Toronto, Canada – Although Canada has remained free of the highly virulent strains of Infectious Bursal Disease (IBD) found in other regions of the world, the disease continues to represent an important challenge for commercial broiler production. At the 27th edition of World’s Poultry Congress (WPC 2026), aviNews International spoke with Dr. Babak Sanei, Associate Director for Poultry and Aquaculture at Zoetis Canada, about why IBD continues to deserve producers’ attention and how surveillance and vaccination strategies can help minimize its impact.
IBD is a global disease. Strains circulating in North America, and specifically in Canada, are primarily variant strains, which differ from the highly virulent forms reported in regions such as Latin America, the Middle East, and parts of Europe. While these variants rarely produce obvious clinical disease or high mortality, they can cause substantial immunosuppression, reducing flock resilience and increasing susceptibility to other infectious diseases.
A “Silent” Disease with Major Economic Consequences
Unlike more aggressive IBD strains that produce visible disease outbreaks, the Canadian variants primarily target the Bursa of Fabricius, the organ responsible for the development of B lymphocytes in young birds.
Damage to this organ during the first 5 to 6 weeks of the bird’s life, which concurs with the time the broilers are grown in Canada, compromises the immune system without producing clear clinical signs, making the disease difficult to detect under field conditions.
“Directly, it doesn’t cause any disease or mortality, so that’s why it’s silent, but it does cause immunosuppression and predisposes for secondary infection”, says Sanei.
Why Controlling IBD is Critical to Canada’s Industry
The importance of controlling IBD extends beyond the disease itself. Canadian poultry producers are simultaneously managing other significant pathogens, including Inclusion Body Hepatitis (IBH) and Infectious Bronchitis (IB), particularly the DMV 1639 strain. When birds are already immunosuppressed by IBD, these diseases can become considerably more severe, leading to higher mortality, poorer performance, and greater economic losses. Rather than acting independently, multiple immunosuppressive pathogens may interact within the same flock, emphasizing the need for comprehensive disease prevention strategies.
Regional Surveillance Supports More Precise Vaccination Programs
One of the key messages from the interview was the importance of ongoing surveillance to understand the regional distribution of IBD variants across Canada.
For more than a decade, Zoetis has collaborated with veterinarians and diagnostic laboratories to characterize circulating field strains through voluntary surveillance programs, via the company’s Diagnostic Offering. These efforts have identified two predominant variant groups with distinct geographic distributions.
“In western Canada, we have the Delaware E variant or BC variant affecting the broiler flocks, while in eastern Canada there’s another variant called Pennsylvania strain or South African) variant”, highlights Sanei.
Understanding which strain is circulating allows veterinarians and producers to make better-informed vaccination decisions and adjust their disease control strategies according to regional disease pressure.
Maternal Immunity and Hatchery Vaccination Remain Essential Tools
Canadian vaccination programs are designed to protect broilers throughout their relatively short production cycle. Protection begins with intensive vaccination of broiler breeder flocks, which receive multiple live and inactivated IBD vaccines and become hyperimmunized, in order to generate a strong maternal antibody transfer to their offspring. These maternal antibodies generally protect broiler chicks during their first two weeks of life. However, as maternal immunity declines, birds become increasingly susceptible to field exposure. To bridge this immunity gap, hatchery vaccination has become a cornerstone of Canadian IBD prevention programs. In ovo vaccination, hatchery spray vaccination, and, in some cases, additional live vaccination during grow-out (15-17 days of age) are used to extend protection through market age.
The optimal vaccination strategy depends on several factors, including local disease pressure, circulating variant strains, and regional epidemiology.
Recognizing the Threat Before Clinical Disease Appears
Because variant IBD rarely produces obvious clinical signs, Dr. Sanei emphasizes the importance of proactive disease management. He encourages veterinarians and producers not to underestimate the disease simply because mortality is absent.
As Canada’s poultry industry continues to address multiple infectious challenges simultaneously, understanding the silent effects of IBD, and tailoring vaccination programs accordingly, remains an important component of protecting flock health, productivity, and overall production efficiency.