Herpes simplex virus type 1 and type 2 (HSV-1 and HSV-2) infections (cold sores, fever blisters, herpes gladiatorum, scrum pox, herpetic whitlow, herpes progenitalis) are common worldwide, usually affecting the orolabial and genital regions, although any skin area may be affected.

Infection is acquired through contact with contaminated saliva or other body fluids during periods of viral shedding. Primary infection denotes the initial inoculation episode, which may be subclinical or cause significant disease, usually in children. The virus establishes lifelong latency in the dorsal root ganglia. Clinical disease occurs with reactivation (spontaneously or with trauma, UV exposure, fever, or immunosuppression) of the latent virus, which travels from the nerve root to innervated skin regions. This occurs in 30%-50% of oral HSV infections and 95% of genital HSV infections. An individual may be coinfected with more than one type of HSV and in more than one location. HSV acquisition at a new site in a previously infected person is designated a nonprimary, first episode infection.

Ninety percent of adults are antibody positive to HSV-1. HSV-2 prevalence is lower, affecting almost a quarter of the US population. Women have a higher seropositivity to HSV-2 than men. Risk factors for genital HSV infection include having multiple sexual partners, lower educational and socioeconomic levels, a man who has sex with men, or HIV infection.

Symptoms of primary disease are usually more severe than recurrent disease and depend upon the site of inoculation. Herpetic gingivostomatitis (usually HSV-1) presents with fever, malaise, bleeding, painful gums, pain upon eating, and sometimes pharyngitis and foul breath. In primary genital herpes, headache, fever, malaise, pain, and dysuria are common. Complications include urinary retention, constipation, and aseptic meningitis. Primary keratoconjunctivitis is associated with pain, eyelid edema, photophobia, and tearing. Localized adenopathy is common with primary infection. Disease occurs 3-7 days after exposure; recovery from a primary episode usually occurs in 2-6 weeks. Disseminated infection and pneumonitis may occur in the immunocompromised. Other complications include bacterial superinfection, radiculoneuropathy, encephalitis, hepatitis, and eczema herpeticum in patients with atopy. Viral folliculitis secondary to HSV (usually inoculated secondary to shaving) has been described. Pregnant individuals with primary HSV infection are at increased risk for severe illness, ie, dissemination and hepatitis, particularly in the third trimester.

Recurrent disease usually lacks constitutional symptoms. Itching, burning, tingling, or pain often precede the skin lesions. Complications include bacterial superinfection, eczema herpeticum, erythema multiforme, Bell palsy, aseptic meningitis, and encephalitis.

HSV infection in HIV-infected patients and other immunodeficiency states with T-cell defects is common and often presents with more severe and chronic disease. Chronic nonhealing, painful ulcers occur, particularly in the perianal location. Others at risk for this include marrow and solid organ transplant patients and patients with lymphoma and leukemia.