Genital herpes is a sexually transmitted viral infection affecting the skin of the genitals.

Herpes is caused by two viruses:

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

HSV-1, the virus responsible for common cold sores, can be transmitted through fluids from the mouth. It is responsible for some cases of genital herpes cases. HSV-1 can spread from the mouth to the genitals during oral sex.

HSV-2 causes most of the genital herpes cases. HSV-2 can be spread through secretions from the mouth or genitals.

Herpes simplex virus (HSV) is spread from one person to another by skin-to-skin contact. The virus is shed from visible sores, blisters, or a rash during outbreaks, but can also be shed from the affected area between outbreaks of symptoms.

HSV is transmitted to the area of skin with which it comes into contact. There are also some cases by which other types of contact can spread HSV. For example, a variant of herpes, known as herpes gladiatorum, can be passed on during body contact sports, such as wrestling.

Because the virus is transmitted through secretions from the mouth or genital tissue (mucosa), common sites of infection in men include:

• Anus
• Inner thighs
• Scrotum
• Shaft and head of the penis

Common sites of infection in women include:

• Anus
• Cervix
• Inner thighs
• Labia
• Vagina

The mouth can also be a site of infection in both sexes.

Research suggests that the virus can be transmitted even when there are no symptoms present, so that a sexual partner without obvious genital herpes sores can still transmit the illness. In fact, asymptomatic spread may actually contribute more to the spread of genital herpes than do active sores.

For people with no prior contact with HSV-1 or HSV-2, initial infection involves both whole body (systemic) and local symptoms.

Generalized symptoms include:

• Decreased appetite
• Fever
• Malaise
• Muscle aches

Local symptoms include repeated eruptions of small, painful blisters filled with clear, straw-colored fluid on the genitals, around the rectum, or covering nearby areas of skin. Before these blisters appear, the person may experience increased skin sensitivity, tingling, burning, itching, or pain at the site where the blisters will appear.

When the blisters break, they leave shallow ulcers that are very painful. These ulcers eventually crust over and slowly heal over 7 - 14 days.

Enlarged and tender lymph nodes in the groin may accompany an outbreak. Women also may develop vaginal discharge and painful urination. Men can develop painful urination if the lesion is near the opening of the urethra.

Once a person is infected, the virus hides within nerve cells, making it difficult for the immune system to find and destroy it. Within the nerve cells, the virus can remain dormant for a long period of time, which is called "latency."

The infection can reactivate at any time, at which point painful blisters again cover the genitals, anus, inner thigh, or mouth. A variety of events can trigger latent infection to become active, including:

• Fatigue
• Mechanical irritation
• Menstruation
• Stress

Attacks can recur as seldom as once per year, or so often that the symptoms seem continuous. Recurrent infections in men are generally milder and shorter in duration than those in women.

• Viral culture of blister fluid from lesion is positive for herpes simplex virus. The herpes simplex virus can grow within 2 - 3 days.
• PCR from the blister fluid detects small amounts of DNA and can tell whether the herpes virus is present in the blister.
• Tzanck test of skin lesion may show results consistent with herpes virus infection. This test involves staining human cells within the blister fluid with a dye. If the cells from the fluid contain viral particles, they become visible. However, the test cannot determine which strain of virus is in the blister.

Recently developed antibody tests can determine whether a person has HSV-1 or HSV-2. These tests can also tell if a person has ever been exposed to either of these strains in the past (IgG test) or was just recently exposed to one of them (IgM test).

Genital herpes cannot be cured. However, antiviral treatment can relieve the symptoms. Medication can quickly relieve the pain and discomfort during an outbreak, and can shorten healing time. Medications have been shown to speed healing and relieve symptoms in first attacks more than in recurrent episodes of genital HSV-1 and HSV-2 infections.

If necessary, patients can use daily suppressive therapy, which may reduce the frequency of recurrence in patients with frequent genital herpes outbreaks.

