Variation over Time in Parasite Prevalence Among Free-ranging Chimpanzees at Gombe National Park, Tanzania

From January to September, 2005, we collected fecal samples from 60 chimpanzees at Gombe National Park, Tanzania and examined them for parasites. We compared current parasite prevalence data with previous studies to obtain a pattern of parasitism over time. There were considerable similarities in the parasite species composition and prevalence, although we noted some variations. Generally, parasite prevalence decreased over time, with the present prevalence being lower than in previous surveys. We identified 8 types of parasites, all of which had previously been documented in the chimpanzees of Gombe. Three nematodes - Oesophagostomum sp., Strongyloides fulleborni, and Abbreviata caucassica- occurred at higher prevalence (41.2-45.5%) but relatively lower than previous findings of 50-91%. We also diagnosed unidentified strongyles at a moderate prevalence (33%), lower than a previous record of 41%. Probstmayria gombensis occurred at relatively low prevalence (16.4%) vs. past observations (23-59%), while the prevalence of Trichuris sp. (7.3%) was closely similar to previous records of 5-9%. We also observed unidentified ciliate at 9% within the same range as in previous studies (5-28%). The prevalence of Troglodytella abrassarti was 78%, closely similar to previous findings of 75%. There was no significant variation in parasite prevalence between chimpanzees of the Kasekela community and those of the Mitumba community, although the former tended to have higher prevalence of helminths than the latter. The causes of the similarities and variations in parasite prevalence over time are discussed. The study provides baseline data for monitoring of chimpanzee health at Gombe.