Cytomegalovirus (CMV) is a common virus belonging to the herpesvirus family, which includes viruses like those causing chickenpox. Over half of adults in the United States have been infected by age 40. Once acquired, CMV remains in the body for life, often in an inactive state without causing noticeable symptoms in healthy individuals.
How Cytomegalovirus Spreads
CMV primarily spreads through direct contact with infected body fluids, including saliva, urine, blood, tears, semen, breast milk, and cervical secretions. Transmission can occur through daily interactions like sharing eating utensils, food, or drinks, as well as kissing and sexual contact. Childcare environments are common settings for spread, as young children often shed the virus in their saliva and urine. CMV can also spread through blood transfusions, organ transplants, or from a pregnant individual to their baby during pregnancy or birth.
Understanding Contagious Periods
The duration an individual remains contagious with CMV, known as viral shedding, varies considerably depending on the type of infection and the person’s immune status. Following a primary CMV infection, the virus can be shed in bodily fluids for weeks to several months, and sometimes even longer. This period is often associated with higher viral loads and a greater likelihood of transmission.
After primary infection, CMV establishes a lifelong presence in the body and can reactivate periodically. During reactivations, the virus can again be shed intermittently in bodily fluids for months or years, typically without causing symptoms in healthy people. However, in individuals with compromised immune systems, reactivations may occur more frequently and lead to new periods of contagiousness.
Infants born with congenital CMV (acquired before birth) can shed the virus for extended periods. These infants may shed CMV in their urine and saliva for prolonged durations, often for a median of two years, and in some cases, for up to eight years or longer. This prolonged shedding, even when asymptomatic, highlights their role as a source of transmission.
Preventing Transmission of CMV
To reduce the risk of CMV transmission, particularly in household and childcare settings, practicing good hygiene is important. Frequent and thorough handwashing with soap and water is recommended, especially after changing diapers, assisting children with toileting, or coming into contact with a child’s saliva or urine. These practices help minimize the spread of the virus from contaminated surfaces or direct contact.
Avoid sharing personal items that come into contact with bodily fluids, such as food, drinks, eating utensils, or pacifiers. For adults, especially those in high-risk groups, practicing safe sex, such as using condoms, can help prevent sexual transmission of CMV.
CMV in Specific Populations
CMV can have significant implications for certain vulnerable populations. Pregnant women are a particular concern, as a primary CMV infection during pregnancy can transmit the virus to the developing fetus. The risk of this transmission is higher if the primary infection occurs earlier in the pregnancy, with rates ranging from 30-40% in the first and second trimesters and 40-70% in the third trimester. Congenital CMV infection can result in serious health issues for the baby, including hearing loss and developmental challenges.
Infants born with congenital CMV often shed the virus for an extended time in their bodily fluids, even if they show no symptoms at birth. This persistent shedding means they can be a source of infection for caregivers and family members, underscoring the importance of hygiene precautions in these households.
Individuals with weakened immune systems, such as organ transplant recipients, those undergoing chemotherapy, or people with HIV/AIDS, face a higher risk of severe illness from CMV. In these individuals, CMV can reactivate more frequently and persist for longer periods, increasing their transmission risk.