Newcastle disease: a review of field recognition and current methods of laboratory detection.

Newcastle disease (ND) remains a constant threat to the poultry industry and is a limiting disease for poultry producers worldwide. The variety of clinical presentations and the emergence and spread of new genetic variants make recognition and diagnosis challenging. The current review details the pertinent features of the clinicopathologic disease in the main susceptible species, including chicken, turkey, duck, goose, pigeon, and other birds such as cormorants, psittacines, and canaries. Furthermore, the available and emerging laboratory diagnostic methodologies for the detection and typing of the virus are reviewed, including traditional techniques such as virus isolation and immunohistochemistry as well as rapid procedures based on molecular tools, such as real-time polymerase chain reaction, gene sequencing, and microarrays. The relevant genetic variability of ND viruses probably represents the major limitation in the validation and application of the current, advanced diagnostic molecular techniques. This underscores the importance of a multidisciplinary and comprehensive diagnostic approach, which should include, next to the new generation assays of the genomic era, the more traditional techniques such as histopathology, immunohistochemistry, and virus isolation.