Soft tick

Ornithodoros spp.

Where found: Throughout the western half of the U.S. and southwestern Canada.

Transmits: Tick-borne relapsing fever (Borrelia hermsii, B. parkerii, or B. turicatae)

Comments: Humans typically come into contact with soft ticks when they sleep in rodent infested cabins. The ticks emerge at night and feed briefly while the person is sleeping. The bites are painless, and most people are unaware that they have been bitten.