About one percent of babies born in the U.S. are infected, and if a newborn's mother is a carrier, about 50 percent will be infected through breastfeeding or other routes. Although infection in the newborn can cause severe disease, this happens almost always when the mother is first infected late in her pregnancy. This is similar to herpes, where serious infections in the newborn occur almost exclusively in children born to mothers who first developed their herpes infection late in pregnancy. If one gets through childhood without becoming infected, the beginning of sexual activity in late adolescence is another common time for infections to occur. As with regular mono, one can be quite ill with high fever, chills, fatigue, and headache for several weeks, but fatalities are rare.
Most infected people carry the infection for life without becoming ill after the initial infection.
Because of the immune suppression common to all these situations, the CMV virus may be reactivated, causing pneumonia or, in AIDS, an infection of the retina of the eye that can lead to blindness. People who have never had CMV but need an organ transplant can contract CMV from the transplanted organ. The antibiotic ganciclovir is effective against CMV, but the virus can still cause severe and fatal disease because of the weakened immune systems in transplant recipients and AIDS patients. My own feeling is that this virus, like herpes, chicken pox, and EBV, is best caught in childhood, when the disease is generally mild, rather than in adulthood, when the resulting disease can be much more severe, and in the case of pregnant women, can lead to severe problems for her newborn child. For more information on AIDS and HIV, check out Thrive's AIDS program.