In summer 2007, an outbreak of chikungunya fever affected the Italian provinces of Ravenna, Cesena-Forli, Rimini and Bologna [1, [42] [43] [44] . Health authorities identified 214 laboratory-confirmed cases with date of onset from July 15 to September 28 2007. Most cases (161) occurred in the two neighboring villages of Castiglione di Cervia and Castiglione di Ravenna, but five smaller clusters of local transmission were also detected in five towns in the same region (i.e., Cervia, Cesena, Ravenna, Rimini, and Bologna) which are located 9 to 75 km from the initially affected villages [1, [42] [43] [44] , see Fig. 3 .