For maximum benefit during recurrences, start therapy as soon as the tingling, burning, or itching begins, or as soon as you notice blisters.

Possible side effects from herpes medications include:

• Fatigue
• Headache
• Nausea and vomiting
• Rash
• Seizures
• Tremor

Some people need medication through a vein (intravenous) for severe herpes infections that can involve the brain, eyes, and lungs. These complications sometimes develop in people with a compromised immune system.

Warm baths may relieve the pain of genital lesions. Gentle cleansing with soap and water is recommended. If you develop a secondary infection of the skin lesions by bacteria, you can use a topical or oral antibiotic.

See: Herpes genital - support group

Once you are infected, the virus stays in your body for the rest of your life. Some people never have another episode, and others have frequent recurrences. In most recurrences, no obvious trigger is identified. Many people, however, find that attacks of genital herpes occur with the following conditions:

• Fatigue
• General illness (from mild illnesses to serious conditions, such as operations, heart attacks, and pneumonia)
• Immunosuppression due to AIDS or medication such as chemotherapy or steroids
• Menstruation
• Physical or emotional stress
• Trauma to the affected area, including sexual activity

In people with a normal immune system, genital herpes remains a localized and bothersome infection, but is rarely life-threatening.

Various complications are associated with herpes infection. The herpes virus is of special significance to women because research has found that it can cause cancer of the cervix. The risk increases when HSV is present in combination with human papilloma virus (HPV), the virus responsible for genital warts (condyloma).

For pregnant women, HSV-1 or HSV-2 on the outside of the genitals or in the birth canal is a threat to the infant. Infection of the newborn can lead to herpetic meningitis, herpetic viremia, chronic skin infection, and even death.

Herpes infection also poses a serious problem for people who have a weakened immune system because they have AIDS, are undergoing chemotherapy or radiation therapy, or take high doses of cortisone. These people may develop infections of various organs, including:

• Encephalitis (rare)
• Herpetic esophagitis (herpes infection of the esophagus)
• Herpetic keratitis (herpes infection of the eye)
• Herpetic hepatitis (herpes infection of the liver)
• Incontinence
• Persistent infection of the mucous membranes and skin of the nose, mouth, and throat
• Pneumonitis (herpes infection of the lung)
• Recurrent disease
• Spread of the virus to other organs of the body
• Transverse myelopathy (damage that extends across the spinal cord)

Call for an appointment with your health care provider if you have any symptoms of genital herpes, or if you develop fever, headache, vomiting, or widespread symptoms during or after an outbreak of herpes.

Condoms remain the best way to protect against catching genital herpes during sexual activity. Using a condom correctly and consistently will help prevent the spread of the disease.

The use of latex condoms is mandatory. Do not use animal membrane condoms, because the virus can go through them. The female condom has been tested and shown to successfully reduce transmission risk as well.

Recent data show that using an antiherpes drug can help prevent spreading the virus to others.

Otherwise, prevention is difficult, due to the fact that the virus can be spread to others even when the infected person has no obvious symptoms (asymptomatic shedding). People with genital herpes should avoid sexual contact when they have active lesions.

In addition, people with known genital herpes, but without current symptoms, should inform their partner that they have the disease. This precaution allows both parties to use barrier protection to prevent the spread of the illness.

Pregnant women with the herpes simplex infection should have weekly viral cultures of the cervix and outer genitals as the delivery date approaches. If the viral culture is positive for herpes, or active lesions are present at delivery, a cesarean delivery (C-section) is recommended to avoid infecting the newborn.

Vaccines against herpes have been developed but are still considered experimental drugs. Vaccines are not, however, a cure or treatment for people who already have herpes.

Centers for Disease Control and Prevention, Workowski KA, Berman SM. Sexually transmitted diseases treatment guidelines, 2006. MMWR. 2006;55(RR-11):1-94.

Mandell GL, Bennett JE, Dolin R. Principles and Practice of Infectious Diseases. 5th ed. Philadelphia, Pa: Churchill Livingstone; 2000.