Relapsing fever, louse-borne

This code signifies a systemic bacterial infection caused by Borrelia recurrentis, transmitted to humans via the body louse. It is characterized by recurrent episodes of fever, headache, muscle aches, and often hepatosplenomegaly, separated by afebrile periods. The relapses are due to antigenic variation of the spirochete.

Apply this code when documentation clearly indicates a diagnosis of relapsing fever specifically identified as louse-borne. Supporting documentation should include laboratory confirmation of Borrelia recurrentis or a strong epidemiological link to louse exposure in an endemic area, along with the characteristic relapsing fever pattern.

• Differentiate carefully from tick-borne relapsing fever, which is caused by different Borrelia species and has a distinct transmission vector.
• Ensure documentation specifies "louse-borne" to avoid miscoding with other forms of relapsing fever.
• Consider co-morbid conditions or complications, such as myocarditis or neurological involvement, and code them separately if documented.