Cytomegalovirus as a Sexually Transmitted Disease

Summary

In the developed nations, one of the important mechanisms of CMV transmission is sexual contact. This has been demonstrated to occur between heterosexual men and women and between homosexual men. Sexual intercourse, including anal receptive intercourse, is a risk for this transmission but salivary exchange, i.e., kissing may also facilitate cross infection. Reinfection by additional strain(s) of CMV may occur as a result of sexual transmission. Condoms, tested in laboratory simulations of sexual intercourse, reduce transmission of CMV and may be useful in clinical practice.

In the developed or industrialized nations, approximately one half of the adult population is seronegative for cytomegalovirus (CMV) antibody. This is in marked contrast to the age-related prevalence of CMV antibody in the underdeveloped countries of the world where > 90% of the population is seropositive by the age of 2 years. The probable explanations for this are that in the underdeveloped countries the living conditions are more crowded, there is more close and repeated contact with infected urine, and more frequent breast feeding of infants. Thus, in the developed countries, there is a large pool of uninfected adults who then acquire this virus at a slow rate, i.e., approximately 1% –2% seroconversions per year. It appears that these seroconversions result from close contact with virus-positive individuals. Such contact may be sexual with exchange of body fluids, including saliva, but other types of close contact may bring about transmission. For example, adults may be infected during maternal or paternal contact with a virus-positive child, or by blood transfusion or organ transplantation. In this chapter we will concentrate on evidence supporting the role of sexual transmission as an effective means of spreading the virus. In so doing we will consider the evidence in two different settings, heterosexual and homosexual.