By Rachael Rettner, Senior Writer
Published: 05/20/2014 11:20 AM EDT on LiveScience
More than two-thirds of healthy Americans have a human papillomavirus (HPV) infection on some part of their body, a new study suggests.
Researchers examined DNA from tissue samples of about 100 men and women and found that 69 percent were infected with HPV.
The most common place to have an HPV infection was the skin — 61 percent of participants had an HPV infection on the skin, followed by 41 percent who had vaginal infections, 30 percent who had mouth infections and 17 percent who had gut infections. [Quiz: Test Your STD Smarts]
Altogether, the researchers found 109 strains of HPV, out of 148 known strains.
However, most of these infections are likely harmless, as participants did not have symptoms of illness, the researchers said. Just 4 percent of people in the study were infected with HPV-16 or HPV-18, the two strains of HPV that cause the majority of cervical cancers.
"We don’t want people to be alarmed," about the commonness of this infection, said study researcher Dr. Zhiheng Pei, a pathologist at New York University's Langone Medical Center. In fact, although people tend to think of viral infections as "bad," it's possible that infection with some HPV strains may have benefits, Pei said. For example, infection with some "good" HPV strains may stimulate the immune system so that the body is able to fight off the harmful, cancer-causing HPV strains, Pei said.
More research is needed to better understand how non-cancer causing strains of HPV interact with cancer-causing strains, the researchers said.
HPVs are a group of more than 150 related viruses that infect different parts of the body. Most infections go away on their own, but some can linger and lead to health problems, including genital warts and cancer, according to the Centers for Disease Control and Prevention. There are at least a dozen types of HPV linked to cancer, according to the National Cancer Institute.
Previous studies have shown that HPV infections are common. Most people get an HPV infection at some point in their lifetime, and a 2011 study found that, at any given point in time, about 42 percent of women have a genital HPV infection, the NCI says.
However, most earlier studies tested for only a small fraction of the known HPV types — those that are linked to cancer, Pei said. The method used in the new study detected all types of HPV, Pei said.
The researchers analyzed publicly available data from the National Institutes of Health, which was collected as part of a NIH project to understand how microorganisms affect health. The data included genetic information from tissue samples taken from participants' skin, vagina, mouth and gut. (Although HPV also infects the penis, the researchers were not able to look at penile infections, because samples from the penis were not collected in the NIH project.)
The study will be presented today (May 20) at the annual meeting of the American Society for Microbiology in Boston.