1. Institute for Global Health and Infectious Diseases, University of North Carolina-Chapel Hill, 130 Mason Farm Road, Chapel Hill, NC 27599, United States of America (USA).
2. Department of Geography, University of North Carolina-Chapel Hill, Chapel Hill, USA.
3. University of North Carolina Project, Lilongwe, Malawi.
4. Department of Medicine, University of North Carolina-Chapel Hill, Chapel Hill, USA.