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.
The most common reason that people develop cold sores on their mouths is due to becoming infected with HSV-1. (4) HSV-1 usually causes cold sore breakouts around the lips or mouth, or what some people describe as “fever blisters.” Someone can become infected with HSV-1 starting as a child, and then the virus can lay dormant in the body until the immune system is weakened, at which point symptoms can surface.
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.