1. a Enteric Diseases Epidemiology Branch , Centers for Disease Control and Prevention , Atlanta , USA
2. b HOPE worldwide , Lagos , Nigeria
3. c Society for Family Health , Abuja , Nigeria
4. d Rollins School of Public Health , Emory University , Atlanta , USA
5. e Biostatistics Information Management Branch , Centers for Disease Control and Prevention , Atlanta , USA
6. f Population Services International , Washington , DC , USA