SCHISTOSOMA-MANSONI INFECTION IN A NATURAL-POPULATION OF OLIVE BABOONS (PAPIO-CYNOCEPHALUS-ANUBIS) IN GOMBE STREAM NATIONAL-PARK, TANZANIA

Infection with Schistosoma mansoni was studied in 5 troops of olive ba boons (Papio cynocephalus anubis) in Gombe Stream National Park, Tanza nia. Three troops were infected with S. mansoni. An aggregated distrib ution of parasites was observed among hosts. Troop membership was foun d to be the most significant factor influencing parasite prevalence. A ge and reproductive status had no significant effect, but there was a trend for males to acquire higher levels of infection. However, age-pr evalence curves showed a high infection in young baboons declining in the older baboons. Behavioural components of exposure-as measured in w ater-contact pattern-may be related to parasite burden. A 'peak shift' between infection in different age-classes in the different troops wa s observed: troops with higher schistosome prevalences displayed an ea rlier peak in prevalence of infection. The baboon troop with the most contact with people showed highest prevalence of infection possibly du e to longer exposure to the parasite than the other troops and/or high er host density.