Brief report: Mobility and circular migration in Lesotho: implications for transmission, treatment, and control of a severe HIV epidemic.

We analyzed georeferenced data on mobility and HIV infection from the 2009 Demographic and Health Survey of Lesotho. We found ∼50% of the population traveled in the preceding year. By constructing gender-specific mobility maps, we discovered that travel is highest in the urban areas bordering South Africa and in the mountainous interior of the country. For both genders, increased mobility was associated with increased levels of "recent" sexual behavior. Notably, mobility was only associated with an increased risk of HIV infection for men who traveled frequently. We discuss the implications of our results for designing effective treatment programs and HIV interventions.