Human case of pseudoparasitism by a “horsehair worm” (Nematomorpha) in the Isla Grande de Chiloé, Chile

Abstract

Species of the phylum Nematomorpha, or "horsehair worms" or “hairworms”, are parasites whose adult stage develop in terrestrial arthropods (beetles, grasshoppers, and others), which, when falling into a freshwater bodies, facilitate their release to reproduce. Females lay eggs that develop into larvae capable of infecting insects and other aquatic invertebrates, amphibians, and fish. Terrestrial arthropods (definitive host) become infected by preying on parasitized insects with larvae or by ingesting the free larvae. The case of a 39-year-old man who orally eliminated an adult specimen, that was identified as Gordius cf. paranensis, is presented.  The human cases are rare and accidental, occurring by ingestion of the infected definitive hosts or free adults parasites in freshwater environments. Its presence in humans is transient, and is usually excreted through the mouth or in feces.