Community composition, correlations among taxa, prevalence, and richness in gastrointestinal parasites of baboons in Senegal, West Africa.

Studies of gastrointestinal parasite prevalence in Papio have either focused on a single troop or compared prevalence among troops that share migrants but differ in degree of human contact. Little is known about the extent of variation in prevalence where obvious factors that may drive prevalence (e.g., human contact) are absent, so it is difficult to interpret variation when these factors are present. To address this issue, we studied troops of Guinea baboons (Papio papio) that had almost no contact with humans or domesticated species of plants or animals. We tested the null hypotheses that community composition, richness, and prevalence would be similar between groups in two comparisons: (1) between troops in the same locality with no known differences in drivers of prevalence, and (2) between samples at the same location taken more than 20 years apart. We collected anonymous fecal samples from two troops of baboons living in a wilderness site, Mt. Assirik, in the Niokolo-Koba National Park, Republic of Senegal, West Africa. We collected samples from two valleys and analyzed prevalence and richness with respect to place and time. Both prevalence and richness were similar in the two valleys, but significant changes emerged in both prevalence and community composition compared with the previous survey in 1978-1979. We also found that the nematode Enterobius and a fluke, Watsonius, co-occurred within hosts more frequently than expected. This phenomenon has not been previously noted in the literature, and it suggests common environmental drivers or facilitation among these parasites.

Patterns of gastro-intestinal parasites and commensals as an index of population and ecosystem health: the case of sympatric western chimpanzees (Pan troglodytes verus) and guinea baboons (Papio hamadryas papio) at Fongoli, Senegal.

The exponential decline of great apes over the past 50 years has resulted in an urgent need for data to inform population viability assessment and conservation strategies. Health monitoring of remaining ape populations is an important component of this process. In support of this effort, we examined endoparasitic and commensal prevalence and richness as proxies of population health for western chimpanzees (Pan troglodytes verus) and sympatric guinea baboons (Papio hamadryas papio) at Fongoli, Senegal, a site dominated by woodland-savanna at the northwestern extent of chimpanzees' geographic range. The small population size and extreme environmental pressures experienced by Fongoli chimpanzees make them particularly sensitive to the potential impact of pathogens. One hundred thirty-two chimpanzee and seventeen baboon fecal samples were processed using sodium nitrate floatation and fecal sedimentation to isolate helminth eggs, larvae, and protozoal cysts. Six nematodes (Physaloptera sp., Ascaris sp., Stronglyloides fuelleborni, Trichuris sp., an unidentified hookworm, and an unidentified larvated nematode), one cestode (Bertiella sp.), and five protozoans (Iodamoeba buetschlii, Entamoeba coli, Troglodytella abrassarti, Troglocorys cava, and an unidentified ciliate) were detected in chimpanzee fecal samples. Four nematodes (Necator sp., S. fuelleborni, Trichuris sp., and an unidentified hookworm sp.), two trematodes (Shistosoma mansoni and an unidentified fluke), and six protozoans (Entamoeba histolytica/dispar, E. coli, Chilomastix mesnili, Balantidium coli, T. abrassarti, and T. cava) were detected in baboon fecal samples. The low prevalence of pathogenic parasite species and high prevalence of symbiotic protozoa in Fongoli chimpanzees are indicative of good overall population health. However, the high prevalence of pathogenic parasites in baboons, who may serve as transport hosts, highlight the need for ongoing pathogen surveillance of the Fongoli chimpanzee population and point to the need for further research into the epidemiology and cross-species transmission ecology of zoonotic pathogens at this site.