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 due to their higher sensitivity 1. The EIA or ELISA measures the level of measles-specific antibodies in the blood, indicating whether an individual is immune to measles.
Key Points to Consider
- The test is crucial for determining immunity in individuals, especially healthcare workers, international travelers, women planning pregnancy, and during measles outbreaks.
- A positive test result indicates the presence of measles antibodies, suggesting immunity, while a negative result suggests susceptibility to the disease.
- In cases of equivocal test results, individuals should be considered susceptible unless they have other evidence of measles immunity or subsequent testing confirms immunity 1.
- The EIA or ELISA is a blood test that requires a simple blood draw, and the results are typically reported as "immune" or "non-immune".
- If an individual is found to be non-immune, vaccination with the MMR (measles, mumps, rubella) vaccine is recommended to prevent measles 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