VHOSPITAL.CLINIC · Serology Test
Strongyloides ELISA is the most sensitive screening test for strongyloidiasis — far superior to stool microscopy and critical for pre-immunosuppression screening to prevent hyperinfection syndrome.
Enzyme-linked immunosorbent assay detecting IgG/IgM antibodies against parasite-specific antigens — used for diagnosis, monitoring, and surveillance.
Stool microscopy detects Strongyloides larvae in only 30–40% of cases (low larval output). Serology detects IgG against Strongyloides antigens with 85–95% sensitivity, making it the preferred screening test, especially before immunosuppressive treatment.
Venous blood sample. ELISA using crude Strongyloides or recombinant antigen (NIE recombinant antigen provides highest specificity). IgG levels reported as optical density ratios or arbitrary units. Cross-reactivity with filariasis and other nematodes occurs with crude antigen ELISAs.
Positive serology: confirms strongyloidiasis in appropriate clinical context — treat with ivermectin. Negative serology: does not exclude infection in immunocompromised patients (reduced antibody response). In HIV or transplant patients, stool O&P should also be performed regardless of serology.
Sensitivity: 85–95% (crude antigen ELISA); 90–97% (NIE recombinant antigen). Specificity: 85–95% (crude, due to nematode cross-reactivity); >97% (NIE recombinant antigen). Sensitivity decreases in immunocompromised patients (reduced antibody response to ~70%).
In strongyloidiasis, corticosteroids trigger uncontrolled autoinfection (hyperinfection syndrome) by suppressing the immune control of larval autoinfection. Larvae penetrate the gut wall in massive numbers, carrying gut bacteria — causing gram-negative sepsis, meningitis, and death (mortality 50–70%). All patients receiving immunosuppression should be screened first.
IgG titres decline after successful treatment but can remain positive for 6–12 months. A decline of >50% from baseline titre at 6 months suggests cure. For immunocompetent patients, negative stool O&P 3 months post-treatment is the practical cure criterion.
Yes. Unlike other parasitic infections where observation may be appropriate, any confirmed strongyloidiasis should be treated regardless of symptoms, because of the lifelong autoinfection potential and catastrophic risk of hyperinfection with future immunosuppression.
Strongyloidiasis is caused by Strongyloides stercoralis, a soil-transmitted nematode capable of autoinfection and chronic persistence for decades. In immunocompromised patients, hyperinfection syndrome can be life-threatening. Ivermectin is the treatment of choice.
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