Genotype D4 was no longer isolated after the end of 2006, being replaced by B3 genotype starting in October 2006. Despite an accurate epidemiological investigation, the origin of this genotype was not identified. B3 is not considered endemic in Italy and is most frequently detected in Sub-Saharan Africa, although transmission of this virus within Europe has been reported. The isolated B3 was similar, but not identical, to the strain circulating in UK in 2005 [12] . This serotype was first identified in Lazio and subsequently introduced in Puglia (Figure 4) , a region of South Italy, where it was responsible for an outbreak from November 2006 to January 2007 [21] .