Listeriosis in wild rabbits & hares in Saskatchewan

Photo courtesy: Hamilton Greenwood

A bacterium infamous for its association with food borne illness has caused the death of two wild hares and a rabbit in Saskatchewan.

The bacterium, Listeria monocytogenes, was involved in one of the most serious outbreaks of food-borne illness in Canada: the deli meat outbreak in 2008.  In fact, Listeria is the 3^rd most common bacteria associated with food-borne illness in people.

But this bacterium also causes significant disease in domestic animals and wildlife. Found throughout the world and able to grow at temperatures close to freezing, this bacterium is found in the environment including soil. Sheep, goats and cattle can become infected from eating poorly-fermented silage.

In wild animals, Listeria is known to cause three types of disease, collectively called Listeriosis: 1) septicemia (blood poisoning); 2) female reproductive illness including death of fetuses, miscarriage, uterine infection; and 3) infection in the brain, known as encephalitis.

The rabbit and hares that died of Listeriosis in this instance were all females with severe uterine infections.  The inflammation and tissue damage were so severe from this infection that the bacteria eventually spread within the body to other organs and ultimately caused their death.

What is unusual about this cluster of cases is it has not been documented in Western Canada before.  Although all three were found within urban areas, this probably reflects that people are more likely to find sick or dead wildlife in the city rather than rural areas. The true impact of Listeriosis on rabbits and hares is unknown and further research will be necessary to understand how widespread it is and how these animals become infected. Listeriosis is not thought to be transmissible between animals and because the bacteria is found in the environment, this form of the disease in rabbits and hares should pose no risk to human or domestic animal health. If you find sick or dead hares or rabbits, please contact the CCWHC.