Human Papillomavirus and Genital Warts

Human papillomavirus (HPV) is one of the most common causes of sexually transmitted diseases (STDs) in the United States. Experts estimate that as many as 24 million Americans are infected with HPV, and the incidence of the diseases it causes 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 can be spread through sexual contact. Several types of HPV can lead to genital warts, the most recognizable sign of genital HPV infection. Certain other types of HPV have been closely associated with the development of cervical cancer and other genital cancers.

Like many STDs, HPV infection often does not cause visible symptoms. One study reported that almost half of the women infected with HPV had no obvious symptoms. Because the virus can remain latent in the skin, infected persons may not be aware of their infection and 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 this disease, usually within 3 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 vulva, labia, inside the vagina, on the cervix, or around the anus. In men, genital warts usually appear on the tip of the penis; however, the warts 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 groups and can be very tiny or can accumulate 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

It is important for a person who thinks he or she may have genital warts to see a doctor so that other types of similar-looking infections or conditions can be ruled out or treated. Genital warts are usually diagnosed by direct visual examination.

Women with genital warts should be examined for possible HPV infection of the cervix. The doctor may be able to identify some otherwise invisible lesions 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 taken from the uterine cervix to detect cervical cancer. Abnormal Pap smear results can indicate possible HPV infection. Women with abnormal Pap smears should be examined further to detect and treat cervical problems.

Several new laboratory tests can identify specific types of HPV. Such tests may help a doctor determine whether the infection is likely to progress to precancerous lesions or be transmitted from a pregnant woman to her newborn.

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 these medications 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) or electrocautery (burning). Occasionally, surgery is needed to remove large warts that have not responded to other treatment. Doctors at some medical centers also use laser surgery to remove genital warts.

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

Scientists have found an association between several types of HPV and the development of cervical cancer, vulvar cancer, anal cancer, and cancer of the penis (a rare cancer). Much more research needs to be done to clarify the role of HPV in such cancers and to explore the possible role of other factors such as cigarette smoking, the use of oral contraceptives, and the presence of other STDs in increasing a person's risk of developing genital cancers. Although most HPV infections do not progress to cancer, it is particularly important for women who have had evidence of HPV infection or genital warts to have regular Pap smears. Potentially precancerous 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.

Infants born to women with genital warts can develop laryngeal papillomatosis (warts in the throat). Although a relatively rare occurrence, 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 (rubber) during sexual intercourse may provide some protection.

Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.