- Herpes is a group of viruses that infect humans. Types of herpes viruses include herpes simplex virus types 1 and 2 (HHV-1 and HHV-2 respectively), human herpesvirus type 3 (varicella-zoster virus), human herpesvirus type 4 (including Epstein-Barr virus and lymphocryptovirus), human herpesvirus type 5 (cytomegalovirus), human herpesviruse type 6 (HHV-6, including human B-cell lymphotrophic virus and roseolovirus), human herpesvirus type 7 (HHV-7), and human herpesvirus type 8 (rhadinovirus and Kaposi's sarcoma-associated virus).
- The viruses fall into three categories: Alpha herpes viruses (HSV-1, HSV-2, and varicella-zoster virus), beta herpes viruses (cytomegalovirus, HHV-6, and HHV-7), and gamma herpes viruses (Epstein-Barr virus, lymphocryptovirus, and HHV-8). The viruses are different and cause various conditions with many unique signs and symptoms. However, all herpes viruses share some common properties, including a pattern of active symptoms followed by latent (inactive) periods with no symptoms that can last for months, years, or even for a lifetime. Herpes symptoms may even never reappear. The severity of herpes symptoms depends on the type of virus with which the individual is infected.
- Herpes simplex type 1 (HHV-1) is also known as a cold sore or fever blister. Herpes simplex type 2 (HHV-2) is also known as genital herpes. Human herpes virus 3 is also referred to as varicella-zoster or VZV. Herpes varicella is the primary infection that causes chickenpox, and herpes zoster is the reactivation of the varicella virus that causes shingles.
- Herpes 1 and 2 infections are generally marked by painful, watery blisters in the skin or mucous membranes (such as the mouth or lips) or on the genitals. Lesions heal with a crust-forming scab, the hallmark of herpes. This is particularly likely during an outbreak, although individuals may shed virus between outbreaks. Although no cure is yet available, antiviral treatments exist that reduce the likelihood of viral shedding. An HSV infection on the lips, commonly known as a "cold sore" or "fever blister," should not to be confused with a canker sore; canker sores (painful sores on the tongue or oral membranes in the mouth) are not caused by the HSV virus.
- Herpes is a contagious infection that spreads when the carrier is producing and releasing ("shedding") virus. Herpes viruses are transmitted from human to human in different ways. With HSV-1, contact and infection can occur directly from another human (such as mouth-to-mouth, hand-to-mouth contact) or through the use of everyday objects that have come in contact with the virus, including razors, towels, dishes, and glasses. Genital herpes or HSV-2 can only be contracted through direct sexual contact (genital-to-genital, mouth-to-genital, or hand-to-genital; not kissing) with an infected partner. Occasionally, oral-genital contact can spread oral herpes to the genitals (and vice versa). Individuals with active herpes lesions on or around their mouths or on their genitals should avoid oral sex. The varicella-zoster (chickenpox) virus spreads through the humidity in the air when inhaled and mainly spreads during the incubation period, which is just before an outbreak of symptoms.
- After an initial or primary infection, herpes viruses establish a period called latency, during which the virus is present in the cell bodies of nerves that innervate (attach) to the area of the original viral outbreak (such as genitals, mouth, and lips). At some point this latency ends, and the virus becomes active again. While active, the virus begins to multiply (called shedding), and becomes transmittable again. This shedding may or may not be accompanied by symptoms. During reactivation, virus is produced in the nerve cell and transported outwardly via the nerve to the skin. The ability of herpes virus to become latent and reactive explains the chronic (long-term), recurring nature of a herpes infection.
- Recurrence of the viral symptoms is usually milder than the original infection. Recurrence may be triggered by menstruation, sun exposure, illness with fever, stress, immune system imbalances, and other unknown causes.