Exotic Newcastle Disease Diagnosis
Information about how the disease is diagnosed.
The clinical signs of END closely resemble those of a number of other avian diseases including fowl plague, laryngo-tracheitis, the diphtheritic form of fowl pox in poultry, psittacosis, and Pacheco's disease in parrots.
Therefore, confirming a diagnosis through a veterinarian and clinical laboratory test is critical.
- Laboratory confirmation -
- The surest method for confirmation of END is the isolation and identification of the causative virus.
- Specimens for attempting viral isolation should be selected from cases in the early or even the prodromal stages of the disease. The END viral strains are widely distributed in the avian body, and can be isolated from lung, trachea, spleen, terminal gut, and brain.
- Tissue triturates or media from cloacal and tracheal swabs are inoculated into 8-11 day embryonated chicken eggs, and after a variable period of incubation, depending on the virulence of the strain, the virus will be found in the amnionic-allantoic fluids, which are then tested for avian erythrocyte agglutinating activity. Subsequently, it is determined if the hemagglutination reaction is inhibited by known ND antiserums.
- The Newcastle disease virus isolates are characterized by determining the time necessary to kill chicken embryos and the lesions produced in chickens inoculated with the virus.
- Clinical diagnosis -
- Respiratory and/or nervous signs:
- gasping and coughing
- drooping wings, dragging legs, twisting of the head and neck, circling, depression, inappetence, complete paralysis
- Partial or complete cessation of egg production
- Eggs are misshapen, rough-shelled, thin-shelled and contain watery albumen
- Greenish watery diarrhoea
- Swelling of the tissues around the eyes and in the neck
- Morbidity and mortality depend on virulence of the virus strain, degree of vaccinal immunity, environmental conditions, and condition of the flock