Prevalence of tapeworm parasites in mountain gorillas (Gorilla Beringei Beringei) and olive baboons (Papio Anubis) in Bwindi-Mghahinga Conservation Area

Abstract

Cestode are common gastrointestinal parasites of non-human primates and may influence wildlife health and conservation. Cestodes are gastrointestinal parasites that infect a wide range of vertebrate hosts, including rodents, ungulates, primates, elephants, and hyraxes. Although the epidemiology of cestode infections has been well documented in some host species, information on free-ranging primates remains limited. This cross-sectional study was conducted in the Bwindi– Mgahinga Conservation Area (BMCA), Uganda, between November and December 2025 to determine the prevalence, diversity and egg burden of tapeworm infestations among mountain gorillas (Gorilla beringei beringei) and olive baboons (Papio anubis). A total of 273 fecal samples were collected, comprising 245 samples from mountain gorillas obtained from fresh night nests and 28 samples from olive baboons collected during daytime by following troop trails. Tapeworm eggs per gram (EPG) were quantified using the Mini-FLOTAC® technique, and cestode eggs were identified morphologically to the genus level. Mountain gorillas exhibited a markedly higher prevalence of tapeworm infection than olive baboons. Overall prevalence was 94.1% (222/236) in BINP and 100% (9/9) in MGNP for gorillas, compared with 25.0% (7/28) in olive baboons. Within BINP, gorilla prevalence ranged from 87.0% in Buhoma to 98.0% in Rushaga. Adults showed the highest prevalence (95.7%), while females had slightly higher prevalence (97.0%) than males (93.6%). Three tapeworm genera—Anoplocephala, Moniezia, and Bertiella—were identified in mountain gorillas, whereas only Bertiella species were detected in olive baboons. Mean tapeworm egg counts were significantly higher in gorillas from MGNP than BINP (319.20 ± 39.51 vs. 162.17 ± 11.80 EPG; p = 0.011). Within BINP, gorillas had significantly higher mean EPG than olive baboons (162.17 ± 11.80 vs. 4.29 ± 2.91; p < 0.001). Tapeworm egg burdens also differed significantly among gorilla sectors, with Rushaga recording the highest median EPG (p < 0.0001), while differences by age and sex were not statistically significant. These findings indicate a higher occurrence of tapeworm infections in mountain gorillas than in olive baboons and provide information on the distribution of cestode genera in sympatric primate populations within BMCA. However, because parasite identification was based on morphological characteristics of eggs, future studies incorporating molecular techniques are recommended to enable species-level identification and improve understanding of cestode diversity and transmission dynamics.