Adult resistance to schistosomiasis mansoni: age-dependence of reinfectionremains constant in communities with diverse exposure patterns

In a fishing community on Lake Albert in Uganda the pattern of intensity of Schistosoma mansoni infection 6 months after treatment with praziquantel w as found to be very similar to reinfection patterns seen in previously stud ied endemic communities: the profile peaks sharply at around the age of 10 years falling away rapidly to much lower levels in adults. This is in stark contrast to the patterns of water contact, which differ greatly between fi shing and non-fishing communities. On Lake Albert, adults appear to be more heavily exposed than children. From these observations we conclude that ad ults are physiologically (perhaps immunologically) more resistant to infect ion after treatment than children.