Case Definition
Clinical evidence of illness1 with laboratory confirmation by one of the following methods:
- Isolation of Borrelia hermsii from a clinical specimen through culture or animal inoculation.
- Detection of Borrelia hermsii nucleic acid in a clinical specimen by Nucleic Acid Amplification Test (NAAT).
Clinical evidence of illness1 with history of exposure to mountainous regions above 450m in western Canada or United States.
AND
Laboratory evidence of infection in the form of one of the following:
- Identification of spirochete in peripheral blood smear, bone marrow, or cerebrospinal fluid.
- A single antibody titre of at least 1:128.
1Clinical evidence of illness is characterized by one or more episodes of relapsing high fever (typically between 38oC to 43oC) lasting 2-9 days and separated by afebrile periods of 2-14 days, often accompanied by headache, chills, and myalgia.
