The worker are the first presumed human cases of the H5 bird flu virus under investigation in Washington state, the Washington state Department of Health said Sunday. The workers have had mild symptoms and have been given antiviral medication by the Benton Franklin Health District.

Washington state health officials said four agricultural workers tested presumptively positive for avian influenza, marking the first presumed human cases in the state.

Four agricultural workers in southeast Washington have preliminarily tested positive for bird flu after working around an infected poultry flock at a commercial egg farm. The cases, if confirmed, would be the first time people in Washington have contracted the virus since officials began tracking a notable rise of it in birds and other animals

Four people have reportedly developed symptoms of avian influenza after working with infected poultry in Franklin County.

Four agricultural workers have tested “presumptively positive” for avian influenza after working with infected chickens at a commercial egg farm in Franklin Cou