The herpes family of viruses includes 8 different viruses that affect human beings. The viruses are known by numbers as human herpes virus 1 through 8 (HHV1 - HHV8).
Human herpes virus 1 (HHV1) is also known as herpes simplex virus 1 (HSV1). It is typically the cause of cold sores around the mouth. HHV1 can also lead to infection in the genital area causing genital herpes usually through oral-genital contact, such as during oral sex. HHV1 infections are contagious and are usually spread from skin-to-skin contact with an infected person through small breaks in the skin or mucous membrane. The HHV1 virus is more likely to be spread through things like sharing eating utensils, razors, and towels from a person who has an active lesion.
Human herpes virus 2 (HHV2) is also called herpes simplex virus 2 (HSV2). It typically causes genital herpes, a sexually transmitted infection. However, it can also cause cold sores in the facial area. Like HHV1, the HHV2 infection is contagious and is spread by skin-to-skin contact. The main route of transmission is through sexual contact, as the virus does not survive very long outside the body.
Human herpes virus 3 (HHV3) is also called varicella-zoster virus. HHV3 causes chickenpox. It can also cause a recurrent virus infection of the skin, which is called herpes zoster or shingles. Shingles occurs when dormant varicella-zoster virus from an initial bout of chickenpox becomes reactivated. Like its close relative, HHV1, herpes zoster likes to infect skin cells and nerve cells. This virus may also recur along nerve fibre pathways, causing multiple sores where nerve fibres end on skin cells. Because an entire group of nerve cells is often affected, shingles is generally much more severe than a recurrence of herpes simplex. The lesions generally appear in a band-like or belt-like pattern occurring on one side of the body and are often accompanied by itching, tingling, or even severe pain. Healing usually occurs in 2 to 4 weeks, and scars may remain. Postherpetic neuralgia is a complication of shingles where the pain associated with the infection can persist for months and even years. Most people who experience shingles once do not experience it again.
Human herpes virus 4 (HHV4) is also known as the Epstein-Barr virus. It is the major cause of infectious mononucleosis, or "mono" - the "kissing disease." It is a contagious infection and is transmitted through saliva. Coughing, sneezing, or sharing eating utensils with an infected person can pass the virus from one person to another.
Human herpes virus 5 (HHV5) is the official name of cytomegalovirus (CMV). CMV is also a cause of mononucleosis. In people with healthy immune systems, the virus may not even cause any symptoms. It can be sexually transmitted, can cause problems to newborns, and can cause hepatitis. CMV can be transmitted through sexual contact, breast-feeding, blood transfusions, and organ transplants. CMV infection is one of the most difficult complications of AIDS. It may lead to diarrhea, severe vision problems including blindness, infections of the stomach and intestines, and even death. For a virus that barely causes a problem in most people with healthy immune systems, it can be amazingly nasty in people with damaged immune systems, such as people with AIDS.
Human herpes virus 6 (HHV6) is a recently observed agent found in the blood cells of a few patients with a variety of diseases. It causes roseola (a viral disease causing high fever and a skin rash in small children) and a variety of other illnesses associated with fever in that age group. This infection accounts for many of the cases of convulsions associated with fever in infancy (febrile seizures).
Human herpes virus 7 (HHV7) is even more recently observed and is closely related to HHV6. Like other human herpes viruses, HHV6 and HHV7 are so common that most of humankind has been infected at some point, usually early in life. HHV7 can also cause roseola, but it is not clear what other clinical effects that this virus causes.
Human herpes virus 8 (HHV8) was recently discovered in the tumours called Kaposi's Sarcoma (KS). These tumours are found in people with AIDS and are otherwise very rare. KS forms purplish tumours in the skin and other tissues of some people with AIDS. It is very difficult to treat with medication. HHV8 may also cause other cancers, including certain lymphomas (lymph node cancers) associated with AIDS. The fact that these cancers are caused by a virus may explain why they tend to occur in people with AIDS when their immune systems begin to fail. The discovery also provides new hope that specific treatments for these tumours will be developed that target the virus.
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