From the Guidelines
Strongyloides antibody (Ab) testing is essential for checking the presence of antibodies against Strongyloides stercoralis, a parasitic roundworm that causes strongyloidiasis infection, particularly in individuals with unexplained eosinophilia, those with risk factors such as travel to or residence in endemic areas, immunocompromised patients, or those with gastrointestinal symptoms consistent with strongyloidiasis. This blood test detects IgG antibodies produced by the immune system in response to the parasite, as mentioned in the study by 1. It's particularly useful for diagnosing chronic strongyloidiasis, which can be difficult to detect through direct stool examination since the parasite may be present in low numbers or shed intermittently. Some key points to consider when checking for Strongyloides ab include:
- The test is recommended for individuals with risk factors such as travel to or residence in endemic areas, immunocompromised patients, or those with gastrointestinal symptoms consistent with strongyloidiasis, as highlighted in the study by 1.
- The antibody test is more sensitive than stool examination, though it cannot distinguish between current and past infections, as noted in the study by 1.
- Early detection is crucial because strongyloidiasis can persist for decades and may develop into a severe, potentially fatal hyperinfection syndrome in immunocompromised individuals, as warned by 1. The diagnosis of strongyloidiasis is often made by serologic tests, and many experts recommend therapy for seropositive patients, despite negative stool examinations, as suggested by 1.
From the Research
Strongyloides AB Testing
The following are checked with Strongyloides AB:
- Antibodies to Strongyloides stercoralis larval surface antigens, specifically IgG antibodies, which are present in the majority of patients with chronic uncomplicated strongyloidiasis 2
- IgA and IgM antibodies specific for surface antigens of filariform larvae, although these are typically negative or weakly positive 2
- The presence of Strongyloides using a modified agar plate culture and the formalin-ethyl acetate concentration technique in fecal samples 3
Diagnostic Methods
Different diagnostic methods are used to check for Strongyloides AB, including:
- Indirect immunofluorescence using quantitative fluorescence microscopy 2
- Stool examination using saline and Kato smears and formalin-ether and Baermann concentrations 4
- Modified agar plate culture and the formalin-ethyl acetate concentration technique in fecal samples 3
Treatment Efficacy
The efficacy of different treatments for Strongyloidiasis is also relevant to Strongyloides AB testing, including: