Outbreak of Newcastle disease in commercial poultry flocks, NSW.

ND is a highly contagious virus disease affecting poultry, cage and aviary birds, and wild birds. There are a number of strains of the disease, which differ in the severity of their clinical signs, ranging from inapparent to a rapidly fatal condition. In its highly virulent form, ND can rapidly cause up to 100 per cent mortality in bird flocks and poses a devastating threat to the poultry industry. Strains are found in most countries but the virulent form has not previously occurred in Australia.