Molecular characterization of measles virus is an important surveillance tool for monitoring measles elimination [15, 16] . In this case it was fundamental in tracing the origin of both outbreaks and showing that two distinct chains of transmission took place in the region. It is highly likely that the first outbreak, due to the D4 measles serotype, which is not endemic in Italy [12] , was imported from Romania. In fact, first cases occurred in families of Romanian nationality with family and social links in Romania. In addition, the D4 sequence identified among the first cases in Lazio was found to be identical to the D4 isolated in Romania during the 2004-2006 outbreak [17] in which over 4000 cases and 10 deaths occurred [18] .