Strongyloides stercoralis in Australia – A Parasite That Won’t Go Away On Its Own
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Posted by Rosemary Drisdelle Oct 15, 2009 |
Strongyloides stercoralis infestation is apparently very common in the aboriginal communities of
- People need not be treated unless they have symptoms (and therefore no testing is required in people with no symptoms).
- Hand washing, washing of vegetables and other foods, and excluding dogs from human dwellings is sufficient to control spread.
- The parasite will disappear as the socioeconomic situation in affected communities improves, those currently infected die, and contamination in the environment eases.
All of that sounds good, but it’s an approach that likely won’t work for a number of reasons:
- As many as half of infected people have no symptoms. Unfortunately, while they remain infected they are at risk of serious disease if their immune systems stop controlling the infection. (Among other things, malnutrition can compromise the immune response, and malnutrition is more common in communities with low socioeconomic status.)
- Chronically infected, asymptomatic people can continue to contaminate the environment with the parasite for many years. (Infections can last forty years or more).
- Washing hands and food is fine, but most infections occur when bare skin contacts contaminated soil – when people go barefoot or sit on the ground.
- Dogs pass on the parasite in their feces – keeping them out of houses will not prevent infected dogs from defecating outside and contaminating the soil.
- Preventing transmission of the parasite means good sanitation with a sanitary sewage system – and people who never resort to relieving themselves outside. This is as difficult to achieve as getting everyone to wear shoes all the time. Meanwhile infected dogs and other animals will continue to contaminate the soil.
- The parasite has a life cycle stage where adults reproduce in the soil, keeping the environment contaminated indefinitely.
It would be very difficult to eradicate S. stercoralis in an area where it is so well established that a third of the residents have it. An integrated approach would certainly be needed including screening and treatment of infected people and domestic animals, a sanitary sewage treatment system, cleanup of known contaminated areas, public education, and ongoing surveillance over a number of years.
Further Reading
Doctors Concerned Over Killer Parasite.
Foundations of Parasitology 6th Ed. Roberts, Larry S. and John Janovy Jr.