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Cytomegalovirus Infections

Cytomegalovirus is a member of the herpesvirus group, which includes the herpes simplex viruses 1 and 2, varicella-zoster virus, Epstein_Barr virus (EBV), human herpesvirus 6 (roseola), and human herpesvirus 7 (nonspecific febrile illness). These viruses are widely distributed in humans and have a propensity for latency and cytomegalovirus.

One percent of newborns have CMV in the urine at the time of birth, which makes CMV the most common congenital infection. Maternal infection is transmitted to 30-50% of fetuses when the mother has no antibody prior to the pregnancy. Prior maternal infection that recurs during pregnancy is transmitted to the fetus in 1.5% of cases.

Transmission of a primary maternal CMV infection to the fetus results in disease in 20% of involved infants and is responsible for almost all of the mortality and morbidity.

CMV can be transmitted to the infant via the maternal cervicovaginal secretions, urine, saliva, and breast milk.

Virus is also acquired during the preschool years, especially among children attending day care centers. The prevalence of active CMV infection among such children is 22-78%.

The spread of virus in day care centers is caused by saliva-contaminated toys and poor hygiene.

Seronegative pregnant mothers are at risk of acquiring infection from an infected toddler attending a day care center.

Transmission of CMV after puberty usually results from heterosexual and homosexual activity, and the transmission rate increases with the number of sexual partners.

There is no evidence that health-care workers can acquire CMV from infected hospitalized patients. However, an infected infant can transmit infection to other infants in the nursery.

CMV can also be transmitted through blood transfusion, bone marrow.

Treatment

Severe CMV infections are treated with ganciclovir, a nucleoside analog which is structurally similar to acyclovir. Ganciclovir is virostatic, only suppressing viral replication. Ganciclovir is indicated for CMV retinitis, colitis, meningoencephalitis, esophagitis, hepatitis.

Foscarnet inhibits CMV DNA polymerase.