INFECTION with the herpes simplex VIRUS 1 (HSV-1) or HSV-2. HSV-1 primarily causes cold sores on the lips and in the MOUTH, transmitted through saliva. HSV-2 primarily causes GENITAL HERPES, a sexually transmitted disease (STD) that causes ulcerative sores on the genitals. However, either form of the virus can cause infection anywhere in the body. HSV-1 and HSV-2, like other herpes viruses, are highly contagious through contact with the sores and may also spread from one person to another even when no sores are present. Herpes simplex infection is lifelong, though symptoms characteristically wax and wane. About 90 percent of Americans have HSV-1 and about 30 percent have HSV-2.
The typical course of an outbreak begins with itching or tingling, called the prodrome, which gives way to the eruption of a BLISTER within 48 hours. Cold sores typically form as single blisters though may occur as multiple blisters in several locations; genital herpes sores tend to erupt in clusters. After two or three days the blisters rupture and form crusted sores that subsequently heal. The cycle from prodrome to HEALING lasts about 10 days. Because the course of illness is so characteristic, the doctor can usually make the diagnosis on the appearance of the sores. Laboratory culture of the fluid within a blister or sore can provide a definitive diagnosis.
After an outbreak of symptoms the virus retreats to the local NERVE roots where it remains dormant until the next outbreak. Researchers are not certain what factors initiate outbreaks though stress and exposure to sunlight appear to play key roles. Doctors sometimes prescribe ANTIVIRAL MEDICATIONS such as acyclovir for people who have six or more outbreaks of herpes simplex infection in a year or who have severe symptoms during outbreaks. Herpes infections may involve the eyes or the BRAIN, where they can cause permanent damage.
See also CANKER SORE; CHICKENPOX; COLD SORE; HERPES ZOSTER; SEXUALLY TRANSMITTED DISEASE (STD) PREVENTION; SEXUALLY TRANSMITTED DISEASES (STDS).
Resource: Facts On File Encyclopedia Of Health And Medicine
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