Two chicken vaccines have recombined to produce more virulent viruses in Sydney and Melbourne, research has found, prompting the regulator to examine new controls over the approval and use of veterinary vaccines.
A study by a team from the Asia-Pacific Centre for Animal Health at the University of Melbourne and NICTA found that two different vaccine viruses used to control a chicken respiratory disease — the herpesvirus infectious laryngotracheitis (ILT) — have recombined, or crossed, to form two new virulent forms of the ILT virus.
The findings are published today in the journal Science.
As a result of the discovery, the Australian Pesticides and Veterinary Medicines Authority (APVMA) is considering new measures to regulate the use of vaccines in animals, the body said.
Australian strains of ILT vaccine were developed from the 1950s. In 2008, shortly after authorities approved a European strain for use, two new ILT strains were observed in outbreaks of disease in New South Wales and Victorian flocks.
Study author Joanne Devlin, a Doctor of Veterinary Science at the University of Melbourne, said the viruses emerged “mainly around the outskirts of Melbourne and Sydney, which is where a lot of our poultry production takes place”.