Total antibodies (IgM and IgG class) against the Strongyloides parasite are measured to diagnose strongyloidiasis.
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Strongyloidiasis is caused by the Strongyloides stercoralis, a filamentous worm spread mainly in tropical and subtropical regions. Strongyloides stercoralis has a complex life cycle that begins with the ripening of the filariform larva in the soil. The larvae penetrate the exposed skin and migrate through the bloodstream to the lungs, from where they ascend to the bronchial tree and are swallowed. Once found in the small intestine, the filariform larva matures into adult worms that enter the intestinal mucosa. Mature females produce eggs that grow in non-infectious rhabditiform forms in the gastrointestinal tract and are eventually released into the faeces. The time from skin penetration to the appearance of Strongyloides in the faeces is about 3 to 4 weeks.
The most common manifestations of the infection are mild and may include abdominal pain, mild diarrhea, nausea, and vomiting. At the site of penetration, the skin can be inflammatory and itchy. The larvae's migration through the lungs and trachea can cause dry cough, wheezing, and mild hemoptysis. Although common, eosinophilia in peripheral blood does not always exist.
In immunosuppressed patients, rhabditiform larvae can mature into infectious filariform larvae within the gastrointestinal tract and lead to cycles of self-infection. The larvae then penetrate the gastrointestinal mucosa, migrate to the lungs, and can complete their life cycle. This infection can maintain the parasite in the host for many years.
