Human Papilloma Virus

There are over 100 strains of the human papillomavirus (HPV). Approximately a third of these strains are sexually transmitted and cause genital HPV. Some types of genital HPV cause warts that infect the genital tract. These warts can grow on the cervix, vagina, vulva, penis, scrotum, urethra, and anus. HPV can also cause other abnormal cells to grow on the cervix. Some strains of HPV can lead to cervical cancer.

HPV is transmitted by direct skin-to-skin contact with an infected individual. It can also be transmitted when warts are not present. It is sometimes transmitted from mother to infant during childbirth.

Certain strains of HPV are considered the primary risk factor for cervical cancer. The majority of such cancers develop through a series of gradual precancerous lesions that are easily detected by a Pap smear, and can be removed.

A Pap smear is a routine gynecological test in which a health care provider uses a cotton swab or similar instrument to collect cells from the cervix. The test looks for abnormal or precancerous cells. These cells may be signs of cervical cancer.

Regular Pap smears reduce the risk of invasive cervical cancer by early detection of abnormal cells.

Researchers at the pharmaceutical companies Merck and GlaxoSmithKline have developed vaccines that target particular strains of HPV. Merck’s vaccine, Gardasil, targets HPV types 16 and 18, which are associated with 70% of all cervical cancer and types 6 and 11 which are associated with 90% of all genital warts. GlaxoSmithKline’s vaccine only targets HPV types 16 and 18. Both vaccines have been shown to be nearly 100% effective in preventing infection with the HPV strains they target. Merck’s vaccine, Gardasil, was approved by the Food and Drug Administration (FDA) for females ages 9–26 and was recommended for routine use with females ages 11–12.

It is important to note that not every HPV infection will become cervical cancer. The National Cancer Institute points out that while HPV infection is common, cervical cancer is not.

Signs and Symptoms:

  • People with HPV may experience no visible signs or symptoms or may have warts in places they cannot see (such as the cervix).
  • Genital warts are raised or flat growths that are usually flesh colored or whitish in appearance.
  • Genital warts usually do not cause itching or burning.
  • If left untreated, genital warts may disappear. However, HPV infection remains and warts can reappear.



  • HPV is often diagnosed through a visual examination of genital warts. In some cases, a biopsy is necessary. The presence of HPV on the cervix is detected through a Pap smear.



  • There is no cure for HPV. There are, however, a number of methods to remove warts.


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  • National Data - CDC's Tracking the Hidden Epidemics, Trends in STDs in the United States, 2000:
  • Every year, about 5.5 million people acquire a genital HPV infection.
  • An estimated 75% of the reproductive-age population has been infected with sexually transmitted HPV.
  • Research indicates that approximately 1% of sexually active adults in the United States have genital warts.


Data by Sex and Age:

  • Eileen F. Dunne, et al., "Prevalence of HPV Infection Among Females in the United States," Journal of the American Medical Association, 297.8 (February 28, 2007): 813-819. The full text of this article may be obtained online for a fee through the Journal of the American Medical Association. An abstract is available here:
  • National Data ? CDC?s National Health and Nutrition Examination Survey, 2003-2004:
  • For females the percent of the population infected is listed by age group:
    • 25% for young women 14-19,
    • 45% for women 20-24,
    • 27% for women 25-29,
    • 28% for women 30-39,
    • 25% for women 40-49,
    • 20% for women 50-Y.
  • In the U.S., about 1 in 4 females (27%) ages 14-59 are infected with HPV. This is equivalent to 25 million American women.
  • 57% of females aged 14-19 and 97% of females aged 20-59 years are sexually active. The prevalence of HPV infection is highest in these groups, affecting approximately 40% of sexually active 14-19 year old girls and 50% of sexually active 20-24 year old women. HPV prevalence is substantially lower in sexually active women aged 24-59 years.
  • For females 15-49, about 2% have HPV strains 16 and 18, which together cause about 70% of cervical cancer cases. These two strains are the target of the two vaccines in development or on the market.
  • Although less data are available on HPV among men, levels of current infection in men appear to be similar to those in women.



Condoms and HPV Prevention
Rachel L. Winer, et al., "Condom Use and the Risk of Genital Human Papillomavirus Infection in Young Women," New England Journal of Medicine, 354.25 (June 22, 2006): 2645-2654.

Among newly sexually active women, consistent condom use reduced the risk of HPV infection by 70%.

Even women whose partners used condoms more than half the time had a 50 percent risk reduction, as compared with those whose partners used condoms less than 5% of the time.

The full text of this article may be obtained online for free through the New England Journal of Medicine (

National Institutes of Health, Workshop Summary: Scientific Evidence on Condom Effectiveness for Sexually Transmitted Disease (STD) Prevention (June 12-13, 2000).

This comprehensive review found that of ten studies of condoms and precancerous or cancerous changes in the cervix, six found statistically significant reductions in risk, ranging from 39% to 80%.

The full text of this article may be obtained online for free through the National Institutes of Health

U.S. Centers for Disease Control and Prevention, Report to Congress: Prevention of Genital Human Papillomavirus Infection (Jan. 2004)

The CDC panel found that "available studies suggest that condoms reduce the risk of the clinically important outcomes of genital warts and cervical cancer."

The full text of this article may be obtained online for free through the Centers for Disease Control (

HPV and Sexual Active Young Women
Gloria Ho, et al., "Natural History of Cervicovaginal Papillomavirus Infection in Young Women," New England Journal of Medicine, 338.7 (February 12, 1998), 423-428.

The incidence of HPV infection among sexually active young women in college was 43%.

The median duration of new infections was 8 months.

In 91% of young women with new HPV infections, HPV became undetectable within two years.

The full text of this article may be obtained online for a fee. For more information:

See the abstract at the New England Journal of Medicine (, or Contact your local librarian.

If you have difficulty finding this article, you may contact SIECUS (