Studies on the biology of schistosomiasis with emphasis on the Senegal river basin

The construction of the Diama dam on the Senegal river, the Manantali dam on the Bafing river, Mali and the ensuing ecological changes have led to a massive outbreak of Schistosoma mansoni in Northern Senegal, associated with high intensity of infections, due to intense transmission, and the creation of new foci of S. haematobium. Data on the vectorial capacity of Biomphalaria pfeifferi from Ndombo, near Richard Toll, Senegal are presented with sympatric and allopatric (Cameroon) S. mansoni. Comparisons are made on infectivity, cercarial production, chronobiology of cercarial emergence and longevity of infected snails. Recent data on the intermediate host specificity of different isolates of S. haematobium from the Lower and Middle Valley of the Senegal river basin (SRB) demonstrate the existence of at least two strains of S. haematobium. The role of Bulinus truncatus in the transmission of S. haematobium in the Lower and Middle Valleys of the SRB is reviewed. Both S. haematobium and S. mansoni are transmitted in the same foci in some areas of the SRB

possibility of transplacental transmission of experimental schistosomiasis

Congenital transmission of Schistosoma mansoni and S. hematobium in mice was studied by experimentally infected pregnant mice on day 3, 9 or 14 of gestation. None of the pups born to mothers infected in early or mid- pregnancy were infected. However, several pregnancies ended in abortion ranging between 10% to 40%. On the other hand, 8 out of 30 pups born to mice infected with S. hematobium in late pregnancy were found to harbor Schistosomes with granulomas recovered in their livers and intestines. These findings showed that congenital infection of mice with S. mansoni and S. hematobium could occur when pregnant mice were infected during late pregnancy. This may have important implications not only for mice but also for other mammalian hosts of Schistosomes including man

Schistosomiasis in newly reclaimed areas in Egypt 2- patterns of transmission

The distribution, abundance and seasonality of infected Biomphalaria alexandrina and Bulinus truncatus were studied for two years [1992-1994] in two newly reclaimed areas; namely, El-Manayef and El- Morra located on both sides of Suez Canal near Ismailia City. The results confirmed the occurrence of transmission of both Schistosoma mansoni and S. hematobium since infected snails of both species were recovered in these areas. Consequently, this proved that reclamation of parts of the desert utilizing Nile water had led to the spread of Schistosomiasis to these areas. Analysis of the Delta showed that the infected snails, especially B. alexandrina, was found clustered in a relatively few number of transmission sites. Furthermore, the greater majority of these sites were found to be located within a less number of transmission foci. This pattern of focality was clearly demonstrated by geographical information system [GIS] produced maps