Herpes simplex is a viral disease caused by Herpes simplex viruses (HSV). Infection with the herpes virus is categorized into one of several distinct disorders based on the site of infection. Oral herpes, the visible symptoms of which are colloquially called cold sores, infects the face and mouth. Infection of the genitals, commonly known as herpes, is the second most common form of herpes. Herpes simplex is not typically life-threatening for immunocompetent people.
Herpes viruses cycle between periods of active disease—presenting as blisters containing infectious virus particles—that last 2–21 days, followed by a remission period, during which the sores disappear. Genital herpes, however, is often asymptomatic, though viral shedding may still occur. After initial infection, the viruses move to sensory nerves, where they reside as life-long, latent viruses. Causes of recurrence are uncertain, though some potential triggers have been identified. Over time episodes of active disease reduce in frequency.
HSV is most easily transmitted by direct contact with a sore or the body fluid of an infected individual. Transmission may also occur through skin-to-skin contact when no symptoms are present if the infected person is experiencing asymptomatic shedding.