Community water-contact patterns and the transmission of Schistosoma haematobium in the highveld region of Zimbabwe.

The patterns of community water-contact, their relationships to Schistosoma haematobium infection in the human population and also in Bulinus globosus, snail host for S. haematobium and S. mattheei were carried out at 12 human water contact sites located in stream habitats in the temperate highveld region of Zimbabwe over a 27-month period during 1982-1984. It was shown that water contact was markedly heterogeneous with sex, age, type of activity and village location being the major variables affecting water-contact patterns. This heterogeneity in contact appears to be related to variations in levels of infection with S. haematobium among residents of the villages and by sex but in adults high water-contact was not associated with increased levels of infection and this discrepancy is attributed to the influence of acquired immunity in adults. An association was found between total body exposure indices and prevalence of S. haematobium in B. globosus in the cool dry and hot dry period of the year indicating that the level of input of schistosome eggs into water play an important role in determining snail infection rates, although the absence of clearcut relationships between the two parameters in the rainy and post-rainy periods suggest that other factors may be involved.