More than 20 percent of US adults have 'high-risk' HPV

About 1 in 5 U.S. adults under age 60 is infected with a "high-risk" strain of genital human papillomavirus (HPV) that increases the risk of cancer, according to a new report.

For the report, researchers analyzed information from a nationally representative sample of Americans ages 18 to 59 who took part in a health survey from 2013 to 2014. As part of the survey, the participants underwent a physical exam in which they swabbed their genitals, and these samples were tested for DNA from 37 different types of HPV. Fourteen of these HPV types are known as high-risk strains because they are linked with an increased risk of certain cancers, including cancers of the cervix, vagina, vulva, anus, penis and throat.

Overall, about 23 percent of the participants were infected with a high-risk strain of genital HPV, the report found. These strains were slightly more common in men than in women. About 25 percent of the men were infected with a high-risk strain of genital HPV, compared with 20 percent of women. [Men vs. Women: Our Key Physical Differences Explained]

The researchers hope the findings will make people aware of the significance of HPV and the importance of getting vaccinated against the virus, said Geraldine McQuillan, an epidemiologist at the Centers for Disease Control and Prevention and co-author of the new report.

The finding "is disturbing, and really needs to be noted so parents will get their young adolescents vaccinated before they become sexually active," McQuillan told Live Science.

Human papillomaviruses are a group of more than 150 related viruses that infect different parts of the body. HPVs that infect the genital area can spread as sexually transmitted infections. Most infections go away on their own, but some can linger and lead to health problems, including genital warts and cancer, according to the CDC.

The new report also found that, overall, the prevalence of any type of genital HPV infection was 45 percent in men and 40 percent in women.

Until recently, data on the prevalence of genital HPV infections in men in the general U.S. population was limited. HPV infections among women have been much more widely studied given the strong link between HPV and cervical cancer, a connection that has been known for decades.

A study published in the journal Pediatrics in February 2016 by the same group of researchers found that high-risk HPV infections in women decreased after the HPV vaccine became available in 2006. That study found that, among girls and women ages 14 to 19, the prevalence of four high-risk strains of HPV (6, 11, 16 and 18) decreased from 11.5 percent in the years 2003 to 2006 to 4.3 percent in the years 2009 to 2012. Among women ages 20 to 24, the prevalence of these four strains decreased from 18.5 percent to 12.1 percent over that same period.

The prevalence of high-risk HPV among women in the new report is higher than it was in some previous studies, in part because the new report included women who were ages 18 to 59 years old in 2013 to 2014, which means they most likely were not vaccinated against HPV, McQuillan said. The HPV vaccine is recommended for children ages 11 to 12 years old because it is most effective if given before a person becomes sexually active. (However, "catch up" vaccination is also recommended for people ages 13 to 26 who did not previously get the vaccine.)The report also looked at oral HPV infections among Americans ages 18 to 69 in the years 2011 to 2014, and found that oral infections occur in about 11.5 percent of men and 3.3 percent of women.

It's unknown why HPV infections are more common in men than in women, but some studies suggest that men's immune systems don't respond as strongly to fight off HPV infections as women's systems do.

The report was published today (April 6) by the CDC's National Center for Health Statistics.

Original article on Live Science.