Foreskin Raises HIV Risk 6 to 8 Times but Doesn't Affect Other STDs
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March 25, 2004 -- It's long been noted that uncircumcised men are more likely that their foreskin-shorn brethren to acquire the virus that causes AIDS. What's less clear is whether it's because of their sexual behavior or that extra flap of skin.
In the latest study to try to settle the issue, Johns Hopkins researchers provide some compelling evidence that it's the foreskin itself. They find that independent of condom use or sexual activities, HIV infection occurs six to eight times more often in uncircumcised men than in those who have been circumcised.
In fact, despite their lower infection rates, circumcised men were more likely to report they didn't wear condoms during sex. Another twist: Unlike previous findings that also indicate a higher risk of other sexually transmitted diseases among the uncircumcised, the researchers find similar rates of those other STDS among both groups of men.
"What this suggests to us is there is something very specific concerning contact of the HIV virus in the foreskin that facilitates HIV transmission," says researcher Robert Bollinger, MD.
He points to what has been shown in previous studies: The foreskin is rich in certain cells that attract and bind with HIV. "These cells contain a marker that you might consider to be a magnet for HIV infection," he tells WebMD.
Bollinger, a professor of infectious diseases and international health, led a team of researchers to study how circumcision affects HIV infection rates among 3,000 men in India. That country has an estimated 5 million HIV patients, second in overall number only to South Africa, he says.
"It's been well known from previous studies that circumcised men have a lower risk of acquiring and transmitting HIV infection, but no one is quite sure why," he says. "Some have hypothesized that circumcision is culturally linked to lower-risk behavior, while others suggest that circumcision reduces the risk of genital ulcer diseases and other STDS that themselves are associated with increased risk of HIV."
But in his study, published in the March 27 issue of The Lancet, his team finds that uncircumcised men did not have higher rates of syphilis, gonorrhea, and the virus that causes genital herpes -- three STDs linked to higher risk of HIV infection.
This suggests that condom use remains important, even for circumcised men. "Circumcised men are not at zero risk, and we demonstrated that circumcised men have similar risks for other STDS that themselves increase risk of HIV infection. Wearing a condom remains very important," he tells WebMD.
His findings also give credence to efforts by drug companies currently working on products that contain virus-killing substances that could be wiped on the foreskin to reduce the risks of infection.
The men studied were primarily either Hindu, who are typically uncircumcised, or Muslim, who are circumcised. All were HIV-negative at the beginning of the study, which lasted seven years, and were evaluated at least three times at a clinic that treats people with sexually transmitted diseases. By study's end, uncircumcised men had been infected with HIV between six to eight times more than those who had been circumcised.
"This doesn't surprise me at all, since there have been more than 40 studies since 1987 showing that uncircumcised men are more likely to become infected with HIV than those who have been circumcised," says Edgar J. Schoen, MD, former chairman of the American Academy of Pediatrics Task Force on Circumcision. "In most of these studies, circumcision is associated with a two- to sevenfold lower risk of HIV infection."
Schoen, who served as chief of pediatrics for Kaiser Permanente in Oakland, Calif., agrees that circumcision causes a loss of cells that are the target for infection with the virus.
"But it's also believed that because foreskin tissue is very thin, the act of intercourse causes min-abrasions -- tiny cracks in the skin -- that allows the virus to enter the body," he tells WebMD. "That doesn't happen with a circumcised penis."
SOURCES: Reynolds, S. The Lancet, March 27, 2004; vol 363; pp 1039-1040. Robert Bollinger, MD, professor of infectious diseases and international health, Johns Hopkins School of Medicine, Baltimore. Edgar J. Schoen, MD, private practitioner, Oakland, Calif.; past chairman, American Academy of Pediatrics Task Force on Circumcision; retired, chief of pediatrics, Kaiser Permanente, Oakland.