In this week's PLoS Medicine Magazine, Daniel Halperin from the Harvard School of Public Health and colleagues examine reasons for the remarkable decline in HIV in Zimbabwe, in the context of severe social, political, and economic disruption.

Funding: Some of the studies upon which this paper is based were funded by the United Nations Population Fund (UNFPA), which provided some logistical support as well as helping with coordination between the studies. Two of the authors of this paper (Benedikt and Campbell) are employed by UNFPA and helped edit the manuscript. The United Nations HIV-AIDS Program (UNAIDS) and the Zimbabwean Ministry for Health and Child Welfare also sponsored this study. TBH and SG thank the Wellcome Trust for funding support. The funders had no other role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests: The authors have declared that no competing interests exist.

Citation: Halperin DT, Mugurungi O, Hallett TB, Muchini B, Campbell B, et al. (2011) A Surprising Prevention Success: Why Did the HIV Epidemic Decline in Zimbabwe? PLoS Med 8(2): e1000414. doi:10.1371/journal.pmed.1000414