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).

Although it’s not caused by either the HSV-1 or HSV-2 virus, herpes zoster falls under the umbrella of herpes diseases. Also known as shingles, it’s an infection caused by the varicella-zoster virus, and is characterized by the development of painful skin rashes on one side of the face or body.23 These rashes are red patches of fluid-filled blisters that tend to crack easily.24,25


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.
HSV-2 is commonly referred to as genital herpes because it usually causes cold sores to erupt around the genitalia. In fact, genital herpes is the No. 1 cause of genital ulcers worldwide, according to the Centers for Disease Control and Prevention (CDC), and affects up to 1 in 3 adults (although most who are infected don’t even know it). (5) Both types of herpes viruses are highly contagious, and both can cause cold sores in either area of the body (or sometimes both). 
Cullins explains that even if you’ve never had an outbreak, if you’ve been exposed to herpes, it lies dormant in your body. A blood test could reveal antibodies for HSV-1 and/or HSV-2, which means that you have been exposed to the infection in your past, you have been infected, and you have developed antibodies because your body has or is fighting the infection.
A 2004 study in the New England Journal of Medicine found that suppressive therapy decreases the risk of HSV-2 transmission from symptomatic, infected partners to uninfected partners by 48%. So “the risk of transmission is significantly reduced, but cannot be eliminated even with suppressive therapy,” Johnston explains, and she stresses that the virus can be passed along even without signs or symptoms.
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