INDIANAPOLIS (AP) — Avian influenza has been detected in a northern Indiana duck farm, state officials said Thursday, marking the disease’s spread to a third poultry species.

Laboratory testing of a commercial duck flock in Elkhart County has come back as presumptively positive for the virus, the Indiana State Board of Animal Health said. The samples are being verified at the U.S. Department of Agriculture’s National Veterinary Services Laboratory in Iowa.

The duck flock has an estimated 4,000 birds, the agency said.

The animal health board in an announcement Thursday night did not say whether the ducks would be destroyed, as happened with six turkey farms in southern Indiana’s Dubois and Greene counties.

So far this year, there have been cases of bird flu in 24 states affecting chickens and turkeys.