Influence of rheumatoid factor on the specificity of a rapid immunochromatographic test for diagnosing dengue infection

In order to determine the influence of rheumatoid factor in serum specimens on the specificity of an immunochromatographic test for the detection of a ntibodies against dengue virus, 50 clinical specimens containing rheumatoid factor were evaluated for cross reactivity with a commercially available a ssay. While specificity for the detection of immunoglobulin (Ig) G antibodi es was 100%, the IgM component of the test showed false-positive results in 26% of cases. Thus, it is important to consider interference by rheumatoid factor when using immunochromatographic assays for the detection of specif ic IgM produced during dengue infection.