Newcastle disease is a highly contagious disease of birds caused by a para-myxo virus. Birds affected by this disease are fowls, turkeys, geese, ducks, pheasants, partridges, guinea fowl and other wild and captive birds, including ratites such ostriches, emus and rhea.
Humans aren’t normally affected, but people in direct contact with infected birds may develop a very short-term eye infection, which passes without treatment.
The clinical signs in affected birds can vary. The disease can be present in a very acute form with sudden onset and high mortality or as a mild disease with respiratory distress or a drop in egg production as the only detectable clinical signs. A sub-clinical (asymptomatic) form of Newcastle disease and many intermediate forms of the disease can also occur. The main signs are:
- nasal discharge
- greenish, watery diarrhoea
- muscular tremors
- drooping wings
- complete paralysis
- swelling of the tissues around the eyes and in the neck
- sudden death
- increased death loss in a flock
- in laying birds there can be partial to complete drop in egg production; and production of thin-shelled eggs
How Newcastle disease is spread
The disease is transmitted through infected birds' droppings and secretions from the nose, mouth and eyes. The disease is spread primarily through direct contact between healthy birds and the bodily discharges of infected birds. Virus-bearing material can also be picked up on shoes and clothing and carried from an infected flock to a healthy one.
Possible routes of transmission therefore include contact between poultry and also through movements of contaminated vehicles, equipment, manure, feed and water.
The virus can survive for several weeks in a warm and humid environment on birds' feathers, manure, and other materials.
The disease is spread by direct contact with bodily fluids of infected birds, especially their faeces and aerosol contact.
Effective vaccines are available and some poultry are vaccinated routinely.
Human health implications
People may become infected with Newcastle disease virus, the resulting disease is typically limited to conjunctivitis. Recovery is usually rapid, and the virus is no longer present in the eye fluids after four to seven days. Such infections occurred mostly in laboratory workers and vaccination crews. No instance of transmission to humans through handling or consuming of poultry products is known.
How to control the disease
An outbreak will be controlled in line with the contingency framework for exotic notifiable animal diseases.
There is a legal requirement for all poultry keepers with 50 or more birds to register their premises on the Great Britain Poultry Register. The voluntary registration of premises with fewer than 50 birds is encouraged.
The Notifiable Avian Diseases Control Strategy sets out the disease control measures we would take if Newcastle disease was suspected or confirmed in the UK.
The best defence, as with all exotic animal diseases, is a high level of awareness and good biosecurity. Poultry keepers and businesses in Scotland are reminded of the importance of maintaining biosecurity in their flocks and being vigilant to any signs of disease in their birds.
Guidance published jointly by the Scottish Government, Defra, and the Welsh Government on biosecurity and preventing welfare impacts in poultry and captive birds is available.
If you suspect signs of any notifiable diseases, you must immediately notify your Scotland: field service local office at the Animal and Plant Health Agency (APHA). Failure to do so is an offence.
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