FRIDAY, Sept. 23 (HealthDay News) -- U.S. health authorities now recommend that girls and young women be vaccinated against human papillomavirus, a sexually transmitted disease that is a known cause of cervical cancer, but that recommendation does not extend to boys and young men.

At least for now.

A debate that's been simmering over whether males also should be vaccinated for human papillomavirus, or HPV, could be resolved in October at a meeting of a key advisory committee of the U.S. Centers for Disease Control and Prevention, said CDC spokesman Tom Skinner.

HPV is widespread among men. An international study published in March in The Lancet found that half of all adult males in the United States may be infected with the virus.

More than 40 strains of HPV exist, and all are passed along by skin-to-skin contact, usually during sexual relations, according to the U.S. Centers for Disease Control and Prevention.

The most well-known strain of HPV causes genital warts. But other strains show no obvious symptoms and clear up on their own with no medical treatment, said Dr. Jean Bonhomme, an assistant professor at the Morehouse School of Medicine in Atlanta and president of the National Black Men's Health Network.

"Because it normally causes no symptoms, men and women can get it and pass it on without even knowing they have it," Bonhomme said.

There is an eventual price to pay for infection, even without any obvious symptoms. HPV has been shown to increase a man's chances of contracting penile and anal cancer, particularly for gay males. Men who have sex with men are about 17 times more likely to develop anal cancer than straight men, according to the CDC.

"These are relatively rare cancers," said Debbie Saslow, director of breast and gynecologic cancer programs for the American Cancer Society. "However, for men who have sex with other men, their risk is significantly higher than the general population."

About 1 percent of sexually active men in the United States have genital warts at any particular time, according to the CDC. Annually, about 800 U.S. men contract HPV-related penile cancer and about 1,100 men get HPV-related anal cancer.

Because the virus spreads through skin contact, normal protections that prevent the spread of disease through body fluids won't work, Bonhomme said.

"Diseases like herpes and HPV cannot be completely prevented by condoms because they are both spread by contact with skin," Bonhomme said. "If the virus comes into contact with the scrotum or thighs, you can still be infected."

To make matters worse, men do not have the screening tools for HPV-related cancers that are available to women. A Pap test can detect cervical cancer in women, Bonhomme said, but there's no comparable test for penile or anal cancer in men. As a result, many men don't realize they have these cancers until they begin showing late-stage symptoms.

The U.S. Food and Drug Administration approved the HPV vaccine Gardasil for use in women in 2006. Three years later, the FDA approved a second HPV vaccine, Cervarix. Vaccination currently is recommended for 11- and 12-year-old girls and for young women ages 13 through 26 who have not yet been vaccinated.

"The idea is to vaccinate before they become sexually active," Saslow said. "Afterward, it's much less effective."

The debate now among public health officials is whether that recommendation should extend to boys and young men. A working group of the CDC's Advisory Committee on Immunization Practices reported in June that most of its members believe that males should be vaccinated for HPV and that the guidelines for males ought to be harmonized to match existing recommendations for females, according to slides from the meeting.

When it meets again next month, Skinner said, the committee will again take up the issue.

Saslow and Bonhomme said that beyond the direct health risks, there are other compelling reasons to extend HPV vaccinations to males.

For one thing, it would be simpler to vaccinate everyone than to have separate guidelines for boys and girls, Saslow said. There's also an argument for gender equity, in that only women are being vaccinated for a disease that affects both sexes, she added.

Another strong argument in favor of male HPV vaccination, Bonhomme said, is the fact that by only immunizing half the population, health officials are not attacking the problem with full force.

"Where are women getting the virus from?" he asked. "If you don't vaccinate the guys, then you aren't helping the women."

More information

The U.S. National Institute of Allergy and Infectious Diseases has more on HPV and genital warts.

A companion article offers a man's perspective on HPV.