There are two different strains of herpes simplex viruses: - Herpes simplex virus type 1 (HSV-1) is usually associated with infections of the lips, mouth, and face. It is the most common herpes simplex virus and is usually acquired in childhood. HSV-1 often causes lesions inside the mouth such as cold sores (fever blisters) and is transmitted by contact with infected saliva. By adulthood, up to 90% of individuals will have antibodies to HSV-1.
- Herpes simplex virus 2 (HSV-2) is sexually transmitted. Symptoms include genital ulcers or sores. In addition to oral and genital lesions, the virus can also lead to complications such as meningoencephalitis (infection of the lining of the brain and the brain itself) or cause infection of the eye -- in particular the conjunctiva, and cornea. However, some people have HSV-2 but do not display symptoms. Up to 30% of U.S. adults have antibodies against HSV-2. Cross-infection of type 1 and 2 viruses may occur from oral-genital contact.
A finger infection, called herpetic whitlow, is another form of herpes infection. It usually affects health care providers who are exposured to oral secretions during procedures. Sometimes, young children contract the disease. A herpes virus can infect the fetus and cause congenital abnormalities. It may also be transmitted to a newborn during vaginal delivery in mothers infected with herpes viruses, particularly if the mother has active infection at the time. However, the virus may be transmitted even in the absence of symptoms or visible lesions.
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