Background
Avian botulism is a paralytic disease caused by ingestion of a toxin produced by the bacteria, Clostridium botulinum. This bacteria is widespread in soil and requires warm temperatures, a protein source and an anaerobic (no oxygen) environment in order to become active and produce toxin. Decomposing vegetation and invertebrates combined with warm temperatures can provide ideal conditions for the botulism bacteria to activate and produce toxin. Outbreaks occur from coast to coast in the United States and Canada, generally from July through September. Thousands of birds may die during a single outbreak. Botulism in humans is usually the result of eating improperly home-canned foods, which contain types A or B toxin. Type E toxin has been associated with improperly smoked fish. People, dogs, and cats are generally thought to be resistant to type C toxin, but a few cases have been reported in people and dogs.
WHAT THE CWHC IS DOING
Since this disease first appeared on the lower Great Lakes in 1998, the CWHC has been involved in cooperative efforts to monitor for the occurrence of suspected botulism events and to diagnostically confirm the presence of Type E botulism. Surveillance for this disease has, over time, required the combined efforts of personnel from the Canadian Wildlife Service, Parks Canada, Ontario Provincial Parks, the Ontario Ministry of Natural Resources and members of the public. The CWHC continues to encourage all of these groups to report unusual occurrences of avian mortality around the shores of the lower Great Lakes and facilitates the submission of carcasses to our laboratory. The ecological factors that drive the occurrence of Type E botulism remain poorly understood, which means that maintaining surveillance is important as we seek to learn more about these ecological drivers.
