From the Guidelines
To determine measles antibody (immunoglobulin) titer, an enzyme immunoassay (EIA) or enzyme-linked immunosorbent assay (ELISA) is the most sensitive and recommended test. These assays have replaced the traditional hemagglutination-inhibition (HI) test as the preferred method for assessing immunity to measles in most laboratories 1. The EIA or ELISA test measures the level of measles-specific antibodies in the blood, indicating whether an individual has immunity from previous infection or vaccination.
Key Points to Consider
- The test results will indicate whether an individual has protective antibodies (positive/immune) or lacks protection (negative/non-immune) against measles.
- A positive test result confirms immunity, while a negative result suggests susceptibility to measles.
- In cases of equivocal test results, individuals should be considered susceptible unless they have other evidence of measles immunity or subsequent testing indicates they are immune 1.
- The EIA or ELISA test is particularly important for certain groups, such as healthcare workers, international travelers, women planning pregnancy, and during measles outbreaks.
Test Procedure
The test involves a blood draw, which is then sent to a laboratory for analysis. Results typically take a few days, and if the test shows an individual is not immune, vaccination with the MMR (measles, mumps, rubella) vaccine is recommended. The test detects memory antibodies produced by the immune system after exposure to the measles virus or vaccine, which remain in the bloodstream and provide ongoing protection against future infection.
From the Research
Measles Antibody Tests
To determine measles antibody (immunoglobulin) titer, several tests can be utilized, including:
- Enzyme-linked immunosorbent assay (ELISA) 2
- Hemagglutination-inhibition (HI) assay 2, 3
- Enzyme-immunoassay (EIA) 3
- Particle agglutination (PA) 3
- Neutralizing test (NT) 3
- Solid-phase radioimmunoassay (RIA) for IgG and IgM antibodies 4
- Measles IgG avidity assays 5
Test Characteristics
These tests have varying characteristics, such as:
- Sensitivity: ELISA is approximately 23 times more sensitive than HI 2
- Specificity: Measles IgG avidity assays can distinguish recent from distant measles virus infections 5
- Correlation with protective level: HI antibody titer appears to reflect the protective level, while EIA-IgG antibody titer does not correlate with the protective level 3
Interpretation of Results
The interpretation of results from these tests can provide information on:
- Measles immunity level: EIA-IgG antibody titer can be used to estimate the measles prevention level 3
- Post-vaccinal immune response: Measles virus-specific IgG4 antibody titer can be used as a serologic marker of post-vaccinal immune response 6
- Differentiation between natural and vaccinal source of measles infection: IgG4 measles antibody titer can be used to differentiate between natural and vaccinal source of measles infection 6