In adults and older children, CMV infection may be present without symptoms. Sometimes, a flu-like illness may occur, including fever, fatigue, or a rash. Individuals who are immunocompromised (have a weakened immune system), such as persons who have human immunodeficiency virus (HIV) infection or patients who have had an organ transplant, a bone marrow transplant, or certain types of cancers, may become seriously ill if they are exposed to CMV. A type of severe eye infection, CMV retinitis, can cause blindness. CMV can also be responsible for pneumonia in persons with weak immune systems.