Clinical signs associated with Newcastle disease (ND) are variable. Affected birds can display any of the following signs:

• Sudden death or elevated flock mortality
• Decreased feed and/or water consumption
• Reduction in egg production or increased number of misshapen or shell-less eggs
• Swelling/cyanosis of comb/wattles
• Diarrhoea
• Depression, ruffled feathers.
• Respiratory signs: coughing, sneezing, breathing difficulty, increased respiratory rate
• Nervous signs: loss of balance, circling, convulsive somersaulting, spasms, tremors, stiff or wry neck, paralysis.

Post-mortem findings associated with ND are not pathognomonic (they can be found across a range of endemic, notifiable and emergency animal diseases of poultry) and may include:

• Tracheal haemorrhage and necrosis
• Air-sacculitis
• Necrosis and haemorrhagic lesions of the lymphoid dependant areas of the intestinal tract (eg. caecal tonsils, Peyer’s patches)
• Haemorrhage and congestion of various visceral organs such as the spleen, and proventriculus
• Thymic atrophy
• In birds in lay, egg yolk peritonitis, atrophied follicles and oviducal degeneration may be observed.

Virulent Newcastle disease (ND) is a nationally notifiable disease which means if you suspect an animal is showing signs of the disease, you must report it. If any bird owner is suspicious of ND, they should contact a veterinarian or the Emergency Animal Disease Hotline on 1800 675 888 to arrange for sampling and testing.

Notifiable disease testing is conducted by NSW DPI as a cost-free service to the submitter/owner.

As the clinical signs of Newcastle disease (ND) are so variable and can be similar to those observed in a range of other notifiable and endemic avian diseases, diagnosis of ND must be confirmed by isolation of the virus or identification of parts of the viral genome (polymerase chain reaction – PCR).

The NSW DPI Animal & Plant Health Laboratory (EMAI) utilises the following tests for ND testing:

• PCR: for confirmation or exclusion of infection using fresh tissue or swabs, see Table 1 for sampling requirements.
• ND antibody HI test: for surveillance, using clotted blood.

Table 1: Sampling requirements for ND exclusion testing via PCR

For veterinarians needing to submit to EMAI for ND testing, note the following:

• Place swab samples in transport media (PBGS) or in saline if other media is unavailable. PBGS can be obtained from the following:
• your local LLS District Veterinarian (1300 795 299),
• EMAI (1800 675 623), or
• Laboratory Services - Order media
  
• Chill swabs and unpreserved tissue samples at either 4°C (refrigerator) or with ice bricks.
• If whole dead birds are being submitted, they should be securely packed (i.e. double bagged and in a rigid container that is clearly labelled as SUSPECT NEWCASTLE DISEASE).
• Clearly label specimens and send in appropriate packaging via courier to the NSW APHL:

NSW Animal and Plant Health Laboratories 
Elizabeth Macarthur Agricultural Institute (EMAI) 
Woodbridge Road 
Menangle NSW 2568 
Phone: 1800 675 623

• If you do not routinely dispatch samples to EMAI, contact laboratory customer service (1800 675 623, laboratory.services@dpi.nsw.gov.au) in advance for assistance with dispatch logistics.

For more information on sample submission for ND testing, visit the NSW DPI Laboratory (EMAI) website .

Newcastle disease (ND) virus can be rapidly spread by close contact between birds or contact with bird faeces. Movements of contaminated people, equipment and vehicles are also possible pathways of ND spread.  Australia is currently free of virulent Newcastle disease (vND). There are two likely pathways for introduction of vND into Australia:

1. Australian origin avirulent ND viruses evolving to become vND.
2. Exotic ND variants entering Australia, e.g. via migratory birds, contaminated persons, poultry products or fomites.

ND viruses are classified based on their ability to cause disease in poultry, defined by their genetic characteristics as:

• Highly pathogenic/virulent (velogenic)
• Moderately pathogenic (mesogenic)
• Non-pathogenic/avirulent (lentogenic or v4-like).

Australia has experienced outbreaks of virulent ND in 1930 (Victoria), 1932 (Victoria), 1998 (Dean Park NSW), 1999-2000 (Mangrove Mountain, western Sydney and Tamworth, NSW), and 2002 (Meredith, Victoria and Horsley Park, NSW). The outbreaks from 1998 onwards evolved from endemically circulating ND viruses of lower pathogenicity.

vND has the potential to cause significant mortality in domestic poultry and wild bird populations. A significant outbreak of ND would have significant impacts due to the importance of poultry produce to the domestic economy and the costs associated with handling of an emergency animal disease response.

Newcastle disease can cause conjunctivitis and flu-like symptoms in humans. The risk of humans becoming infected with ND after contact with infected birds or bird carcasses is low; however, if suspect live birds or carcasses must be handled, precautions should be taken such as the use of a facemask, eye protection and gloves. If needing to move a bird carcass (e.g., for submission for testing, or disposal) an inverted bag should be used to grasp the carcass for secure bagging.

There is not any risk of ND to humans from eating cooked chicken meat or egg products.  Chicken meat or eggs from infected flocks cannot enter the human food chain, and the virus is killed through the cooking process.

1-Prevention and management

The ongoing risk posed by Newcastle disease (ND) in Australia is managed under the National Newcastle Disease Management Plan (NNDMP). Under the plan in NSW, all commercial poultry (flocks of 1,000 or more birds) are vaccinated against ND.

Furthermore, in NSW ongoing surveillance for ND in poultry occurs via submission to the NSW DPI Animal & Plant Health Laboratory, including:

• For broiler chicken flocks:
  • Any shed experiencing unexplained disease-related mortalities of 1% or more in 24 hours after the first week of placement
  • Any shed with evidence of respiratory signs lasting more than 2 consecutive days
  • Any shed with nervous signs
• For laying or breeding flocks:
  • Any shed suffering a 10% drop in egg production or the appearance of 5% white or shell-less eggs over a 2–3-day period
  • Any shed suffering increased mortality of more than 0.5% per day for 3-5 consecutive days
  • Any shed with nervous signs.

Vaccination of small flocks of poultry (fewer than 1,000 birds) is not required due to the lower risk scenario posed by smaller flocks in relation to ND. However, it is important to ensure a high level of biosecurity for small flocks to manage ND risk, including:

• Only sourcing new birds from reputable sources
• Isolating introduced birds or birds returning from exhibitions (minimum 21 days) before introducing them to the rest of your flock
• Preventing interaction between domestic and wild birds
• Preventing feed, water and bedding material from contact with wild birds or their faeces.

2-Additional information for veterinarians

National Newcastle Disease Management Plan (2020)

AUSVETPLAN Response Strategy – Newcastle Disease

NSW DPI Laboratory (EMAI) Website