Newcastle Disease (ND)
Questions & Answers
Newcastle disease is a highly contagious viral disease of domestic poultry, cage and aviary birds and wild birds. It is characterised by digestive, respiratory and/or nervous signs. The disease has a number of strains that differ in the severity of their clinical signs, ranging from inapparent infection to a rapidly fatal condition.
Where does the name come from?
Newcastle disease first came to international attention in Newcastle on Tyne, England, in 1926. It has nothing to do with Newcastle, NSW.
Which species are affected?
Newcastle disease virus can infect many species of domestic and wild birds. Most susceptible are domestic fowls, turkeys, pigeons and parrots. Milder disease is seen in ducks, geese, pheasants, quail, guinea fowl and canaries.
What are the symptoms?
The severity of the clinical signs is influenced by the strain of virus and the age, condition and species of the bird. Clinical signs in poultry range from a mild, almost inapparent respiratory disease to a very severe depression, drop in egg production, increased respiration, profuse diarrhoea followed by collapse, or long-term nervous signs (such as twisted necks) if the birds survive. Death rate can be up to 100 per cent in severe forms of the disease. The incubation period is usually 5–6 days, but can vary from 2–15 days.
Is there a public health risk?
Medical authorities have confirmed that the disease poses NO public health risk to consumers of eggs or poultry products. Chickens that show signs of disease are destroyed and are not used for human consumption; any virus in birds that failed to show symptoms would be completely destroyed by normal cooking.
Human infection with Newcastle disease virus is extremely rare, and usually occurs only in people who have close direct contact with infected birds — for example, poultry processing workers, veterinarians or laboratory staff. The virus causes only mild, short-term conjunctivitis or influenza-like symptoms.
Where is the disease found, and how is it spread?
Strains of ND virus are present in most countries, including Australia. Outbreaks of virulent ND in recent years in localised areas of NSW were eradicated between 1998 and 2001.
Spread is usually by direct physical contact with infected or diseased birds. The virus is excreted in manure and is breathed out into the air. Other sources of infection are contaminated equipment, carcases, water, food and clothing. People can easily carry the virus from one shed or farm to another.
Where did this outbreak originate?
The disease is suspected in only one layer farm in Western Victoria. Extensive investigation has not identified the way in which the virus was introduced to the flock. Tests carried out indicate that the virus responsible for this suspected outbreak is closely related to the viruses that caused outbreaks in NSW in recent years. These viruses evolved from an existing Australian strain. Further work is continuing to clarify these preliminary results.
There’s no evidence that this or past outbreaks have been caused by a virus recently introduced from overseas.
How can you destroy the virus?
The virus can easily be destroyed by heat or by treatment with acids or alkalis. It is destroyed by direct sunlight within 30 minutes, but in cool weather can survive in manure or in contaminated poultry sheds for many weeks. Normal cooking — at a minimum core temperature of 80°C for one minute, 75° for 5 minutes or 70° for 30 minutes — completely destroys the virus in meat.
What should be done when an outbreak occurs?
Accepted international practice is to attempt to stamp out (eradicate) the disease by destroying all birds that may have been exposed to the virus and to dispose of any infected or exposed products. This is done in conjunction with strict quarantine and movement controls to contain the virus; decontamination to remove any remaining virus; tracing and surveillance to determine the extent of infection; and zoning to define at-risk and disease-free areas.
Action will be taken to eradicate the disease from the farm through destruction of the flock and this will done as quickly as possible. The usual risk management strategies have been implemented in accordance with the emergency veterinary plan.
A new agreement between the Federal Government, State/Territory Governments, and industry has been invoked to share the costs of controlling and eradicating the disease in Victoria effective from May 8, the date of formal notification from the Victorian Chief Veterinary Officer of the suspect case.
In recognition of the future threat posed by Newcastle disease of Australian origin, an immediate review is to be coordinated by Animal Health Australia to consider the need for active monitoring and surveillance and compulsory vaccination.
How are infected birds and product disposed of?
Disposal of any destroyed birds and potentially contaminated or infected products is undertaken in conjunction with animal welfare authorities in strict accordance with standards and controls established by the relevant State Environment Protection Authority.
Is it the same as Hong Kong bird flu?
No — the two diseases are entirely unrelated. Avian influenza (which has been responsible for ‘Hong Kong bird flu’ outbreaks in recent years) is caused by an orthomyxovirus; Newcastle disease is caused by a paramyxovirus, a member of a different family of viruses.
What is the impact on our overseas trade?
Australia has a significant trade in poultry and poultry products, including day-old chickens. The export of poultry and poultry products from Victoria was suspended early on Saturday morning (May 11, 2002) as a precautionary measure ahead of confirmation. The Australian Quarantine and Inspection Service (AQIS) has contacted individual authorities as well as Australia’s overseas posts regarding trade in these commodities based on existing or revised certification.
As required under international obligations, Australia has also notified the world animal health organization (OIE) that a virulent strain of the disease has been identified. With the confirmation of the animal disease, the AQIS suspension has been extended to include the export of all poultry and poultry products where importing country conditions require Australia to be free of the disease. AQIS is contacting individual authorities and Australia’s overseas posts as required regarding the continuation of trade based on existing or revised certification and animal health measures applied by the Victorian Department of Natural Resources and Environment.
By Department of Agriculture and Water Resources - Last updated 16 November 2012
