Tests

1st tests to order

measles-specific IgM and IgG serology (ELISA)

Test
Result
Test

Blood test identifying measles-specific IgM indicates acute infection.[31]​ Sensitivity is highest 3 to 14 days after rash onset.[32] Presence of IgG indicates an infection occurring sometime in the past or prior vaccination. Sensitivity is 83% to 92% and specificity is 87% to 100%.[33]

Rubella and parvovirus B19 infection may cause false-positive IgM ELISAs.

Result

positive

Investigations to consider

acute and convalescent sera for measles-specific IgG

Test
Result
Test

Paired acute and convalescent sera can be used to detect a rise in IgG antibody by hemagglutination inhibition, complement fixation, ELISA, or fluorescent antibody detection. Confirmation results from detection of 4-fold rise in IgG antibody titer.[31]​ Useful if initial IgM test is not informative. Convalescent titers are drawn 3 to 4 weeks after acute titers.

Result

≥4-fold rise in antibody

measles RNA detection by PCR

Test
Result
Test

Measles RNA can be detected by polymerase chain reaction (PCR) from throat or nasopharyngeal swabs or urine samples.[31]​ Best yield is obtained when samples are collected on days 1 to 3 of the rash, but virus still may be detected up to 10 to 14 days after rash onset.[34]

Result

positive

antigen detection by fluorescent antibody or PCR techniques

Test
Result
Test

Targets antigen detection. Labor-intensive; usually restricted to research laboratories.

Result

positive

isolation of virus in tissue culture system

Test
Result
Test

Labor-intensive; usually restricted to research laboratories.

Result

Positive

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