There are two types of herpes simplex virus, type 1 (HSV-1) and type 2 (HSV-2).[1] HSV-1 more commonly causes infections around the mouth while HSV-2 more commonly causes genital infections.[2] They are transmitted by direct contact with body fluids or lesions of an infected individual.[1] Transmission may still occur when symptoms are not present.[1] Genital herpes is classified as a sexually transmitted infection.[1] It may be spread to an infant during childbirth.[1] After infection, the viruses are transported along sensory nerves to the nerve cell bodies, where they reside lifelong.[2] Causes of recurrence may include: decreased immune function, stress, and sunlight exposure.[2][3] Oral and genital herpes is usually diagnosed based on the presenting symptoms.[2] The diagnosis may be confirmed by viral culture or detecting herpes DNA in fluid from blisters.[1] Testing the blood for antibodies against the virus can confirm a previous infection but will be negative in new infections.[1]
Herpes simplex type 1, which is transmitted through oral secretions or sores on the skin, can be spread through kissing or sharing objects such as toothbrushes or eating utensils. In general, a person can only get herpes type 2 infection during sexual contact with someone who has a genital HSV-2 infection. It is important to know that both HSV-1 and HSV-2 can be spread even if sores are not present.
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.

Some people have recurrent outbreaks with the so-called “classic” blister-like herpes lesions that crust over, or with painful sores. In recurrent herpes, however, this process usually takes about half the time it does in first episodes. In addition, many people have very subtle forms of recurrent herpes that heal up in a matter of days. And lastly, herpes is capable of reactivating without producing any visible lesions (asymptomatic reactivation).
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.
Neonatal herpes simplex is a HSV infection in an infant. It is a rare but serious condition, usually caused by vertical transmission of HSV-1 or -2) from mother to newborn. During immunodeficiency, herpes simplex can cause unusual lesions in the skin. One of the most striking is the appearance of clean linear erosions in skin creases, with the appearance of a knife cut.[20] Herpetic sycosis is a recurrent or initial herpes simplex infection affecting primarily the hair follicles.[21]:369 Eczema herpeticum is an infection with herpesvirus in patients with chronic atopic dermatitis may result in spread of herpes simples throughout the eczematous areas.[21]:373
Pain, sore lips, burning sensation, tingling, or itching occurs at the infection site before the sores appear. These are the early symptoms (prodrome). Sometimes these symptoms happen prior to the appearance of sores, bumps, pimple-like lesions, or blisters (herpes or herpetic stomatitis). Thereafter, clusters or groups of painful blisters (also termed fever blisters) or vesicles erupt or ooze with a clear to yellowish fluid that may develop into a yellowish crust. These blisters break down rapidly and appear as tiny, shallow gray ulcers on a red base. Fever blisters are smaller than canker sores. A few days later, they become crusted or scabbed and appear drier and more yellow.

^ McNeil DG. Topical Tenofovir, a Microbicide Effective against HIV, Inhibits Herpes Simplex Virus-2 Replication Archived 2017-04-09 at the Wayback Machine. NY Times. Research article: Andrei G; Lisco A; Vanpouille C; et al. (October 2011). "Topical Tenofovir, a Microbicide Effective against HIV, Inhibits Herpes Simplex Virus-2 Replication". Cell Host. 10 (4): 379–89. doi:10.1016/j.chom.2011.08.015. PMC 3201796. PMID 22018238.

What's to know about eczema herpeticum? Eczema herpeticum occurs when the herpes virus meets an area of skin that is affected by herpes. This MNT Knowledge Center feature introduces eczema, the herpes simplex virus, and how they combine to produce the effects of eczema herpeticum. Learn also about the treatments available and how it may be prevented. Read now
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