Tick Paralysis in a Snowshoe Hare by Ixodes pacificus Ticks in British Columbia, Canada

We provide the first reported case of tick paralysis in a wildlife animal caused by the western blacklegged tick, Ixodes pacificus Cooley & Kohls. Six I. pacificus females and one male were collected from a feral Snowshoe Hare roaming the coastal area of southwestern British Columbia, Canada. When the hare was rescued from the forest habitat, it was unable to walk, and showed typical symptoms of tick paralysis, including ascending flaccid paralysis. At the nearby wildlife rehabilitation centre, engorged I. pacificus females were collected from the hare. Because of the rapid progress of tick paralysis, the Snowshoe Hare, Lepus americanus Erxleben, died shortly after the start of rehabilitation. X-rays were normal, and reveal no physical injury. Since the Lyme disease spirochete, Borrelia burgdorferi sensu lato (s.l) Johnson, Schmid, Hyde, Steigerwalt, and Brenner, was circulating enzootically in this area, we tested all ticks infesting the Snowshoe Hare. Using PCR, a single male was positive for B. burgdorferi s.l., whereas all of the attached I. pacificus females were negative. Since only the single I. pacificus male was infected with Lyme disease spirochetes, we intuitively conclude that the engorged I. pacificus females were the cause of tick paralysis. Medical practitioners and wildlife rehabilitators are advised to consider tick paralysis in their differential diagnosis when people, livestock, companion animals, and wildlife animals present with acute ascending motor deficits after exposure in grassy and wooded areas.