Optimal Timing of Specimen Collection after Rash Onset for Diagnosis of Measles IgM Antibody

  Antibody detection is the most versatile and commonly used method for measles diagnosis. Detection of specific IgM antibodies in a single serum specimen collected within the appropriate time after rash onset can provide a good presumptive diagnosis of current or recent measles infection and is the test of choice for rapid diagnosis of measles cases. So, optimal timing for collection of a single serum specimen to diagnose measles by IgM capture Enzyme Immunoassay (EIA) was evaluated. 399-paired sera were tested for measles IgM antibody. 149-paired sera were measles IgM negative. Two hundred fifty paired sera had at least one IgM positive. 223-paired sera were positive in both first and second samples. 19-paired sample were negative in first and positive in second sample and 8-paired sera were positive in the first and negative in the second samples. 85% and 100% of first specimens within 7 and 7-21 and 94% of all second samples were IgM positive at 28th days after rash onset, respectively. Analysis of data indicates that a single serum specimen collected between 7 to 27 days after rash onset can be used to diagnose most cases of measles with an IgM capture EIA.