Cytomegalovirus infection: causes and epidemiology
Last reviewed: 23.04.2024
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Causes of cytomegalovirus infection
In the classification of viruses, the causative agent of a cytomegalovirus infection, under the specific name Cytomegalovirus hominis, is assigned to the Herpesviridae family, the subfamily Betaherpesviridae, of the genus Cytomegalovirus.
Features of cytomegalovirus infection:
- a large DNA genome;
- low cytopathogenicity in cell culture;
- slow replication;
- low virulence.
The virus is inactivated at a temperature of 56 ° C, stored for a long time at room temperature, rapidly inactivated by freezing to -20 ° C. Cytomegalovirus infection is weakly susceptible to interferon, not susceptible to antibiotics. Three strains of the virus were registered: AD 169, Davis and Kerr.
[Epidemiology of cytomegalovirus infection
Cytomegalovirus infection is a widespread infection.
The source of the causative agent of infection is a person. Cytomegalovirus infection is characterized by a state of prolonged latent carriage of the virus with its periodic release into the environment. The virus can be found in any biological fluid, as well as in organs and tissues used for transplantation. In 20-30% of healthy pregnant women, cytomegalovirus is present in the saliva, 3-10% in the urine, 5-20% in the cervical channel or vaginal secretion. The virus is found in breast milk 20-60% of seropositive mothers. About 30% of homosexual men and 15% of men who marry have a virus in semen. Blood of about 1% of donors contains cytomegalovirus. Infection is possible with the sexual, parenteral, vertical pathways, as well as the contact-household way, which is provided by the aerosol mechanism of transmission of the pathogen through saliva at close contacts.
Cytomegalovirus infection is a classic congenital infection, the frequency of which is 0.3-3% among all the babies born. The risk of antenatal fetal infection in primary cytomegalovirus infection in pregnant women is 30-40%. With the reactivation of the virus that occurs in 2-20% of mothers, the risk of infection of the child is much lower (0.2-2% of cases). Intranatal infection of a child in the presence of cytomegalovirus in the genital tract in pregnant women occurs in 50-57% of cases. The main way of infection of a child under the age of one year is transmission of the virus through breast milk. Children of seropositive mothers who have been breastfed for more than one month become infected in 40-76% of cases. Consequently, up to 3% among all newborns are infected with cytomegalovirus during the period of intrauterine development, 4-5% - intranatally; By the first year of life the number of infected children is 10-60%. The contact-household way of transmission of the virus in young children plays an important role. Infection with cytomegalovirus of children attending preschool institutions is significantly higher (80% of cases) than "home" pupils of the same age (20%). The number of seropositive persons increases with age. About 40-80% of adolescents and 60-100% of adults have antibodies of IgG class to cytomegalovirus. Infection of an adult with cytomegalovirus is most likely by sexual intercourse, also with blood transfusions and parenteral manipulations. Transfusion of whole blood and its components containing leukocytes leads to the transmission of the virus at a frequency of 0.14-10 per 100 doses.
There is a great danger of developing a serious disease with repeated blood transfusions from seropositive donors to newborns, especially premature ones. Clinically expressed cytomegalovirus infection is one of the most frequent and serious infectious complications in organ transplantation. About 75% of recipients have laboratory signs of active cytomegalovirus infection in the first 3 months after transplantation. In 5-25% of patients who have undergone a kidney or liver transplant. 20-50% of patients after allogeneic bone marrow transplantation. 55-75% of lung and / or heart recipients develop CMV etiology, cytomegalovirus infection significantly increases the risk of graft rejection. Manifest cytomegalovirus infection occupies one of the first places in the structure of opportunistic diseases in HIV-infected patients and is observed in 20-40% of AIDS patients who do not receive HAART and 3-7% of patients with HIV infection when it is prescribed. The development of severe cytomegalovirus infection is described in oncohematological patients, patients suffering from pneumocystis pneumonia, tuberculosis, radiation sickness, burn trauma, and those suffering from prolonged corticosteroid therapy, who suffered various stressful situations. Cytomegalovirus infection can cause post-transfusion and chronic hepatitis, a variety of gynecological pathologies. The role of cytomegalovirus as one of the cofactors in the development of systemic vasculitis, atherosclerosis of chronic disseminated lung diseases, cryoglobulinemia, tumor processes, atherosclerosis, cerebral palsy, epilepsy is supposed. Guillain-Barre syndrome. Chronic fatigue syndrome. Seasonality, outbreaks and epidemics are not characteristic of a disease associated with cytomegalovirus.