Risk factors for respiratory illness in a community of wild chimpanzees (Pan troglodytes schweinfurthii)

Respiratory disease has caused significant mortality in African great ape populations. While much effort has been given to identifying the responsible pathogens, little is known about the factors that influence disease transmission or individual susceptibility. In the Kanyawara community of wild chimpanzees, respiratory illness has been the leading cause of mortality over 30 years, contributing to 27% of deaths. Deaths were common in all age groups except juveniles. Over 22 years of health observations, respiratory signs were rare among infants and most common among older adults of both sexes. Signs were also common among males during the transition to adulthood (ages 10-20 years), particularly among those of low rank. Respiratory signs peaked conspicuously in March, a pattern that we could not explain after modeling climatic factors, group sizes, diet, or exposure to humans. Furthermore, rates of respiratory illness in the chimpanzees did not track seasonal rates of disease in the near...