H7N9 bird flu strain appears in U.S. for first time since 2017

A Mississippi operation had to cull more than 47,000 chickens

A strain of bird flu not seen in the United States since 2017 has re-emerged.

A poultry flock at an operation in Mississippi’s Noxubee County is infected with the H7N9 strain of avian influenza, the USDA’s Animal and Plant Health Inspection Service confirmed on March 12.

The Mississippi Board of Health also confirmed the H7N9 presence that date.

As a result, 47,654 chickens will be depopulated from the broiler facility.

None of the infected birds entered the food system.

The U.S. last encountered H7N9 in poultry flocks in March 2017.

At the time, two broiler breeder flocks in Lincoln County, Tenn., were infected with the illness.

This resulted in the culling of nearly 129,000 chickens combined.

The reappearance of H7N9 is occurring as U.S. farmers continue to try to keep the H5N1 strain at bay.

As of March 18, more than 166 million poultry have been affected by the H5N1 strain, and 989 dairy herds have been affected too.

Both strains can be worrisome for poultry producers.

The H5N1 strain can cause “almost 100% mortality in affected poultry,” but the H7N9 strand of bird flu doesn’t “cause obvious symptoms in poultry thereby increasing the difficulty of virus tracking and surveillance,” the U.S. National Library of Medicine says.

The symptoms of both strains are similar.

Poultry infected with either strain can have reduced egg production or respiratory issues.

Some symptoms more associated with H5N1 include swelling around the head, neck and eyes.

Resources about what to look for, how to protect flocks from infection, and the current U.S. situation can be found on the USDA’s website.