The aim of the project described in this report was to develop tests able to readily detect the presence of virulent (emergency) strains of Newcastle Disease Virus, and to readily differentiate them from the less virulent and benign forms of the virus that circulate all the time in parts of the Australian poultry industry. A specific aim was to be able to do this in flocks that had been naturally infected with benign viruses, an infection that naturally immunised them against the virulent disease. 2004, 21 pgs, pub no. 04/022; $16