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Newcastle disease
What is it?
A highly contagious viral disease, Newcastle disease affects almost all domestic and wild bird species. Domestic fowls, turkeys, pigeons and parrots are most susceptible, with milder disease generally seen in ducks and geese.
Where is it found?
Strains of Newcastle disease virus are present in most countries. Relatively mild strains are endemic in Australia, which is free of the most virulent forms. There have been several outbreaks of virulent Newcastle disease in Australia; the most recent was in New South Wales in 2002.
What are its effects?
Signs vary according to the strain of virus and the age, health and species of the bird. Signs of disease usually occur five or six days, but can be up to 15 days after infection.
Newcastle disease affects respiratory, nervous and digestive systems. Signs in poultry range from mild respiratory disease to severe depression, rapid breathing, diarrhoea, swollen tissue around the eyes, collapse, paralysis and death. Severe outbreaks can kill all birds in an infected flock within 72 hours.
Spread of the disease is usually by direct physical contact with infected or diseased birds. The virus can be present in manure and breathed out into the air, on contaminated equipment and on or in carcases, water, food or clothing.
Stringent quarantine and strict controls over the movement of anything that may have been contaminated by the virus are essential to successful eradication. The most efficient means of controlling an outbreak is the immediate slaughter and incineration or burial of all birds in an affected flock.
Newcastle disease virus can remain infective for several weeks on feathers, manure and other materials, and indefinitely in frozen material; however, it is easily destroyed by heat (including direct sunlight) or acids or alkalis.
Newcastle disease poses no health risk to consumers of poultry or poultry products. Human infection is extremely rare and results in mild, short-term conjunctivitis or flu-like symptoms, generally only in people such as poultry workers who have been in close direct contact with infected birds.
Newcastle disease is not the same as avian influenza – it belongs to a completely different family of viruses.
What’s the risk to Australia?
In April 1999 an outbreak of the disease in NSW resulted in the slaughter of 1.9 million meat chickens, 13,000 laying hens, 5000 ducks, 3000 meat pigeons, 60,000 pullets, 17 ostriches and more than 2000 domestic birds. The outbreak cost almost $24 million to eradicate.
An outbreak of virulent Newcastle disease would have many social and economic costs. The Australian Bureau of Agricultural and Resource Economics has estimated the short term total loss to Australian society from a significant outbreak would amount to about $50 million a year, made up of losses to producers and costs to consumers due to higher prices.
Australia has strict quarantine over imports of birds and bird products. Live birds and eggs can only be imported through special quarantine facilities. Quarantine officers also interview visitors to Australia to make sure they’re not carrying items that could carry Newcastle disease virus.
Northern Australia Quarantine Strategy (NAQS) fact sheet on Newcastle disease
Product Integrity/Animal and Plant Health information on Newcastle disease