Measles and Rubella Diagnostic Guidelines

Diagnostic Testing

The Centers for Disease Control and Prevention recommends serum measles-specific IgM antibody testing as the primary diagnostic method for confirming measles infection, with the direct-capture IgM EIA method being the most sensitive and specific 1, 2
Blood for measles IgM testing should be collected during the first clinical encounter with a person who has suspected measles, and may be detectable at rash onset, peaking approximately 10 days after rash onset, and remaining detectable for 30-60 days 1, 2
The Centers for Disease Control and Prevention recommends that if measles IgM is not detected in serum obtained within the first 72 hours after rash onset, a second specimen should be collected at least 72 hours after rash onset 1, 2
Paired acute and convalescent-phase serum specimens can demonstrate a significant rise in measles antibody titer, with the acute-phase specimen collected within 1-3 days after rash onset and the convalescent-phase specimen collected approximately 2-4 weeks later 1, 3
Virus isolation from clinical specimens (urine or nasopharyngeal mucus) should be collected as close to rash onset as possible 1

The Centers for Disease Control and Prevention recommends serum rubella-specific IgM antibody testing as the most commonly used method for serologic confirmation, with blood for IgM testing obtainable as early as 1-2 days after rash onset 4, 5, 6
Rubella-specific IgM antibody becomes detectable shortly after rash onset, peaks at approximately 7 days, and remains detectable for 4-12 weeks 4, 5, 6
If IgM is not detectable in the first specimen, a second specimen should be collected 5 days after rash onset 4, 5, 6
Paired acute and convalescent-phase serum specimens can demonstrate a significant rise in rubella antibody titer, with the acute-phase specimen collected as soon as possible after rash onset and the convalescent-phase specimen collected at least 10 days after the acute-phase specimen 4, 5, 6

Laboratory confirmation should be attempted for every suspected case of measles and rubella, with immediate notification of local health departments being essential for suspected cases 1, 3, 4, 7
Control activities should not be delayed pending laboratory results, and for congenital rubella syndrome, serologic confirmation can be obtained by testing cord blood for rubella-specific IgM antibodies 3, 5, 6