Risk Factors:

Everyone is at risk for herpes simplex virus. According to the latest U.S. data from 1999 - 2004, about 60% of Americans ages 14 - 49 are infected with herpes simplex virus 1 (HSV-1). About 17% of Americans in the same age range test positive for herpes simplex virus 2 (HSV-2). Infection rates for both viruses have declined since the late 1980s. However, infection is lifelong.

Who Is at Risk for Oral Herpes

Oral herpes is usually caused by HSV-1. The highest incidence of first infection occurs between 6 months and 3 years of age. The incidence in children varies among regions and countries, with the highest rates occurring in crowded and unsanitary regions. Studies suggest that by age 5 more than a third of children in low-income areas are infected compared to 20% of children in middle-income areas. However, by the time Americans of all economic backgrounds reach age 60, about 60 - 85% have become infected with HSV-1.

Who Is at Risk for Genital Herpes

Although the prevalence of genital herpes is declining in the United States, it still remains in epidemic proportions. According to the U.S. Centers for Disease Control and Prevention, at least 45 million Americans age 12 and over have had genital herpes. About 1 in 5 teenagers and adults are infected with genital herpes. While HSV-2 remains the main cause of genital herpes, in recent years, the percentage of cases of genital herpes caused by HSV-1 has significantly increased. Anyone who is sexually active is at risk for genital herpes.

Risk factors for genital herpes include a history of a prior sexually transmitted disease, early age for first sexual intercourse, a high number of sexual partners, and poor socioeconomic status. Women are more susceptible to HSV-2 infection because herpes is more easily transmitted from men to women than from women to men. About 1 in 4 women, compared to 1 in 8 men, have genital herpes

People with compromised immune systems, notably patients with HIV, are at very high risk for HSV-2. Between 68 - 81% of patients with HIV are infected with HSV-2. These patients are also at risk for more severe complications from herpes. Other immunocompromised patients include those taking drugs that suppress the immune system and transplant patients.

Who Is at Risk for Specific Forms of Herpes

The following are examples of people who are at particularly risk for specific forms of herpes.

• Health care providers, including doctors, nurses, and dentists. This group is at higher than average risk for herpetic whitlow, herpes that occurs in the fingers.
• Wrestlers, rugby players, and other athletes who participate in direct contact sports without protective clothing. These individuals are at risk for herpes gladiatorum, an unusual form of HSV-1 that is spread by skin contact with exposed herpes sores and usually affects the head or eyes.

Transmission

To infect people, the herpes simplex viruses (both HSV-1 and HSV-2) must get into the body through broken skin or a mucous membrane, such as inside the mouth or on the genital area. Each virus can be carried in bodily fluids (saliva, semen, fluid in the female genital tract) or in fluid from herpes sores. The risk for infection is highest with direct contact of blisters or sores during an outbreak.

Once the virus has contact with the mucous membranes or skin wounds, it begins to replicate. The virus is then transported within nerve cells to their roots where it remains inactive (latent) for some period of time. During inactive periods, the virus cannot be transmitted to another person. However, at some point, it often begins to multiply again without causing symptoms (called asymptomaticshedding). During shedding, the virus can infect other people through exchange of bodily fluids.

Sometimes, infected people can transmit the virus and infect other parts of their own bodies (most often the hands, thighs, or buttocks). This process, known as autoinoculation, is uncommon, since people generally develop antibodies that protect against this problem.

Transmission of Oral Herpes. Oral herpes is usually caused by HSV-1. HSV-1 is the most prevalent form of herpes simplex virus, and infection is most likely to occur during preschool years. Oral herpes is easily spread by direct exposure to saliva or even from droplets in breath. Skin contact with infected areas is enough to spread it. Transmission most often occurs through close personal contact, such as kissing. In addition, because herpes simplex virus 1 can be passed in saliva, people should also avoid sharing toothbrushes or eating utensils with an infected person.

Transmission of Genital Herpes. Genital herpes is most often transmitted through sexual activity, and people with multiple sexual partners are at high risk. The virus, however, can also enter through the anus, skin, and other areas.

People with active symptoms of genital herpes are at very high risk for transmitting the infection. Unfortunately, evidence suggests about a third of all herpes simplex virus 2 (HSV-2) infections occur when the virus is shedding but producing no symptoms. Most people either have no symptoms or don't recognize them when they appear.

In the past, genital herpes was mostly caused by HSV-2, but HSV-1 genital infection is increasing. This may be due to the increase in oral sex activity among young adults.

Preventing Transmission

Infected people should take steps to avoid transmitting genital herpes to others. It is almost impossible to defend against the transmission of oral herpes since it can be transmitted by very casual contact.

Genital herpes is contagious from the first signs of tingling and burning (prodrome) until the time that sores have completely healed. It is best to refrain from sex during periods of active outbreak. However, herpes can also be transmitted when symptoms are not present (asymptomatic shedding).

The following precautions can help reduce the risk of transmission:

• Use a latex condom. While condoms may not provide 100% protection, they have been proven to significantly reduce the risk of sexual disease transmission. Condoms made of latex are less likely to slip or break than those made of polyurethane. Natural condoms made from animal skin do not protect against HSV infection because herpes viruses can pass through them
• Use a water-based lubricant. Lubricants can help prevent friction during sex, which can irritate the skin and increase the risk for outbreaks. Only water-based lubricants (K-Y Jelly, Astroglide, AquaLube, glycerin) should be used. Oil-based lubricants (petroleum jelly, body lotions, cooking oil) can weaken latex. Many condoms come pre-lubricated. However, do not use condoms pre-lubricated with spermicides (see below).
• Do not use spermicides for protection against herpes. Some condoms come prelubricated with sperm-killing substances called spermicides. Spermicides also come in stand-alone foams and jellies. The standard active ingredient in spermicides is nonoxynol-9. Nonoxynol-9 can cause irritation around the genital areas, which makes it easier for herpes and other STDs to be transmitted.
• Use a dental dam for oral sex.
• Limit the number of sexual partners.

[For more information, see In-Depth Report # 91: Birth control options for women.]

To reduce the risk of passing the herpes virus to another part of your body (eyes, fingers), avoid touching a herpes blister or sore during an outbreak. If you do, be sure to immediately wash your hands with hot water and soap.

The herpes virus does not live very long outside the body. While the chances of transmitting or contracting herpes from a toilet seat or towel are extremely low, it is advisable to wipe off toilet seats and not to share damp towels.