Human papillomavirus, or HPV, is easily transmitted during sex, but it is unlikely to be passed by the hands, Canadian researchers report.
The virus, which infects the skin and genitals, is a cause of several types of cancer in both men and women, including cervical cancer, as well as tumors of the vagina, penis, anus and throat.
Because HPV strains on your hand usually match those found in your genital area or your partner's, some researchers have speculated that hand-to-genital sexual contact might spread the infection.
This new study puts that theory to rest, said lead author Talia Malagon. She's a postdoctoral researcher at McGill University in Montreal.
"Just because we detect HPV DNA in the hand doesn't necessarily mean the viral particles are viable or that there is enough to cause an infection," she said in a university news release. "The DNA might just have been deposited on the hand because a person recently had sex or touched their own genitals."
That's exactly what the researchers found.
For the study, Malagon and her colleagues enlisted hundreds of heterosexual partners who provided hand and genital samples every few months. Researchers analyzed the HPV DNA to see who became infected over time.
People were more likely to become infected when their partner was HPV-positive in the genitals or hands, the investigators found. But the risk was mostly attributable to genital HPV infection, the findings showed.
When researchers accounted for this, the risk of being infected by the hands disappeared.
This finding does not mean it's impossible to transmit HPV from hand-genital sex. But if this mode of infection occurs, the researchers haven't seen it, so it's unlikely, they explained.
Most sexually active adults will become infected with HPV at some point -- without even realizing it -- before their immune system clears the virus, said study co-author Eduardo Franco. He is chairman of the Gerald Bronfman Department of Oncology at McGill.
Condoms can reduce the risk, but they only provide partial protection from infection, he said.
"The most effective prevention against infection and the cancers HPV causes is therefore vaccination," Franco said. In the United States, experts recommend that all girls and boys receive the HPV vaccine starting at age 11 or 12. It's also advised for young adults who did not get it when they were kids.
In addition, Franco noted, "women can also get screened to prevent HPV infections from progressing to cervical cancer."
The report was recently published online in The Lancet Infectious Diseases journal.
To learn more about HPV, visit the U.S. Centers for Disease Control and Prevention.
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