Overview of herpesvirus infections

[Dave Paprocki]

Some common viral infections are caused by herpesviruses. Eight different herpesviruses infect people:

Three herpesviruses—herpes simplex virus type 1, herpes simplex virus type 2, and varicella-zoster virus (herpesvirus type 3, which causes chickenpox and shingles)—cause infections that produce blisters on the skin or mucus membranes.
Epstein-Barr virus (herpesvirus type 4) causes infectious mononucleosis and may be involved in certain cancers (such as nasopharyngeal cancer, Burkitt lymphoma, and Hodgkin lymphoma).
Cytomegalovirus (herpesvirus type 5) is a cause of serious infections in newborns and in people with a weakened immune system. It can also cause symptoms similar to infectious mononucleosis in people with a healthy immune system.
Human herpesviruses 6 and 7 cause a childhood infection called roseola infantum.
Human herpesvirus 8 causes certain cancers (Kaposi sarcoma and some types of lymphoma), in people with a weakened immune system such as people with AIDS.

All of the herpesviruses cause lifelong infection because the virus remains within its host cell in an inactive (dormant or latent) state. Sometimes the virus reactivates and produces further episodes of disease. Symptoms from reactivation can be different than the symptoms of the initial infection. Reactivation may occur rapidly or many years after the initial infection. (See also Overview of Viral Infections.)

[Becky]

Eight types of herpesviruses infect humans (see Table: Herpesviruses That Infect Humans). After initial infection, all herpesviruses remain latent within specific host cells and may subsequently reactivate. Clinical syndromes due to primary infection can vary significantly from those caused by reactivation of these viruses. Herpesviruses do not survive long outside a host; thus, transmission usually requires intimate contact. In people with latent infection, the virus can reactivate without causing symptoms; in such cases, asymptomatic shedding occurs and people can transmit infection.

Despite the fact that the herpesviruses are genetically and structurally similar, they cause a wide array of generally non-overlapping clinical syndromes.

In contrast to other herpesviruses which are not associated with malignancy, Epstein-Barr virus (EBV) and human herpesvirus type 8 (HHV-8), also known as Kaposi sarcoma–associated herpesvirus (KSHV), can cause certain cancers.

Roseola infantum is a childhood disease caused by herpesvirus 6 (and sometimes 7).