WASHINGTON (Reuters) - Circumcision may reduce a man’s risk of infection with the AIDS virus by up to 60 percent if he is an African, but it does not appear to help American men of color, U.S. researchers reported on Monday.

A man receives a free circumcision on the island of Jolo, southern Philippines March 3, 2007. Circumcision may reduce a man's risk of infection with the AIDS virus by up to 60 percent if he is an African, but it does not appear to help American men of color, U.S. researchers reported on Monday. REUTERS/Darren Whiteside

Black and Latino men were just as likely to become infected with the AIDS virus whether they were circumcised or not, Greg Millett of the U.S. Centers for Disease Control and Prevention found.

“We also found no protective benefit for a subset of black MSM (men who have sex with men) who also had recent sex with female partners,” Millett told reporters in a telephone briefing.

Doctors believe circumcision protects men because of specialized cells in the foreskin of the penis, which is removed in the procedure. The foreskin is filled with immune cells called Langerhans cells, which are the immune system’s sentinels and attach easily to viruses -- including HIV.

In addition, sexual intercourse may cause tiny tears in the foreskin, allowing the virus into the bloodstream.

The data has been so clear that the World Health Organization now recommends circumcision as one of the ways to prevent HIV infection. But circumcision does not protect men 100 percent -- the studies in Africa have suggested it is 50 to 60 percent protective.

Millett’s team studied 1,079 black and 957 Latino bisexual and homosexual men from New York City, Los Angeles, and Philadelphia. They filled out a computer survey and were tested for the AIDS virus.

“Overall, we found no association between circumcision status and HIV infection status among black or Latino (men who have sex with men),” said Millett, who presented his findings to the CDC’s National HIV Prevention Conference in Atlanta.

Experts knew circumcision would not protect a female sex partner, nor the male sex partner being penetrated.

But Millett’s study found no benefit of circumcision to any of the men. “We also found no protective benefit of circumcision among those men reporting recent unprotected sex with a male partner in which they were exclusively the insertive male partner,” he said.

HIV is much more common among black and Latino men than whites and this may offset any protection offered by circumcision, Millett said. Black and Latino men are more likely to have sex with other black and Latino men, and thus may be exposed to HIV more often than white men.

The CDC is about to release new estimates of how many people become infected with the fatal and incurable human immunodeficiency virus each year in the United States.

The CDC estimates that more than 1 million Americans are infected, of the 33 million infected people globally.