The emerging HIV epidemic on the Mexico-U.S. border: an international case study characterizing the role of epidemiology in surveillance and response.

PURPOSE Human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome surveillance data are critical for monitoring epidemic trends, but they can mask dynamic subepidemics, especially in vulnerable populations that underuse HIV testing. In this case study, we describe community-based epidemiologic data among injection drug users (IDUs) and female sex workers (FSWs) in two northern Mexico-U.S. border states that identified an emerging HIV epidemic and generated a policy response. METHODS We draw from quantitative and qualitative cross-sectional and prospective epidemiologic studies and behavioral intervention studies among IDUs and FSWs in Tijuana, Baja California, and Ciudad Juarez, Chihuahua. RESULTS The recognition that the HIV epidemic on Mexico's northern border was already well established in subgroups in whom it had been presumed to be insignificant was met with calls for action and enhanced prevention efforts from researchers, nongovernmental organizations, and policy makers. CONCLUSIONS Successful policies and program outcomes included expansion of needle-exchange programs, a nationwide mobile HIV prevention program targeting marginalized populations, a successful funding bid from the Global Fund for HIV, TB, and Malaria to scale up targeted HIV-prevention programs, and the establishment of bi-national training programs on prevention of HIV and substance use. We discuss how epidemiologic data informed HIV prevention policies and suggest how other countries may learn from Mexico's experience.