Rhabditiform larvae mature and penetrate the skin in perianal area, leading eventually to
autoinfection. (6)
Aberrantly, humans can assume the role of intermediate host by accidental ingestion of eggs in contaminated water or uncooked vegetables; by
autoinfection due to unsanitary personal habits; or by reverse peristalsis of the eggs from the intestine to stomach.
Infections are generally soil transmitted, with the exception of Strongyloides and Enterobius, where infection can result from direct transmission and is perpetuated by
autoinfection. Strongyloides hyperinfection can result from
autoinfection in immunocompromised individuals, where infective larvae can cause a severe disseminated illness with a high fatality rate.
Ultrastructural details of the xenoma of Loma myrophis (phylum Microsporidia) and extrusion of the polar tube during
autoinfection. Dis.
Upon fertilization, the oocyst may either pass out with feces or excyst in the host's intestine, thus starting a new life cycle (
autoinfection).
Autoinfection can occur and represents a permutation of the life cycle.
* Humans develop cysticercosis by ingestion of Taenia solium eggs in fecally contaminated food or by
autoinfection (from eggs carried from the intestine into the stomach by reverse peristalsis).
Once rhabditiform larvae mature in the host,
autoinfection occurs and the filariform larvae are now free to reinfect.
Transmission occurs in three ways: direct patient-to-patient contact, nosocomial spread, and
autoinfection (Smith et al., 1993).
In the latter two strategies, definitive hosts were generally infected by eating infected second intermediate hosts, but some infections occurred by
autoinfection (digestion of their own infected skin), as seen in Glypthelmins sp.
Strongyloidiasis hyperinfection syndrome (SHS) is a manifestation of accelerated
autoinfection in an immunocompromised host (chronic steroid users and HTLV-1-infected individuals) involving multiple organs (disseminated disease) and extensive gastrointestinal (GI) involvement.