Butt pirates, beware. In a study of 64 HIVer men who have sex with men, University of Washington researchers unexpectedly discovered more virus in rectal secretions (saliva-like fluids from membranes down under) than in either blood or semen. The study, published July 1 in The Journal of Infectious Diseases, reported average viral-load counts 25 times higher in booty swabs than in cum shots from guys not receiving HIV meds.

While stunned by his data bombshell, the lead reasearcher Richard Zuckerman, MD, cautions against drawing conclusions about bottom-to-top infection rates, since the study did not examine transmission. “Although HIV levels in rectal secretions are higher,” Zuckerman said, “the insertive partner is exposed to the secretions for a shorter period of time than the receptive partner, who may be exposed to semen long after intercourse.”

A 1999 transmission study reported that bareback catchers risked infection rates 4 to 14 times higher than pitchers’—a stat supporting longstanding anecdotal reports that condomless topping was relatively unrisky. Zuckerman says more studies are needed to examine how other factors may increase viral loads and infectivity. “These data are intriguing, but really bring home the message that HIV transmission is complex and in the future prevention will need to be addressed in a number of ways. Currently, condom use is the most important means we have.” Now that’s an indisputable position.