Epidemic Schistosoma mansoni in a known S. haematobium area.

An epidemic of bloody diarrhoea was observed in 1997 and 1998 in Bessoum, north Cameroon. Of 1176 inhabitants, 16.7% went for medical consultation to a public health centre located 10 km away. This epidemic was probably due to the recent introduction of Schistosoma mansoni in an ancient focus of S. haematobium, following the development of irrigated farming. The prevalences amongst primary school children were 76.6% for S. haematobium in urine, and 60.9% for S. mansoni in stool. S. mansoni was found in urine in 28.1%. This epidemic emergence may be secondary to interspecific competition between the 2 schistosomes.