Tick-borne relapsing fever is spread by the soft tick, a type of tick prevalent in mountainous areas of the western U.S. The disease is particularly linked to sleeping in rustic cabins. Symptoms are also similar to Lyme disease, and include muscle and joint pain, fever and headache; the main difference is that symptoms generally follow a “three days on, seven days off” pattern (hence the “recurring”) until it’s treated with antibiotics.