[Urban schistosomiasis in Cameroon: a longitudinal study of its transmission in a new site of an extension of the intestinal schistosomiasis focus in Mélen, Yaoundé].

In order to to set up the present situation on schistosomiasis in the neighbourhoods around the University of Yaounde I campus, a malacological survey (collection of freshwater snails, their identification and tests on cercarial emergence) was carried out monthly over 12 months in 2 water sources, followed by a parasitological diagnosis of intestinal schistosomiasis in subjects who acknowledge having come into contact with the infested water course. The malacological survey revealed 4 freshwater gastropod species, two (Bulinus globosus and Biomphalaria pfeifferi) of which are intermediate hosts of schistosomes. Biomphalaria pfeifferi specimens from the former quarry pond of Ngoa-Ekellé neighbourhood showed an average infestation rate of 9.7%, and emitted schistosome cercariae throughout the whole period of study The parasitological diagnosis included 112 (81.2%) out of the 138 individuals identified, including 55 males and 57 females; 27 out of the 112 subjects had S. mansoni eggs in stools, making a prevalence rate of 24.1%. These patients were composed of 21 males and 6 females. The prevalence of S. mansoni is therefore significantly higher in males. The average parasitic load for our sample was 248 eggs/g of stools. It was much higher (384 eggs/g stools) for males (280 eggs/g stools) than for females (136 eggs/g stools). The differences of prevalences and parasitic loads between sex can be explained in part by the varying activities of interest according to the different groups in the infested watering places.