Veterinary advisory: Update on ILT in Ontario — understanding the risks for infection in poultry (March 15, 2021)
Both small flock owners and commercial poultry producers should be aware of the risks for infectious laryngotracheitis (ILT) infection and spread between flocks and to surrounding farms.
From November 2020 to March 2021, ILT outbreaks have been reported in commercial flocks in Niagara Region and in small or backyard flocks in the counties of Bruce, Peterborough, Prince Edward, Simcoe and the district of Sudbury.
From November 2020 to January 2021, 7 premises in the Niagara region were involved in an outbreak of ILT. OMAFRA assisted the Feather Board Command Centre with an analysis of possible routes of transmission of the virus. While no direct epidemiological links were found, airborne transmission and movement of infected broilers to processing plants may have played a role in the outbreak. However, the spread of ILT by activities such as manure spreading or poor compliance with biosecurity could not be ruled out and are common risk factors for disease spread.
During outbreaks of ILT in small or backyard flocks in 2020 and 2021, OMAFRA found that birds came from a variety of sources and were often mixed with existing flocks. Mixing of birds with different health status is a significant risk factor for the introduction of ILT to a flock. Vaccinated birds should not be mixed with birds of unknown vaccination status. In addition, new birds should be segregated and monitored for at least 30 days before introducing them to an existing flock. New birds should always come from reputable suppliers that have strict biosecurity and disease controls practices in place, such as licensed brokers or dealers or registered hatcheries. All-in/all-out procedures are recommended to ensure that all the birds are of equal health status.
Following biosecurity measures and understanding the health status of the birds that are being purchased are critical to controlling ILT. Producers as well as small flock owners should work with their veterinarian to ensure that proper health protocols are followed. Veterinarians concerned about potential cases of ILT infection may contact an OMAFRA veterinarian through the Agricultural Information Contact Centre at
ILT is a contagious respiratory disease that causes morbidity and mortality in chickens and gamebirds. It is caused by a herpesvirus that is easily spread and can become activated during times of stress. Clinical signs of ILT include increased discharge from the nose and eyes, sneezing, coughing, gasping, blood stained mucus and severe drop in egg production. Morbidity is high (90-100%) while mortality can range from 5-20%. A laboratory diagnosis for ILT is required as other respiratory diseases of poultry can cause similar clinical signs.
ILT is not a food safety or human health concern.
ILT is most commonly spread by direct contact between infected and susceptible birds. The disease can also be spread by manure, equipment, clothing or bird carcasses contaminated with the virus. In some cases, wind-borne transmission or darkling beetles may play a role in the spread.
The disease is controlled through biosecurity, vaccination and communication. Biosecurity is critical to contain the disease through proper management of litter, cleaning and disinfection of facilities and stopping unnecessary visits by people. Litter should be heat-treated at 38°C (100°F) for 100 hours prior to movement and if possible should not be moved for 8 weeks to help destroy the virus. Vaccines for ILT are available, including attenuated or recombinant vaccines. Producers and small flock owners should consult a veterinarian for vaccination recommendations. All-in/all-out procedures should be used to avoid mixing infected and susceptible birds. Communication is essential to help industry and government manage the disease, especially in areas densely populated with poultry.
OMAFRA monitors cases of ILT in the province and works with industry through the Feather Board Command Centre, the Ontario Association of Poultry Veterinarians and the Ontario Animal Health Network to control the disease. ILT is an immediately notifiable hazard which requires all veterinary laboratories in Ontario to notify OMAFRA when the virus is identified by a laboratory test.
Further information on ILT can be found at: