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Herpes simplex virus |
Microscopy image of a herpes simplex virus. |
| Virus classification |
| Group: |
Group I (dsDNA) |
| Family: |
Herpesviridae |
| Subfamily: |
Alphaherpesvirinae |
| Genus: |
Simplexvirus |
| Species: |
Herpes simplex virus 1 (HSV-1) |
| Species: |
Herpes simplex virus 2 (HSV-2) |
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The herpes simplex virus (HSV) (also known as cold sore, night fever, or fever blister) is a virus that manifests itself in two common viral infections, each marked by painful, watery blisters in the skin or mucous membranes (such as the mouth or lips) or on the genitals. The disease is contagious, particularly during an outbreak, and is incurable with present technology. An infection on the lips is commonly known as a "cold sore" or "fever blister". These are sometimes confused with canker sores or aphthous ulcers, which have a similar appearance; these appear inside the mouth and are not caused by the herpes simplex virus. When not symptomatic HSV lies dormant in the bodies of the nerve cells, growing up the axons to the skin during an outbreak. When the outbreak passed, the virus 'dies back' along the nerve until it is only present in the nerve body.[1] The dormancy of the virus within the nerve bodies contributes to the difficulty of treatment
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Contents
- 1 Transmission
- 2 Treatment
- 3 HSV disease
- 4 Other herpes viruses
- 5 References
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Transmission
HSV is generally transmitted by direct contact of lips and/or genitals when the sores are present, or just before they appear (known as shedding). In addition, herpes may be transmitted during childbirth, which can be fatal to the infant. The immature immune system of the child is unable to defend against the virus and even if treated, infection can result in brain damage. Transmission occurs while passing through the birth canal and the risk of infection is minimal if there are no symptoms or exposed blisters during delivery. The first outbreak after exposure to HSV is commonly more severe than future outbreaks, as the body has not had a chance to produce antibodies; this first outbreak also carries the risk of developing meningitis.
Outbreaks are generally preceded by sensations of burning, itching or tingling before visible blistering occurs. Subclinical shedding can also occur at any time, resulting in transmission without symptoms.
Treatment
There is currently no cure or vaccine for HSV. Treatment is restricted to anti-viral medication, which reduces the duration of symptoms and accelerates healing. Treatment should begin at the first symptoms of an outbreak for best results as far as duration and healing; should treatment begin before the lesions appear, it is possible that the outbreak can be averted.
Another option is the use of daily suppressive therapy, in which antivirals are taken every day over the course of years. Suppressive therapy reduces frequency of symptoms and recurrence of outbreaks. In addition, suppresive therapy reduces subclinical shedding, lowering the risk of transmission through sexual contact or kissing.
The amino acid lysine has demonstrated the ability to reduce the duration of infection through inhibiting the replication of the HSV. When foods high in lysine are consumed in preference to foods high in arginine, HSV replication may be inhibited; conversely, consuming foods high in arginine may interfere with the therapeutic use of lysine.
HSV disease
- See Herpes simplex.
Many persons with HSV are not aware of it.
Other herpes viruses
There are eight members of the herpes virus family that are known to cause human disease, including not only the herpes simplex viruses (HSV-1 and HSV-2), but also the following:
- varicella-zoster virus (VZV, or HHV-3) which causes shingles, chickenpox, and Ramsay Hunt syndrome type 1
- Epstein-Barr virus (EBV, or HHV-4)
- cytomegalovirus (CMV, or HHV-5)
- human B cell lymphatic virus (HHV-6)
- roseola poorly characterised virus (HHV-7)
- Kaposi's sarcoma-associated herpesvirus (KSHV, or HHV-8)
References
Herpes during pregnancy
Symptoms of herpes infection
