Rubella: antibodies of class IgM and IgG to the rubella virus in the blood
Last reviewed: 23.04.2024
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There are no antibodies of IgM to the rubella virus in the blood serum. For IgG antibodies, values greater than 35 IU / ml are considered to be diagnostic.
Rubella ( rubeola ) is an acute infectious anthroponotic disease transmitted by airborne droplets. Rubella is caused by a virus that is attributed to the family of Togaviridae, the genus Rubivirus. Virions contain RNA. Rubella is characterized by a winter-spring seasonality of morbidity. In 30-50% of infected rubella occurs in asymptomatic form.
15-50% of women have a potential risk of rubella infection during pregnancy. The greatest danger to the offspring is the presence of pregnant and latent rubella in pregnant women, accompanied by the persistence of the pathogen. Infection of the fetus with the rubella virus, depending on the period of pregnancy, causes various defects in its development. When a woman is infected in the first 2 months of pregnancy, the fetus develops heart defects (open arterial duct, pulmonary artery stenosis and its branches, defects of the interatrial or interventricular septum, etc.), damage to the visual organ (cataract, glaucoma, retinopathy). Infection of a woman during the 3-4th month of pregnancy leads to the formation of CNS defects (microcephaly, paralysis of the limbs, impaired mental development) and damage to the hearing organ (deafness, defects of the organ of Corti). The earlier the infection of the pregnant woman occurs, the higher the probability of the fetus and the wider range of possible developmental anomalies. When a woman is ill in the first 6 weeks of pregnancy, the incidence of congenital anomalies in a newborn is 56%, with infection at the 13-16th week of pregnancy, 6-10%. After the 16th week of pregnancy, the virus usually does not affect the fetus.
The exact diagnosis of rubella in children can be established only through the isolation and identification of the virus or on the basis of changes in the titers of specific antibodies. For serological diagnosis, ELISA is used.
For the diagnosis of rubella, the ELISA method is used, which allows to detect specific antibodies of classes IgM and IgG. The dynamics of detection of antibodies when using the ELISA method corresponds to the results of RTGA. IgM antibodies to the rubella virus appear in the acute period of infection: on the first day of rashes - in 50% of patients, in 5 days - more than 90%, in 11-25 days - in all patients. The presence of specific antibodies of IgM class indicates a recent infection with rubella (within 2 months). Six weeks after the rash, IgM antibodies are detected in 50% of patients, but in some cases they can persist for up to 1 year. With a congenital infection, IgM antibodies are detected immediately after birth, they persist up to 6 months in 90-97% of newborns. False positive results of the study of antibodies of IgM class can be obtained in patients infected with parvovirus B19.
Detection of IgM class antibodies to the rubella virus is used to diagnose an acute rubella period. After vaccination, IgM antibodies are detected after 15-25 days in 60-80% of cases. When reinfection, the IgM antibodies to rubella virus do not increase (it is necessary to study the dynamics of IgG antibodies - a 4-fold increase in titre in paired sera confirms the diagnosis). A low concentration of IgM antibodies to the rubella virus can be found in infectious mononucleosis and other viral infections (eg, cytomegalovirus infection, measles, herpetic infection).
IgG antibodies to the rubella virus are detected 3 days after the appearance of rashes in 50% of patients, after 8 days - more than 90%, on the 15-25th day - almost in all patients. The patients have IgG antibodies up to 10 years or more. The determination of IgG class titer for rubella virus is also used to assess the intensity of post-vaccination immunity (appearing on the 25th to the 50th day after vaccination) and the determination of the infection in the anamnesis. The absence of IgG antibodies to the rubella virus in newborns excludes congenital infection.
When evaluating the vaccination, its effectiveness is indicated by the values for ELISA: the IgG-class antibodies to the rubella virus are above 15 IU / L.
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