1. Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
2. Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
3. Kilimanjaro Christian Medical Center, Moshi, Tanzania
4. Department of Biology, Campbell University, Buies Creek, NC, USA
5. Experimental Biology Research, Abbott Laboratories, North Chicago, IL, USA
6. Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC, USA