Human Cytomegalovirus (CMV) is a widespread virus that belongs to the herpesvirus family. This common virus is found globally, with seroprevalence ranging from 24% to 100% depending on the region. While CMV often remains without symptoms in healthy individuals, it can pose health risks to certain vulnerable populations, including those with weakened immune systems and newborns.
How CMV is Transmitted
CMV spreads through direct, prolonged contact with various bodily fluids from an infected person. These fluids include saliva, urine, blood, tears, semen, breast milk, and vaginal fluids. The virus is not airborne.
Transmission scenarios involve direct contact with saliva or urine, particularly from babies and young children who can shed the virus. Sexual contact is another route, as CMV can be found in semen and cervical secretions. Additionally, the virus can be transmitted through transplanted organs or blood transfusions. A significant mode of transmission is from a mother to her baby during pregnancy or childbirth, known as congenital CMV infection.
Understanding CMV Symptoms
CMV infection manifests differently depending on an individual’s immune status. In healthy adults and children, the initial infection often produces no noticeable symptoms. When symptoms do occur in immunocompetent individuals, they are typically mild and resemble common illnesses like mononucleosis or a flu-like syndrome. These can include fever, fatigue, sore throat, muscle aches, and swollen glands, usually resolving within approximately three weeks.
For individuals with weakened immune systems, such as those with HIV/AIDS or organ transplant recipients, CMV can cause more severe disease. The virus can reactivate and impact various organs, leading to conditions like pneumonia, retinitis (eye inflammation), or gastrointestinal inflammation (e.g., colitis or esophagitis). Other serious manifestations may include hepatitis, encephalitis, or myelitis.
Babies infected with CMV before birth, known as congenital CMV infection, can present a spectrum of symptoms. Some newborns may appear healthy at birth with no immediate signs, though about 20% of these may develop symptoms later. Other babies may show symptoms at birth, which can include a rash, jaundice, low birth weight, an enlarged liver and spleen, or microcephaly. Hearing loss is a common long-term problem associated with congenital CMV, sometimes appearing months or years after birth.
Once a person is infected with CMV, the virus remains in their body for life, establishing a state of latency. During latency, the virus resides in cells without causing active illness. However, the virus can reactivate later, particularly if the immune system becomes suppressed, leading to a recurrence of symptoms or new complications. Reactivation can be triggered by inflammation, infection, or injury.
Serious Health Risks and Approaches to Care
Congenital CMV infection carries long-term health risks for affected babies. Approximately 1 in 5 babies born with congenital CMV will experience birth defects or other health problems. These can include progressive hearing loss, developmental delays, vision impairment, and neurological issues such as seizures or cognitive impairment. In the most severe instances, congenital CMV can lead to organ damage and, rarely, can be fatal.
For individuals with compromised immune systems, CMV infection or reactivation can lead to life-threatening complications. These can involve damage to organs such as the lungs, liver, gastrointestinal tract, eyes, and brain. For transplant recipients, CMV can increase the likelihood of transplant rejection.
There is no cure that eradicates CMV from the body, but management strategies exist to address severe infections. Antiviral medications, such as ganciclovir and valganciclovir, are used to treat CMV infections. They are employed in immunocompromised individuals and symptomatic congenital cases to control viral replication and reduce complications.
Preventive measures are available, especially for pregnant individuals and those with weakened immune systems. Good hygiene practices, such as thorough handwashing with soap and water after contact with bodily fluids from young children, can reduce the risk of transmission. Avoiding sharing food, utensils, cups, or pacifiers with young children is also recommended. Screening practices for CMV are sometimes implemented in specific high-risk populations, though routine screening for all pregnant women is not standard practice.