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

Nematodes belonging to the genus <italic>Oesophagostomum</italic> frequently infect wild chimpanzees (<italic>Pan troglodytes</italic>) across widely separated field sites. Nodular lesions (granulomas) containing <italic>Oesophagostomum</italic> are commonly seen in the abdomen of infected chimpanzees post‐mortem. At Taï National Park, Côte d'Ivoire, previous studies have identified larvae of a variety of <italic>Oesophagostomum</italic> spp. in wild chimpanzee stool, based on sequencing of larval DNA, and nodular lesions associated with <italic>Oesophagostomum</italic>, identified morphologically to the genus level but not sequenced. 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 and from adult worms found inside the nodules. In all three cases, we identify <italic>Oesophagostomum stephanostomum</italic> as the causative agent. The sequences from this study were identical to the only other published sequences from nodules in nonhuman primates—those from the wild chimpanzees of Gombe, Tanzania. [ABSTRACT FROM AUTHOR]