HPV or Human papillomavirus is a group of more than 100 different types of viruses that only affect humans. More than 30 of these virus types are sexually transmitted and can infect the genital area of men and women including the skin of the penis, vulva (area outside the vagina), anus, the lining of the vagina, cervix and/or rectum. Most people who are infected with HPV will not have any symptoms and will clear the infection naturally.

Some types of HPV are called "high-risk" types and can cause abnormal Pap tests. If a person is infected with "high-risk" HPV and the infection doesn't clear, the infected person is at risk for developing cancer of the cervix, vulva, vagina or anus, if female, and of the anus or penis, if male.

Other types of HPV are called "low-risk" types and may cause mild Pap test abnormalities or genital warts or warts on the skin. Genital warts are single or multiple growths that sometimes have a cauliflower shape and appear in the genital area.

Genital HPV infections usually result from sexual contact. Most infected persons are unaware of their infection and can unknowingly transmit the virus(es) to a sex partner.

In some rare instances, a woman who has the type of HPV that can cause genital warts can transmit that HPV type to her baby during delivery. The baby might, in very rare circumstances, develop warts in the throat or voice box.

Most people infected with HPV do not have any symptoms and do not know they are infected.

Those infected with "high-risk" HPV may or may not have symptoms. Some people may have pre-cancerous changes in the cervix, vulva, anus or penis. Rarely, HPV infection results in anal or genital cancers.

In those infected with "low-risk" HPV who have symptoms, genital warts may appear as soft, moist, pink or flesh-colored swellings. The warts can be raised or flat, single or multiple, small or large and sometimes cauliflower-shaped. They can appear on the vulva, in or around the vagina or anus, on the thigh or on the cervix in women and on the penis, scrotum, groin or thigh in men.

Genital wart HPV infections:

Genital warts ("low-risk" HPV) are diagnosed by visual inspection in men and women.

Non-wart genital HPV infections:

Women: Women are usually diagnosed on the basis of abnormal Pap tests. The Pap test is the primary cancer-screening tool for cervical cancer or pre-cancerous changes in the cervix. Most cancer of the cervix is related to HPV. There is now a test that can detect HPV DNA in women, and some experts recommend the HPV test for a woman who has an abnormal Pap test or is older than 30 years of age at the time of the test. Evidence of "high-risk" HPV DNA can guide the health care provider in recommending further testing or treatment.

Men: Currently, there is no HPV test available to screen men for infection.

There is no cure for HPV; however, genital warts caused by "low-risk" HPV can be removed by medications the patient applies or by treatments performed by a health care provider. There is no single treatment that is recommended above others, and most warts will resolve without treatment.

For "high-risk" HPV, when cervical changes appear on a Pap smear, treatment by a doctor may be required.

All types of HPV can cause mild Pap test abnormalities; these abnormalities are usually transitory and do not have serious consequences. Research has shown that most women (90%) infected with HPV at the cervix had no evidence of infection at the end of two years of follow-up. While approximately 10 of the 30 types of HPV that affect the genitals can lead to the development of cervical cancer, only a small proportion of women have persistent infection, that is, show evidence of infection that lasts longer than two years. Persistent infection with "high-risk" HPV, especially HPV 16 and 18, is the main factor in the development of cervical cancer.

Annual screening with Pap tests is responsible for greatly reducing deaths from cancer of the cervix in the United States. The estimates from the American Cancer Society for 2007 indicate that as many as 11,150 women will develop invasive cervical cancer and 3,670 women will die from the disease. Most women who develop invasive cervical cancer do not have regular Pap tests.