The Tennessee state veterinarian confirmed March 9 that a flock of chickens at a commercial poultry breeding operation in the state has tested positive for low-pathogenic avian influenza (LPAI).

This chicken breeding operation is located in Giles County, Tenn. The company that operates it is different from the one associated with the recent detection of highly pathogenic avian influenza (HPAI) in Lincoln County, Tenn. At this time, officials do not believe one premises sickened the other. (For reference, Giles and Lincoln counties are adjacent to each other along the Tennessee-Alabama border.)

On March 6, routine screening tests at the Giles County premises indicated the presence of avian influenza in the flock. State and federal laboratories confirmed the existence of H7N9 LPAI in tested samples.

“This is why we test and monitor for avian influenza,” state veterinarian Dr. Charles Hatcher said. “When routine testing showed a problem at this facility, the operators immediately took action and notified our lab. That fast response is critical to stopping the spread of this virus.”

As a precaution, the affected flock was depopulated and has been buried. The premises is under quarantine. Domesticated poultry within a 10 km (6.2-mile) radius of the site are also under quarantine and are being tested and monitored for illness. To date, all additional samples have tested negative for avian influenza, and no other flocks within the area have shown signs of illness.

The primary difference between LPAI and HPAI is the mortality rate in domesticated poultry. A slight change to the viral structure can make a virus deadly for birds. Avian influenza virus strains often occur naturally in wild migratory birds without causing illness in those birds. With LPAI, domesticated chickens and turkeys may show little or no sign of illness. However, HPAI is often fatal for domesticated poultry.

The Giles County LPAI incident is similar to the Lincoln County HPAI incident in that both the low-pathogenic and highly pathogenic viruses are an H7N9 strain of avian influenza. The U.S. Department of Agriculture’s National Veterinary Services Laboratories confirmed that the H7N9 virus that affected the Lincoln County premises is of North American wild bird lineage. It is not the same as the China H7N9 virus affecting Asia and is genetically distinct.

The Lincoln County premises affected by HPAI remains under quarantine. To date, all additional poultry samples from the area surrounding that site have tested negative for avian influenza, and no other flocks within the area have shown signs of illness. Testing and monitoring continue.

Neither LPAI nor HPAI pose a risk to the food supply. No affected animals entered the food chain. The risk of a human becoming ill with avian influenza during poultry outbreaks is very low. However, out of an abundance of caution, officials with the Tennessee Department of Health and Tennessee Department of Agriculture are working together to monitor the health of individuals working on either premises or who had contact with affected birds.