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Prevalence of Strongyloides Stercoralis infection in a remote Indigenous community as determined by ELISA testing from dried blood spot for antibodies to the recombinant antigen NIE
Abstract   Peer reviewed

Prevalence of Strongyloides Stercoralis infection in a remote Indigenous community as determined by ELISA testing from dried blood spot for antibodies to the recombinant antigen NIE

Kate E Mounsey, Melanie Rampton, Stacey Llewellyn, Cielo Pasay, Mallory King, Deborah Holt and Bart Currie
American Journal of Tropical Medicine and Hygiene, Vol.89(5), p.150
American Society of Tropical Medicine and Hygiene (ASTMH) Annual Meeting, 62nd (Washington DC, United States, 13-Nov-2013–17-Nov-2013)
2013
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http://www.astmh.org/AM/Template.cfm?Section=Abstracts_and_Education1&Template=/CM/ContentDisplay.cfm&ContentID=5373View
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Abstract

Medical and Health Sciences
Parasitologic diagnosis of infection with the intestinal nematode Strongyloides stercoralis is relatively insensitive and logistically challenging. Serologic assays based on detection of antibodies to crude larval antigen offer increased sensitivity, but specificity is hampered by cross-reactive antibodies and persistence after cure. Further, standardization of antigen for assays is problematic. The use of recombinant antigen can potentially overcome these problems, and the NIE antigen from S.stercoralis has been used widely with good diagnostic sensitivity and specificity. Detection of antibody eluted from dried blood spots has shown utility in large-scale seroepidemiologic studies, and is appealing in children where venipuncture or stool collection is problematic. We adapted an existing NIE-ELISA protocol for the testing of anti-strongyloides antibody response on dried blood spots collected as part of an ivermectin mass drug administration conducted in an Australian Indigenous community. The NIE ELISA was first validated using representative positive, negative, and equivocal timematched serum samples previously tested using S. ratti antigen ELISA. Optimal assay and storage conditions were determined using positive control blood spots, and samples screened with the adapted NIE-DBSELISA. Blood spots were stable for several days at 37oC, or following longer-term storage at 4oC, -20oC or -80oC. The sensitivity of the NIEDBS- ELISA was determined by ROC analysis to be 82%. Of the 219 blood spots tested, 18% were positive for S. stercoralis, a similar prevalence to that documented by standard S. ratti serology. In representative samples positive for S. ratti-specific antibodies, a significant decline in NIE optical density was observed at 6 and 12 months following ivermectin MDA (p less than 0.0001). No time-associated differences were seen in negative or equivocal samples. This further confirms the high seroprevalence of S. stercoralis in remote Australian Indigenous communities, and suggests that collection of dried blood spots may be useful approach for field-friendly diagnosis of strongyloidiasis.

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