One in Four Women Infected with Human Papillomavirus

ATLANTA, Feb. 28 -- One in four women in the U.S. ages 14 to 59 are infected with the human papillomavirus (HPV), according to the first nationally representative study.

Overall, 26.8% of women in the National Health and Nutrition Examination Survey (NHANES) tested positive for any HPV DNA, which represents 24.9 million infected women in this age range.

So reported Eileen F. Dunne, M.D., M.P.H., of the CDC, and colleagues, in the Feb. 28 issue of the Journal of the American Medical Association.

They also found that 3.4% of the women tested positive for the four major types that the new HPV vaccine (Gardasil) protects against.

HPV, the most common sexually transmitted infection in the United States, is associated with genital warts (HPV types 6 and 11) and cervical cancer (HPV types 16 and 18). In June 2006, the FDA approved Gardasil against HPV types 6, 11, 16, and 18, and it is recommended for use in girls 11 and 12 years old.

The overall prevalence, which was higher than anticipated, particularly among the 14 to 24 age group, provided fuel for the ongoing national debate over how widely the vaccine should be administered and whether states should make it mandatory.

Their analysis included data from the 2003 to 2004 NHANES, before the vaccine was approved in June 2006 and recommended for use in girls 11 to 12 years old.

Among the tests performed in larger NHANES study, 1,921 women ages 14 to 59 provided a vaginal swab for HPV DNA testing.

Whereas a previous estimate suggested 4.6 million infections among females age 14 to 24, the researchers' estimate was higher at 7.5 million. The prevalence findings by age were:

• 24.5% for ages 14 to 19 (95% CI 19.6% to 30.5%),
• 44.8% for ages 20 to 24 (95% CI 36.3% to 55.3%),
• 27.4% for ages 25 to 29 (95% CI 21.9% to 34.2%),
• 27.5% for ages 30 to 39 (95% CI 20.8% to 36.4%),
• 25.2% for ages 40 to 49 (95% CI 19.7% to 32.2%), and
• 19.6% for ages 50 to 59 (95% CI 14.3% to 26.8%).

Restricting the analysis to only sexually active females, did not substantially change the prevalence estimates except for the youngest groups (39.6% for ages 14 to 19 and 49.3% for ages 20 to 24).

The most prevalent types were HPV-62 and HPV-84 (3.3% each, 95% CI 2.2% to 5.1%) followed by HPV-53 (2.8%, 95% CI 2.1% to 3.7%), HPV-89 (2.4%, 95% CI 1.4% to 4.3%), and HPV-61 (2.4%, 95% CI 1.6% to 3.8%).

The four types in the vaccine were less prevalent at 3.4% overall representing 3.1 million females. The findings were:

• HPV-6 was detected in 1.3% (95% CI 0.8% to 2.3%),
• HPV-11 was detected in 0.1% (95% CI 0.03% to 0.3%),
• HPV-16 was found in 1.5% (95% CI 0.9% to 2.6%), and
• HPV-18 was identified in 0.8% (95% CI 0.4% to 1.5%).

High-risk HPV types 16 and 18 together cause approximately 70% of cervical cancers, the researchers noted.

Similar to other studies, independent risk factors for HPV detection included number of sex partners in the last year (P