The reports in the Journal of Infectious Diseases are likely to add to the debate over whether men -- and newborn boys -- should be circumcised to protect their health and perhaps the health of their future sexual partners.

Dr. Bertran Auvert of the University of Versailles in France and colleagues in South Africa tested more than 1,200 men visiting a clinic in South Africa,

They found under 15% of the circumcised men and 22% of the uncircumcised men were infected with the human papilloma virus, or HPV, which is the main cause of cervical cancer and genital warts.

"This finding explains why women with circumcised partners are at a lower risk of cervical cancer than other women," they wrote in their report.

A second paper looking at US men had less clear-cut results, but Carrie Nielson of Oregon Health & Science University and colleagues said they found some indication that circumcision might protect men.

The circumcised men were about half as likely to have HPV as uncircumcised men, after adjustment for other differences between the two groups.

In the third report, Lee Warner of the U.S. Centers for Disease Control and Prevention and colleagues tested African-American men in Baltimore and found 10 percent of those at high risk of infection with HIV who were circumcised had the virus, compared to 22 percent of those who were not.

"Circumcision was associated with substantially reduced HIV risk in patients with known HIV exposure, suggesting that results of other studies demonstrating reduced HIV risk for circumcision among heterosexual men likely can be generalized to the US context," they wrote.

Studies supporting circumcision to reduce HIV transmission had all been done in Africa and US studies were less clear.

Dr. Ronald Gray of Johns Hopkins University in Baltimore and colleagues said they found the reports encouraging.

"In the United States, circumcision is less common among African American and Hispanic men, who are also the subgroups most at risk of HIV," they wrote in a commentary.

"Thus, circumcision may afford an additional means of protection from HIV in these at-risk minorities."

But they noted that the American Academy of Pediatrics does not recommend routine circumcision for newborns.

"As a consequence of this AAP decision, Medicaid does not cover circumcision costs, and this is particularly disadvantageous for poorer African American and Hispanic boys who, as adults, may face high HIV exposure risk," Gray and colleagues wrote.

"It is also noteworthy that circumcision rates have been declining in the US, possibly because of lack of Medicaid coverage."

Medicaid is the state-federal health insurance program for the poor and disabled.

Thirty-three million people globally are infected with AIDS, which has no cure and no vaccine. HPV is the most common sexually transmitted infection in the world, with 20 million people in the United States infected. It causes cervical cancer, which kills 300,000 women globally every year. - Reuters