A new U.S. study has found that being circumcised significantly reduced the risk of HIV
 infection in heterosexual African American men known to have been exposed to the virus.
 The findings complement those of recently reported clinical trials in Africa, where
 interventional use of adult male circumcision similarly reduced the risk of HIV infection in
 heterosexual men.

 The findings of the new study, along with similar results from other studies, suggest that
 circumcision may protect other heterosexual males in the U.S. The promising new findings
 are reported in the January 1 issue of The Journal of Infectious Diseases, now available
 online.

 Lee Warner, PhD, MPH, and colleagues at the Centers for Disease Control and Prevention
 (CDC) and the Johns Hopkins University School of Medicine studied the records of more
 than 26,000 African American men who had had HIV testing during visits to two Baltimore,
 Maryland, STD clinics from 1993 to 2000. The subjects selected for the study said that
 they did not inject drugs and had sex only with women. Their visits to the clinics were
 classified as involving known HIV exposure if there had been a recent notification of such
 exposure by a sex partner or by a clinic’s disease intervention specialists; clinic visits for
 other reasons were classified as involving unknown HIV exposure. By these criteria, the
 investigators found 394 visits with known exposure and 40,177 visits with unknown
 exposure.

 In visits by men with known HIV exposure, being circumcised was associated with a 51
 percent reduction in HIV prevalence (10.2 percent of circumcised men vs. 22.0 percent of
 uncircumcised men). In contrast, HIV prevalence did not significantly differ in circumcised
 compared to uncircumcised men with unknown HIV exposure (2.5 percent vs 3.3 percent).

 The investigators noted that three other U.S.-based studies had previously suggested that
 circumcision may be associated with reduced HIV risk, but the findings were limited by
 small sample size or extremely low HIV prevalence and did not achieve statistical
 significance. Indeed, HIV prevalence in the United States is very low (about 0.4 percent),
 and the proportion of circumcised adult males is high (about 80 percent), which could make
 it hard for conventional observational studies (i.e., studies that are not clinical trials) to
 discern whether circumcision actually has a protective effect. By focusing on patients who
 had documented exposure to an HIV-infected female partner, the current study was able to
 reveal that there was indeed a protective effect. This approach, the investigators said,
 “represents a significant methodological advancement over most previous observational
 studies.”

 In a separate editorial on the topic, Ronald H. Gray, MBBS, MSc, of Johns Hopkins  University, pointed out that circumcision may be especially important for minority U.S.
 populations, including Hispanic as well as African American men—subgroups most at risk
 for HIV infection. He also noted that the American Academy of Pediatrics has thus far not
 recommended routine neonatal circumcision, and that Medicaid does not cover the
 procedure.  “It is to be hoped,” he said, “that the paper by Warner et al., in conjunction
 with the weight of evidence from international studies, will persuade the Academy to
 recognize the public health importance of this surgery for prevention of HIV in minority U.S.
 populations.”