Parasitological analyses of the male chimpanzees (Pan troglodytes schweinfurthii) at Ngogo, Kibale National Park, Uganda

Abstract

Numerous intestinal parasites identified in populations of wild nonhuman primates can be pathogenic to humans. Furthermore, nonhuman primates are susceptible to a variety of human pathogens. Because of increasing human encroachment into previously nonimpacted forests, and the potential for disease transmission between human and nonhuman primate populations, further detailed investigations of primate ecological parasitology are warranted. For meaningful comparisons to be made, it is important for methods to be standardized across study sites. One aspect of methodological standardization is providing reliable estimates of parasite prevalence and knowing how many samples are needed to adequately estimate an individual's parasite prevalence. In this study the parasitic fauna of 37 adult, adolescent, and juvenile male chimpanzees from the Ngogo group, Kibale National Park, Uganda, were assessed from 121 fecal samples collected over a 3-month period. Twelve taxa of intestinal species (five helminth and seven protozoan) were recovered from the samples. The four most prevalent species were Troglodytella abrassarti (97.3%), Oesophagostomum sp. (81.1%), Strongyloides sp. (83.8%), and Entamoeba chattoni (70.3%). No one species was found in all samples from any one animal, and Troglodytella abrassarti, the most common intestinal organism, was found in all of the serial samples of only 69.4% of the chimpanzees. The cumulative species richness for individuals significantly increased for every sequential sample (up to three to four samples) taken per animal during this study. The results indicate that to accurately diagnose total intestinal infection and evaluate group prevalence, three to four sequential samples from each individual must be collected on nonconsecutive days. This conclusion applies only to short study periods in which possible seasonal effects are not taken into consideration. Validation of these results at different study sites in different regions with different climatic patterns is needed.

Prevalence of Troglodytella abrassarti Brumpt and Joyeux, 1912 in Wild Chimpanzees (Pan troglodytes schweinfurthii) at Mahale Mountains National Park in Western Tanzania

“…They found that 97% of the 37 chimpanzees were positive for trophozoites of T. abrassarti, while 84% of the 121 total samples from these chimpanzees were positive for trophozoites of T. abrassarti. Our study is in agreement with the findings of Ashford et al (2000) and Muehlenbein (2005), indicating that chimpanzees are frequently hosts for trophozoites of T. abrassarti. It should be noted that Murray et al (2000) were not focusing on the prevalence of T. abrassarti in their study and used only a direct smear to detect infections; this may explain the lower prevalence of 20% (3 of 20) of positive chimpanzees that they observed.…”

“…There have been a few studies examining the prevalence of T. abrassarti in chimpanzees in their natural habitat (File et al, 1976;Ashford et al, 2000;Murray et al, 2000;Krief et al, 2005;Muehlenbein, 2005). Trophozoites of T. abrassarti were observed in 24 (75%) of 32 wild chimpanzees from Gombe National Park, Tanzania, using the formalinether concentration technique (File et al, 1976).…”

“…They based their results on examination of 200 ml of formalin-fixed stool sample from each animal. Muehlenbein (2005) conducted a study on 121 stool samples from 37 male chimpanzees from the Ngogo area of Kibale National Park, Uganda, using the formalin-ethyl acetate sedimentation technique. They found that 97% of the 37 chimpanzees were positive for trophozoites of T. abrassarti, while 84% of the 121 total samples from these chimpanzees were positive for trophozoites of T. abrassarti.…”

Phylogeography, conservation genetics and parasitology of chimpanzees (Pan troglodytes verus) in Guinea-Bissau, West Africa.

“…Prevalence of T. cava reached 55.5% in individuals sampled only once, 79.3% in individuals sampled twice, 92% in individuals sampled 3 times, and 95.5% if four and more samples were collected. These results conform to other studies suggesting that ideally three or four samples per animal are necessary to assess the real prevalence of a particular parasite/symbiont (Huffman et al 1997;Muehlenbein 2005). Therefore, we predict that T. cava is present in all individuals in wild chimpanzee populations, a pattern documented previously for T.…”

Life on the edge: gastrointestinal parasites from the forest edge and interior primate groups

“…However, repeat samples likely occurred, and thus this should be viewed as an index of prevalence. This is a concern because a small number of animals with consistently high infection levels and high richness could be overrepresented in the sampling scheme, particularly considering that sick animals may defecate more than healthy individuals (see Muehlenbein [2005] for a discussion of this issue). In a quantitative evaluation of this issue, Huffman et al [1997] contrasted incidences of infection based on the number of fecal samples obtained from chimpanzees (Pan troglodytes) from Mahale vs. that based on the number of known individuals, and documented that individual infection rates, the preferred unit of comparison, was statistically higher than rates based on all samples.…”