Chicken pox is also known as varicella. It is caused by a virus known as varicella-zoster. This is the same virus that causes shingles, also known as zoster. It is in the family of viruses known as human herpesviridae, or HHV. These are viruses that contain linear, double stranded DNA, a protein layer and an envelope of fat-like molecules called lipids. There are eight types known to infect humans.
HHV-1 and HHV-2
HHV-1 is also known as herpes simplex virus type 1, and HHV-2 is also known as herpes simplex virus type 2. HHV-1 typically causes oral herpes. The lesions occur on the face and in the mouth and are commonly known as cold sores or fever blisters.
HHV-2 commonly causes genital herpes. Genital herpes causes painful, small sores on the genitals. HHV-1 can also cause genital herpes, and HHV-2 can also cause oral herpes, however. In rare cases, they can infect other areas such as the eyes, lungs, brain or fingers according to "Harrison's Principles of Internal Medicine" by Anthony Fauci, M.D.
Herpes simplex viruses are transmitted by direct contact with a lesion or infected bodily fluids. The symptomatic periods are cyclical. The disease is active for days to weeks and then inactive during the remission stage. At this time, they remain latent in sensory nerves until reactivated. A person can be contagious even if not symptomatic. Medications exist to treat the active stage, but no cure exists.
HHV-3
HHV-3 is the varicella-zoster virus, or VZV. It causes chicken-pox, also known as varicella, and zoster, also known as shingles. The first time a person is infected he develops chicken pox. This is characterized by a skin rash followed by malaise, fever and weight loss, nausea and headache. The virus remains latent in sensory nerves. Decades later the virus can reactivate as shingles, causing a rash and pain along an affected area of skin.
HHV-4
HHV-4 is the Epstein-Barr virus. Instead of infecting nerves, this virus infects cells of the immune system called B cells. It causes a number of diseases including infectious mononucleosis, known as the kissing disease "mono," or glandular fever. It causes fever, sore throat, fatigue and swelling of the spleen. It has also been associated with several cancers. It causes a few types of lymphoma, which are cancers of the immune system, and cancer of the nose and throat.
HHV-5
HHV-5 is the cytomegalovirus. It is thought to cause a similar illness to mononucleosis illness in normal persons, according "Jawetz, Melnick & Adelberg's Medical Microbiology" by George F. Brooks, M.D. It can cause birth defects in a fetus if contracted during pregnancy. In people with weakened immune systems it can cause infections in a number of organs including the gastrointestinal tract, eyes, liver and brain.
HHV-6 and HHV-7
HHV-6 and HHV-7 are roseola viruses, both cause roseola infantum, which is also called exanthema subitum or sixth disease. It usually affects children younger than 2. Symptoms include a high fever followed by a red rash that begins on the trunk and spreads outwards.
HHV-8
The last herpes virus is HHV-8. This is the Kaposi's sarcoma-associated herpesvirus. It affect certain immune cells in patients with weak immune systems and can cause a number of cancers. Kaposi's sarcoma causes nodules on the skin, as well as the mouth, lungs and gastrointestinal tract.
References
- "HIV and Herpesvirus Infections" Cedric Spak, Anna Wald; 2007
- "Harrison's Principles of Internal Medicine" Anthony S. Fauci; 17th Ed. 2008
- "Jawetz, Melnick & Adelberg's Medical Microbiology"; Brooks et al; 24th Ed 2007
