Detection of West Nile virus lineage 2 in mosquitoes during a human outbreak in Greece.

A human outbreak of West Nile virus (WNV) infections occurred in 2010 in central Macedonia, northern Greece. Most cases were observed close to four rivers forming a large Delta, a major Mediterranean wetland. WNV lineage 2 sequences were obtained from two pools of Culex pipiens mosquitoes trapped in sites where encephalitis cases occurred a few days before the trapping. The Greek strain showed the highest homology to Hungarian and South African strains, differing from the Russian WNV lineage 2 strain, which suggests that at least two lineage 2 strains have been introduced and established in Europe, causing severe disease to humans.