Autoinfection

This term autoinfection refers to the ability of certain parasites, particularly helminths, to establish a life cycle within the host, eliminating the need for an intermediate stage, and secondary hosts. Organisms capable of this Strongyloides stercoralis, Enterobius vermicularis and Hymenolepis nana.

Strongyloidiasis, for example involves premature transformation of noninfective larvae in infective larvae, which can  then penetrate the intestinal mucosa (internal autoinfection) or the skin of the perineal area (external autoinfection). Infection can be maintained by repeated migratory cycles for the remainder of the person's life. Hyperinfection syndrome is most often present in immunocompromised hosts (HIV/AIDS, diabetes, people with autoimmune diseases being given immunosuppressor medication) and is notable for generating tremendous worm burdens and can generate life threatening infestations.

Massive transit of the larvae in intestinal autoinfection, causes erosions of the epithelial lining and subsequent escape of enteric bacteria into the systemic circulation. Strongyloidiasis must be included in differential diagnosis when mixed bacteremias (two or more organisms) and eosinophilia are coincident.