Home range, diet pattern and parasite's burden of the wild Bornean orangutans in Sebangau National Park Indonesia

Fecal samples from five representative age classes of Pongo pygmaeus ssp. wurmbii were collected between 18/02/2022 and 29/11/2022. Intestinal parasites were screened using the MiniFlotac technique. We hypothesized that home range reflects the energy budget while the burden of intestinal parasites may influence the fitness of orangutans across age group. Variations in behavior were predicted to affect parasite species richness, prevalence, and intensity of infection, measured as egg per gram (EPG)/oocyst per gram (OCG)/cyst per gram (CPG) in fecal samples. We identified a variety of Protozoa (including Entamoeba, Endolimax, and Giardia) and nematode (such as Trichuris, Ascaris, Enterobius, and hookworms). One un-identified larval form was also observed. The highest prevalence was recorded for Entamoeba coli (100 % of individuals), followed by hookworm egg (70 %), Ascaris lumbricoides (50 %), Dientamoeba fragilis (40 %), Entamoeba hartmanni (20 %) and Giardia sp. (10 %). The CPG of E. coli ranged from 50 to 120 in all orangutan fecal samples. Site-specific differences were observed between sites Punggualas (PA) vs. Natural Peat Laboratory (NPL), hereafter referred to as NPL-CIMTROP, and between male and female orangutans. However, no significant differences were detected in parasite burden relative to home range size. To our knowledge, this is the first report documenting the parasite burden of wild orangutans in Punggualas. Notably, a high prevalence of Ascaris lumbricoides eggs was detected (p-value = 0.0000). Our findings imply that environmental disturbances such as the 2021 flooding event and subsequent pseudo-gaharu collection activities in Punggualas may have contributed to this elevated prevalence of Ascaris spp. Further investigation is urgently needed to elucidate the dynamics of zoonotic transmission between humans and orangutans and to assess risks related to emerging and re-emerging infectious diseases.