Snapshot A 25-year-old woman presents to the clinic for routine check-up. She reports that about a month ago, she had what she thought was mononucleosis. She had fevers, chills, a red rash, muscle pain, and joint pains. She works in a daycare center, and some of her colleagues had similar symptoms. This resolved in 1 week. Today, there are no significant findings on physical exam. Laboratory evaluation reveals that she is positive for CMV-specific immunoglobulin M. Other laboratory tests are negative. Introduction Classification cytomegalovirus (CMV) or human herpesvirus-5 (HHV-5) double-stranded DNA virus largest virus that causes human infections transmission via body fluids or vertical transmission Associated conditions congenital CMV infection Epidemiology Incidence very common Risk factors immunosuppression men who have sex with other men poor socioeconomic status working in childcare transplant recipients prone to CMV pneumonia ETIOLOGY Pathogenesis CMV-caused diseases can either result from a primary infection or reactivation of a latent infection replication of host cells (including epithelial cells, macrophages, and neurons) results in viremia and symptoms from primary infection cellular immunity is crucial in clearing this virus Presentation Symptoms immunocompetent patients most cases are asymptomatic if symptomatic, CMV infections often result in a mononucleosis syndrome with fevers, myalgias, arthralgias, and cough immunocompromised patients esophagitis colitis (most common) encephalitis hepatitis pneumonia retinitis congenital CMV hemolytic anemia Physical exam fever cervical lymphadenopathy hepatosplenomegaly maculopapular rash Studies Labs lymphocytosis with atypical lymphocytes thrombocytopenia transaminitis negative heterophile antibody CMV-specific immunoglobulin G (persists for 4-6 months) CMV-specific immunoglobulin M (2-3 weeks) active infection viral load does not distinguish active vs past infection Histology if warranted, may reveal CMV on immunohistochemistry Making the diagnosis based on clinical presentation and laboratory studies Differential Epstein-Barr viral (EBV) mononucleosis distinguishing factors CMV mononucleosis often includes more myalgias, arthralgias, and cough than EBV infection CMV infection also does not typically present with sore throat or lymphadenopathy Treatment Management approach mainstay of treatment is supportive care Conservative supportive care indication all patients modalities hydration Medical antiviral medications indications immunocompromised patients severe disease or organ damage drugs ganciclovir valganciclovir Complications Thrombosis Colitis Permanent vision changes Prognosis Often self-limited in immunocompetent patients