Bird flu has been found in a pig for the first time in the U.S.

Finding bird flu in a pig raises worries that the virus may be hitting a stepping stone to becoming a bigger threat to people, said Jennifer Nuzzo.

If we're trying to stay ahead of this virus and prevent it from becoming a threat to the broader public, knowing if it's in pigs is crucial, Nuzzo said.

The USDA has conducted genetic tests on the farm's poultry and has not seen any mutations that suggest the virus is gaining an increased ability to spread to people.

This version of bird flu known as Type A H5N1 has been spreading widely in the U.S. among wild birds, poultry, cows.

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