Washington: If a person is infected with human papillomavirus (HPV), there`s a 20 percent chance that his or her partner will pick up the virus within six months, a new study has found.
The study, the largest-yet analysis of HPV transmission cases and published in the Journal of Infectious Diseases, found no difference between male-to-female transmission rates and female-to-male transmission rates.
It also found no link between the number of partners in a person`s sexual past and their chances of picking up HPV, the most common sexually transmitted virus that can cause genital warts as well as cervical cancer.
Most cases only last a year or two, but other cases can linger for longer and lead to cancer.
"There`s been very little work done on how frequently HPV transmits. Most of the work on HPV has revolved around how common it is within a population," study author Ann Burchell, of McGill University in Montreal, was quoted as saying by LiveScience.
Combining the data on transmission and frequency, she said, can help researchers get a fuller picture of how the virus spreads.
To study how often HPV spread from an infected person to an uninfected sex partner, Burchell and her team looked at hundreds of college-age women in relationships and identified 179 couples in which one person was infected with HPV, but the other wasn`t.
Four months after the study began, Burchell asked the couples to return to the clinic for follow-up testing and questionnaires.
When the researchers tallied the final numbers of who had been newly infected with HPV, they found that the overall probability of transmission was 20 per cent over a six-month period.
According to the researchers, the couples reported having sex four times a week, on average, and 50 per cent said they never used condoms.
Other smaller studies have suggested that HPV more easily spreads from females to males than from males to females. The new study, however, saw nearly similar rates of transmission in both the cases.
"Our hypothesis is that female-to-male transmission may occur more often, but results in shorter infections, and by the time we saw these couples again, some of those male infections had cleared," Burchell said.
Researchers had also previously hypothesized that those who`ve had many sexual partners are more likely to have gained immunity to HPV -- so they were thought to be less likely to pick up a new HPV infection from a current partner.
When someone is infected with a virus, the body often saves antibodies to fight off the virus in the future.
The new study, however, found no correlation between the number of sex partners and immunity.