Impact of human activities on chimpanzee ground use and parasitism (Pan troglodytes)

The potential of human activities, including research, to alter parasite transmission ecology in wildlife is unknown. We examined gastrointestinal parasitism in chimpanzees (Pan troglodytes schweinfurthii) in Budongo Forest, Uganda. Trail use and time spent on the ground was recorded during 10 months of observations in four sites with differing human disturbance. Disturbance was quantified using transect plots (n = 320). Fecal (n = 435) samples were examined for helminth eggs, larvae, and for protozoan cysts. Individuals that spent more time on the ground had more infections and higher intensity infections. Prevalence of 13 parasite species was similar across sites, but percentage of multiple infections and infection intensity differed, as did ground use. Chimpanzees at the long-term research site spent more time on the ground or on human trails. We hypothesize that researcher presence and trail creation may influence ground use, and thereby parasite burden, by altering trade-offs between foraging and predation risk.