The rapidly changing HIV subepidemic at the border of the United States and Mexico, likely caused by population mobility and the drug and sex trades, may be rapidly affecting the overall HIV epidemic in Mexico. In a recent editorial, NIDA-funded researchers discussed studies of HIV infection at the United States–Mexico border in an effort to better understand factors shaping individual and network-level risks for acquiring HIV. Two different studies in the Mexican border cities of Tijuana and Ciudad Juarez showed a high prevalence of HIV infection among sex workers who were also injection drug users: 6 percent and 12 percent, respectively. Considerable population mobility exists at the Tijuana–San Diego (United States) border in both directions, with one study showing that one-fifth of injection drug users in Tijuana had traveled to the United States in the previous year. This mobility also occurs in other high-risk populations—for example, “nearly half of men having sex with men (MSM) in Tijuana and three-quarters of MSM in San Diego report having male sex partners from across the border,” explain the authors. The populations of border cities such as Tijuana largely come from other states in Mexico, and HIV-positive people can carry the infection back to their home states. Mexico now faces several challenges at the national level, including integrating treatment for HIV and other sexually transmitted infections that are risk factors for HIV infection, and increasing the availability of antiretroviral therapy. The authors conclude that due to the high level of migration in all directions, bordering countries must be involved for HIV prevention, diagnosis, and treatment in Mexico to be effective.

Source: Strathdee SA, Magis-Rodriguez C. Mexico’s evolving HIV epidemic. JAMA. 2008;300(5):571–573.