Prevalence and diversity of gastrointestinal parasites in long-tailed macaques at Kosamphi Forest Park, Kumphawapi Monkey Garden, and Dong Ling Don Chao Pu Park, North-east Thailand

Background and Aim: These three parks in North-east Thailand, Kosamphi Forest Park, Kumphawapi Monkey Garden, and Dong Ling Don Chao Pu Park, are internationally recognized for sheltering long-tailed macaques. Overfeeding by tourists and locals significantly increases the frequency of human-macaque encounters. Being close to each other raises the chances of contracting gastrointestinal (GI) parasites. This study was designed to estimate the prevalence and range of GI parasite infections in long-tailed macaques among the three major natural habitats. Materials and Methods: Three hundred fecal samples were collected from long-tailed macaques, with 100 samples from each of the three study sites. The samples underwent Formalin-ethyl acetate concentration technique examination. Parasites were identified based on their morphology and size as observed under a light microscope. Results: About 66.67% of the population had GI parasitic infection. Balantidium coli had the highest occurrence (41.66%), whereas Strongyloides spp. (24.33%), Trichuris spp. (18.33%), Entamoeba coli (10.33%), and Endolimax nana (2.33%) followed next in prevalence. A higher rate of single infections (41%) was reported compared to mixed infections (25.66%). At Dong Ling Don Chao Pu Park, the prevalence rate of B. coli in long-tailed macaques was 70%, markedly higher than those reported at the other two study sites. In these areas, the first known case of B. coli infection occurred in long-tailed macaques. In the Kumphawapi Monkey Garden, the prevalence of Strongyloides spp. and Trichuris spp. infections was significantly greater (45% and 28%, respectively) compared to the other two areas. Conclusion: In northeast Thailand, long-tailed macaques are predominantly infected with B. coli, causing GI protozoal infections. In this primate population of the region, Strongyloides and Trichuris species are common helminths. This study offers new knowledge on parasitic loads in Thai long-tailed macaques, essential for devising effective One Health approaches to prevent and manage zoonotic diseases. Keywords: Dong Ling Don Chao Pu Park, gastrointestinal parasite, Kosamphi Forest Park, Kumphawapi Monkey Garden, long-tailed macaques.