Oral herpes, commonly referred to as mouth herpes, is a viral infection of the mouth and gums primarily by the Herpes simplex virus type 1 (HSV-1) but may also be due to the genital variant (HSV-2). It is also known as recurrent herpetic stomatitis or acute herpetic gingivostomatitis. The infection of the mouth typically causes small fluid-filled blisters known as vesicles on the roof of the mouth (palate), inside of the cheeks (buccal muscosa), tongue, gums and even the lips (herpes labialis). It may also occur on the skin around the mouth and extend to the nose and into the nasal cavity.
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.
When herpes flares up again, it is called a "recurrence" or "outbreak." Herpes does not always recur, and if it does recur, the timing and severity are different from person to person. Some people rarely have recurrences. Others have them often. Herpes is most likely to recur in the first year after infection. Recurrences may be more frequent for people with weakened immune systems.
Oral herpes (HSV-1) infection (or exposure without noticeable infection) is common. About 65% of the U.S. population has detectable antibodies to HSV-1 by age 40. This article will focus on HSV-1, or oral herpes, not on HSV-2, also commonly known as genital herpes. Genital herpes is considered to be a sexually transmitted disease (STD). In addition, HSV-2 virus should not be confused with human papillomavirus (HPV), the cause of genital warts, and some cervical and other cancer types.
How to get rid of a cold sore The herpes simplex virus that causes cold sores, often on people’s mouths, is highly contagious and a lifelong infection with no cure. Learn about how to treat cold sores when they appear, including anti-viral tablets and creams and home remedies, plus the life cycle of the virus, and how to prevent its spread. Read now
In all cases, HSV is never removed from the body by the immune system. Following a primary infection, the virus enters the nerves at the site of primary infection, migrates to the cell body of the neuron, and becomes latent in the ganglion. As a result of primary infection, the body produces antibodies to the particular type of HSV involved, preventing a subsequent infection of that type at a different site. In HSV-1-infected individuals, seroconversion after an oral infection prevents additional HSV-1 infections such as whitlow, genital herpes, and herpes of the eye. Prior HSV-1 seroconversion seems to reduce the symptoms of a later HSV-2 infection, although HSV-2 can still be contracted.
“You don’t want an infant delivered through infected birth canal or vulva because the infant can be infected,” Cullins explains. A neonatal herpes infection is a real risk because it can cause problems with brain development and eye and skin infections, or even be fatal. And since there is more risk for transmission from mother to baby during an initial outbreak than during a recurrent outbreak, the CDC stresses that it’s incredibly important for pregnant women to avoid contracting a new herpes infection.