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BACKGROUND: Tickborne relapsing fever (TBRF) is caused by Borrelia species spirochetes transmitted by Ornithodoros ticks. During 1982–2013, a total of 22 TBRF cases (0–3 cases annually) were reported in Arizona. In August, Coconino County Public Health Services District received a call that 5 high school students who had attended a football camp were hospitalized; several of these students had spirochetes identified on blood smears. We sought to confirm the outbreak, identify the cause, and prevent additional cases.
METHODS: We interviewed camp staff and attendees, reviewed medical records of hospitalized patients, and inspected the campsite for evidence of rodent or tick infestation. A probable case was defined as fever, myalgias, and headache in a person attending the football camp during August 1–3, 2014; a confirmed case was spirochetemia identified in an attendee’s blood smear or by isolation.
RESULTS: Forty (95%) of 42 male camp attendees were interviewed. We identified 6 confirmed cases (5 [83%] by spirochetes detected on blood smear and 1 [17%] by isolation) and 5 probable cases (attack rate: 26.2%). Patients were ages 15–17 years (10 students) and 33 years (1 coach). All 10 (100%) students with known sleep locations slept in one cabin. A professional pest control company rodent-proofed the cabin in July 2014; no tick acaricides were applied. The cabin had evidence of rodents and ticks. Trapped rodents tested positive for Borrelia hermsii.
CONCLUSIONS: Health care providers should consider TBRF in febrile patients who have stayed in rustic cabins in endemic areas. By removing rodents from buildings, ticks might lose their primary food source and feed on persons; therefore, acaricide spraying should be concurrent with rodent-proofing.