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Herpes simplex virus (HSV)

Author: Wikipedia, Posted on Tuesday, September 14 @ 12:04:30 IST by RxPG  

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Scientific classification

dsDNA viruses
Family: Herpesviridae
Genus: Simplexvirus
Species: Herpes simplex virus 1 (HHV-1 or HSV-1)
Species: Herpes simplex virus 2 (HHV-2 or HSV-2)

The Herpes simplex virus infection (common names: herpes, cold sores) is a common, contagious, incurable, and in some cases sexually transmitted disease caused by a double-stranded DNA virus. The infection can also affect the brain, in which case the consequent disease is called herpes simplex encephalitis.

The most obvious symptom of herpes is blisters anywhere on the body, but especially near the mouth or genital areas. Some people may experience prodromal symptoms: tingling, pain, burning, or itching in the area a few days before the blisters appear. The period from the time the blisters appear until the sores heal is known as an active outbreak.

Course of outbreak
The ways in which herpes infections manifest themselves vary tremendously among individuals. The following are general descriptions of the courses outbreaks may take in the oral and genital regions.

"Oral" infections
Prodromal symptoms
Skin appears irritated
Sore or cluster of fluid-filled blisters appear
Lesion begins to heal, usually without scarring
These infections may appear on the lips, nose or in surrounding areas. The sores may appear to be either weeping or dry, and may resemble a pimple, insect bite, or large chicken-pox lesion. Lesions typically heal after a few days to a week (or more); this varies among individuals.

"Genital" infections
Prodromal symptoms
Sore appears
Lesion begins to heal, usually without scarring
In men, the lesions may occur on the shaft of the penis, in the genital region, on the inner thigh, buttocks, or anus. In women, lesions may occur on or near the pubis, labia, clitoris, vulva, buttocks, or anus.

The appearance of herpes lesions and the experience of outbreaks in these areas varies tremendously among individuals. Herpes lesions on/near the genitals may look like cold sores. An outbreak may look like a paper cut, or chafing, or appear to be a yeast infection. Symptoms of a genital outbreak may include aches and pains in the area, discharge from the penis or vagina, and discomfort when urinating.

Initial outbreaks are usually more severe than subsequent ones, and generally also involve flu-like symptoms and swollen glands for a week or so. Subsequent outbreaks tend to be periodic or episodic, typically occur four to five times a year, and can be triggered by stress, illness, fatigue, menstruation, and other changes. The virus sequesters in the nerve ganglia that serve the infected dermatome during non-eruptive periods, where it cannot be conventionally eliminated by the body's immune system. The blisters can spread to any part of the body, and can cause damage if spread to the eyes.

Herpes simplex encephalitis
Herpes simplex encephalitis is a very serious disorder, thought to be caused by transmission of the infection from a peripheral site by nerve cells. Without treatment, it results in rapid death in around 70% of cases. Even with the best modern treatment, it is fatal in around 20% of cases, and causes serious longterm neurological damage in over half the survivors. A small population (perhaps 20%) of survivors show little long term damage. It is commonest in children and middle-aged adults. Although herpes simplex is by no means the commonest cause of viral encephalitis (accounting for about 10% of cases in the US), because of the high risk associated with it if its not treated, patients presenting with encephalitis symptoms are likely to be treated against this disorder without waiting for a positive diagnosis.

Herpes is contracted through direct skin contact (not necessarily in the genital area) with an infected person. The virus travels through tiny breaks in the skin or through moist areas, but symptoms may not appear for at least a month after infection. Transmission was thought to be most common during an active outbreak, however in the early 1980s scientists and doctors realized that the virus can be shed from the skin in the absence of symptoms. It is estimated that between 50 and 80% of new HSV2 cases are from asymptomatic viral shedding.

HSV-1 and HSV-2
There are two main kinds of herpes simplex virus; types 1 (HSV-1) and 2 (HSV-2). Both types of HSV can infect either the oral or genital regions. It is easier to acquire an HSV-1 infection in the oral region, and for most people with HSV-1, that is where outbreaks occur. It is easier to acquire an HSV-2 infection in the genital region, and for most people with HSV-2, that is where outbreaks occur.

The terminology of herpes can be quite confusing; the two viruses are sometimes referred to by the sites they preferentially infect. Thus, HSV-1 can be called "oral herpes," (or sometimes "cold sores") and HSV-2 can be called "genital herpes." However, it is perfectly possible to have an HSV-1 infection of the genitals, or an HSV-2 infection of the oral area.

Another factor adds to the confusion; herpes is also sometimes described by the site of the infection. Thus, a herpes infection located in the genital region may be called "genital herpes," and a herpes infection located in the oral region may be called "oral herpes," irrespective of which virus is actually present.

People whose herpes infections are not located in the virus' "preferred" location may experience fewer, less severe outbreaks. For example, if Alfred has an HSV-1 infection of the mouth, and Bill has an HSV-1 infection of the genitals, Alfred is likely to experience more frequent and/or severe outbreaks than Bill.

Although thousands of years old, herpes garnered media prominence in 1982, and the incidence of herpes has risen 30% since the 1970s. The most recent data from the National Health and Nutrition Examination Survey (NHANES) suggests that 20% of men and 35% of women in the United States have HSV2. Women over 30 are especially susceptible to this disease and have more potential complications. Infected women can give their children herpes at birth, but this is rare, and can be prevented with a Caesarean section.

Condoms can help prevent contracting herpes, but do not work consistently because some blisters might not be covered by the condom. Abstinence is an effective way to prevent contracting or spreading this disease (including abstinence from oral sex). When one partner has herpes simplex infection and the other doesn't, the use of Valtrex, in conjunction with a condom, has been demonstrated to further decrease the chances of transmission to the uninfected partner, and the FDA approved this as a new indication for the drug in August 2003.

There are several prescription anti-viral medications for controlling herpes outbreaks, including valcyclovir (brand name Valtrex), famciclovir (Famvir), acyclovir (Zovirax) and Docosanol (Abreva). Acyclovir was the original antiviral drug of this family and is now available in generic form at a much reduced cost. For genital herpes infected pregnant women, acyclovir and valtrex are considered safe to be used suppressively to reduce outbreaks in the last trimester. Non-prescription painkillers can reduce pain and fever during initial outbreaks. Eating dairy products and other foods high in lysine and arginine might help also.

Long-term effects
The long-term effects of herpes are not well known, but the blisters may leave scars, and historically it was thought to contribute to the risk of cervical cancer in women. However, it has been shown that another virus, Human Papilloma Virus, also called HPV, is the cause of cervical cancer in women. Additionally, people with herpes are at a higher risk for HIV because of open blisters. In newborns, however, herpes can cause serious damage: death, neurological damage, mental retardation, and blindness.

Some common myths and misconceptions about herpes are that it is fatal (only true for newborns, where it is rare, or if it infects the brain, which is again unusual), that it only affects the genital areas (it can affect any part of the body), that condoms are completely effective in preventing the spread of this disease, that it is transmittable only in the presence of symptoms, that it is possible to contract it from toilet seats, that it can make you sterile, that PAP smears detect herpes, and that only promiscuous people get it (it is so common that anyone having sex is at risk).

Other herpesviruses
There are eight members of the herpesvirus family that are known to cause human disease, including not only the Herpes Simplex virus (HSV-1 and HSV-2), but also the varicella-zoster virus (VZV), Epstein-Barr virus (EBV) and the cytomegalovirus (CMV).

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