Tickborne relapsing fever (TBRF), which is endemic in the western United States, typically causes mild symptoms, and many people who get sick don’t seek medical attention. But TBRF can cause serious complications—acute respiratory distress syndrome, spontaneous abortion or preterm delivery in pregnant women, or death.
During 1990 to 2011, 12 western states reported 504 TBRF cases to the Centers for Disease Control and Prevention. About 70% of the cases originated in California, Washington, and Colorado. Most occurred during the summer, and two-thirds of the infections were in people visiting the area. Cases were most common among men and children aged 10 to 14 years as well as adults aged 40 to 44 years (Forrester JD et al. MMWR Morb Mortal Wkly Rep. 2015;64:58-60).
Controlling Tickborne Fever. JAMA. 2015;313(12):1201. doi:10.1001/jama.2015.1858