Attention: these worms can be picked up by running around barefoot in British parks!
Strongyloides stercoralis is a worm distributed all over the tropics and subtropics but has recently been found in British soil as well.
Adult worms live in the small intestines of humans only, with the female buried deeply in the mucosa of the gut. Larvae escape faecally into the soil and develop into free- living worms in a week. The free-living female produces infective larvae, which, on contact with a human, penetrate the skin and get carried to the lungs, where the larvae climbs up the bronchial tree, just to be swallowed and to reach its normal habitat the small intestine. Infection can persist for up to 40 years.
Symptoms of infection can include
- An itchy eruption at the penetration site, although most patients tend not to notice this.
- Cough and wheeze due to the larvae in the lungs
- Abdominal pain and steatorrhoea (very white, fatty stools)
- Weight loss
Very rarely, during auto-reinfection (which happens when the larvae on their way out penetrate the rectal skin), the Larvae currens symptoms occur which are:
- raised wriggly lines on the skin (where the larva burrows)
- which are only temporary
- extremely itchy
- confined to trunk
- tend to appear in intervals
Diagnosis is via direct microscopy or stool culture, treatment with Thiabendazole or Albendazole, and prevention is as usual better than treatment, so don't run around with bare feet.
..and no, flip-flops don't count!
Dion R. Bell: Tropical Medicine, 4th Edition, Blackwell Science, 2000