Botulism confirmed as cause of August duck die-off on Beaver Dam Lake
CONTACT: Tami Ryan, DNR Wildlife Health Section Chief, 608-266-3143
MADISON – About 50 sick or dead ducks reported on Beaver Dam Lake in Dodge County in early August tested positive for botulism, federal wildlife health officials have confirmed.
Wisconsin Department of Natural Resources wildlife officials investigated reports of ducks that appeared paralyzed and could not lift their heads or fly from August 10-13. Staff collected duck carcasses and samples were submitted to the U.S. Geological Survey National Wildlife Health Center in Madison. The center confirmed on Sept. 17 that the ducks tested positive for botulism type C toxin.
State officials say that no more carcasses have been found or reported since this outbreak occurred in mid-August.
Avian botulism is a neuromuscular illness caused by a toxin that is produced by the bacteria Clostridium botulinum. These bacteria typically live in lake, pond or wetland substrates, and sporadically produce toxin when certain environmental conditions develop such as low water levels in combination with warm temperatures.
Affected waterfowl typically show signs of weakness, dizziness, inability to fly, muscular paralysis and respiratory impairment. While this group of bacteria can produce several types of toxin, wild birds are typically affected by botulism type C and botulism type E. Usually type C is associated with waterfowl die-offs on smaller lakes and wetlands.
Botulism only poses a risk to human health through consumption of the bacteria or toxin. While thorough cooking of food destroys the botulism toxin, state wildlife health specialists recommend as a safety precaution, any waterfowl that appear sick should not be eaten and hunters should wear gloves while handling harvested game and wash hands after processing. All game should be cooked thoroughly. Additionally, pets should be kept away from wildlife carcasses that are found dead from unknown reasons.
People can report dead birds to the Dead Bird Hotline (1-800-433-1610). If multiple dead birds are found please contact your local DNR office.