Jarisch–Herxheimer Reaction Among Patients with Leptospirosis: Incidence and Risk Factors

A Jarisch-Herxheimer reaction (JHR) may be precipitated after initiation of chemotherapy in spirochetal diseases, including leptospirosis. However, a clear idea of the importance of JHR in this disease is lacking. The incidence of and risk factors for JHR were investigated retrospectively among 262 patients with confirmed leptospirosis who received amoxicillin treatment in New Caledonia and Futuna. The overall rate of JHR was 21% (12% in New Caledonia and 44% in Futuna). Two risk factors were independently associated with JHR occurrence: Leptospira interrogans serogroup Australis as the infecting strain (odds ratio [OR] = 2.60, confidence interval [CI] = 1.40-5.62) and delays < 3 days between the onset of symptoms and the initiation of antibiotherapy (OR = 2.14, CI = 1.11-4.38). Clinicians should be aware of JHR as a potential complication of leptospirosis. Strain-related factors associated with JHR occurrence and its impact on outcome remains to be explored.