Measles (Rubeola) Antibodies, IgG

Measles (Rubeola) Antibodies, IgG—also referred to as Anti-Measles Virus IgG or Measles Virus Specific IgG—is used to establish serologic status for documentation of immunity or evidence of past exposure or vaccination. A positive result generally indicates previous infection or vaccination and is regarded as adequate laboratory evidence of immunity, whereas an equivocal result does not constitute presumptive immunity. Documented, age-appropriate vaccination takes precedence over serologic results; individuals with two documented doses of a measles-containing vaccine are considered presumptively immune and do not require further doses even when serology is negative or equivocal.

Measles is a highly contagious paramyxovirus infection spread by respiratory droplets. Initial replication involves the respiratory mucosa and oropharynx. Clinical features include fever, dry cough, conjunctivitis with photophobia, coryza, sore throat, and Koplik spots, followed by a cephalocaudal maculopapular rash. Most patients recover within weeks; however, approximately 20% develop complications such as otitis media, bronchitis, pneumonia, diarrhea, encephalitis, or blindness. Illness is more severe in adults and in persons with immunodeficiency, vitamin A deficiency, or malnutrition. Infection during pregnancy increases the risk of miscarriage and preterm delivery. Following infection, measles virus–specific IgM appears first, peaks within days, and wanes over subsequent weeks. IgG develops after 2–4 weeks and persists for decades, providing long-term immunity. IgG is also induced by vaccination, and maternally derived IgG may be detectable in some infants up to 6–7 months of age.