Gastro-intestinal parasite infections in the Angolan black and white colobus monkey (colobus angolensis palliatus) in southern Kenya in relation to age, sex and habitat interference

Abstract

Approximately 2000 black and white Angolan Colobus, (Colobus angolensis palliatus) remain in Kenya, Kwale District. The arboreal primate species is threatened by unchecked deforestation for private development currently ongoing in Kwale District, and also countrywide. The aim of this study was to determine the prevalence of gastrointestinal parasites in C. angolensis in Diani in relation to age, sex and habitat disturbance. Parasites of C. angolensis were compared to those of C. Guereza in Kitale and other non-human primates in Diani. It was viewed as important to establish the ,gastro-intestinal parasitic fauna of the Angolan Colobus and other Diani non-human primates in the interests of public health, and also to determine whether habitat change influences Colobus parasite patterns. The study was undertaken in collaboration with the Colobus Trust, an organization dedicated to conserving the Angolan Colobus. The primary study area was Diani Beach, Kwale District. The second area of study (for the sampling of C. Guereza) was located near Kitale town, TransNzoia District. Faecal samples were collected from several C. angolensis troops with comparative samples collected from Guereza Colobus in Kitale an,d non-human primates in Diani. Samples were processed using the Formol-Ether concentration technique, the McMaster's floatation technique and the Harada-Mori larval culture technique. Vegetation transects were conducted through Angolan Colobus troop territories to assess the vegetation integrity; three Colobus troops (from areas of varying integrity) were followed to gather behavioural and other data regarding the troops' environment. Angolan Colobus faecal samples had Entamoeba coli and Entamoeba histolytica cysts, and eggs of Trichuris spp, Strongyloides spp and Enterobius vermicularis nematode species. Guereza Colobus faecal samples exhibited only E. coli and E. histolytica cysts. Balantidium coli cysts were also found, but only in the Baboon samples. Age and sex showed no influence on parasite prevalence or intensity. E. coli and E. histolytica prevalence was similar in the Angolan and Guereza Colobus and other primates sampled, whereas intensities of Trichuris and Strongyloides eggs were highest in Baboons. Thirteen out of 29 of the Colobus samples from the Harada-Mori larval culture were positive for Strongyloides species. There was less than 10% variation in the prevalence of parasitic fauna found between Angolan Colobus troops from varying habitat types. Colobus angolensis and C. Guereza troops showed similar activity patterns throughout the day, with variations occurring in feeding (p < 0.05) and moving (p < 0.005) patterns and a significant difference found between mean height above ground (p < 0.01), with C. Guereza maintaining a higher height above ground. Ground contact was viewed as the main mode of parasitic infection in the Angolan Colobus. The minimal influence of habitat on parasite prevalence suggests that factors alternative to forest degradation may be responsible for increased ground contact in C. angolensis. However diminishing forest cover has negative implications for public health in Diani, bringing human and primate populations into closer proximity and increasing the potential for zoonotic infections. Further observations may reveal more about factors potentially facilitating parasite infection. A policy aimed at preserving the Diani forest and raising awareness to the impacts of deforestation will invariably contribute towards the conservation of Angolan Colobus in Kenya.