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Newcastle Disease
Where does the name come from?
Which species are affected?
What are the symptoms?
Is there a public health risk?
Where is the disease found and how is it spread?
Where and when have Newcastle disease outbreaks occured in Australia?
What is known about Newcastle diseases viruses circulating in Australian poultry flocks?
How can you destroy the virus?
What should be done when an outbreak occurs?
How are infected birds and product disposed of?
Is it the same as bird flu?
What is the impact on our overseas trade?
Further information on Newcastle disease
What is Newcastle disease?
Newcastle disease (ND) 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 (low virulence) to a rapidly fatal (highly virulent) condition.
Where does the name come from?
ND first came to international attention in Newcastle on Tyne, England, in 1926. The name has nothing to do with Newcastle in New South Wales, Australia.
Which species are affected?
ND 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 (virulent) forms of the disease. The incubation period is usually 5 – 6 days, but can vary from 2 – 15 days.
Strains of ND virus that cause no disease, known as avirulent, low virulence or lentigenic strains, are common in Australian poultry flocks.
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 and when have Newcastle disease outbreaks occured in Australia?
- September 1998 - western Sydney and Rylstone, New South Wales;
- April 1999 - Mangrove Mountain, New South Wales;
- August 1999 - western Sydney, New South Wales;
- January/February 2000 - western Sydney and Tamworth, New South Wales;
- May 2002 - Meredith, Victoria; and
- October 2002 - western Sydney, New South Wales.
Each outbreak was successfully eradicated. In most cases the number of farms involved was small. The Mangrove Mountain outbreak required destruction and disposal of 1.9 million birds from 32 commercial flocks as well as several non-commercial flocks.
In each case the ND virus is thought to have evolved from certain low-virulence Australian strains that caused little, if any, disease. There is no evidence that Australian outbreaks have been caused by a virus recently introduced from overseas.
What is known about ND viruses circulating in Australian poultry flocks?
In January 2001 a national survey was conducted to collect information on the type and distribution of ND viruses in Australian poultry flocks. The survey detected no virulent ND virus, and no ND viruses similar to the viruses associated with the New South Wales outbreaks. All ND viruses detected were V4 virus (a low-virulence strain which can be used for vaccinating birds) or V4-like viruses genetically remote from virulent ND virus.
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? celsius 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 as quickly as possible and disposing 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.
Australia's strategy for responding to an outbreak of ND is described in the Australian Veterinary Emergency Plan (AUSVETPLAN) 
PDF [469kb]
Under an agreement between the Federal Government, the state and territory governments and industry, the costs of controlling and eradicating the disease are shared.
How are infected birds and product disposed of?
Destruction of potentially infected birds, and disposal of destroyed birds and potentially contaminated or infected products are undertaken in conjunction with, respectively, animal welfare authorities and the relevant State Environment Protection Authority.
Is it the same as bird flu?
No - the two diseases are entirely unrelated. Avian influenza (which has been responsible for the H5N1 ‘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. Where importing country conditions require Australia to be free of the disease, export of poultry and poultry products from Australia is suspended if an outbreak is suspected or confirmed. The Australian Quarantine and Inspection Service (AQIS) then contacts importing countries and Australia’s overseas posts regarding amended conditions for trade in these commodities.
As required under international obligations, Australia also notifies the World Organisation for Animal Health (OIE) when a virulent strain of ND has been identified.
Further information on Newcastle disease.
Newcastle disease information - AHA
Newcastle disease management plan - AHA
OIE technical disease card on Newcastle disease
