FRIDAY, Oct. 17 2003 (HealthDayNews) -- New research from India lends more support to the theory that uncircumcised men are much more likely to contract the AIDS virus from women during sex.

Due to the limitations of their studies, scientists haven't precisely linked lack of circumcision to higher rates of AIDS. But more definitive research results are expected in the next few years, and medical officials in Africa are already exploring the idea of circumcising adult men.

Many questions remain about circumcision campaigns, however. "Is it feasible, how do you provide the services, what are the obstacles, can it be done safely and affordably?" asks Daniel Halperin, an expert in AIDS and circumcision and senior technical advisor at the U.S. Agency for International Development.

Researchers began examining the relationship between AIDS and circumcision a few years after the epidemic began in the early 1980s. "At the time, there were a lot of questions about heterosexual transmission," Halperin said. "The big question was, how does a woman infect a man?"

Researchers noticed AIDS rates appeared to be higher in regions where circumcision wasn't practiced, Halperin says. Then, several studies suggested circumcision provides a protective effect against HIV transmission and men may be vulnerable without it.

In the new study, researchers examined the results of a larger study into risk factors for HIV infection among men who visited three sexually transmitted disease clinics in Pune, India. The researchers, including Indians and Americans, released their findings at the recent annual meeting of the Infectious Diseases Society of America in San Diego.

From 1993 to 2000, researchers enrolled 2,298 HIV-negative men in the study. Two of the 191 circumcised men became infected with HIV (0.7 percent) as did 165 of the 2,107 men (5.5 percent). In other words, the uncircumcised men were eight times more likely to develop HIV.

The rates of HIV infection between the two groups were similar even when other factors such as condom use and sexual behavior -- such as patronage of prostitutes -- were taken into account.

"The power in the study is its size and the rather definitive results," says Dr. Cynthia Sears, a professor of medicine at Johns Hopkins University and colleague of researchers who took part in the study.

The protective effects of circumcision seem to have something to do with the vulnerability of the foreskin to HIV infection, experts say.

The outside of the foreskin is tough and sturdy. But the inside layer is more delicate and filled with protective immune cells, Halperin says. "Unfortunately, when it comes to AIDS [the immune cells] are exactly where HIV enters the body, through the immune system."

The researchers behind the new study acknowledge the value of circumcision remains to be confirmed by more rigorous studies. Three are underway in Uganda, Kenya and South Africa.

For now, international medical officials are exploring whether adult men in Africa would accept circumcision. "Obviously, we're not going to go out there and cut men's foreskins against their will," Halperin say.

Surveys have shown that most men are indeed interested in circumcision, mainly because it would improve hygiene, Halperin says. "Some men are starting to hear about the AIDS data, and that's accelerating the interest in it."

In the United States, transmission of HIV from women to men remains relatively rare. Meanwhile, there has been little research into the role of circumcision in transmission between men, Halperin says.

Sears cautions that circumcision should not be seen as a magic bullet to prevent AIDS infection. "Circumcision does not replace safe sex and condom use," she says.

More information

Learn more about circumcision and HIV from this article in The Lancet. Or try the U.S. Agency for International Development.