Cytomegalovirus (CMV) | Antibodies IgM

Cytomegalovirus (CMV) Belongs to the same family of viruses as the herpes simplex and varicella-zoster viruses.

Cytomegalovirus was isolated in 1956 and given its name because of its characteristic cytopathic effect: virus-infected cells hypertrophy and contain large amounts of eosinophilic intrathecal inserts reminiscent of "owl eyes".

Cytomegalovirus infection is widespread, and clinical disease is a more rare outcome of this infection (80–100% of the adult population has specific antibodies as the predominant outcome of asymptomatic infections).

Cytomegalovirus infection is currently considered a significant public health problem for the following reasons: Increased incidence of congenital infections, persistent viral infection with reactivation, especially in immunocompromised and organ transplant recipients, and its frequent manifestations in posttransfusion syphilis (posttransfusion syphilis).

Humans are the only natural reservoir of human cytomegalovirus (animal cytomegalovirus does not infect humans). Ways of transmitting the infection are varied. The virus is found in the urine and saliva of an infected person, as well as in vaginal secretions, semen and breast milk. The fetus can be infected within the uterus; However, more often, the infection develops perinatally, by contact of the newborn with the cervix, mucus-rich secretions, or postnatally - by contact of the newborn with the mother's secretions (saliva, milk, etc.). Another common route of transmission (more than 50% of infections) is through kissing and sex. Iatrogenic routes of transmission are also common - infection through blood transfusions (the virus is in leukocytes) or by organ transplants (eg kidneys).

The virus stays in the body for a long time. Infection does not give a person strong immunity, the virus continues to be excreted from the body even in the presence of specific antibodies. When the body's resistance is reduced (prolonged immunosuppressive therapy, AIDS), latent infection may be clinically manifested (hepatitis, pneumonia, encephalitis), sometimes with lethal consequences. The contagious period lasts (intermittently) for months, years or a lifetime.

Primary infection Is asymptomatic in most cases in adults; The clinical picture of its manifestation is diverse: febrile condition of unspecified etiology, picture of infectious mononucleosis with negative heterophilic antibodies, hepatitis with jaundice.

In pregnant women There is an increase in susceptibility to cytomegalovirus infection (6 times more than in the rest of the adult population). During primary infection of a pregnant woman, the risk of infection of the fetus is maximal (up to 50%). Vertical transmission of the infection during the first 4 months of pregnancy can have particularly serious consequences (hepatitis, deafness, microcephaly). In case of reactivation of latent infection (0,7-0,9% of pregnant women) the risk of fetal infection is very low or non-existent.

Posttransfusion syndrome Manifested after blood transfusion with fever, lymphadenopathy, hepato-splenomegaly, rash and immunopathological changes (rheumatoid factor, antibodies, cold agglutinins, cryoglobulins, positive Coombs test). Patients experience an increase in the titer of antibodies specific for cytomegalovirus infection, confirming cytomegalovirus disease.

IgM Antibodies - appear for the first time in the body (after 5-7 days) in response to the entry or reactivation of cytomegalovirus (almost with the activation of the virus), therefore, they are in the acute stage of primary infection (when IgG antibodies are not yet produced) or chronic reactivation (IgG detection) They give us. IgM does not have high specificity and therefore can give false positive results (due to cross-reactivity with other members of the herpesvirus group), especially during pregnancy. This should be taken into account when interpreting a positive outcome. Is most optimal in these cases Determination of IgG dynamics (A fourfold increase confirms the activity of the process). The average duration of its detection in the blood during primary infection is up to 3 months, during reactivation - from a few days to several weeks. The length of the period depends on the body's immunity and the activity of the process. The peculiarities of the formation of the immune system in infants can lead to a deficiency of these antibodies during infection, so it is inadmissible to interpret the negative result as the absence of infection: in these cases, molecular diagnostic methods (PCR) can detect the virus in various biological fluids.

When should we get tested for cytomegalovirus IgM?

IgM Represents a marker of the acute stage of the infectious process (primary infection or reactivation).

• Differential diagnostics of the etiology of the infectious process in the following conditions: Mononucleosis syndrome clinic, fever of unknown origin, pneumonia, hepatitis, encephalitis, meningoencephalitis, myelitis, neuropathy, pericarditis, myocarditis, colitis, etc .;
• Assessment of virus activity during pregnancy;
• Control of primary infection of seronegative pregnant women;
• Diagnosis of congenital CMV infection.

How to prepare for the test?

No special preparation is required for the test.

Research material

Venous blood

Possible interpretation of the results

In case of doubtful result it is necessary to determine IgG. Repeating the test is recommended after 2 weeks (determination of IgM and IgG)

Positive result:

• Acute stage of primary CMV infection;
• Reactivation of CMV infection;
• Congenital CMV (in newborns);
• False positive result.

Negative result:

• No CMV infection was reported;
• Early incubation period of CMV infection;
• Absence of acute stage during primary infection or reactivation;
• Congenital CMV infection is not excluded;
• Presence of CMV infection in the past.

Resources

https://www.synevo.ro/shop/citomegalovirus-anticorpi-igm/

https://spravochnik.synevo.ua/ru/torch-infekcii/cytomegalovirus.html