One of the world’s largest outbreaks of bird flu, which led to the slaughter of millions of chickens to limit its spread, appears to be spilling over into mammals.

Though most cases were detected in Oregon, positive tests in mammals were confirmed in the following states, according to the USDA's Animal and Plant Health Inspection Services:

The U.S. Centers for Disease Control and Prevention said the “bird flu situation remains primarily an animal health issue.” Only four human infections have ever been reported in the U.S., the CDC said.

Eye redness Fever Cough Sore throat Runny or stuffy nose Muscle or body aches Headaches Fatigue Shortness of breath

Anyone going to buy a dozen eggs these days will have to be ready to pay up because the lingering bird flu outbreak, combined with soaring feed, fuel and labor costs, has led to prices more than doubling over the past year.

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