Autoinfection
An unusual feature of S. stercoralis is autoinfection. Only one other species in the Strongyloides genus, S. felis, has this trait. Autoinfection is the development of L1 into small infective larvae in the gut of the host. These autoinfective larvae penetrate the wall of the lower ileum or colon or the skin of the perianal region, enter the circulation again, travel to the lungs, and then to the small intestine, thus repeating the cycle. Autoinfection makes strongyloidiasis due to S. stercoralis an infection with several unusual features.
Persistence of infection is the first of these important features. Because of autoinfection, humans have been known to still be infected up to 65 years after they were first exposed to the parasite (e.g., World War II or Vietnam veterans). Once a host is infected with S. stercoralis, infection is lifelong unless effective treatment eliminates all adult parasites and migrating autoinfective larvae.
Read more about this topic: Strongyloides Stercoralis