Herpes is a family of viruses that can infect humans and cause skin lesions, rashes or sores. Of the 25 or so known strains of the virus, eight can cause disease in people. The type of the sore, the severity and whether the virus will cause repeated outbreaks depends on the viral strain, the location of infection and the health of the body's immune system.
Herpes Simplex Virus
Genital herpes and facial cold sores are caused by either herpes simplex virus, type 1--HSV-1--or herpes simplex virus, type 2--HSV-2. After a person is infected with either strain of the virus, the virus remains in the body for life and reactivates from time to time. When it does, the virus follows nerve pathways back to the area where the first infection occurred and replicates, possibly causing new sores. Reactivation of the virus does not always cause sores, however. Instead, viral particles can be shed from skin in an event called "asymptomatic shedding," according to the Illinois Department of Public Health. Asymptomatic shedding occurs about 5 to 20 percent of the time in infected people. The particles can transmit the virus to new individuals during close contact.
Shingles
Chickenpox and shingles are caused by the varicella-zoster virus, a strain of the herpes virus. Like most herpes viruses, chickenpox is contagious and, in the United States, most people have the disease during childhood. Like HSV, the varicella-zoster virus remains in the body for life, though it usually does not cause a recurrence of chickenpox. Instead, when the virus reactivates, it causes a disease called "shingles," usually later in life. Like chickenpox, shingles causes a blister-filled rash to erupt but, unlike chickenpox in which the rash is widespread, the shingles rash most often appears a localized band, most often on the trunk, neck or face. Medline Plus reports that, like chickenpox, shingles usually appears only once.
Roseola
Human herpes virus 6, HHV-6, or herpes lymphotropic virus, causes roseola, a disease that is found worldwide in at least 90 percent of adults, according to the University of South Carolina. The virus is passed from person to person via saliva or respiratory fluids and most people are infected at a very early age. Infection usually causes a high fever, beginning about 14 days after infection, along with upper respiratory symptoms. As the fever subsides, a reddish, macropapular rash appears, usually beginning on the trunk and then spreading to the neck and face, and possibly to the arms and legs. While most people will test positive for HHV-6, a healthy immune system generally controls the virus after the initial infection and it is unlikely that symptoms will appear again in later life.
