Article by Anne Tordoff BVSc MRCVS
Newcastle Disease
Whilst struggling to think what veterinary topic I should write about this time, the outbreak of Newcastle Disease last month provided the answer and stimulated me to put pen to paper.
Causal Agent
Newcastle Disease is caused by a Paramyxovirus which may be endemic in certain wild bird populations. It is highly infectious and affects the majority of bird species from pigeons to ostriches including poultry and waterfowl.
There are isolated outbreaks of disease occurring the world over, the last one in the UK being, 1997, before the present outbreak.
Clinical Signs
Like many poultry diseases, this can be very difficult to diagnose clinically as the signs can be so variable and often one sick bird looks very like another whatever the cause.
There is a very acute form with sudden onset of high mortality,
A more variable form with symptoms that include:- Depression, Off food, Respiratory distress with beak gaping, coughing, sneezing stinking yellow/green diarrhoea, Nervous signs such as “off its legs” or torticollis (twisted neck)
And a milder form which may only show as loss in egg production often with soft shelled eggs or mild respiratory disease.
Some birds may harbour disease without showing any outward signs.
Disease Control
The virus is spread by - direct contact with secretions / excretions especially faeces from infected birds, - contaminated feed, water, implements, premises, clothing etc.
Both live and dead vaccines are available to protect poultry
Once disease has been confirmed on a premise the response is governed by: The Diseases of Poultry Order 2003 and The Avian Influenza and Newcastle Disease (England and Wales) Order 2003
On the infected premise there is compulsory slaughter of diseased poultry and those considered exposed to infection, eggs will be destroyed and there is no movement of birds, litter, or initially, vehicles on or off the premise. There will be cleansing and disinfection of the premise and vehicles.
There is compensation for non-diseased birds taken for compulsory slaughter.
An infected area is declared within a 10km radius of the infected premise.
Within this area there are movement restrictions on poultry and hatching eggs, poultry must be kept within their living quarters, and no markets, fairs or shows are allowed to take place. Restrictions will remain in place for at least 30 days after disinfection has taken place.
