BEIJING, March 19 (Xinhuanet) -- Although girls and women have been getting all the attention, recent unpublished data reveals as many as 60 percent of men between the ages of 18 and 70 are infected with human papillomavirus.

    American parents and states legislatures are debating whether vaccination should be mandatory, while researchers are trying to determine if the new vaccine will be effective in blocking diseases linked to the virus unless men also are immunized.

    Several studies are underway to better understand the virus in males and whether the new HPV vaccine, Gardasil, also will work for them. As researchers already know and as the new data confirms, HPV is not just a women's issue.

    "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 by the Food and Drug Administration last year for girls and women ages 9 to 26. It protects against four strains of the HPV virus 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 question, as well as ones about what strains of HPV are most common in men. 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 before declining and then spiking again in women in their 40s and 50s.

    HPV infection isn't inconsequential in men. Certain strains of the virus are known to cause genital warts in men as well as women.

    Those infections are estimated to be the cause of about half of all anal, penile, vulvar and vaginal cancers and about 20 percent of the cause of all oral cancers, says Dr. Dean Blumberg, an associate professor of pediatric infectious disease at UC Davis. Blumberg is a member of Merck's speakers bureau but does not get paid directly by Merck for his services. A speaker's bureau is a roster of experts who provide educational lectures on particular topics.

    Worldwide, the consequences of HPV infection in both men and women are even more severe than in the United States, notes Broker, president of the nonprofit International Papillomavirus Society.

    More women in developing countries die of cervical cancer than in the United States, he says. Moreover, "we need to know how much real disease men are getting. If you look worldwide, there are about 100,000 new cases of penile cancer each year."

    (Agencies)