Oesophagostomum in Taï chimpanzees. Oesophagostomum stephanostomum causing parasitic granulomas in wild chimpanzees (Pan troglodytes verus) of Taï National Park, Côte d’Ivoire

Nematodes belonging to the genus Oesophagostomum sp. frequently infect wild chimpanzees (Pan troglodytes) across widely separated field sites. Nodular lesions (granulomas) containing oesophagostomes are commonly seen in the abdomen of infected chimpanzees post-mortem. At Taï National Park, Côte d’Ivoire, previous research has identified larvae of a variety of Oesophagostomum spp. in wild chimpanzee stool, based on sequencing of larval DNA, and nodular lesions associated with unspecified Oesophagostomum. Here we present three recent cases of parasitic granulomas found post-mortem in chimpanzees at Taï. We complement descriptions of gross pathology, histopathology and parasitology with PCR and sequencing of DNA isolated from the parasitic nodules. In all three cases, we identify Oesophagostomum stephanostomum as the causative agent, meaning the known distribution of nodular disease in nonhuman primates caused by this parasite species now extends to West Africa.