Oesophagostomum is a genus of parasitic nematodes (round worms) belonging to the superfamily Strongyloidea. They are commonly known as ‘nodule’ or ‘nodular worm’ and are found worldwide.
Adult worms live in the large intestine. Host species include ruminants, pigs and other animals. Primates including humans can also be affected, with most human cases being reported from Africa.
Nodule worm (Oesophagostomum columbianum) is a parasite of the large intestine of sheep and goats, and a number of wild antelopes.