Cytomegalovirus (CMV) is one of the most widespread infections on the planet. Globally, prevalence ranges from about 45% in developed countries to nearly 100% in parts of Africa and Asia. In Europe and North America, roughly 80% of adults carry the virus. Most people who have it never know, because the initial infection rarely causes noticeable symptoms in healthy individuals.
CMV Prevalence in the United States
In the U.S., overall infection rates vary significantly by race, ethnicity, and sex. Among non-Hispanic White adults, about 57% test positive for CMV antibodies. That number jumps to 88% among non-Hispanic Black adults and 92% among Hispanic adults. Women are also more likely to carry the virus than men (67% versus 57%). These differences are thought to reflect a mix of socioeconomic factors, household density, breastfeeding patterns, and childcare exposure rather than any biological susceptibility.
By the time most Americans reach middle age, the odds are better than even that they’ve been infected at some point. The virus spreads through saliva, urine, breast milk, sexual contact, and blood. Once you’re infected, CMV stays in your body for life, tucked away in a dormant state inside certain immune cells.
Most Infections Cause No Symptoms
The vast majority of CMV infections in healthy adults produce no symptoms at all, or only a mild, vague illness that resembles a cold or brief fatigue. Some people develop a mono-like syndrome with fever, sore throat, and swollen glands, but this is the exception. Because symptoms are so rare and so nonspecific, most people pick up the virus without ever realizing it.
Even after the initial infection resolves, the virus doesn’t leave. It enters a dormant phase and can periodically reactivate. Studies have detected CMV DNA shedding from sites like the nose, mouth, skin, or vagina in 7 to 8% of healthy adults with no symptoms at all. This silent shedding is one reason the virus spreads so easily through populations.
Who Faces the Highest Exposure Risk
Young children, especially toddlers in group childcare, are major transmitters. They shed the virus in saliva and urine for months or even years after their initial infection. Adults who work closely with young children pick up CMV at notably higher rates: pooled data from multiple studies show that about 59% of childcare workers are seropositive, and roughly 7.4 out of every 100 childcare workers who haven’t already been infected will acquire CMV in a given year. Parents of children under three face similarly elevated exposure, though precise rates for this group are harder to pin down because most studies don’t separate data by children’s ages.
For women who are pregnant or planning to become pregnant, this is particularly relevant. A first-time CMV infection during pregnancy carries the highest risk of passing the virus to the fetus. Despite this, the American College of Obstetricians and Gynecologists does not recommend routine CMV screening before or during pregnancy. The reasons: about 90% of positive screening results for recent infection turn out to be false positives, no vaccine exists, and no proven treatment reliably prevents transmission to the fetus. Congenital CMV is typically suspected only after an ultrasound shows suggestive findings.
Congenital CMV in Newborns
About 1 in 200 babies in the United States is born with congenital CMV, making it one of the most common infections present at birth. Most of these infants appear healthy at delivery and never develop complications. However, about 1 in 5 babies born with congenital CMV will have birth defects or long-term health problems, most commonly hearing loss. CMV is actually the leading non-genetic cause of childhood hearing loss in the U.S., and the hearing damage can be present at birth or develop gradually over the first few years of life.
CMV in Transplant Recipients and Immunocompromised People
For people with weakened immune systems, CMV is a different story entirely. The virus can reactivate from its dormant state and cause serious organ damage when the immune system can no longer keep it in check.
Organ transplant recipients face some of the highest rates. Without preventive antiviral treatment, CMV infection occurs in 54 to 92% of lung transplant patients, roughly 50 to 75% of heart-lung transplant patients, and about 50% of those receiving a pancreas or kidney-pancreas transplant. Rates after heart transplantation range from 9 to 23%, liver transplantation from 22 to 29%, and kidney transplantation from 8 to 32%. The wide ranges reflect differences in whether the donor, the recipient, or both carried the virus before the transplant.
Bone marrow transplant recipients are also vulnerable. Around 30% of patients receiving donor stem cells develop CMV disease, and reactivation of dormant virus occurs in up to 70% of high-risk patients, such as those who already carried CMV but received cells from a donor who did not. Among patients receiving their own stem cells back (autologous transplant), the rate drops to about 5%.
People living with advanced HIV are another high-risk group. Before effective antiretroviral therapy became widespread, CMV was a leading cause of blindness and gastrointestinal disease in people with AIDS. Modern HIV treatment has dramatically reduced these complications by keeping immune function intact enough to suppress the virus.
Why Global Rates Vary So Widely
The gap between 45% seroprevalence in some wealthy nations and near-universal infection in lower-income regions comes down to living conditions and early childhood exposure. In settings with crowded housing, shared childcare from infancy, and prolonged breastfeeding, children encounter the virus very early in life. In higher-income countries with smaller household sizes and less communal childcare, first exposure often happens later, in adolescence or adulthood, and some people avoid it altogether.
This pattern also explains the racial and ethnic disparities seen within the U.S. The differences in CMV rates between demographic groups closely mirror differences in household density, childcare arrangements, and socioeconomic conditions rather than any inherent biological factor. The practical consequence is that women in communities with higher seroprevalence are more likely to have already been infected before pregnancy, which somewhat lowers (though doesn’t eliminate) the risk of passing a new infection to a fetus.