Epidemiology - Herpes Simplex Virus

Epidemiology

Herpes simplex viruses are distributed worldwide.

◗ Geographical distribution

HSV-1 infection is more common than HSV-2 infection. By the age of 30 years, 80% individuals in high socioeconomic status and 80% in a low socioeconomic status are seropositive. Serum antibodies to HSV-2 begin to appear at puberty, cor-relating with degree of sexual activity. The HSV-2 infection is a major problem in the United States. It has been estimated that five of every 12 adults are infected with HSV-2. A total of 45 million individuals are infected, with up to 1 million newly infected people added every year.

◗ Reservoir, source, and transmission of infection

Herpes simplex virus infections are exclusively human diseases. Humans are the only natural reservoirs. No vectors are involved in transmission of the disease. An infected person is a lifelong source and reservoir of the virus. Vesicle fluid, saliva, and vagi-nal secretions are the important sources of infection for both types of HSV.

HSV-1 infection is transmitted orally through saliva. It is usually transmitted by oral contact, such as by kissing or by sharing of the toothbrushes or other saliva-contaminated items. The HSV infection can also occur following mouth-to-skin contact, with the virus entering through minor abrasions in the skin. Autoinoculation may also cause infection of the eye.

Children are at risk for acquiring HSV-1 infection, whereas sexually active people are at increased risk to HSV-2 infection. Medical and paramedical staffs on coming in contact with oral and genital secretions are at increased risk for acquiring herpetic whitlow. Immunocompromised individuals and neonates are at high risk for developing life-threatening disseminated disease.