Human-Macaque Contact and Zoonotic Infections in Wild Taiwanese Macaques: Evidence From Southern Taiwan

Direct contact between humans and non-human primates is on the rise, bringing with it the risk of transmission of zoonotic pathogens in habitats with a high level of human-primate interactions. Given the threats to the health and well-being of both humans and non-human primates, more attention is needed to this topic. By comparing the infection status of zoonotic pathogens in primate populations with contrasting levels of human interaction, we can better understand the relationship between human-primate contact and the prevalence of pathogens. To this end, we collected fecal samples from two Taiwanese macaque (Macaca cyclopis) populations in southern Taiwan: Shoushan National Nature Park (Kaohsiung), characterized by extremely high human interface, and the Dahan Forest Trail (Pingtung), characterized by very low human interface. These samples were molecularly screened for Helicobacter pylori, four common pathogenic Campylobacter species, and four gastrointestinal zoonotic parasites (Strongyloides fuelleborni, Oesophagostomum aculeatum, Entamoeba coli, and Entamoeba chattoni). In both populations, the prevalence rates of H. pylori and the two amoebic protozoa were quite high (exceeding 70%), while Campylobacter and the two nematodes ranged between 10% and 20% of samples. The Shoushan high-interface macaques were infected with pathogenic Campylobacter coli (detected in four samples from that site), whereas a higher sample prevalence of Campylobacter (genus) and O. aculeatum was found in the low-interface Dahan population. Our findings highlight that even macaque groups with minimal human contact harbor significant zoonotic pathogens, whereas highly provisioned groups can acquire human-associated bacteria, underlining the importance of managing human-primate interactions to mitigate bidirectional disease transmission risks.