Laboratory confirmation of
infection is an essential component of
measles surveillance. Detection of
measles-specific
IgM in serum by
enzyme-linked
immunosorbent assay (ELISA) is the most common method used to confirm
measles infection. ELISA formats vary, as does the sensitivity and specificity of each assay. Specimens collected within 3 days of
rash onset can yield a false-negative result, which can delay confirmation of
measles cases. Interfering substances can yield a false-positive result, leading to unnecessary public health interventions. The
IgM capture assay developed at the Centers for Disease Control (CDC) was compared against five commercially available ELISA kits for the ability to detect measles virus-specific
IgM in a panel of 90 well-characterized specimens. Serum samples were tested in triplicate using each commercial kit as recommended by the manufacturer. Using the CDC
measles IgM capture assay as the reference test; the sensitivity and specificity for each commercial kit ranged from 50 to 83% and 86.9 to 98%, respectively. Discrepant results were observed for samples tested with all five commercial kits and ranged from 13.8 to 28.8% of the specimens tested. False-positive results occurred in 2.0 to 13.1% of sera, while negative results were observed in 16.7 to 50% of sera that were positive by the CDC
measles IgM capture assay. Evaluation and interpretation of
measles IgM serologic results can be complex, particularly in
measles elimination settings. The performance characteristics of a
measles IgM assay should be carefully considered when selecting an assay to achieve high-quality
measles surveillance.