At the end of 2010 and beginning of 2011 several Newcastle disease outbreaks in unvaccinated poultry associated with pigeon paramyxovirus type 1 (PPMV-1) infection were officially reported by two northern European countries. Infected wild birds were suspected to be the source of the virus, presumably coming into contact with poultry, or gaining access to poultry houses, during the severe winter conditions. When PPMV-1 is found in any domestic poultry species, under EU legislation the infection must be regarded as Newcastle disease, with resultant sanitary and other disease control measures being implemented.