A small new study suggests that some common beliefs about the spread of sexually transmitted diseases may not apply to human papillomavirus, also known as HPV.
“We shouldn’t assume that we understand transmission” of the virus, said study lead author Dr. Lea Widdice, an assistant professor of pediatrics at Cincinnati Children’s Hospital Medical Center.
Widdice and colleagues found evidence that heterosexual couples who share razors and towels and engage in some seemingly risky sexual practices aren’t at higher risk of giving the disease to each other. “This might be counterintuitive since HPV is thought to infect cells near abrasions and cuts,” Widdice said.
Still, Widdice said, the study findings are preliminary and based on an analysis of only 25 couples.
HPV is very common, and research suggests more than 80 percent of people will be exposed to it during their lives, Widdice said. It’s transmitted through skin and sexual contact, causing conditions like genital warts and abnormal Pap smears.
“Most people will clear the infection,” she said. “But the reasons why some women clear the infection and others can’t aren’t well understood.”
Women who fail to vanquish the virus can go on to develop cervical cancer.
Widdice and colleagues examined DNA tests of the HPV strains found in 25 couples. The average age of the men was 25 and 23 for the women. The goal was to determine how many of the couples shared the same strain of HPV, which would suggest that one partner gave it to the other.
The findings appear online in the Journal of Adolescent Health.
Couples who shared towels or razors and had sex involving fingers in anuses (six of the 50 people fell in that category) were less likely to share the same strain.
“Sharing towels and razors and certain types of sex may transmit HPV, but the virus doesn’t hang around and cause an infection,” Widdice said. “So the person can be exposed to the virus but doesn’t get infected. When the couple is tested, they don’t share the same types.”
It’s also possible that the immune systems of men and women respond differently to the virus, she said, with men perhaps being able to quickly eliminate it from their bodies.
Dr. Anna Giuliano, who studies HPV, said that while the new study is useful, researchers still need to figure out exactly how and when HPV is transmitted between couples.
“How many sex acts does it take to get a transmission event to occur? And over what period of time within a relationship: two weeks, one month? What is the probability that an infection will be transmitted from one partner to the next? That’s what we really need,” said Giuliano, chair of the Department of Cancer Epidemiology and Genetics at the H. Lee Moffitt Cancer Center in Tampa, Fla.
That kind of information will shed light on things like the cost effectiveness of vaccinating both men and women against HPV, she said.
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More information: Widdice LE, et al. Human papillomavirus concordance in heterosexual couples. J Adolesc Health online, 2010.