Submitted to: Merck Veterinary Manual
Publication Type: Book / Chapter
Publication Acceptance Date: January 30, 2014
Publication Date: January 31, 2014
Citation: Miller, P.J. 2014. Newcastle disease in poultry (Avian pneumoencephalitis, Exotic or velogenic Newcastle disease). Merck Veterinary Manual [online]. Available: www.merckmanuals.com/vet (search: Newcastle Disease in Poultry) Interpretive Summary: Newcastle disease viruses (NDV), also known as avian paramyxovirus-1 (PMV-1), are able to infect almost all bird species, and infections with virulent strains cause Newcastle disease (IND) leading to sickness and death. The disease is found around the world and is a big problem for poultry producers. The presence of virulent strains of NDV in poultry species is reportable and leads to the inability for those countries affect to trade their poultry products. The United States does not have virulent strains of NDV in their poultry, but these strains can be found in Rock Pigeons and Double Crested Cormorants. In addition to ensuring that wild birds do not mingle with domestic poultry, NDV vaccines are used to control ND. Live, inactivated and vectored vaccines are commercially available for chickens. Other Paramyxoviruses are found in wild birds, but only a few of these produce sickness in turkeys and chickens. There is a vaccine for PMV-3 for turkeys.
Technical Abstract: Newcastle disease (ND) is an infection of domestic poultry and other bird species with virulent Newcastle disease virus (vNDV). It is a worldwide problem that presents primarily as an acute respiratory disease, but depression, nervous manifestations, or diarrhea may be the predominant clinical form. Occurrence of the disease is reportable and may result in trade restrictions. Clinical manifestations vary from high morbidity and mortality to asymptomatic infections. The severity of an infection is dependent on virus virulence and the age, immune status, and susceptibility of the host species. Virulent NDV strains are endemic in poultry in most of Asia, Africa, and some countries of North and South America. Other countries, including the USA and Canada, are free of those strains in poultry and maintain that status with import restrictions and eradication by destroying infected poultry. Cormorants, pigeons, and imported psittacine species are more commonly infected with vNDV and have also been sources of vNDV infections of poultry. NDV of low virulence (loNDV) is prevalent in poultry and wild birds, especially waterfowl. Infection of domestic poultry with loNDV contributes to lower productivity. Infected birds shed virus in exhaled air, respiratory discharges, and feces during incubation, during the clinical stage, and for a varying but limited period during convalescence. Virus may also be present in eggs laid during clinical disease and in all parts of the carcass during acute vNDV infections. Vaccines are available for chickens, turkeys, and pigeons and are used to induce an antibody response that will make it necessary for the vaccinated birds to be exposed to a larger dose of vNDV to be infected. Unfortunately, ND vaccines do not provide sterile immunity and in many areas of the world vaccines are used to prevent losses from sickness and death. Well-vaccinated birds may not show any signs of being infected except for a decrease in egg production, but these birds will shed virus in saliva and feces. Poorly vaccinated birds may develop torticollis, ataxia and body or head tremors 10-14 days after infection and may recover with supportive care. While NDV (avian paramyxovirus-1 or PMV-1) is the most important pathogen for poultry of the 11 recognized PMV serotypes, PMV-2, -3, -6, and -7 are occasionally associated with disease in chickens and turkeys. Infections by PMV-2, -3, -6, and -7 in turkeys have produced mild to severe respiratory disease, drops in egg production, reduced hatchability and infertility of eggs, and increased numbers of white-shelled eggs. Infection with PMV-2 has produced mild respiratory disease in chickens, but PMV-2 infection is usually most severe in turkeys, especially breeders. No vaccines are available for PMV-2, -6, and -7. Inactivated oil emulsion vaccines against PMV-3 have been used in turkey breeder flocks.