Newcastle disease (ND)
Occurrence: Worldwide. Very common. Very virulent NDV is a notifiable disease
Species affected: All. One of the most common respiratory diseases of poultry.
Age affected: All.
Causes: Virus- Newcastle disease virus is a single-stranded, non-segmented enveloped RNA virus belonging to the family Paramyxoviridae. There are three pathotypes: lentogenic (mild disease), mesogenic (moderate disease) and velogenic (severe morbidity and mortality). Spread is airborne by inhalation or by ingestion of the virus.
Effects: Incubation period is 2-15 days. Paralysis, incoordination and central nervous signs following the initial respiratory signs are diagnostic of NDV. Watery eyes and a plug in the eye are seen with lentogenic strains. Coughing, gasping and sane mortality are seen with mesogenic strains. Egg production and quality are affected. It may produce torticollis, paralysis and bloody diarrhoea. High morbidity and mortality occur with velogenic pathotype.
Special note: VVND is a notifiable disease. It is a very common viral disease of poultry worldwide. Most poultry are vaccinated several times against this virus.
This disease was named after a town in England where it was first seen. All species of birds of all ages are susceptible to this acute to chronic disease. It is one of the most common respiratory diseases of poultry and occurs worldwide. The agent involved in the aetiology of this disease is a single-stranded, nonsegmented, enveloped, RNA virus belonging to paramyoviruses. Three pathotypes or strains exist. The lentogenic cause mild disease, the mesogenic produce moderate disease and the velogenic produce severe morbidity and mortality.
Mode of transmission
It is airborne and spread by inhalation or ingestion of virus. Free-flying birds maybe infected with lentogenic viruses and can spread them readily. Exotic birds and backyard birds from tropical areas are also commonly infected with velogenic viruses.
The incubation period is 2-15 days. Watery eyes and a plug in the eye are seen with lentogenic strains. Coughing, gasping and sane mortality are seen with mesogenic strains. It affects egg production and quality (brown broiler eggs turn to white eggs). It may produce torticollis, paralysis and bloody diarrhoea. High morbidity and mortality occur with visceral tropic velogenic (VVND). VVND (exotic) rarely occurs in commercial poultry in the United States. Outbreaks in pet bird populations are more frequent. It is a common problem in many countries such as the Middle East, Africa and the Far East.
Vaccination at day of age in the hatchery using a course spray machine. In areas with VVND multiple live and a killed vaccine can be given to broilers. Pullets and often layers are given multiple live and killed NDV vaccines. B1 type B1 strain and Lasota strains are normally used. A recombinant NDV vaccine also is available for hatcheries by in ovo or SQ injection.
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