Both HSV-1 and HSV-2 infections are acquired from direct contact with someone who carries the virus. The infectious secretions that pass on HSV-1 or HSV-2 live on oral, genital or anal mucosal surfaces. They’re passed through skin-to-skin transmission, and any form of direct contact with sores on the mouth, buttocks or genitals can cause the virus to be passed.
There are two types of herpes simplex viruses (HSV), they are termed HSV-1 and HSV-2. These two viruses have distinctly different DNA, and both cause oral and genital lesions. However, HSV-1 causes about 80% of all oral lesions and only about 20% of genital lesions while HSV-2 causes the reverse (about 80% genital and 20% oral). Studies also suggest that in adolescents, up to 40% of genital herpes is caused by HSV-1 because of reported increased oral/genital contact (transmission by oral sex).
It should not be confused with conditions caused by other viruses in the herpesviridae family such as herpes zoster, which is caused by varicella zoster virus. The differential diagnosis includes hand, foot and mouth disease due to similar lesions on the skin. Lymphangioma circumscriptum and dermatitis herpetiformis may also have a similar appearance.
The herpes simplex virus is probably the most well-known virus of the herpes family, and it is just as contagious. Herpes simplex infects epithelial cells and remains latent in neurons. HSV-1 causes recurrent oropharyngeal lesions, commonly known as “fever blisters" or "cold sores.” It is also the primary cause of sporadic encephalitis (inflammation of the brain), gingivostomatitis (inflammation of the gums and mucous lining of the mouth), and keratoconjunctivitis (severe dryness of the eye that involves the cornea) and dendritic corneal ulcers (also called HSV keratitis) in which the cornea becomes affected by herpetic lesions that look like the dendrites of neurons in the brain.
If you are pregnant and have genital herpes, it is very important for you to go to prenatal care visits. Tell your doctor if you have ever had symptoms of, or have been diagnosed with, genital herpes. Also tell your doctor if you have ever been exposed to genital herpes. There is some research that suggests that genital herpes infection may lead to miscarriage, or could make it more likely for you to deliver your baby too early.