This happens if larvae that have hatched from eggs in the small intestine penetrate the intestinal mucosa, enter the blood stream and undergo the same journey through the lungs as their mothers did. stercoralis has a particularly complex life cycle as it can also give rise to autoinfections lasting many years. They can then pass through 2 moults to produce infective juveniles, the skin-penetrating stage, or develop into free living adults, mate and produce eggs that eventually give rise to infective juveniles.ĭevelopmental cycles of Str. These eggs hatch in the small intestine and the larvae are expelled with the faeces. Female worms in the intestine produce eggs without the need to mate, a phenomenon known as parthenogenesis. They burrow into the lining of the small intestine and moult twice to become adult females. They are then coughed up into the throat and swallowed. The larvae can also be transmitted by textiles such a bed clothing or even in shower cubicles.Īfter penetrating the skin, the infective larvae are carried in the blood stream to the lungs.
Behaviours that put people in endemic areas at risk include walking bare foot, coming into contact with human faecal material and occupations such as farming and mining. In the US, outbreaks of strongiloidiasis have been associated with institutionalised populations and veterans returning from tropical regions. It has a global distribution but is most common in rural areas of the tropics and semi tropics in communities where sanitation is poor and faecal material can contaminate the ground or the water supply. Larval Strogyloides stercoralis from a faecal sample.
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