How the Herpes Simplex Virus Works

About the Spread of This Common Infection

Girl with Cold Sore
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The herpes virus is a very common viral infection, and one of the most difficult viruses to control. The word "herpes" is derived from the Greek word herpein, which means "to creep." The herpes simplex viruses are double-stranded DNA viruses that only infect humans, and there are two different strains:

  • Herpes simplex virus type 1 (HSV-1)
  • Herpes simplex virus type 2 (HSV-2)

HSV-1, or oral herpes, is responsible for the majority of cold sores, or fever blisters.

If you've ever had a cold sore, then you've had HSV-1. HSV-2, however, causes genital herpes. According to the World Health Organization (WHO), in 2012 an estimated 3.7 billion people under age 50 had HSV-1. WHO also estimates that in 2012 approximately 417 million people worldwide were living with HSV-2, which affects women more than it does men.

A person can be infected with one or both herpes viruses. Previously it was believed that HSV-1 infections occur in the mouth and HSV-2 infections occur in the genital area. Now it has been proven that either type of virus can infect either site.

How the Herpes Simplex Virus Works

The herpes virus spreads when it comes in contact with broken skin, or with the lining of the mouth, vagina or anus. It penetrates cell nuclei and replicates. Even though the cells are infected, most people do not experience symptoms.

Sometimes the virus's replication process destroys the cell it has invaded, causing blisters or ulcers to form under the skin.

The blisters crust over and heal without scarring. Cold sores, in particular, are at their most contagious while blisters are oozing. But the virus can be transmitted even if blisters are not present. Sharing beverages, towels and kissing can all spread HSV-1. HSV-2 is usually spread through sexual contact.

The virus is then transported back through the nerve to important nerve branching points, known as ganglia, deep within the body. The virus stays in the ganglia in an inactive state. During this time, the virus does not replicate. Rather, it's dormant for periods of time.

What Causes a Herpes Simplex Virus Recurrence

Certain triggers can cause the herpes virus to travel back through the nerve to the surface of the skin. This is known as a recurrence. Recurrences can and do happen, even for people who have normal immune systems. The following are known triggers that can stimulate a recurrence:

Symptoms of Herpes Simplex Virus

The herpes simplex virus is asymptomatic, meaning that most people infected with either type of the herpes virus don't know it.

Still, symptoms will occur. Symptoms of HSV-1 include:

  • Tingling, burning sensation around the mouth
  • Cold sores (also known as fever blisters)

Symptoms of genital herpes, HSV-2, include:

See Also


CDC. "Sexually Transmitted Diseases Treatment Guidelines, 2006." Morbidity and Mortality Weekly Report. 55(2006): 16-20.

Habif, Thomas. "Warts, Herpes Simplex, and Other Viral Infections." Clinical Dermatology, 4th Edition. Ed. Thomas Habif, MD. New York: Mosby, 2004. 381-388.

Yeung-Yue, Kimberly. "Herpes simplex viruses 1 and 2." Dermatologic Clinics 20(2002): 1-21.

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