Premier cas de chronobiologie des émissions cercariennes de type infradien chez Schistosoma mansoni dans deux foyers du Sud Bénin

International audienceLa schistosomose constitue au Bénin un réel problème de santé publique comme dans la plupart des autres pays africains. L'étude de la chronobiologie des émissions cercariennes horaires de deux populations de Schistosoma mansoni du sud-Bénin révèle, aussi bien en conditions de laboratoire qu'en conditions naturelles, un rythme particulier d'émission de type infradien avec 3 périodes de production : à l'aube entre 6 heures et 8 heures (Heure Locale, HL), en milieu de journée entre 09 heures et 15 ou 16 heures (HL) et le soir entre 17 heures et 20 heures (HL). Ce rythme d'émission est contraire à celui du type circadien, avec un seul pic d'émission, connu à ce jour pour les schistosomes de ce groupe. Ces deux populations de schistosomes ont été soumises à une pression sélective de même nature induisant des modifications dans le sens de l'harmonisation des processus de transmission du parasite à l'hôte vertébré. Une étude ultérieure permettra de mieux apprécier les causes de la modification du rythme circadien au type infradien

Epidemiology of urinary schistosomiasis among school children in Péhunco area, Northern Benin. Malacological survey

International audienceSchistosomiasis is a public health problem in Benin but prevalence estimates vary widely. Parasitological (from May to September 2010) and malacological surveys (from September 2010 to June 2012) were conducted to determine the current status of urinary schistosomiasis among 1 585 schoolchildren from 18 primary schools of Péhunco area, North-West Benin, using two parasitological tests. Pupils were enrolled with a mean age of 11 years (from 7 to 16 years-old age) and 51.48% of them were girls. Urines samples were examined using both urine reagent strips and filtration method. Structured questionnaires were used to identify environmental and socio-economic factors. Malacological surveys were conducted to ascertain general freshwater snail diversity and specific diversity of the schistosome host snails. The results showed a general prevalence of 29.40% with boys (36.67%) significantly more affected than girls (22.55%). Among the 844 collected snails, 5 species freshwater snails were identified: two species known as potential schistosome intermediate host snails, Bulinus forskalii and B. globosus, and three species known as non-schistosome transmitting snails Lymnaea natalensis, Physa marmorata and Melanoides tuberculata. B. forskalii was a most largely distributed snail and none of snails were found naturally infected by schistosome. No freshwater snails were found naturally infected by schistosome

Introgressive hybridizations of Schistosoma haematobium by Schistosoma bovis at the origin of the first case report of schistosomiasis in Corsica (France, Europe)

International audienceThis study concerns the first urinary schistosomiasis case observed in Corsica (France, Europe) occurring in a 12-year-old German boy. The aim was to identify the relationship between this Schistosoma haematobium infection and other schistosomes of the Schistosoma group with terminal-spined ova. Morphological and molecular analyses were conducted on the ova. The results showed that the schistosome responsible for the emergence of schistosomiasis in Corsica was due to S. haematobium introgressed by genes from S. bovis

Forecasting the effectiveness of the DeWorm3 trial in interrupting the transmission of soil-transmitted helminths in three study sites in Benin, India and Malawi

Funding Information: The DeWorm3 study is funded through a grant to the Natural History Museum, London, from the Bill and Melinda Gates Foundation (OPP1129535). This award is jointly funded by the UK Medical Research Council (MRC) and the UK Department for International Development (DFID) under the MRC/DFID Concordat agreement and is also part of the EDCTP2 programme supported by the European Union. Publisher Copyright: © 2021, The Author(s).BACKGROUND: The DeWorm3 project is an ongoing cluster-randomised trial assessing the feasibility of interrupting the transmission of soil-transmitted helminths (STH) through mass drug administration (MDA) using study sites in India, Malawi and Benin. In this article, we describe an approach which uses a combination of statistical and mathematical methods to forecast the outcome of the trial with respect to its stated goal of reducing the prevalence of infection to below 2%. METHODS: Our approach is first to define the local patterns of transmission within each study site, which is achieved by statistical inference of key epidemiological parameters using the baseline epidemiological measures of age-related prevalence and intensity of STH infection which have been collected by the DeWorm3 trials team. We use these inferred parameters to calibrate an individual-based stochastic simulation of the trial at the cluster and study site level, which is subsequently run to forecast the future prevalence of STH infections. The simulator takes into account both the uncertainties in parameter estimation and the variability inherent in epidemiological and demographic processes in the simulator. We interpret the forecast results from our simulation with reference to the stated goal of the DeWorm3 trial, to achieve a target of [Formula: see text] prevalence at a point 24 months post-cessation of MDA. RESULTS: Simulated output predicts that the two arms will be distinguishable from each other in all three country sites at the study end point. In India and Malawi, measured prevalence in the intervention arm is below the threshold with a high probability (90% and 95%, respectively), but in Benin the heterogeneity between clusters prevents the arm prevalence from being reduced below the threshold value. At the level of individual study arms within each site, heterogeneity among clusters leads to a very low probability of achieving complete elimination in an intervention arm, yielding a post-study scenario with widespread elimination but a few 'hot spot' areas of persisting STH transmission. CONCLUSIONS: Our results suggest that geographical heterogeneities in transmission intensity and worm aggregation have a large impact on the effect of MDA. It is important to accurately assess cluster-level, or even smaller scale, heterogeneities in factors which influence transmission and aggregation for a clearer perspective on projecting the outcomes of MDA control of STH and other neglected tropical diseases.Peer reviewe