Detection of immune complexes and evaluation of alcoholic individuals' serological profile in the diagnosis of strongyloidiasis.

Strongyloidiasis is a human parasitosis that is considered a public health problem. Early diagnosis of this infection is extremely important in immunocompromised patients (i.e. subjects with alcoholism). This study aimed to evaluate anti-Strongyloides immunoglobulin G (IgG) and immunoglobulin A (IgA), assess levels of circulating immune complexes (IC) and determine IgG avidity in serum samples from alcoholic and nonalcoholic individuals. A total of 140 blood samples were collected from male individuals (70 alcoholic and 70 nonalcoholic subjects). Serum was obtained and analysed by enzyme-linked immunosorbent assay for IgG, IgA, IC detection and avidity determination. Anti-Strongyloides IgG was detected in 55.7% of alcoholic subjects and 32.8% nonalcoholics, while IC levels showed frequencies of 38.6% and 17.1% in these groups, respectively. Anti-Strongyloides IgA was lower among alcoholics (4.3%) than nonalcoholics (34.3%). Spearman's correlation coefficient reported a positive correlation between IgG, IC and IgA in alcoholic individuals and no correlation in nonalcoholics. The median avidity index was higher in alcoholics (83.8%) than nonalcoholic subjects (73.2%). In conclusion, this study shows that alcoholic subjects produced specific antibodies against S. stercoralis regardless of the possible immunosuppression caused by chronic alcoholism. Considering that alcoholics are more susceptible to the severe forms of strongyloidiasis, the implementation of immunological methods as a complementary approach to parasitological diagnostics (i.e. detection of IgG, IC and antibody avidity) appears to be an alternative method for early diagnosis in these individuals.