Specific immunoglobulin M enzyme-linked immunosorbent assay for confirming the diagnosis of measles

An enzyme-linked immunosorbent assay (ELISA) was evaluated for the detection of measles virus-specific immunoglobulin M (IgM) (MIgM). The ELISA was standardized by deriving a seronegative range of values from sera which should not contain MIgM (24 cord sera, 59 sera from immune health care workers, and 47 sera from infants before the administration of measles vaccine). These values were separable from those obtained from individuals convalescing from measles. Twenty sera containing rheumatoid factor were MIgM seronegative. Of 30 acute-phase sera from suspected measles cases, 26 contained MIgM; those that were seronegative were obtained on day 0, 0, 2, or 9. All 25 convalescent-phase samples contained MIgM. Of the 25 paired samples, 22 were IgG positive at the first sampling; 3 of the 22 did not show a rise in IgG titer. The MIgM ELISA can be used for confirming suspected measles cases, often requiring only a single serum specimen.