Millions In U.S. Infected With HPV
Wednesday, February 28, 2007
More than one-third of American women are infected with human papillomavirus (HPV), which in rare cases can lead to cervical cancer, by the time they are 24 years old, according to a study being published today.
The new estimates suggest that there are 7.5 million girls and women 14 to 24 years old infected with the microbe -- about two-thirds more than an earlier but less comprehensive study had found.
Overall, about one-quarter of women under age 60 are infected at any given time, making HPV by far the most common sexually transmitted disease in the country.
News of the higher-than-expected prevalence of HPV infection was balanced by the discovery that only 2.2 percent of women were carrying one of the two virus strains most likely to lead to cervical cancer -- about half the rate found in previous surveys.
The lead researcher cautioned the findings do not mean that HPV infection rates are rising, only that they are higher than previously thought.
"For us, it's just a different measurement -- and a more accurate one," said Eileen F. Dunne, a physician and epidemiologist at the Centers for Disease Control and Prevention.
The estimate comes from the federal government's ongoing National Health and Nutrition Examination Survey, which provides the clearest snapshot of the U.S. population's health through dozens of measurements, laboratory tests and survey questions.
The new findings, published in today's Journal of the American Medical Association, are likely to further encourage use of a vaccine against HPV approved in June by the Food and Drug Administration for females 9 to 26. Its maker, Merck, until recently was lobbying state legislatures to mandate vaccination of middle-school girls -- a step that more than 18 states are moving toward.
In its just-completed session, Virginia's General Assembly enacted legislation, which is now before the governor, requiring the vaccine in schoolgirls. Texas's governor earlier this month issued an executive order doing the same thing.
"Our perspective is that many women would benefit from the protection that [the vaccine] would provide," said Richard M. Haupt, the executive director for medical affairs at Merck Vaccines. The company is running studies trying to prove the vaccine's usefulness in women 25 to 45, and also in boys and men 9 to 23.
Some parents have objected to school mandates for HPV vaccination of girls, arguing that because the infection is transmitted only through sexual contact, it can be avoided by choice. Others believe the vaccine may lower inhibitions against sexual activity, although there is no evidence that fear of HPV infection is a reason many teenagers abstain.
There are dozens of strains of HPV, but only some can lead to cancer. Two -- HPV-16 and HPV-18 -- are responsible for about 70 percent of cervical cancers worldwide. The Merck vaccine protects against both, as well as two other strains that cause genital warts.