Cytomegalovirus (CMV) is a common virus belonging to the Herpesviridae family, related to the viruses that cause chickenpox and mononucleosis. Like other herpesviruses, CMV establishes a lifelong presence in the body after initial infection, often remaining dormant. The virus is widespread; in the United States, more than half of adults have been infected by age 40. For most healthy individuals, infection causes no noticeable illness or only mild, flu-like symptoms. The complexity of CMV relates to its multiple transmission routes, leading to questions about whether it qualifies as a sexually transmitted disease.
CMV Transmission: The Role of Sexual Contact
The answer to whether CMV is an STD is nuanced: it is frequently transmitted through sexual contact, but it is not officially classified as a Sexually Transmitted Disease (STD) or Sexually Transmitted Infection (STI) by major health organizations. The virus is shed in various bodily fluids, including semen and vaginal secretions, allowing for efficient transmission during sexual intercourse. CMV shedding can also occur in saliva, meaning deep kissing can serve as a sexual route of transmission as well.
In sexually active individuals, CMV infection is often acquired through this exchange of genital fluids or saliva. The presence of the virus in these fluids means that a person with CMV can transmit it to a partner, especially during a primary infection when the viral load is high.
CMV does not fit the strict definition of an STD because sexual contact is only one of many ways it can pass from person to person. Viruses like HIV and herpes simplex virus (HSV) are also transmissible through sexual contact, but CMV’s high rate of non-sexual spread, particularly in childhood, distinguishes it from these traditional STDs. Therefore, it is more accurately described as a virus that is sexually transmissible rather than an exclusive STI.
Other Transmission Pathways
The broad range of non-sexual pathways is precisely why CMV is not categorized exclusively as an STD. The most common route of transmission, particularly in developed countries, is through contact with the saliva and urine of young children. Nearly one in three children in the U.S. has been infected by age five, and they often shed high concentrations of the virus in their body fluids for months.
Caregivers, parents, and those who work in daycare settings are at a high risk of exposure through close, non-sexual contact. Simple actions like changing diapers, wiping a child’s nose, or sharing food and utensils can facilitate the transfer of the virus.
CMV is also readily transmitted through blood transfusions and organ transplants. Transmission from mother to child is another significant pathway, occurring before, during, or after birth. The virus can cross the placenta, resulting in a congenital infection. Postnatal transmission is also possible through breast milk or contact with the mother’s genital secretions during delivery.
Health Consequences and At-Risk Groups
While CMV infection is usually benign in healthy people, it poses risks to two specific populations: the developing fetus and individuals with compromised immune systems.
Congenital Infection
When a pregnant individual acquires a primary CMV infection, there is a risk of transmitting the virus to the fetus, leading to congenital CMV infection. This is the most common infectious cause of birth defects in the United States. About one in five babies born with congenital CMV infection will develop long-term health problems. The most common long-term effect is hearing loss, which can be present at birth or develop later in childhood. Other potential issues include developmental and motor delays, vision problems, microcephaly (small head size), and poor growth.
Immunocompromised Individuals
For people who are immunocompromised, such as solid organ transplant recipients, stem cell transplant patients, or individuals with HIV, CMV can reactivate from its dormant state and cause severe disease. The virus can attack specific organs, leading to conditions like retinitis (damaging the retina), pneumonitis (lung inflammation), or colitis (inflammation of the colon). In these vulnerable groups, CMV infection or reactivation can be life-threatening and requires immediate and sustained medical management.
Prevention and Management
Preventing the spread of CMV relies heavily on practicing good hygiene, especially for individuals who are pregnant or caring for young children. Thorough and frequent handwashing with soap and water is the most effective way to reduce the risk of transmission. This is particularly important after changing diapers, feeding a young child, or handling toys.
Pregnant individuals should also avoid sharing food, drinks, or eating utensils with young children and should refrain from kissing a child on the mouth. The broad transmission routes of CMV mean prevention must extend beyond just sexual contact.
Most healthy adults who contract CMV do not require treatment, as their immune system manages the infection effectively. However, antiviral medications, such as valganciclovir, are used to manage severe cases. These drugs are administered to newborns with symptomatic congenital CMV infection and to immunocompromised patients facing active CMV disease. Treatment aims to limit viral replication and reduce the severity of organ damage or long-term complications.