The human papillomavirus (HPV) spreads surprisingly quickly between two people in a new relationship, a new study finds.
In fact, couples in the study were actually more likely to be infected with the same strain or strains of HPV if they had been together less than one year, as opposed to a longer period, the researchers said.
"HPV is very infectious," said study researcher Alan Nyitray, of the H. Lee Mofitt Cancer Center and Research Institute at the University of South Florida. "When a couple comes together...they're going to share their HPV microbiota very, very quickly."
But people clear the virus at different rates, and so couples who have been together longer are less likely to "match" in terms of their HPV status, Nyitray said.
The study also found that in general, it's common for couples to be infected with the same strain of HPV, or to both be free of infection. About one fourth of heterosexual couples in committed relationships in the study shared at least one strain of HPV, the researchers found. And in more than a third of couples, both people were HPV free.
Nyitray emphasized that for most people, HPV infections are transient, and are not something to worry about.
But because the virus is known to cause cervical cancer, women should undergo regular screening for this cancer, Nyitray said. In addition, those eligible for HPV vaccination should receive it, Nyitray said.
Nyitray and colleagues tested 88 couples ages 18 to 70 for HPV infection. Seventy-five percent had been in a monogamous relationship for at least the last six months. None of the participants had a disease associated with HPV.
Overall, about 55 percent of men and 45 percent of women were infected with any strain of HPV.
In 31 couples (35 percent), neither partner had an HPV infection, while 21 couples (24 percent) shared at least one strain of HPV.
In 11 couples (12 percent) both people were infected with HPV, but did not share strains, and 25 couples had only one partner with an HPV infection (28 percent.)
Couples were more likely to share HPV strains if both people were of similar age, a finding that may be related to the strength of the immune response to HPV in older versus younger people. Couples with one young person, who may be exposed to the virus for the first time and take longer to clear it, and one older person, who may clear the infection more quickly, may be less likely to have "matching" strains, the researchers said.
Pairs were more likely to be HPV free if, together, the sum of their total lifetime sexual partners was low, Nyitray said.
Better immunity in women?
Among the couples in which one partner had HPV and the other did not, in 17 cases it was the woman who was HPV free, while in 8 couples it was the man. This finding suggests women have a stronger immune response to HPV, the researchers said.
Couples who were monogamous were no more likely to be infected with the same HPV strains than couples who were not monogamous.
Because the study was small, and monogamy was defined as sex with one partner for at least 6 months, more research is needed to confirm the results, and to see what happens in couples that are monogamous for longer periods, the researchers said.
Nyitray and colleagues are now analyzing information from a second study that followed the participants for two years. Nyitray said he hopes future research will reveal other ways to prevent spread of HPV between sex partners besides vaccination, which currently, most people do not receive.
The study will be published July 15 in the Journal of Infectious Diseases.
Pass it on: About 1 in 4 couples share an HPV infection.