Clinical, immunological and epidemiological aspects of strongyloidiasis in an endemic area of Brazil.

Eighty-eight residents of Curitiba, Brazil, with parasitologically proven Strongyloides stercoralis infection were assessed clinically and evaluated for their specific and non-specific responses to the parasite. A control group of 73 patients with other intestinal parasites, but with negative stools for S. stercoralis were also evaluated. Abdominal symptoms and/or weight loss were present in 24% of the patients with strongyloidiasis and in 25% of the patients with other parasites only. Elevated peripheral eosinophilia (greater than 5%) was present in 68% of the patients with strongyloidiasis (mean = 10.6%) and in 73% of the individuals with other parasites only (mean = 8.8%). Total serum IgE were elevated (greater than IU/ml) in 84% of the patients with strongyloidiasis (mean = 2872 IU/ml), and in 79% of the patients with other parasites only. Over 90% of the patients with proven strongyloidiasis had detectable levels of parasite specific IgG and IgE antibodies, as detected by the ELISA and the RAST, respectively. These antibodies were present in 23% of the individuals in whom fecal examinations had failed to reveal S. stercoralis. We conclude that in an endemic area, gastrointestinal manifestations and non-specific indicators of parasitic infections, such as elevated peripheral eosinophilia and total IgE, are not useful indexes of the presence of strongyloidiasis. Immunoserologic tests, such as the ELISA and the RAST may represent sensitive and specific tools for the screening of candidates for immunosuppression and for gathering needed epidemiological information about this increasingly important opportunistic nematode.