Cytomegalovirus infection - Causes and epidemiology

Causes of cytomegalovirus infection

In the classification of viruses, the causative agent of cytomegalovirus infection under the species name Cytomegalovirus hominis is assigned to the Herpesviridae family, Betaherpesviridae subfamily, Cytomegalovirus genus.

Features of cytomegalovirus infection:

• large DNA genome;
• low cytopathogenicity in cell culture;
• slow replication;
• low virulence.

The virus is inactivated at a temperature of 56 °C, is preserved for a long time at room temperature, and is quickly inactivated when frozen to -20 °C. Cytomegalovirus infection is weakly sensitive to the action of interferon and is not susceptible to antibiotics. Three strains of the virus have been registered: AD 169, Davis, and Kerr.

[ 1 ], [ 2 ], [ 3 ], [ 4 ], [ 5 ], [ 6 ], [ 7 ], [ 8 ], [ 9 ]

Epidemiology of cytomegalovirus infection

Cytomegalovirus infection is a widespread infection.

The source of the infectious agent is a person. Cytomegalovirus infection is characterized by a state of long-term 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 saliva, 3-10% in urine, 5-20% in the cervical canal or vaginal secretions. The virus is found in breast milk of 20-60% of seropositive mothers. About 30% of homosexual men and 15% of men entering into marriage have the virus in their sperm. The blood of about 1% of donors contains cytomegalovirus. Infection is possible sexually, parenterally, vertically, as well as by contact-household means, which is provided by the aerosol mechanism of transmission of the pathogen through saliva during close contacts.

Cytomegalovirus infection is a classic congenital infection, the incidence of which is 0.3-3% among all born infants. The risk of antenatal infection of the fetus in primary cytomegalovirus infection in pregnant women is 30-40%. In case of virus reactivation, which occurs in 2-20% of mothers, the risk of infection of the child is significantly lower (0.2-2% of cases). Intranatal infection of a child in the presence of cytomegalovirus in the genital tract of pregnant women occurs in 50-57% of cases. The main route of infection of a child under one year of age is transmission of the virus through breast milk. Children of seropositive mothers who are breastfed for more than one month become infected in 40-76% of cases. Consequently, up to 3% of 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%. Contact-household transmission of the virus in young children plays a significant role. The infection rate 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 individuals increases with age. About 40-80% of adolescents and 60-100% of the adult population have IgG antibodies to cytomegalovirus. Infection of an adult with cytomegalovirus is most likely sexually transmitted, as well as with blood transfusions and parenteral manipulations. Transfusion of whole blood and its components containing leukocytes leads to transmission of the virus with a frequency of 0.14-10 per 100 doses.

There is a high risk of developing a serious disease with repeated blood transfusions from seropositive donors to newborns, especially premature babies. Clinically expressed cytomegalovirus infection is one of the most common 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 kidney or liver transplantation. 20-50% of patients after allogeneic bone marrow transplantation. 55-75% of lung and/or heart recipients develop CMV disease, cytomegalovirus infection significantly increases the risk of transplant 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 in 3-7% of HIV-infected patients when it is prescribed. The development of severe cytomegalovirus infection has been described in oncohematological patients, patients who suffered from pneumocystis pneumonia, tuberculosis, radiation sickness, burn injury, in persons undergoing long-term corticosteroid therapy, and those who have experienced various stressful situations. Cytomegalovirus infection can cause post-transfusion and chronic hepatitis, various gynecological pathologies. The role of cytomegalovirus as one of the cofactors in the development of systemic vasculitis, atherosclerosis, chronic disseminated lung diseases, cryoglobulinemia, tumor processes, atherosclerosis, cerebral palsy, epilepsy, Guillain-Barré syndrome, chronic fatigue syndrome is assumed. Seasonality, outbreaks and epidemics are not characteristic of the disease associated with cytomegalovirus.

[ 10 ], [ 11 ], [ 12 ], [ 13 ], [ 14 ], [ 15 ], [ 16 ], [ 17 ], [ 18 ]