1. Department of Demography, University of California , Berkeley, Berkeley, CA, USA
2. Department of Microbiology, University of Illinois Urbana-Champaign , Champaign, IL , USA
3. Department of Statistics, University of Illinois Urbana-Champaign , Champaign, IL , USA
4. Department of Epidemiology, School of Public Health, Brown University , Providence, RI , USA
5. Institute at Brown for Environment and Society, Brown University , Providence, RI , USA