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Wild chimpanzees, like other great apes, are increasingly endangered, and disease is one of the major threats to their survival and conservation. Nevertheless, our knowledge of the pathogens and parasites affecting chimpanzees in their natural habitat is still very limited. In this study the spectrum of gastrointestinal helminths as well as the pattern and parameters of helminth infection of three habituated groups of individually known wild western chimpanzees (Pan troglodytes verus) in the Taï NP, Côte d’Ivoire were investigated between June 2007 and March 2010. Objective was to determine detailed and up-to-date helminthological reference data for this chimpanzee population.
For this unpreserved or formalin-fixed fecal samples collected from 72 chimpanzees between ca. 2 and 52 years of age were analyzed using four conventional examination methods (modified Wisconsin Sugar Flotations, Harada-Mori fecal cultures, NaNO3-flotations and sedimentations). Additionally, to allow for more specific identification, cultured strongyle and Strongyloides developmental stages were examined employing molecular markers.
Overall, sample analysis revealed the study population to harbour infections with an – as compared to other chimpanzee populations – seemingly high diversity of gastrointestinal helminths, comprising a minimum of three different Oesophagostomum species, Ternidens deminutus, two Necator species (including the potentially human-transmitted N. americanus), one trichostrongylid nematode (possibly of the genus Paralibyostrongylus), at least one Strongyloides species (S. fuelleborni), Enterobius spp., Trichuris spp., Capillaria spp., one cestode (Bertiella spp.), and one trematode of the family Dicrocoeliidae.
The prevalence of the different helminth types and the examined parameters of helminth infection however were found to vary considerably among the study population. While all chimpanzees were found to be infected with gastrointestinal helminths, substantial, albeit clearly sex- and age-independent inter-individual variations were observed regarding their respective cumulative helminth morphotype richness. Considerable variations were equally noted regarding the fecal strongyle and Strongyloides spp. propagule output of the different individuals. Additionally, significant seasonal variations as well as a significant male bias towards higher propagule output were detected The respective underlying causes for these apparent variations could not unambiguously be determined in the course of this study. Several potential influencing factors, including various methodological constraints were identified and are discussed, but their respective true impact needs to be verified in further, more specific studies.
More specific studies are equally necessary to assess the impact of helminth infections on the overall health and fitness of the study population.