Newcastle disease virus surveillance in Hong Kong on local and imported poultry.

Surveillance of apparently healthy ducks, geese and fowl originating in Hong Kong and the People's Republic of China at a poultry dressing plant in Hong Kong yielded 67 isolates of Newcastle disease virus. More than twice as many viruses were isolated from the cloaca than from the trachea. Twelve representative isolates were examined in virulence tests--all six of the fowl isolates and two of five duck isolates behaved as velogenic strains, the other four were lentogenic.