Nearly 25% of females ages 14-59 have HPV, study finds

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Data from a national study suggest one in four U.S. females ages 14 to 59 is infected with the sexually transmitted human papillomavirus (HPV), with an infection rate of 34 percent for females between the ages of 14 and 24.

The report by federal researchers provides the first broad national estimate of the prevalence of HPV infection, which in some forms can cause cervical cancer. It found prevalence of the virus among those in the youngest age group analyzed (ages 14 to 24) to be substantially higher than previous estimates: 7.5 million versus 4.6 million.

"Prevalence of HPV infection was highest among females aged 20 to 24 years," nearly 45 percent, Dr. Eileen F. Dunne and other authors wrote in their study, published in the Feb. 27 issue of Journal of the American Medical Association.

"There was a statistically significant trend for increasing HPV prevalence with each year of age from 14 to 24 years, which was followed by a nonsignificant gradual decline in HPV prevalence through 59 years," they added.

Females in the 14 to 59 age range were interviewed as part of the 2003-04 National Health and Nutrition Examination Survey. About 2,000 survey participants provided vaginal swabs that were analyzed for presence of any type of HPV infection.

A vaccine licensed by the Food and Drug Administration in June protects against two strains of HPV that cause nearly 70 percent of cervical cancer cases. The same vaccine, Gardasil, produced by Merck &. Co., also prevents two other strains linked to 90 percent of genital wart cases.

The FDA has approved Gardasil for females from ages 9 to 26. At least 20 states and cities are considering requiring the vaccination of girls 11 to 13 for school attendance. But reports in The Washington Times have challenged the value of the vaccine for girls so young because Merck acknowledges it is effective only about five years, and most cervical cancer patients are older than 40.

The CDC research found nearly 27 percent of vaginal specimens collected tested positive for any type of HPV. Using Census data, they extrapolated that finding into 24.9 million HPV infections nationally among females ages 14 to 59.

But the analysis found that only 3.4 percent of samples were positive for one of the four HPV strains that the current vaccine protects against.

"That is not surprising," Dr. Dunne, a medical epidemiologist in the CDC's Division of STD Prevention, said yesterday. "That is the assessment at this point in time. It does not include infections (from HPV strains 6, 11, 16 and 18) that have occurred previously and have cleared, nor does it include infections from those strains that occur in the future."

She pointed out that the 3.4 percent infection rate with HPV types 6, 11, 16, or 18 corresponds with 3.1 million women.

Dr. Dunne was unable to predict just how likely it is for someone infected with the so-called HPV "high-risk oncogenic" strains 16 or 18 to contract cervical cancer.

"But 90 percent of those infections are cleared within two years," she said.