Immunological features in different clinical forms of strongyloidiasis

Serum immunoglobulin levels, skin test response to PPD, lymphocyte surface markers and eosinophil count in peripheral blood were studied in 35 patients with strongyloidiasis diagnosed by stool examination. The patients were divided into three groups based on clinical history, physical examination and laboratory examination: an asymptomatic group (14 patients), a symptomatic group (14 patients) and a group with severe parasitic infection (seven patients). In three of the seven patients with severe strongyloidiasis, massive infection caused by Strongyloides stercoralis had been diagnosed at least once before this study. The IgG levels were significantly lower (p less than 0.05) in patients with severe strongyloidiasis (1180 +/- 529 mg/dl) than in the asymptomatic group (2347 +/- 1224). IgA and IgM levels were also lower in the patients with massive infection when compared to the asymptomatic and symptomatic groups. No decrease of T cells or B cells was found in patients with severe strongyloidiasis. However, the eosinophil count was significantly lower in patients with severe strongyloidiasis than in asymptomatic or symptomatic patients (p less than 0.05). The authors suggest that eosinophils and antibodies may play an important role in the defence mechanism against S. stercoralis larvae.