What newer ILT genotyping reveals about outbreak sources and vaccination
Recent genotyping of U.S. infectious laryngotracheitis cases indicates that most isolates are non-vaccine field strains, particularly Group 6. The findings suggest vaccination decisions should rely on current diagnostic evidence rather than assumptions that outbreaks stem from CEO vaccines. Effective control still depends on proper vaccine application, biosecurity, and data-driven management.
Diagnostic genotyping from a North Carolina laboratory examined more than 200 ILT samples in 2024. About 87% belonged to Group 6, described as a non-vaccine field strain; early 2025 data showed a similar share, near 89%. This challenges older assumptions that many outbreaks originated from CEO vaccines.
ILT was once viewed mainly as seasonal, but testing now indicates year-round pressure. The virus can spread quickly, with high illness and typical mortality of 10% to 20%. Control combines careful modified-live vaccine delivery—correct water withdrawal, stabilizers, dye checks, line flushing, and bird movement—with strong biosecurity.
The findings may influence how poultry veterinarians and producers design vaccination and biosecurity programs. If diagnostic evidence reduces mistaken blame on CEO vaccines, farms could avoid unnecessary changes and focus resources on field-strain control. This may help protect flock health and stabilize poultry meat and egg supply, though outcomes depend on application quality, biosecurity compliance, and continued surveillance.