Reported increases in unprotected sexual behaviors and risk taking since the arrival of protease inhibitors in 1996 threatens to eliminate any benefits from such antiretroviral therapy to reduce sexual infectiousness, according to a new study in the journal AIDS, AIDSmap reports ( 7/10).

The impact of antiretroviral therapy on sexual transmission has been the subject of intense debate when some experts—including renowned HIV researcher Dr. Julio Montaner—have said an individual with an undetectable viral load is not infectious. Much of the discussion has centered on increased sexual risk taking canceling out any gains in antiretroviral therapy effect on infectiousness.

The recent AIDS report, which focused on sexual HIV transmission among gay men in the Netherlands, concluded that unprotected behaviors must be reduced to pre-1996 levels for treatment to have an impact on the gay HIV epidemic there.

“On the basis of these model estimates,” the study’s authors wrote, “[antiretroviral therapy] has played an important role in limiting transmission, but that any gains made have been more than offset by increases in the risk behavior rate.”