Cytomegalovirus (CMV) infection is a common viral infection that is usually harmless in healthy people. It is caused by the herpes virus and can be spread through contact with body fluids, such as saliva, urine, and blood. Symptoms of CMV infection can include fever, fatigue, swollen glands, and sore throat. In some cases, it can cause more serious complications, such as pneumonia, hepatitis, and encephalitis.