Gastrointestinal Parasites in Humans and Rhesus Macaques: A Cross-Sectional Study in Bhaktapur, Nepal.

Background and Aims: Gastrointestinal parasitism in wild animals at the human-wildlife interface may be a warning concern both for wildlife health and human health. The current study was conducted to determine the prevalence of gastrointestinal parasites in humans and rhesus macaques (Macaca mulatta) in the Nilbarahi area, an area with increasing human-macaque interaction in Bhaktapur, Nepal. Methods: A total of 200 fecal samples (N = 200) were collected via a non-invasive technique. Fecal samples of macaques (N 1 = 100) were conveniently collected, while a purposive sampling was carried out for collecting human feces (N 2 = 100). Microscopic examination of these samples was carried out via direct wet mount, concentration (flotation and sedimentation), and acid-fast staining techniques. Results: The prevalence of intestinal parasites was 13% among humans and 81% among macaques. In humans, the identified parasites included protozoa, such as Cryptosporidium sp., nematodes, like Ascaris lumbricoides, and cestodes, such as Taenia sp. Moreover, the Chi-square test indicated that females (20.37%) had a significantly higher prevalence rate than males (4.35%) (p < 0.05). Similarly, protozoa such as Balantidium coli, Cryptosporidium sp., Cyclospora sp., Eimeria sp., Endolimax sp., Entamoeba spp., Giardia sp., nematodes, like Ascarid, hookworms, Strongyles, and Trichuris sp., cestodes, such as Taeniid, and trematodes, like Controrchis sp. and Fasciola sp., were reported from macaques. Conclusion: The study reported a significantly greater prevalence and diversity of gastrointestinal parasites in macaques than in humans. Since a few species are implicated in zoonoses, the study highlights the need for a health awareness campaign and management of the macaque population in the study area. Additionally, public education, appropriate waste management near the temples, and controlled feeding to macaques must be implemented to reduce parasitism and spillover risks to humans.