1. Department of Global Health and Development, London School of Hygiene & Tropical Medicine , London WC1H 9SH, UK
2. Oswaldo Cruz Foundation-Fiocruz , Pernambuco 50740-465, Brazil
3. University of Brasilia , Brasília 70910-900, Brazil
4. Centro Acadêmico de Vitória, Federal University of Pernambuco , Recife, Pernambuco 55608-680, Brazil
5. Centre for Medical Sciences, Federal University of Pernambuco , Recife, Pernambuco 50670-901, Brazil
6. Department of Health Promotion, Federal University of Paraíba , João Pessoa, Paraíba 58051-900, Brazil