schools. Moderate sensitivity and Negative Predictive Value, with high specificity and Positive Predictive Value of "blood in urine" and "Schistosomiasis" have been found. Those diagnosis values increase with age. The first symptom should be used in older children.

[Current epidemiological situation of bilharziasis in the Antananarivo plain]. / Situation épidémiologique actuelle des bilharzioses dans la plaine d'Antananarivo.

In 1994, prior to the Project of Development of the Plain of Antananarivo, an epidemiological survey was conducted in primary schools to assess the level of schistosomiasis. The results of stool examination by the Kato-Katz method demonstrated a prevalence of 4.3% among 6,169 randomized schoolchildren. The most infected four villages are located close the Mamba river. In 1999, after the realization of the project, another study had been done in the same Public Primary School to evaluate the evolution of schistosomiasis endemicity. 5,222 randomized pupils aged 5 to 16 years old took part in the study. The sex ratio was 1.4/1. The global prevalence was 1.8%. High prevalence are respectively notified in Antanandrano Primary school (23%) close to the Mamba river in the Northern part of the capitol and in Ambohitsoa Primary School (16.3%) located near the Mahazoarivo lac. Thus, between 1994 and 1999, a significant overall decrease in prevalence was observed (p < 10(-1)), although a few areas still have relatively high rates. Many factors may explain this improvement, including sanitary education, urbanization and a lack of conditions needed in the development of intermediate host. In addition, a high prevalence of ascaridiasis (79%) and trichocephalosis (67%) was observed. 4.3% of schoolchildren had been infected by Taenia sp. Schistosomiasis is hypoendemic in the plain of Antananarivo. The strategy against this disease must include an IEC programme, focusing in childhood exposure.

Geographic differences in hepatosplenic complications of schistosomiasis mansoni and explanatory factors of morbidity.

In a study in three neighbouring villages of southern Madagascar, where Schistosoma mansoni is hyperendemic, ultrasound examination using the Niamey protocol showed marked differences in the burden of disease from one village to another. Hepatosplenic schistosomiasis was more frequent in the village with the highest geometric mean egg counts and the earliest onset of infections, demonstrating that the morbidity induced by S. mansoni may vary greatly within a given area. True representativeness of study populations, a keystone of epidemiological studies, is mandatory to obtain a clear picture of a wide area. Ultrasound examinations in a small number of villages, or even a single one, may be a questionable approach. Using logistic regression analysis, the explanatory variables found to be significantly associated with a risk of severe hepatosplenic disease in our study were sex, age, village of residence and S. mansoni egg counts. On the other hand, a concurrent infection with an intestinal helminth seems to reduce the risk of severe hepatosplenic disease. Further studies should assess the role and possible impact of intestinal helminths on S. mansoni associated-morbidity.

[Identification of communities endemic for urinary bilharziosis by the "Lot Quality Assurance Sampling" method in Madagascar]. / Identification des communautés cibles en zone de bilharziose urinaire par la méthode de "Lot Quality Assurance Sampling" à Madagascar.

Reduction of morbidity is the main component in the National Schistosomiasis Control Program in Madagascar. The lot quality assurance sampling (LQAS) method has previously been shown as a useful tool in assessment of immunization coverage. A study was carried in the western part of Madagascar aiming to evaluate the applicability of the method in measuring the level of Schistosoma haematobium endemic level in different communities. Parasitological examination of urine samples from 1,124 children aged 5 to 19 years from 12 different schools by use of filtration technique constituted the reference in determining the prevalence. Three schools were found hyper-endemic (prevalence more than 60%), 5 schools were intermediate-endemic (prevalence between 30 to 59%), and 4 were hypo-endemic (prevalence less than 30%). Those figures indicate a heterogeneous distribution of S. haematobium in the study area. A sampling plan (16.6) was then tested in the same area while other sampling plans were simulated in the laboratory. School teachers randomized under supervision the children to participate in this study and collected urine samples. All sampling plans (16.6), (14.5), (12.4), (10.3), (8.2), (6.1) et (4.0) allowed correct identification of hyper-endemic and hypo-endemic areas. Misclassifications occurred frequently for intermediate-endemic areas. The study confirms that the LQAS method by use of a (16.6) sampling plan constitute a valuable tool for large scale screening of hyper-endemic areas for therapeutic intervention as part of the control program. The study has also shown that school teachers may offer a potential source of manpower locally in such screening operations.

[Ultrasonographic evaluation of Schistosoma mansoni morbidity: comparison of Cairo/WHO and Managil-Hannover classifications]. / Evaluation échographique de la morbidité liée à Schistosoma mansoni: comparaison des classifications Cairo/OMS et Managil-Hannover.

A ultrasonographical survey of morbidity in schistosomiasis mansoni was carried out in two villages of an endemic area of Madagascar. Using the Managil-Hannover classification, the overall prevalence of morbidity in the first village was of 49.4% and of 39.4% in the second one, while modified Cairo/WHO classification found 9.1% and 1.9% respectively. Thus, results given by the two classifications for a same individual are often discordant. This discrepancy is essentially observed in the lower stage of morbidity while advanced cases are generally well-staged by either of these two methods. These differences in the sonographical assessment of morbidity related to hepatosplenic schistosomiasis make it necessary to continue investigations in order to establish a classification that will have the agreement of everybody.