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

AbstractA 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.

Risk factors and predictors of severe leptospirosis in New Caledonia.

BACKGROUND: Leptospirosis is a major public health concern in New Caledonia (NC) and in other tropical countries. Severe manifestations of the disease are estimated to occur in 5-15% of all human infections worldwide and factors associated with these forms are poorly understood. Our objectives were to identify risk factors and predictors of severe forms of leptospirosis in adults. METHODS AND FINDINGS: We conducted a retrospective case-control study of inpatients with laboratory-confirmed leptospirosis who were admitted to two public hospitals in NC in 2008-2011. Cases were patients with fatal or severe leptospirosis, as determined by clinical criteria. This approach was meant to be pragmatic and to reflect the routine medical management of patients. Controls were defined as patients hospitalized for milder leptospirosis. Risk and prognostic factors were identified by multivariate logistic regression. Among the 176 patients enrolled in the study, 71 had criteria of severity including 10 deaths (Case Fatality Rate = 14.1%). Three risk factors were independently associated with severe leptospirosis: current cigarette smoking (OR = 2.94 [CI 1.45-5.96]); delays >2 days between the onset of symptoms and the initiation of antibiotherapy (OR = 2.78 [CI 1.31-5.91]); and Leptospira interrogans serogroup Icterohaemorrhagiae as the infecting strain (OR = 2.79 [CI 1.26-6.18]). The following post-admission laboratory results correlated with poor prognoses: platelet count ≤50,000/µL (OR = 6.36 [CI 1.79-22.62]), serum creatinine >200 mM (OR = 5.86 [CI 1.61-21.27]), serum lactate >2.5 mM (OR = 5.14 [CI 1.57-16.87]), serum amylase >250 UI/L (OR = 4.66 [CI 1.39-15.69]) and leptospiremia >1000 leptospires/mL (OR = 4.31 [CI 1.17-15.92]). CONCLUSIONS: To assess the risk of developing severe leptospirosis, our study illustrates the benefit for clinicians to have: i) the identification of the infective strain, ii) a critical threshold of qPCR-determined leptospiremia and iii) early laboratory results. In New Caledonia, preventative measures should focus on early presumptive antibacterial therapy and on rodent (reservoir of Icterohaemorrhagiae serogroup) control.