herpes simplex (hûr`pēz), an acute viral infection of the skin characterized by one or more painful, itching blisters filled with clear fluid. It is caused by either of two herpes simplex viruses: Type 1, herpes labialis, which generally involves the lip (producing what are commonly known as cold sores) or the mouth area (producing canker sores), but can involve the genital area; and Type 2, herpes genitalis, which involves the genitals, but may involve the mouth. It is believed that invasion of Type 1 herpes occurs in most persons during infancy and childhood, either as a systemic or severe local infection. Type 2 herpes, or genital herpes, is a sexually transmitted disease sexually transmitted disease (STD) or venereal disease, term for infections acquired mainly through sexual contact. Five diseases were traditionally known as venereal diseases: gonorrhea , syphilis , and the less common granuloma inguinale,
..... Click the link for more information. that became epidemic in the United States in the late 1960s. Newborns exposed to active herpes in the mother's birth canal can contract a serious form of the disease. The herpes simplex virus can be spread by an infected but asymptomatic person.

Outbreaks of both types of herpes simplex alternate with periods when the virus lies dormant in the nerve cells. The reappearance of blisters may be triggered by such factors as fever, infectious diseases, exposure to sunlight, menstruation, or pregnancy. The blisters usually last from 10 to 14 days. Treatment for recurrent herpes includes elimination of the precipitating conditions, local antibiotic treatment to prevent bacterial infection, and treatment with antiviral drugs antiviral drug, any of several drugs used to treat viral infections. The drugs act by interfering with a virus's ability to enter a host cell and replicate itself with the host cell's DNA.
..... Click the link for more information. such as acyclovir, although some resistant strains (see drug resistance drug resistance, condition in which infecting bacteria can resist the destructive effects of drugs such as antibiotics and sulfa drugs . Drug resistance has become a serious public health problem, since many disease-causing bacteria are no longer susceptible to
..... Click the link for more information. ) have developed. There is no cure. The herpes simplex virus is also the cause of a form of viral encephalitis encephalitis (ĕnsĕf'əlī`təs)
..... Click the link for more information. .

See also herpes zoster herpes zoster, infection of a ganglion (nerve center) with severe pain and a blisterlike eruption in the area of the nerve distribution, a condition called shingles.
..... Click the link for more information. (shingles).

herpes simplex

Infection caused by herpes simplex virus. Type I typically produces a cluster of small blisters (cold sores, or fever blisters), usually on the lips or face; it can also infect the eyes. Type II, transmitted mostly through sexual contact, causes genital blisters, which rupture, becoming very painful. Oral sex can give either type the chance to infect the usual site of the other. In both types, the virus remains after symptoms end and can reactivate, causing blisters to reappear. Babies born to mothers with active herpes can become infected during birth; this can be prevented by cesarean section. There is no cure, but drugs can reduce severity and risk of transmission.