So what is going on here? There are several possible explanations for why the foreskin may be promoting infection and transmission of infection to female partners, Tobian says. There may be micro-tears in the skin that lead to higher viral infection. Perhaps the quality of foreskin allows for easier infection of epithelial cells. It's also possible that the moist environment beneath the foreskin may be favorable to infection.
"Once you remove that area," Tobian says, "it's harder for the virus to enter and infect."
And when the infection rate is lower for men, they are less likely to transmit this infection to their female partners. This is especially important, Tobian says, because an HPV infection -- unlike HIV can clear and become non-active.
"Viruses are permanent, but the activity of the virus is what we're more concerned with," says director of Gynecology at Albert Einstein Medical School Dr. Erika Banks. "It's not really HPV that's the problem, it's the persistence of infections with high-risk strains."
Study authors cautioned, however, that while circumcision reduced the risk of infection, it did not eliminate the need for other forms of protection from sexually transmitted diseases. They said men should still use condoms and women should get the HPV vaccine.
For developing nations with particularly high levels of HIV and HPV, circumcision may offer a cost-effective means of reducing transmission rates in an environment where access to vaccines and medical care are lacking.
"Circumcision may offer a low cost minimal risk one-time procedure that could decrease the transmission of the virus that can cause cervical cancer" in developing nations who do not have access to regular screenings, says Banks.
In Africa circumcision programs to provide the procedure to adult males have been "ramping up," says Dr. Thomas Quinn, co-author on the study and researcher for Johns Hopkins University and the National Institute of Allergy and Infectious Diseases. For instance in Kenya, more than 250,000 males have been circumcised so far as part of HIV prevention programs sponsored by the government.
Back in the U.S., the health benefit may not be as "imminently relevant," she says, but the evidence is compelling enough nonetheless to consider strengthening recommendations for circumcision.
American Academy of Pediatrics recommendations say the data are "not sufficient to recommend routine neonatal circumcision," and as a result, Medicaid in many states does not cover the practice. The academy is currently reviewing the recent data emerging from African studies like Thursday's in order to update the guidelines.
"The data on sexually transmitted diseases [and circumcision] are the data we didn't have five to ten years ago when we were making the recommendations," says Dr. Doug Diekema, a member of the academy's circumcision task force. He says new recommendations will likely come out within a year. Though he couldn't say for certain whether the academy's stance on circumcision would change, he said he "wouldn't be very surprised if the academy leaves it ultimately up to the parents and says it's the physician's job to make sure the parents understand fully the benefits and risks of this procedure."
Study authors are hoping for a more substantial change in policy, however.
"We are not at all mandating that everyone should be circumcised, but we disagree that the evidence is 'conflicting' as the AAP says. We believe the public should be aware of the existing evidence and it should be a decision among parents that are informed of this evidence," Tobian says.
"There's no doubt that male circumcision provides a certain degree of protection against sexually transmitted diseases," adds Quinn, "and male circumcision needs to be reevaluated by leading health authorities as to its true public health benefit, not just to men but to future female partners."