“Circumcision reduces a man’s risk of acquiring and transmitting HIV and other sexually transmitted diseases, and now researchers have found a possible explanation: the procedure reduces the quantity and diversity of bacteria at the head of the penis,” the New York Times’ “Well” blog reports (Bakalar, 4/18). In a study published this week in mBio, “researchers studied the effects of adult male circumcision on the types of bacteria that live under the foreskin before and after circumcision,” and they found that one year post-circumcision, “the total bacterial load in that area had dropped significantly and the prevalence of anaerobic bacteria, which thrive in locations with limited oxygen, declined while the numbers of some aerobic bacteria increased slightly,” according to a press release from the American Society for Microbiology (4/16). “By reducing the number of anaerobic bacteria, the body’s immune cells may be better able to destroy the virus — and less likely to fall prey to its Trojan horse-style of attack, the authors suggest,” the Los Angeles Times writes. The newspaper notes, “Further research must be done to draw a direct connection between these changes in the microbiome and subsequent HIV infection” (Morin, 4/15).