Changes

==Description==

==Description==

Newcastle disease virus (NDV) is the causative agent of Newcastle Disease, an acute viral disease of domestic poultry and many other bird species that is usually fatal. It is characterised primarily by respiratory disease but neurological and gastrointestinal signs may also be a feature of Newcastle Disease.  Virulent strains of the virus are endemic in most of Asia, Africa and South, Central and North America. Hosts of the virus include gallinaceous birds, pigeons, parrots and finches and the disease may be carried subclinically by ducks and ostriches.

Newcastle disease virus (NDV) (Avian Paramyxovirus type 1) is the causative agent of Newcastle Disease, an acute viral disease of domestic poultry and many other bird species that is usually fatal. It is characterised primarily by respiratory signs but neurological and gastrointestinal forms of the diseas may also be seen.  

==Transmission==

==Transmission==

Infected birds shed the virus through droppings and secretions from the nose, mouth and eyes. The virus may also be present in eggs laid during the clinical disease. The virus is commonly transferred by the movement of people and contaminated equipment.

Infected birds are the primary source of infection and shed the virus through droppings and secretions from the nose, mouth and eyes. The virus may also be present in eggs laid during the clinical disease. NDV is commonly transferred by the movement of people and contaminated equipment and birds are easily infected by inhalation of the virus or ingestion of contaminated feed or water.

==Clinical signs==

==Clinical signs==

NDV affects the gastrointestinal, respiratory and nervous systems and clinical signs reflect the system(s) affected. Clinical signs are usually acute and may appear throughout the flock within 2-12 days. Respiratory signs may include dyspnoea, sneezing, nasal discharge and coughing and are common with low virulence infections. Neurological signs such as tremors, paralysis, circling and depression may accompany respiratory signs and are often seen in cormorants and exotic bird species. Pigeons frequently display neurological signs accompanied by diarrhoea.

NDV affects the gastrointestinal, respiratory and nervous systems and clinical signs reflect the system(s) affected. Clinical signs are usually acute and may appear throughout the flock within 2-12 days with young birds particularly susceptible.

[[Image:Newcastle Disease.jpg|150px|thumb|right|''Newcastle Disease'' <br> L. Mahin, Wikimedia Commons]]

Clinical signs in affected birds are variable and a subclinical form of the disease can occur which may only be suspected following a drop in egg production. Respiratory signs may include dyspnoea, sneezing, nasal discharge and coughing and are common with low virulence infections. Neurological signs such as tremors, paralysis, circling and depression may accompany respiratory signs and are often seen in cormorants and exotic bird species. Pigeons frequently display neurological signs accompanied by diarrhoea.

 

[[Image:Newcastle Disease.jpg|150px|thumb|right|''Newcastle Disease'' <br> L. Mahin, Wikimedia Commons]]

Disease ranges from subclinical respiratory tract infections -> torticollis -> haemorrhages and death

==Diagnosis==

==Diagnosis==

Diagnosis is commonly performed using ELISA or PCR. In the UK, Newcastle Disease is notifiable and if suspected, must be reported to DEFRA. If the disesae is suspected, movement of birds, people, animals, eggs and vehicles may be restricted pending investigation by an Animal Health Veterinary Inspector. If the disease is confirmed, all poultry on the premises must be slaughtered and eggs must be destroyed. Thorough cleaning and disinfection of the premises must be carried out and an infected premises may not be re-stocked until at least 21 days after this as been completed.

1. Samples of trachea and gut of 20 birds are tested in eggs

'''HI''' using anti-NDV serum (to differentiate '''HA''' caused by [[Avian Influenza]]

 

2. DNA test (which will soon replace the animal test):

Sequencing the cleavage site of H gene

The more basic amino acids the more virulent the virus

==Control==

==Control==