-- Infection with human papilloma virus, or HPV, continues to be the most common sexually transmitted infection in the U.S., according to a new report from the U.S. Centers for Disease Control and Prevention.
Contrary to views that associate the virus only with cervical cancer, HPV has dozens of strains, which overall are more prevalent in men than women.
Strains of HPV are so common, the CDC estimates "that nearly all sexually active men and women get the virus at some point in their lives."
Today researchers released a CDC report on the status of HPV infection. They examined data from 2011 to 2014 from the CDC-run National Health and Nutrition Examination Survey, designed to "assess the health and nutritional status of adults and children."
During one study period from 2013 to 2014, approximately 4 in 10 people ages 18 to 59 were infected with genital HPV in the U.S., the CDC said.
The findings show that everyone is at risk for complications from HPV, Dr. William Schaffner, an infectious-disease expert at Vanderbilt University Medical Center, told ABC News. He added that the study will hopefully encourage more people to seek the vaccine.
"These viruses affect men and women," he said. "Let's stop thinking about HPV [vaccine] as only a cervical cancer vaccine."
There are 40 strains of HPV easily spread through sexual contact, according to the National Cancer Institute. Some of these HPV strains can cause oral or genital warts, and some can increase the risk for various cancers. In women, having certain strains of HPV can increase the risk of cervical or vaginal cancer, and in men it can increase the risk of penile or anal cancer. Both sexes may be at risk for cancer in the oropharynx or throat from certain strains of HPV.
From 2011 to 2014, the prevalence of any oral HPV was 7.3 percent among people 18 to 69, with men having a far higher rate of 11.5 percent, compared with 3.3 percent among women, the report said. Black adults were most at risk, with 9.7 percent infections, compared with 7.3 percent for white adults, 7 percent for Hispanic adults and 2.9 percent for Asian adults.
Approximately 4 percent of adults had high-risk strains of oral HPV that indicate increased cancer risk. Again, men were vastly more at risk for these strains than women, with 6.8 percent of men infected, compared with 1.2 percent of women.
Schaffner said the report sheds light on one reason head and neck cancers were increasing.
"HPV is associated with these cancers," he said. "What we see is that the proportion of people carrying, at any one moment, HPV in their throats is very substantial. It adds to the understanding of why head and neck cancers are increasing."
More than 40 percent of the adult population studied in 2013 and 2014 had genital HPV, according to the report.
Researchers found 42.5 percent of people 18 to 59 had some form of genital HPV in the U.S. in the study period. Rates were slightly higher in men than women, with 45.2 percent of men infected, compared with 39.9 percent of women.
Almost two-thirds of black adults studied during this time, or 64.1 percent, were infected with genital HPV. They were followed by Hispanic adults, who had a 41.4 percent rate of infection; white adults, who had a 40.0 percent rate of infection; and Asian adults, who had a 23.8 percent rate of infection.
High-risk genital HPV
About 1 in 5 people ages 18 to 59 had high-risk genital HPV, which increases the likelihood of developing cancer. Researchers found 22.7 percent of these adults had strains of high-risk HPV, with 25.1 percent of men affected, compared with 20.4 percent of women.
Black adults were most at risk, with a 33.7 percent rate of infection, compared with a 21.7 percent rate of infection in Hispanic adults, a 21.6 rate of infection in white adults and a 11.9 percent rate of infection in Asian adults.
While the study did not examine HPV vaccination rates, Schaffner hoped the findings would encourage more parents to have their children vaccinated against HPV.
"It reinforces powerfully the current standard recommendations of the CDC [and other groups] that all boys and girls — preteens and teens — should be vaccinated with HPV vaccine," he said.
The CDC reports that HPV vaccination rates remain significantly lower than the goal of 80 percent. In 2015 the CDC reported that 42 percent of girls 13 to 17 had received all three doses in the series and that 63 percent had received at least one dose of the HPV vaccine. In boys 13 to 17, approximately 28 percent received all three doses and 50 percent received at least one dose.
The full series of the vaccine can prevent infections from the strains of HPV, which the National Cancer Institute said are associated with 70 percent of cervical cancers and "an even higher percentage of some of the other HPV-associated cancers."
The CDC advises that boys and girls should be routinely vaccinated for HPV starting at age 11 or 12.