any of the parasitic worms of the superfamily Metastrongyloidea (phylum Nematoda) that infest the lungs and air passages of mammals, including dolphins and whales. Examples include those of the genus Metastrongylus that live in pigs, and those of the genus Dictyocaulus that live in sheep and cattle. Many species of lungworms are of veterinary importance. Members of the genus Angiostrongylus, normally occurring as parasites in rats, are known to be pathogenic in humans. The life cycle of lungworms can be direct or can require intermediate hosts, such as snails and slugs, depending on the lungworm species. Lungworms should not be confused with lung flukes, such as those of the genus Paragonimus, which are trematodes (phylum Platyhelminthes).