Idaho reported 36 cases between 1980-1999, primarily from the panhandle region. Reports of illness peak in the spring and summer months. The soft ticks responsible for disseminating this spirochete are the Ornithodoros species. They feed on squirrels, mice, chipmunks, rabbits, hares, and humans. Larva, nymphs, and adults are all infectious.
Rodents carry and shed the soft ticks within structures, such as cabins.
The ticks then seek out blood meals from human inhabitants. The responsible tick feeds at night obtaining a blood meal within 15-45 minutes. Most bites go unrecognized as the soft tick does not attach to it's host for days at a time like the more recognizable hard tick. Soft ticks can survive up to 10 years with infrequent blood meals every year or two, making certain cabins 'hot spots' for infection year after year. Due to the persistent nature of the offending ticks within structures, thorough environmental assessments accompany any disease investigation.