The state Department of Natural Resources has expanded a ban on deer feeding to 11 central and north-central counties to guard against the spread of chronic wasting disease (CWD) in the state's wild herd, the agency announced Monday.

The new ban runs until March 2019 and applies to backyard recreational feeders and hunters in Kandiyohi, McCleod, Meeker, Stearns, Wright, Aitkin, Crow Wing, Morrison and portions of Cass, Mille Lacs and Renville counties. The no-feeding zones were mapped to correlate with areas of concern around two deer farms where the disease recently was detected in captive whitetails.

One of those contaminated farms is in Merrifield in Crow Wing County. The other is near Litchfield, in Meeker County. The DNR will monitor both zones this fall for the possible spread of CWD by testing wild deer killed by hunters.

The same type of surveillance last year in southeastern Minnesota detected CWD in a cluster of 11 whitetails hunted over a period of months in the wooded hills around Preston and Lanesboro. The DNR is investigating to determine if that outbreak is linked to the possible escape of diseased, farmed deer. No conclusions have been reached. As part of the DNR's disease management plan in the southeast, deer feeding was banned in Fillmore, Houston, Olmsted, Mower and Winona counties last fall. The DNR has extended that ban until late June 2018.

"Not feeding deer is a simple step that anyone can take to help prevent the spread of disease,'' said Lou Cornicelli, the DNR's top big game researcher.

The congregation of deer over a food source that puts them in close contact with each other is one of the most probable mechanisms for the spread of CWD, a fatal brain disease in deer, elk and moose. According to the U.S. Centers for Disease Control and Prevention (CDC), there have been no reported cases of CWD infection in humans. But studies have raised concerns that CWD may pose a risk to people, the agency has said.

Cornicelli said the no-feeding ban covers salt, mineral blocks, grains, fruits, vegetables, nuts, hay and any other food that is capable of enticing deer. The southeast Minnesota feeding ban includes attractants used by hunters such as deer urine, blood, gland oil, bottled estrus or other bodily fluids.

In any zone where deer feeding is banned, people who feed birds or small mammals must do so in a manner that prevents access by deer or places the food at least 6 feet above the ground, the DNR said.