Infection with schistosomiasis and soil-transmitted helminthiasis are widespread in sub-Saharan Africa and the burden of disease associated with parasites is enormous. A study was performed to determine the transmission and prevalence of human schistosomiasis and soil-transmitted helminthiasis among school children of Nikki and Perere, two north eastern towns of Benin, bordering Republic of Nigeria. Parasitological investigations by urine filtration and Kato-Katz conducted on 1,344 school children indicated a mean prevalence of S. haematobium and S. mansoni 48.44% and 0%, respectively, in the children of Nikki area and 45.24% and 4.11% in Perere area. Only schoolchildren of Sonon locality were infected by S. mansoni with a mean prevalence rate of 36.24%. KatoKatz tests releaved five species of soil-transmitted helminths: Ankylostoma duodenale (8.16% and 6.73%), Ascaris lumbricoides (6.26% and 2.30%), Enterobius vermicularis (1.09% and 1.97%), Trichuris trichiura (1.97% and 1.90%) and Strongyloides stercoralis (2.04% and 0.99%), respectively, in the schoolchildren of Nikki and Perere areas. The malacological investigations carried out in the freshwater points of each visited locality highlighted the presence of four species of freshwater snails known as intermediate host of schistosome: Biomphalaria pfeifferi, Bulinus forskalii, B. globosus and B. truncatus.Two B. globosus and B. pfeifferi collected in Sonon locality were naturally infected by schistosome, indicated the importance of their two species of snail in schistosome transmission cycle.
Predation by larvae of Sepedon ruficeps (Diptera: Sciomyzidae) and population dynamics of the adult flies and their freshwater prey. -The biology, phenology, and population dynamics of the adults of Sepedon ruficeps, the most widely distributed species of Sciomyzidae in Africa, were studied in Benin in permanent and temporary freshwater habitats. The feeding behavior of the larvae, expressed as the number of snails consumed, varies as a function of the species of prey utilized (Bulinus forskalii or Biomphalaria pfeifferi), as a function of the sizes of the predator/prey, and as a function of the stages of development of the larvae. In relation to the snail-prey, the second-and third instar-larvae show a food choice varying according to the specific ethology of the prey attacked. In all cases, the third-instar larvae always consume the largest number of snails and indifferently attack all of the species of snails utilized in laboratory rearings. The larvae consume, equally well, B. forskalii that are healthy or parasitized by the larvae of trematodes. Curiously, in laboratory rearings, in the absence of snails, the larvae of S. ruficeps are equally capable of attacking and developing at the expense of Aulophorus furcatus, a small, freshwater, oligochaete annelid (Naididae).
All studies during the last six decades have stated that sciomyzid larvae are strictly malacophagous. However, the Afrotropical sciomyzid Sepedonella nana species was found in this study to feed only on the small freshwater oligochaete, Aulophorus furcatus. The divergent oligophagous feeding behaviour of this species was investigated. The physical attributes of the egg, first-, secondand third-instar larvae, and the puparium are described. Four types of sensilla—coeloconicum, trichodeum, chaeticum, and styloconicum—are present with a characteristic distribution on each tagma. Each thoracic segment is distinguished by presence of a pair of Keilin’s organ on ventral surface. Each abdominal segment has eleven pairs of the same sensilla types; their variable locations are presented. Population dynamics of the adults are shown from our field investigations in permanent and temporary freshwater biotopes during 1996–2008. The life cycle of the species is presented from our field observations and laboratory experiments. Among the 62 species of Afrotropical Sciomyzidae, this is the eighth species for which life-cycle is entirely resolved.
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