The Indiana Department of Natural Resources is asking Hoosiers to take down their birdfeeders as a bird death investigation expands to 15 Indiana counties.

The agency said it was investigating reports of several species of songbirds with neurological problems, eye swelling and crusty discharge in Clark, Delaware, Hamilton, Jackson, Jefferson, Johnson, LaGrange, Marion, Monroe, Newton, St. Joseph, Union, Washington and Whitely Counties.

At least five other states and Washington, D.C. have faced similar bird illnesses and deaths since late May.

DNR said it was working with the Indiana Animal Disease Diagnostic Laboratory and the U.S. Geological Survey National Wildlife Health Center to determine the cause of the bird deaths.

Samples sent to IN ADDL have tested negative for avian influenza and West Nile virus, although final test results are pending.

DNR said Hoosiers should stop feeding birds until the illness stops and clean bird feeders and baths with a 10% bleach solution.

The agency said Hoosiers should report dead birds found on their property to DNR’s wildlife reporting tool.

People should avoid handling dead birds unless they are wearing disposable gloves. The bird should be placed in a sealable plastic bag and disposed of with household trash while being kept away from pets.