Tularemia is caused by a bacterium known as Francisella tularensis . There are two major cycles of this disease. The first occurs on land.
Snowshoe hares are the primary host.
The disease is spread from an infected hare to a susceptible hare by means of ticks. Ticks are only present on hares from May through September. The disease essentially disappears from October through April. The second cycle occurs in water. Beaver and muskrats are the primary hosts.