Potentially Zoonotic Enteric Infections in Gorillas and Chimpanzees, Cameroon and Tanzania

Despite zoonotic potential, data are lacking on enteric infection diversity in wild apes. We employed a novel molecular diagnostic platform to detect enteric infections in wild chimpanzees and gorillas. Prevalent Cryptosporidium parvum, adenovirus, and diarrheagenic Escherichia coli across divergent sites and species demonstrates potential widespread circulation among apes in Africa.


Conclusions
Real-time PCR testing of noninvasively collected wild gorilla and chimpanzee fecal samples from Cameroon and Tanzania provided evidence of widespread enteric infections and demonstrates their potential circulation in ape populations in Africa before 2018.Several pathogen targets detected in the ape species are highly relevant to humans, including those commonly associated with diarrheal disease, such as diarrheagenic E. coli, adenovirus, Shigella spp., Giardia spp., and enterovirus.As human-nonhuman primate contact increases in tropical forest communities, opportunities will continue to arise for both anthroponotic and zoonotic exchange and exposure (11).
Adenoviruses and Cryptosporidium species infect a broad range of hosts (including humans and nonhuman primates), can cause mild to severe disease, and are also associated with high rates of illness and death in children and immunocompromised persons, especially in developing countries (12).Although the pathogenesis of those organisms is less understood in nonhuman primate populations, they are of major zoonotic importance, given the increasing overlap between humans and wild primates and high HIV/ AIDS prevalence in humans in regions inhabited by primate populations.Furthermore, because C. parvum and adenoviruses can spread through the fecal-oral route and persist in the environment for extended periods, diverse opportunities exist for direct and indirect transmission between humans and great apes (e.g., tourism and research activities, crop-raiding by apes, and events related to humans living in close proximity to parks).
Of note, many of the observed simian adenoviruses show high degrees of sequence relatedness to human strains, suggesting evidence of past cross-species transmission events and potential risk for such events in the future (10).Differentiating between strains was beyond the scope of this study, but the high detection rate of this viral target and its zoonotic potential warrants further characterization of this viral group and continued surveillance of great ape populations.
The first limitation of our study is that, because of logistical challenges and budgetary constraints, we were only able to focus our surveillance on 2 populations of great apes at specific points in time.In addition, sex and age classes sampled were representative of each ape population apart from infants, which are nearly impossible to sample noninvasively.
Despite those challenges, our data provide insight into the diversity of enteric infections circulating in wild gorilla and chimpanzee populations before 2018.Detection of gene targets of zoonotic potential in 83% of gorillas and 70% of chimpanzees suggests potential health and disease transmission risks.These results are especially pertinent for monitoring these ape species given the previously documented cases of disease and epizootics (e.g., respiratory infections, polio, mange) in Gombe (13), and the lack of such in Cross River gorilla populations.As research, ecotourism, and forest encroachment in wild ape habitat increases, the risk for novel pathogen exposure is heightened, which could have catastrophic impacts on populations.Continued epidemiologic research among wild primate populations has the potential to predict which pathogens might enter both human and great ape populations as contact between species intensifies.Because pathogen exchange occurs across species boundaries, the potential for changes in pathogenicity and host specificity exists, which could have substantial adverse effects on human and wildlife health (14,15).