La lutte contre les schistosomoses en Afrique de l'Ouest

#Schistosoma haematobium est largement distribué au Bénin et présent dans tout le pays. #S. mansoni est restreint à quelques foyers généralement de faible intensité. Les prévalences à #S. haematobium sont plus fortes dans le sud et le centre du pays que dans le nord où, il est vrai, peu d'enquêtes ont été menées. Une étude récente conduite à Adjarala, site d'un barrage hydroélectrique en construction, a mis en évidence la forte prévalence de #S. haematobium avec une morbidité importante et celle, faible mais confirmée, de #S. mansoni$

Malaria infection and disease in an area with pyrethroid-resistant vectors in southern Benin

<p>Abstract</p> <p>Background</p> <p>This study aimed to investigate baseline data on malaria before the evaluation of new vector control strategies in an area of pyrethroid-resistance of vectors. The burden of malaria was estimated in terms of infection (prevalence and parasite density) and of clinical episodes.</p> <p>Methods</p> <p>Between December 2007 and December 2008 in the health district of Ouidah - Kpomassè - Tori Bossito (southern Benin), a descriptive epidemiological survey of malaria was conducted. From 28 selected villages, seven were randomized from which a total of 440 children aged 0 to 5 years were randomly selected. Clinical and parasitological information was obtained by active case detection of malaria episodes carried out during eight periods of six consecutive days scheduled at six weekly intervals and by cross-sectional surveys of asymptomatic infection. Entomological information was also collected. The ownership, the use and the correct use of long-lasting insecticide-treated nets (LLINs) were checked over weekly-survey by unannounced visits at home in the late evening.</p> <p>Results</p> <p>Mean parasite density in asymptomatic children was 586 <it>P. falciparum </it>asexual forms per μL of blood (95%CI 504-680). Pyrogenic parasite cut-off was estimated 2,000 <it>P. falciparum </it>asexual blood forms per μL. The clinical incidence of malaria was 1.5 episodes per child per year (95%CI 1.2-1.9). Parasitological and clinical variables did not vary with season. <it>Anopheles gambiae </it><it>s.l</it>. was the principal vector closely followed by <it>Anopheles funestus</it>. Entomological inoculation rate was 5.3 (95%CI 1.1-25.9) infective bites per human per year. Frequency of the L1014F <it>kdr </it>(West) allele was around 50%. Annual prevalence rate of <it>Plasmodium falciparum </it>asymptomatic infection was 21.8% (95%CI 19.1-24.4) and increased according to age. Mean rates of ownership and use of LLINs were 92% and 70% respectively. The only correct use of LLINs (63%) conferred 26% individual protection against only infection (OR = 0.74 (95%IC 0.62-0.87), p = 0.005).</p> <p>Conclusion</p> <p>The health district of Ouidah-Kpomassè-Tori Bossito is a mesoendemic area with a moderate level of pyrethroid-resistance of vectors. The used LLINs rate was high and only the correct use of LLINs was found to reduce malaria infection without influencing malaria morbidity.</p

The impact of the expansion of urban vegetable farming on malaria transmission in major cities of Benin

BACKGROUND: Urban agricultural practices are expanding in several cities of the Republic of Benin. This study aims to assess the impact of such practices on transmission of the malaria parasite in major cities of Benin. METHOD: A cross sectional entomological study was carried out from January to December 2009 in two vegetable farming sites in southern Benin (Houeyiho and Acron) and one in the northern area (Azèrèkè). The study was based on sampling of mosquitoes by Human Landing Catches (HLC) in households close to the vegetable farms and in others located far from the farms. RESULTS: During the year of study, 71,678 female mosquitoes were caught by HLC of which 25% (17,920/71,678) were Anopheles species. In the areas surveyed, the main malaria parasite, Plasmodium falciparum was transmitted in the south by Anopheles gambiae s.s. Transmission was high during the two rainy seasons (April to July and October to November) but declined in the two dry seasons (December to March and August to September). In the north, transmission occurred from June to October during the rainy season and was vehicled by two members of the An. gambiae complex: Anopheles gambiae s.s. (98%) and Anopheles arabiensis (2%).At Houeyiho, Acron and Azèrèkè, the Entomological Inoculation Rates (EIRs) and the Human Biting Rates (HBRs) were significantly higher during the dry season in Households Close to Vegetable Farms (HCVF) than in those located far from the vegetable areas (HFVF) (p 0.05).The knock-down resistance (kdr) mutation was the main resistance mechanism detected at high frequency (0.86 to 0.91) in An. gambiae s.l. at all sites. The ace-1R mutation was also found but at a very low frequency (< 0.1). CONCLUSION: These findings showed that communities living close to vegetable farms are permanently exposed to malaria throughout the year, whereas the risk in those living far from such agricultural practices is limited and only critical during the rainy seasons. Measures must be taken by African governments to create awareness among farmers and ultimately decentralize farming activities from urban to rural areas where human-vector contact is limited

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

[Seroprevalence of Toxoplasmosis among Pregnant Women in Benin: Meta-Analysis and Meta-Regression].

International audienceTo assess the seroprevalence of toxoplasmosis among pregnant women in Benin, we conducted a meta-analysis using the PRISMA criteria. Al research published between 1990 and 2018 on toxoplasmosis among pregnant women Benin were eligible. A total of five databases were investigated, and the extracted data were subjected to a meta-analysis under R 3.1 using both random effect model and fixed effect model. The overall prevalence of toxoplasma-specific IgG among pregnant women was 47% (CI 95%: 40-53) and that of specific IgM was 2% (CI 95%: 1-3). The infection rate in urban areas (52%) was significantly higher than in rural areas (33%). The two main risk factors identified by the various eligible studies were the age of the pregnant women and the consumption of raw vegetables. We show that toxoplasmosis is endemic in pregnant women in Benin, implying that primary prevention measures must be put in place by the competent authorities to control this infection