S stercoralis eggs, laid by the female worm, hatch into uninfectious rhabditiform larvae usually passed in the stool, which then molt again in soil to become infectious filariform larvae. This process normally takes 24-48 hours. Infectious larvae gain access to a new host in a manner similar to that of hookworm, in which larvae burrow into bare skin in contact with contaminated soil. Occasionally, the developmental process occurs entirely within the host, with both molts occurring within the digestive tract, before stool passage. This results in autoinfection and maintenance of S stercoralis infection in some hosts for 30-40 years.
Most immunocompetent patients are relatively asymptomatic.
No racial predilection is apparent. No gender predilection is demonstrated. Overwhelming symptoms may develop in the immunocompromised individual. Clinical suspicion is required, as telltale eosinophilia present in the normal host is lost in the immunocompromised hyperinfected patient. Infection is caused by bare skin exposure to fecally contaminated soil containing infective larvae.