Predictive value of an enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of strongyloidiasis

Strongyloides stercoralis is an opportunistic parasite of increasing importance in immunocompromised hosts. Current parasitologic methods for diagnosis are unsatisfactory, and the serologic screening of candidates for immunosuppression and other individuals at risk might prevent fatal disseminated infections. The predictive value of an enzyme-linked immunosorbent assay (ELISA) using S. stercoralis antigens has been evaluated on 268 infected patients, 571 noninfected controls, and 78 individuals with other parasitic infections. A positive test was accurate in predicting the presence of S. stercoralis in 97% of the cases, while a negative test was associated with absence of infection in 95% of the patients. Possible cross-reactivity occurred in some patients with Loa loa filariasis and Ascaris lumbricoides. The authors conclude that the ELISA is a reliable and cost-effective method for the screening of patients at risk, and its results can be used to determine the appropriateness of more in-depth parasitologic evaluation.