Poultry, Fisheries & Wildlife Sciences
Open Access

Newcastle Disease

Newcastle disease is an infection of domestic poultry and other bird species with virulent Newcastle disease virus (NDV). 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. Severity depends on the virulence of the infecting virus and host susceptibility. Occurrence of the disease is reportable and may result in trade restrictions.

NDV, synonymous with avian paramyxovirus serotype 1 (PMV-1), is an RNA virus and the most important of the 11 known PMV serotypes as a pathogen for poultry. The original classification of NDV isolates into one of three virulence groups by chicken embryo and chicken inoculation as virulent (velogenic), moderately virulent (mesogenic), or of low virulence (lentogenic) has been abbreviated for regulatory purposes. Velogens and mesogens are now classified as virulent NDV (vNDV), the cause of Newcastle disease and reportable infection, whereas infections with lentogens, the low virulence NDV (loNDV) widely used as live vaccines, are not reportable. Clinical manifestations vary from high morbidity and mortality to asymptomatic infections. Severity of infection depends on virus virulence and age, immune status, and susceptibility of the host species. Chickens are the most and waterfowl the least susceptible of domestic poultry; however, some differences may be seen if the NDV strain is adapted to a particular species.