Distribution of Zoonotic Entamoeba spp. in Crab-Eating Macaques Across China.

PURPOSE: Entamoeba spp. are globally distributed zoonotic protozoa that infect humans and diverse animals, causing a spectrum of enteric diseases and posing a persistent threat to public health and animal husbandry. This study aimed to investigate the prevalence of Entamoeba spp. in non-human primates (NHPs) and molecularly assess potential zoonotic risk factors associated with these infections. METHODS: A total of 504 fecal samples were collected from Crab-eating macaques at commercial breeding farms in Beijing and Suzhou, China, which were then analyzed by PCR amplification and sequencing of the SSU rRNA gene to identify six distinct Entamoeba species. RESULTS: The infection rates were determined as follows: E. histolytica (8.13%, 41/504, 95% CI 5.7-10.5%), E. chattoni (5.95%, 30/504, 95% CI 3.9-8.0%), E. nuttalli (0.6%, 3/504, 95% CI 0-1.3%), E. moshkovskii (0.79%, 4/504, 95% CI 0-1.6%), E. coli (49.01%, 247/504, 95% CI 44.6-53.4%), and E. dispar (36.51%, 184/504, 95% CI 32.3-40.7%). E. coli was the most prevalent species, with infection risk significantly linked to host age (p < 0.0001). Phylogenetic analysis of 247 E. coli isolates from Crab‑eating macaques identified two distinct genotypes (SZ E. coli CEMs1 and SZ E. coli CEMs2), both clustering within the major E. coli clade and showing close affinity with human and other primate‑derived strains. CONCLUSION: These findings indicate that macaque‑origin E. coli are phylogenetically closely related to isolates from humans and diverse animals, highlighting their potential for cross‑host transmission and underscoring the need for enhanced surveillance.