New research into chicken vaccines
The international journal Science has published a paper which concludes that virus strains in two animal health vaccines have combined to form more virulent viruses. The vaccines were developed to treat a common disease in poultry called infectious layngotracheitis (ILT).
The paper, which was published on 13 July 2012, says that these more virulent strains are contributing to disease outbreaks in poultry flocks in Australia, where the two vaccines have been used in combination.
- There are no immediate concerns over recombination of ILT vaccines in New Zealand because we use a different vaccine regime to Australia. New Zealand has only one registered vaccine for ILT, containing one strain.
- ILT is not transmissible to humans
- The report will be treated as new information and the Ministry for Primary Industries will consider its findings before deciding how they apply to New Zealand.
Questions and Answers
What are the paper’s findings?
The paper found that two different vaccine strains of the ILT virus have been able to recombine (cross) to generate more virulent viruses. However, flocks can be vaccinated against these new viruses.
What is ILT virus?
ILT virus causes an acute respiratory tract disease in chickens. The disease spreads through flocks and can kill up to 20 per cent of the birds. ILT is not transmissible to humans.
Is ILT Virus in New Zealand?
Information gathered to date indicates that the prevalence of ILT in New Zealand is low in poultry flocks. Adverse event reports do not indicate increased instances of ILT or issues with the current registered New Zealand vaccine.
Is this going to happen in New Zealand?
The likelihood of a similar scenario of recombination occurring in New Zealand remains very low as New Zealand has only one registered vaccine for ILT, containing one strain. This vaccine has been registered for approximately 36 years.
In the Australian case, two ILT vaccines using different strains of the same virus (one native Australian strain, one European strain) were used concurrently in the same flocks.
Is New Zealand getting diseased chickens from Australia?
Importation of live poultry into New Zealand is not permitted. Hatching eggs are permitted to be imported into New Zealand and are subject to import health standard requirements. However, ILT is not shown to be transmissible in eggs.
The importation of raw chicken meat to New Zealand is not permitted. The process of cooking chicken meat would kill the virus.
What happens now?
The Ministry for Primary Industries is considering the report.
It will work closely with relevant authorities to evaluate the information in light of the way that vaccines are registered, sold and used in New Zealand.