Comparative Detection of Measles Specific IgM Antibody in Serum and Saliva by an Antibody-Capture IgM Enzyme Immunoassay (EIA)

Laboratory diagnosis of acute measles is usually achieved by serology assays for measle-specific IgM antibody. For comparison of measle-specific IgM antibody in saliva and serum, 95 paired blood and saliva samples were collected 1-14 days after the onset of rash. The specimens were tested for specific IgM antibody by an IgM antibody-capture Enzyme Immunoassay (EIA). Measles IgM antibody was detected in 89 (93.7%) of serum samples and in 85(89.5%) of saliva specimens. Of the 6(6.3%) serum samples that were IgM antibody-negative, 2 (2.1%) of the paired saliva samples were IgM antibody-positive. The sensitivity and specificity of saliva testing compared with serum was 95.5% and 66.7% respectively. Positive predictive value (PPV) and negative predictive value (NPV) of saliva testing were 97.7% and 50.0% respectively and the accuracy of saliva testing was 93.7%. Our results indicate that saliva samples provided Enzyme Immunoassay results that were in good agreement with results from serum samples. Salivary IgM antibody detection is a suitable non-invasive method for diagnosing recent measles infections and epidemiological studies, especially in children.