Human papillomavirus (HPV) is one of the most common causes of sexually transmitted disease (STD) in the world. Experts estimate that as many as 24 million Americans are infected with HPV, and the frequency of infection and disease appears to be increasing. More than 60 types of HPV have been identified by scientists. Some types of the virus cause common skin warts. About one-third of the HPV types are spread through sexual contact and live only in genital tissue. Low-risk types of HPV cause genital warts, the most recognizable sign of genital HPV infection. Other high-risk types of HPV cause cervical cancer and other genital cancers.

Like many sexually transmitted organisms, HPV usually causes a silent infection -- one that does not have visible symptoms. One study sponsored by the National Institute of Allergy and Infectious Diseases (NIAID) reported that almost half of the women infected with HPV had no obvious symptoms. Because the viral infection persists, individuals may not be aware of their infection or the potential risk of transmission to others and of developing complications.

Genital Warts

Genital warts (condylomata acuminata or venereal warts) are caused by only a few of the many types of HPV. Other common types of HPV infections, such as those that cause warts on the hands and soles of the feet, do not cause genital warts. Genital warts are spread by sexual contact with an infected partner and are very contagious. Approximately two-thirds of people who have sexual contact with a partner with genital warts will develop warts, usually within three months of contact. Scientists estimate that as many as 1 million new cases of genital warts are diagnosed in the United States each year.

In women, the warts occur on the outside and inside of the vagina, on the cervix (the opening to the uterus), or around the anus. In men, genital warts are less common. If present, they are seen on the tip of the penis; however, they also may be found on the shaft of the penis, on the scrotum, or around the anus. Rarely, genital warts also can develop in the mouth or throat of a person who has had oral sexual contact with an infected person. Genital warts often occur in clusters and can be very tiny or can spread into large masses on genital tissues. Left untreated, genital warts often disappear. In other cases, they eventually may develop a fleshy, small raised growth with a cauliflower-like appearance. Because there is no way to predict whether the warts will grow or disappear, however, people who suspect that they have genital warts should be examined and treated, if necessary.

Diagnosis

A doctor usually can diagnose genital warts by direct visual examination. Women with genital warts also should be examined for possible HPV infection of the cervix. The doctor may be able to identify some otherwise invisible changes in the tissue by applying vinegar (acetic acid) to areas of suspected infection. This solution causes infected areas to whiten, which makes them more visible, particularly if a procedure called colposcopy is performed. During colposcopy, a magnifying instrument is used to view the vagina and uterine cervix. In some cases, it is necessary to do a biopsy of cervical tissue. This involves taking a small sample of tissue from the cervix and examining it under the microscope.

A Pap smear test also may indicate the possible presence of cervical HPV infection. A Pap smear is a microscopic examination of cells scraped from the uterine cervix in order to detect cervical cancer. Abnormal Pap smear results are associated with HPV infection. Women with abnormal Pap smears should be examined further to detect and treat cervical problems.

Treatment

Depending on factors such as their size and location, genital warts are treated in several ways. Although treatments can eliminate the warts, none eradicate the virus and warts often reappear after treatment. Patients should consult their doctors to determine the best treatment for them.

The U.S. Food and Drug Administration (FDA) has approved imiquimod cream, which the patient can apply to the affected area, to treat genital warts. Other treatments include a 20 percent podophyllin solution, which the patient can apply to the affected area and later wash off, and a 0.5 percent podofilox solution, which also is applied to the affected area, but is not washed off. Pregnant women should not use podophyllin or podofilox because they are absorbed by the skin and may cause birth defects in babies. The doctor may also prescribe 5 percent 5-fluorouracil cream, which also should not be used during pregnancy, or trichloroacetic acid (TCA).

Small warts can be removed by cryosurgery (freezing), electrocautery (burning), or laser treatment. Occasionally, surgery is needed to remove large warts that have not responded to other treatment.

Some doctors use the antiviral drug alpha interferon, which they inject directly into the warts, to treat warts that have recurred after removal by traditional means. The drug is expensive, however, and does not reduce the rate of recurrence.

Complications

Low-risk papilloma viruses cause warts but not cervical cancer. High-risk viruses, however, cause cervical cancer and also are associated with vulvar cancer, anal cancer, and cancer of the penis (a rare cancer). Although most HPV infections do not progress to cancer, it is particularly important for women who have cervical dysplasia to have regular Pap smears. Potentially pre-cancerous cervical disease is readily treatable.

Genital warts may cause a number of problems during pregnancy. Sometimes they enlarge during pregnancy, making urination difficult. If the warts are on the vaginal wall, they can make the vagina less elastic and cause obstruction during delivery.

Rarely, infants born to women with genital warts develop laryngeal papillomatosis (warts in the throat). Although uncommon, it is a potentially life-threatening condition for the child, requiring frequent laser surgery to prevent obstruction of the airways. Research on the use of interferon therapy in combination with laser surgery indicates that this drug may show promise in slowing the course of the disease.

Prevention

The only way to prevent HPV infection is to avoid direct contact with the virus, which is transmitted by skin-to-skin contact. If warts are visible in the genital area, sexual contact should be avoided until the warts are treated. Using a latex condom during sexual intercourse may provide some protection.

Researchers are working to develop two types of HPV vaccines. One type would be used to prevent infection or disease (warts or pre-cancerous tissue changes); another type would be used to treat cervical cancers. Clinical trials are in progress for both types of vaccines.

For More Information

American Social Health Association
ASHA/HPV
P.O. Box 13827
Research Triangle Park, NC 27709
National STD Hotline 800-227-8922

Health Advice Company
2515 East Highway 54
2200 Century Plaza
Durham, NC 27713
888-ADVICE-8 (888-238-4238)
http://www.advicecenter.com

National Cancer Institute
Cancer Information Service
800-4 CANCER
http://www.nci.nih.gov