Measles (Rubeola) Antibodies, IgG, Serum
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
The measles virus is a member of the Paramyxoviridae family of viruses, which include parainfluenza virus serotypes 1-4, mumps, respiratory syncytial virus (RSV), and metapneumovirus. The measles virus is among the most highly contagious infectious diseases among unvaccinated individuals and is transmitted through direct contact with aerosolized droplets or other respiratory secretions from infected individuals. Measles has an incubation period of approximately 8 to 12 days, which is followed by a prodromal phase of high fever, cough, coryza, conjunctivitis, and malaise. Koplik spots may also be apparent on the buccal mucosa and can last for 12 to 72 hours.(1,2) Following this phase, a maculopapular, erythematous rash develops beginning behind the ears and on the forehead and spreading centrifugally to involve the trunk and extremities.
Immunocompromised individuals, pregnant women, and those with nutritional deficiencies are particularly at risk for serious complications following measles infection, which include pneumonia and central nervous system involvement.(1,3)
Following implementation of the national measles vaccination program in 1963, the incidence of measles infection has fallen to <0.5 cases per 1,000,000 population and the virus is no longer considered endemic in the United States.(4) Measles outbreaks continue to occur in the United States due to exposure of nonimmune individuals or those with waning immunity to infected travelers. The measles outbreak in 2011 throughout Western Europe emphasizes the persistence of the virus in the worldwide population and the continued need for national vaccination programs.(5)
The diagnosis of measles infection is often based on clinical presentation alone. Screening for IgG-class antibodies to measles virus will aid in identifying nonimmune individuals.
Determination of immune status of individuals to the measles virus
Documentation of previous infection with measles virus in an individual without a previous record of immunization to measles virus
Positive: Antibody index (AI) value > or =1.1
The reported AI value is for reference only. This is a qualitative test and the numeric value of the AI is not indicative of the amount of antibody present. AI values above the manufacturer recommended cut-off for this assay indicate that specific antibodies were detected, suggesting prior exposure or vaccination.
The presence of detectable IgG-class antibodies indicates prior exposure to the measles virus through infection or immunization. Individuals testing positive are considered immune to measles infection.
Equivocal: AI value 0.9-1.0
Submit an additional sample for testing in 10 to 14 days to demonstrate IgG seroconversion if recently vaccinated or if otherwise clinically indicated.
Negative: AI value < or =0.8
The absence of detectable IgG-class antibodies suggests the lack of a specific immune response to immunization or no prior exposure to the measles virus.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
IgG-class antibodies to measles virus may be present in serum specimens from individuals who have received blood products within the past several months, but have not been immunized or experienced past infection with this virus.
Serum specimens drawn early during acute phase of infection may be negative for IgG-class antibodies to this virus.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Vaccinated: Positive (> or =1.1 AI)
Unvaccinated: Negative (< or =0.8 AI)
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Perry RT, Halsey NA: The clinical significance of measles-a review. J Infect Dis 2004;189(Supp 1):S4-S16
2. Babbott FL, Gordon JE: Modern measles. Am J Med Sci 1954;228:334-361
3. Liebert UG: Measles virus infections of the central nervous system. Intervirology 1997;40:176-184
4. Morbidity and Mortality Weekly Report: Measles-United States, 1999. 2000;49(25):557-560
5. Morbidity and Mortality Weekly Report: Increased Transmission and Outbreaks of Measles-European Region 2011;60(47):1605-1610