Intestinal parasites of sympatric gorillas and chimpanzees in the Lopé Reserve, Gabon.

A coprological survey of intestinal parasites of wild chimpanzees (Pan t. troglodytes) and western lowland gorillas (Gorilla g. gorilla) was carried out in the Lopé Reserve in central Gabon. Most samples (69%) were positive but the prevalence of intestinal parasites in the 61 gorilla samples (84%) was higher than in the 66 chimpanzee samples (56%). At least 11 species of parasite were observed: six protozoan, one trematode and at least four nematodes. Six of the species were found in gorillas and chimpanzees but the remainder only occurred in chimpanzees. All but one parasite occurred at low prevalences. Entodiniomorph ciliates, which occurred frequently in both ape species (particularly in gorillas) in the Lopé survey and in all previous coprological surveys of wild apes, may be symbionts involved in cellulose digestion. The dietary and behavioural strategies of wild primates that serve to reduce infection by pathogenic parasites are reviewed.