Life-cycle

Faecal soil contamination with S stercoralis larvae are most likely to be seen in rurual areas with poor sanitation.

• filariform larvae in the soil penetrate the skin when the host walks barefoot on contaminated soil

parasitic cycle

• larve enters venous circulation and migrate to the lungs. They are coughed up and swallowed.
• the larvae in the small intestine develops into adult female. The reproduce asexually and release eggs into the digestive system
• hatched eggs release non-infectious rhabditiform larvae which is excreted in stools and enter the soil

free living cycle

• these free-living rhabditiform larvae may mature into male and female adult worms, which reproduce sexually or transform directly into filariform larvae (1)

S stercoralis parasite has the ability to reinfect the host through the wall of gastrointestinal system – known as autoinfection:

• this is caused by rhabditiform larvae in the faeces which transforms into infectious filariform larvae inside the gastrointestinal system. These filariform larvae penetrates the gut wall and enter the circulation and migrate to the lungs to begin the cycle again (1)

Reference:

• (1) Greaves D et al. Strongyloides stercoralis infection. BMJ. 2013;347:f4610