1. Institute for Global Health and Infectious Diseases, University of North Carolina at Chapel Hill , Chapel Hill, NC 27599 , USA
2. Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill , Chapel Hill, NC 27599 , USA
3. Carolina Population Center, University of North Carolina at Chapel Hill , Chapel Hill, NC 27599 , USA
4. Department of Entomology and Plant Pathology, North Carolina State University , Box 7613, Raleigh, NC 27695 , USA