- Cytomegalovirus (CMV) is a common, double-stranded DNA virus belonging to the Herpesviridae family, specifically the Betaherpesvirinae subfamily. Like other herpesviruses, CMV has the distinctive ability to establish lifelong latency after primary infection and can reactivate under certain conditions, particularly in immunocompromised individuals.
- CMV is found worldwide and infects people of all ages, with seroprevalence rates varying by geographic region, socioeconomic status, and age. Most infections are acquired during childhood or adolescence, and in healthy individuals, CMV is typically asymptomatic or causes only mild, flu-like illness.
- Transmission of CMV occurs through close contact with bodily fluids such as saliva, urine, breast milk, blood, semen, and vaginal secretions. It can also be transmitted through organ transplantation, blood transfusion, and from mother to fetus during pregnancy—a form of congenital CMV infection that can lead to serious developmental complications. Congenital CMV is the leading infectious cause of birth defects and neurodevelopmental disorders, including hearing loss, intellectual disability, and vision impairment.
- In immunocompetent individuals, CMV infection usually remains unnoticed or presents as a mononucleosis-like illness with fever, fatigue, lymphadenopathy, and atypical lymphocytosis. However, in immunocompromised populations—such as transplant recipients, individuals with HIV/AIDS, or those undergoing chemotherapy—CMV can cause life-threatening systemic infections. These may include pneumonitis, retinitis, colitis, hepatitis, and encephalitis, depending on the organs affected. CMV retinitis, in particular, was once a common cause of blindness in patients with advanced HIV before the advent of effective antiretroviral therapy.
- Diagnosis of CMV infection involves a combination of clinical assessment and laboratory tests. Detection of viral DNA by polymerase chain reaction (PCR) is the most sensitive method and is widely used to monitor viral load in immunosuppressed patients. Serological testing can be used to identify past exposure, especially in pregnant women or transplant recipients, by detecting CMV-specific IgM and IgG antibodies. Histological examination of tissue samples may show characteristic “owl’s eye” intranuclear inclusions, a hallmark of CMV cytopathic effect.
- Treatment of CMV infection is generally reserved for immunocompromised patients or cases of severe disease. First-line antiviral agents include ganciclovir, valganciclovir, foscarnet, and cidofovir. These drugs work by inhibiting viral DNA polymerase but can have significant side effects such as bone marrow suppression and renal toxicity. For transplant recipients, preemptive therapy or universal prophylaxis strategies are often used to prevent CMV disease. Experimental approaches, including CMV-specific immunotherapy and vaccines, are under active investigation, particularly for high-risk groups.
