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

Epidemic leptospirosis is increasingly being reported from northern Kerala during the monsoon months. We investigated the risk factors for mortality during the 2002 epidemic.

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.

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.

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.