Infectious laryngotracheitis (ILT) is a highly contagious viral respiratory infection of chickens and pheasants and the disease is notifiable in most Australian states. A number of other bird species such as turkeys, ducks, geese and quail can be carriers of the virus and recovered birds are long-term carriers. Mortality and morbidity rates vary but mortality in young birds can be as high as 80% and the disease can cause a severe drop in egg production in laying flocks. Clinical signs include watery eyes, wheezy and gasping breathing, watery discharge from nostrils, sneezing and coughing of mucous and blood.
ILT is caused by a herpesvirus. The virus is spread by direct contact with infected birds or through contact with contaminated dead birds, bird tissue, equipment, housing, humans or other animals. Although the virus is easily killed by disinfectants, fumigants and direct sunlight it can survive in infected litter for up to 2 months and dead carcasses for up to 12 months. Outbreaks tend to occur in areas of high broiler farm density and vaccination may be the only avenue of control.
There are no specific treatments for the disease but antibiotics to control secondary bacterial infections may reduce losses. Vaccination is available using attenuated live vaccines but this approach perpetuates the disease. Good biosecurity principles such as effective sanitation and quarantine procedures are important control measures. The A20 vaccine strain was developed in Australia and is mild enough to be used in young broilers (when it’s available).