Assessment of schistosomiasis prevalence among children 5 to 14 years old after several years of mass drug administration in the Senegal River basin / Évaluation de la prévalence des bilharzioses auprès des enfants de 5 à 14 ans après plusieurs années de traitement de masse dans le bassin du fleuve Sénégal.

Introduction: The advent of Diama and Manantali dams in the eighties has altered the schistosomiasis profile in the Senegal River Basin, with the appearance of an intestinal form in the Delta and a high prevalence of the urinary form in all ecological areas of the basin. Methods: The present study was mainly designed to re-evaluate the prevalence of schistosomiasis after many years of mass drug administration with praziquantel 600 mg allowing analysis of the pertinence of World Health Organisation guidelines in terms of dosing frequency, particularly in the Senegal River Basin. Stools and urine from 1,215 public school children from 24 villagesidentified in three ecological areas of the Senegal River Basin (Delta, valley, upper basin), were examined. Results: The results of thisstudy show the endemic prevalences of urinary schistosomiasisin all ecological areas ofthe Senegal River Basin: 57.4% in the Delta, 32.5% in the Valley and 25.1% in the upper basin. The prevalence of the intestinalschistosomiasisform was 21.8 % in the Delta, and this form has also entered the valley. Conclusion: The results ofthisstudy confirm that schistosomiasis is still a public health problem in the Senegal River Basin despite several series of mass praziquantel 600 mg administration. This situation requires detailed reflection concerning dosing frequencies of this drug in the Senegal River basin and the need to take social behaviours and sociological realities into account in order to eradicate schistosomiasis.

Sero-epidemiological evaluation of Plasmodium falciparum malaria in Senegal.

BACKGROUND: In Senegal, a significant decrease of malaria transmission intensity has been noted the last years. Parasitaemia has become lower and, therefore, more difficult to detect by microscopy. In the context of submicroscopic parasitaemia, it has become relevant to rely on relevant malaria surveillance tools to better document malaria epidemiology in such settings. Serological markers have been proposed as an essential tool for malaria surveillance. This study aimed to evaluate the sero-epidemiological situation of Plasmodium falciparum malaria in two sentinel sites in Senegal. METHODS: Cross-sectional surveys were carried out in Velingara (south Senegal) and Keur Soce (central Senegal) between September and October 2010. Children under 10 years old, living in these areas, were enrolled using two-level, random sampling methods. P. falciparum infection was diagnosed using microscopy. P. falciparum antibodies against circumsporozoite protein (CSP), apical membrane protein (AMA1) and merozoite surface protein 1_42 (MSP1_42) were measured by ELISA method. A stepwise logistic regression analysis was done to assess factors associated with P. falciparum antibodies carriage. RESULTS: A total of 1,865 children under 10 years old were enrolled. The overall falciparum malaria prevalence was 4.99% with high prevalence in Velingara of 10.03% compared to Keur Soce of 0.3%. Symptomatic malaria cases (fever associated with parasitaemia) represented 17.37%. Seroprevalence of anti-AMA1, anti-MSP1_42 and anti-CSP antibody was 38.12, 41.55 and 40.38%, respectively. The seroprevalence was more important in Velingara and increased with age, active malaria infection and area of residence. CONCLUSION: The use of serological markers can contribute to improved malaria surveillance in areas with declining malaria transmission. This study provided useful baseline information about the sero-epidemiological situation of malaria in Senegal and can contribute to the identification of malaria hot spots in order to concentrate intervention efforts. TRIAL REGISTRATION NUMBER: PACTR201305000551876 ( http://www.pactr.org ).