Newcastle disease.

Since 1926, there have been three epizootics of ND. The latter two have been directly linked with psittacine species and Racing Pigeons. The modern poultry industry is extremely vulnerable to the effects of NDV, once it gains entry to any facet of the industry. Consequently considerable expense and effort are expended to keep the virus at bay. The main threat continues to come from psittacine species and racing pigeons. The considerable international trade in these birds, together with rapid air transport, can allow virulent NDV to gain entry to a country while exotic birds are incubating the disease. It is hoped that quarantine barriers and requirements will prevent the virus from entering a country, but smuggling continues and constitutes the biggest risk. Domestic avian pets are also vulnerable to the virus. It is hoped that new in vitro testing procedures, such as monoclonal antibody and oligonucleotide fingerprinting techniques, may be used to identify rapidly and characterize emergent virulent strains, so that appropriate measures may be taken to prevent infection of commercial poultry and domestic pets.