DES MOINES, Iowa (AP) — Gov. Terry Branstad has signed a proclamation aimed at extending clean-up efforts involved with the bird flu outbreak. Branstad signed a disaster emergency proclamation Monday for 18 Iowa counties adversely affected by bird flu. It is effective until Dec. 31 and extends a proclamation that was set to expire Wednesday.

The proclamation is aimed at helping chicken and turkey producers with disposal and clean-up efforts on affected sites. The proclamation temporarily allows them to dispose of manure and compost from an affected site if the material is virus-free.

The proclamation applies to Adair, Buena Vista, Calhoun, Cherokee, Clay, Hamilton, Kossuth, Lyon, Madison, O’Brien, Osceola, Palo Alto, Plymouth, Pocahontas, Sac, Sioux, Webster and Wright counties.

The virus has infected more than 31.5 million birds in Iowa, mostly egg-laying chickens.