Tissue viral load, as determined by RNA copy numbers, in organs harvested from birds experimentally infected with different WNV strains and euthanized on day 14 p.i. NY99, two birds euthanized; Greece-10, three birds; FIN, five birds; Ita09, two birds; and 578/10, three birds. Viral titres are represented as geometric mean±SD. A detection limit of 0.95 log10RNA copies g−1 was determined.