With human papillomavirus, girls and women have been getting all the attention.
Parents across the United States have rushed to have their daughters vaccinated against the virus. States are wrestling with whether to require adolescents be vaccinated.
And recent research found that HPV infection rates among girls and women are higher than previously thought - more than one-quarter of females ages 14 to 59.
Now the attention is turning to boys and men.
As many as 60 percent of men ages 18 to 70 are infected with HPV, according to data not yet published, raising the question of whether the new vaccine will be effective unless men, not just women, are immunized.
Several studies are under way to better understand the virus in males and whether the new HPV vaccine, Gardasil, also will work for them.
"With any transmittable disease, you want to understand the entire cycle of how things spread," says Thomas Broker, an HPV expert and professor of biochemical and molecular genetics at the University of Alabama, Birmingham. "With HPV, men are clearly part of that equation."
Human papillomavirus is best known for causing cervical cancer, with about 9,700 cases diagnosed in women in the United States each year.
Gardasil, a three-shot regimen, was approved last year for girls and women ages 9 to 26. It protects against four strains of the HPV virus that are most likely to cause cervical cancer and genital warts in women.
But much less is known about the consequences of HPV infection in men.
"We know they transmit it to women, but what is the rate of transmission?" says Anna Giuliano, a researcher at the H. Lee Moffitt Cancer Center and Research Institute in Tampa, Fla., who is leading three government-funded studies on HPV infection in men. She is also a paid speaker for Merck, the maker of Gardasil.
Several studies are attempting to address this and other questions. New data show that HPV infection is quite common in men of all ages, while the highest rates of infection in women tend to occur in the early 20s, and then again among women in their 40s and 50s.
"We're seeing a really high prevalence in men, and we see little change in prevalence across the age span," says Giuliano, who found the 60 percent prevalence rate in a study to be published this spring in the journal Cancer Epidemiology Biomarkers & Prevention. "We need to know if women in their 40s and 50s are acquiring new infections from their partners."
