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, which indicates whether an individual has immunity to the virus due to previous infection or vaccination.
Key Points to Consider
- The test requires a simple blood draw, which is then sent to a laboratory for analysis.
- Results from the test are typically categorized as positive (immune), equivocal (borderline), or negative (not immune).
- If the results show that an individual is not immune, vaccination with the MMR (measles, mumps, rubella) vaccine is recommended, especially for certain groups such as healthcare workers, international travelers, college students, and women planning pregnancy.
- The EIA or ELISA test detects memory antibodies that the immune system produced after exposure to the measles virus or vaccine, which provide long-term protection against future infections.
Importance of Accurate Testing
Accurate determination of measles immunity is crucial for preventing the spread of the virus, especially in high-risk settings such as healthcare facilities and educational institutions. By using the most sensitive and reliable tests available, such as EIA or ELISA, healthcare providers can make informed decisions about vaccination and other preventive measures 1.
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
- Measles IgG avidity assay 4, 5
- Particle agglutination (PA) titer 3
- Neutralizing test (NT) 3
- Immunofluorescence assay for IgG4 measles specific antibody 6
Test Characteristics
These tests have varying characteristics, such as:
- Sensitivity: ELISA is approximately 23 times more sensitive than HI 2
- Specificity: Measles IgG avidity assay can distinguish recent from distant measles virus infections 4
- Interpretation: EIA-IgG antibody titer does not correlate with the protective level, while HI antibody titer appears to reflect this protective level 3
- Application: Measles virus-specific IgG4 antibody titer can be used as a serologic marker of post-vaccinal immune response 6
Clinical Utility
These tests can be used in various clinical settings, including: