Cytomegalovirus (CMV) is a double-stranded DNA virus and is a member of the Herpesviridae family. CMV shares many attributes with other herpes viruses, including genome, virion structure, and the ability to cause latent and persistent infections. Human CMV grows only in human cells and replicates best in human fi broblasts. About 58.9% of individuals aged 6 and over are infected with CMV while 90.8% of individuals aged 80 and over are positive for CMV antibodies. Symptomatic CMV disease in immunocompromised individuals can affect almost every organ of the body, resulting in fever of unknown origin, pneumonia, hepatitis, encephalitis, myelitis, colitis, uveitis, retinitis, and neuropathy. In patients coinfected with HIV, CMV infection leads to progression to AIDS and eventually death, even in those receiving highly active antiretroviral therapy (HAART).

Epstein-Barr virus (EBV), or human herpesvirus 4, is a gammaherpesvirus that infects more than 95% of the population. The most common manifestation of primary infection with this organism is acute infectious mononucleosis, a self-limited clinical syndrome that most frequently affects adolescents and young adults. Classic symptoms include sore throat, fever, and lymphadenopathy. However, Epstein-Barr virus is also a human tumor virus, the fi rst virus associated with human malignancy. Infection with Epstein-Barr virus is as-sociated with lymphoproliferative disorders, especially in immunocompromised hosts, and is associated with various tumors, including nasopharyngeal carcinoma and Burkitt lymphoma.

Herpes simplex is a viral disease caused by both herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2). Infection with the herpes virus is categorized into one of several distinct disorders based on the site of infection. Oral herpes, the visible symptoms of which are colloquially called cold sores or fever blisters, infects the face and mouth. Oral herpes is the most common form of infection. Genital herpes, known simply as herpes, is the sec-ond most common form of herpes. Other disorders such as herpetic whitlow, herpes gladiatorum, ocular herpes (keratitis), cerebral herpes infection encephalitis, Mollaret meningitis, neonatal herpes are all caused by herpes simplex viruses.