Sometimes known as the threadworm, Strongyloides is an intestinal nematode (roundworm). It has a unique free-living and parasitic generation. Although it contributes little to morbidity worldwide, strongyloidiasis is potentially fatal in immunocompromised patients.


Class: Secernentasida
Subclass: Rhabditia
Order: Rhabditorida
Suborder: Rhabditina
Family: Strongyloididae
Genus: Strongyloides

Stryongyloides stercoralis is the species that causes the large majority of infections in humans. S. stercoralis has been found in dogs and cats. Human infection from dogs has been demonstrated, but is rare. No vector exists for S. stercoralis.



In 1867, Louis Normand, a military physician working at the Toulon Naval Hospital in France, observed small worms in stool samples taken from repatriated soldiers from Vietnam. A colleague of Normand's, Bavay, first named the worm Anguillula stercoralis (from Latin words for "small eel" and "dung"). Increased interest in the new worm led to the scientist Grassi establishing a new genus called Strongyloides and he named the nematode from Normand's samples Strongyloides stercoralis. Scientists Fulleborn (1911), Kreis (1932), and Faust (1933) all worked to elucidate the free-living, parthenogenesis, and the autoinfection cycles of S. stercoralis. Napier, who carried out extensive clinical surveys of repatriated British soldiers infected with S. stercoralis, and Galliard, who conducted experiments in normal and immunosuppressed dogs, both contributed greatly to the understanding of the clinical importance of strongyloidiasis. (Source: Tropical Infectious Diseases Guerrant, Walker, Weller)