Luca Cegolon1, William Heymann2. 1. London School of Hygiene & Tropical Medicine, Department of Infectious Disease Epidemiology, London, UK; Padua University, Department of Medicine, Padua, Italy. E-mail: l.cegolon@gmail.com. 2. Florida Department of Health, Sarasota County Health Department, Sarasota, Florida, US. E-mail: heymannwc@aol.com.