Maryland’s sixth case of bird flu was detected in a backyard flock in Anne Arundel County, officials announced on Wednesday.

Testing revealed the highly pathogenic H5N1 avian influenza in the flock, prompting Maryland Department of Agriculture officials to call for the quarantine of the area and killing the affected birds to prevent spreading. Officials affirmed affected birds will not enter the food system.

Dr. Jen Trout, the state veterinarian for the MDA, said it’s unclear how the flock became infected.

“The owner called to report sick birds, we took samples from his flock and the results were positive on Tuesday,” Trout said in an email to The Banner. “Biosecurity is key to prevent avian influenza from infecting a flock and spreading. We continue routine AI surveillance of flocks on the eastern shore to stop the disease.”

This brings the total cases of bird flu in Maryland up to six, with previous outbreaks in Caroline, Dorchester, Montgomery, Queen Anne’s and Worcester counties.

The outbreaks are in line with a surge in avian influenza among wild birds across the nation. As of Tuesday, bird flu was detected in 12,510 animals in the United States, according to data from the Animal and Plant Health Inspection Service.

Avian influenza is an airborne respiratory virus that spreads easily and impacts ducks, chickens, turkeys and other types of birds. While bird flu poses low public health risk, per the Centers for Disease Control and Prevention. It has been cited as the cause of the record high egg prices this year.