Background: HIV epidemics around the world have been linked to injection drug use. In many instances, the injected drugs are acidic. HIV-1 is known to be labile to acids, but its susceptibility to acids in the conditions in which illicit drugs are injected is unknown.
Methods: We have combined data from ethnographic studies of injection drug use practices with laboratory virology to replicate and evaluate the effects of exposure to acids that are experienced during drug preparation and injection on HIV-1 viability.
Results: Short exposures to the acids significantly reduced the likelihood of recovering viable HIV-1 once pH is reduced to 2.3, but acidic solutions did not totally eliminate infectious HIV-1 that might contaminate syringes or solutions being injected, even at the lowest pH tested (pH 1.7).
Conclusions: Acidification of drugs, which is required for dissolving free-base formulations of drugs, can significantly reduce but not eliminate the likelihood that syringes previously used by HIV-1-infected injection drug users infect the next injector. Methamphetamines, which are manufactured under extremely acidic pHs, are unlikely to harbor viable HIV if stored or sold in contaminated injection equipment.