Comparative diagnosis of strongyloidiasis in immunocompromised patients

Strongyloides hyperinfection syndrome and disseminated strongyloidiasis frequently occur in immunocompromised persons and can lead to high complication and mortality rates. Thus, detection of Strongyloides stercolaris in those patients is crucial. The present study aimed to determine the prevalence of strongyloidiasis and compare the detection rates of different strongyloidiasis detection methods. We conducted a cross-sectional study of 135 adults with various immunocompromising conditions (corticosteroid usage, chemotherapy, hematologic malignancies, organ transplants, use of immunosuppressive agents, and symptomatic human immunodeficiency virus infection) in Phramongkutklao Hospital, Bangkok, Thailand. All patients were asked to undergo serology testing for Strongyloides IgG by indirect enzyme-linked immunosorbent assay (ELISA), and 3 days of stool collection for use in a simple smear along with formalin-ether concentration and agar plate techniques. Prevalence rates of strongyloidiasis were 5% by stool concentration technique, 5.4% by IgG-ELISA, and 6.7% by agar plate culture. Three of the eight strongyloidiasis cases in this study had hyperinfection syndrome. The tested risk factors of age, sex, occupation, and immunocompromising condition were not associated with Strongyloides infestation. Serology was only 42.9% sensitive (positive predictive value), but it was 96.3% specific (negative predictive value). In conclusion, prevalence rates of strongyloidiasis in this study were 5-7%. Although agar plate culture was the most sensitive technique, the other diagnostic methods might be alternatively used.