After spending a year studying 156 penises in Uganda, researchers say male circumcision reduces bacteria on the penis, and perhaps is the reason why circumcision can protect men from contracting HIV.
Scientists have been studying the relationship between circumcision and rates of HIV for more than two decades, and this study led by the Phoenix-based Translational Genomics Research Institute (TGen) apparently provides the reason why.
Men who got circumcised just for this study had 33 percent less bacteria than the guys who kept their foreskins for the year after the study started.
"Past studies have shown that circumcision reduces female-to-male HIV transmission, among other benefits," according to TGen. "This study suggests a possible mechanism for HIV protection -- the shift in the number and type of bacteria living on the penis."
The public-health benefits, and other facts of circumcision have long been debated, and it looks like this study might further that.
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TGen says this research "could help to identify new intervention strategies for decreasing HIV transmission, especially for populations with high HIV prevalence and in places where male circumcision is culturally less acceptable."
Other studies have shown that circumcision reduces risk of infection of HPV and herpes, too, and this might be for the same reason that HIV transmission goes down.
According to the microbiology journal that published the study, the study's author "was circumspect about the implications of the study for public health and circumcision, preferring to focus on the implications it may have for other, less invasive interventions."