1. School of Public Health Sciences, University of Waterloo , 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
2. Western Province Health Office , Plot No. 4503, Independence Avenue, Mongu, Western Province, Zambia
3. School of Public Health, University of Hong Kong , 7 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, China
4. Department of Anthropology, University of Waterloo , 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada