Tickborne relapsing fever
| Pathogen: Borrelia hermsii |
| Tick vectors: Ornithodoros hermsi; less commonly Ornithodoros parkeri and Ornithodoros turicata |
| Geographic distribution: Pacific coast, north-western and southwestern regions |
| Classic presentation: Relapsing fever, headache, myalgia, arthralgia, gastrointestinal symptoms |
| Diagnosis: Detection of spirochetes on peripheral smear with either Wright or Giemsa stain or darkfield microscopy; fourfold increase between acute and convalescent serology with a minimum peak titer ≥ 1:64; polymerase chain reaction assay in research settings. |
| Treatment: Tetracycline for 10 days (based on expert opinion) |