Risk factors for mortality in patients with leptospirosis during an epidemic in northern Kerala.

BACKGROUND: Epidemic leptospirosis is increasingly being reported from northern Kerala during the monsoon months. We investigated the risk factors for mortality during the 2002 epidemic. METHODS: Three hundred and forty patients suspected to have leptospirosis during the epidemic were studied by clinical examination, laboratory investigations and Leptospira serology (microscopic agglutination test). Two hundred and eighty-two seropositive cases were analysed for the clinical and laboratory profile, and risk factors for mortality using univariate and logistic regression analysis. RESULTS: Of the 282 seropositive cases, 58.9% were men. No significant association with occupational risk factors was seen; 62.9% had wounds on the feet. The majority had Weil syndrome with hepatic (69.8%) and renal (56.3%) involvement. Thrombocytopenia (65.8%) was common. Transient hyperglycaemia was observed in 10.3% of cases. Pulmonary haemorrhage (4.7%) and meningism (4.3%) were less common. Jaundice occurred in 46% of cases in the first week. The mortality rate was 6.03%. Hyperkalaemia (OR= 27.3), meningism (OR= 10.6), oliguria (OR=8.2), haemoptysis (OR= 5.4), bilirubin > 15 mg/dl (OR= 5.4), disorientation (OR=5), tachycardia (OR=4.1) and muscle tenderness (p=0.03) were the predictors of high mortality in univariate analysis. Only involvement of the lung and central nervous system were significant predictors of death in logistic regression. CONCLUSIONS: Leptospirosis is no more a mere occupational hazard in Kerala. Early occurrence of complications such as hepatitis mandates caution in the primary care setting. Lung and central nervous system involvement are significant predictors of mortality.