1. Department of Social Medicine and Postgraduate Programme in Infectious Diseases, Federal University of Espírito Santo , Vitória, ES 29043-900 , Brazil
2. Bristol Medical School, University of Bristol , Bristol, BS8 1UD , UK
3. Secretária de Vigilância em Saúde e Ambiente (SVSA), Ministério da Saúde , Brasília, DF 70655-775 , Brazil