A backyard bird flock in Montgomery County has preliminarily tested positive for the H5N1 avian influenza, also known as the bird flu.

The Maryland Department of Agriculture, which announced the case Thursday afternoon, has quarantined all affected premises and depopulated the birds to prevent the spread of the disease. The state agency is waiting on final confirmation by the U.S. Department of Agriculture’s National Veterinary Services Laboratory, which is anticipated in the coming days.

The bird flu is a highly contagious airborne respiratory virus that spreads easily among birds through nasal and eye secretions, as well as manure. The current public health risk is low, according to the United States Centers for Disease Control and Prevention.

The illness is widespread in wild birds worldwide and is causing outbreaks in poultry and U.S. dairy cows. There have been 67 confirmed total reported human cases in the United States, according to the CDC.

In an effort to prevent the infection from coming into contact with humans, Maryland has begun testing milk for bird flu, on par with a recent announcement from the U.S. Department of Agriculture’s national milk testing strategy.

Backyard flock owners are required to register their flocks with the Maryland Department of Agriculture to assist in protecting the state’s poultry industries from diseases such as the bird flu.

There has been no reported person-to-person spread of the virus, according to the CDC, so farmworkers and backyard flock owners are at the greatest risk. They’re advised to wash their hands more often, sanitize their equipment and limit the number of visitors to their facilities.

Other cases have been found in Queen Anne’s and Caroline counties on the Eastern Shore, according to state officials, with two more cases in nearby Delaware.