RESUMO
Objective: To evaluate the serological profile of leptospirosis by microscopic agglutination test (MAT) and dark field microscopy (DFM) and to determine the serovar prevalence rate among patients with pyrexia of unknown origin. Materials and Methods: A total of 3830 blood samples were received from different hospitals and laboratories in and around Chennai. They were screened for leptospirosis by MAT and direct observation of live Leptospira by DFM. Results: A total of 748 (19.5%) Leptospira positive cases were identified; among these, 36.76% were Leptospira australis, 30% were Leptospira canicola, 14.57% were Leptospira autumnalis, 12% were Leptospira icterohaemorrhagiae, 4.68% were Leptospira patoc and 1.87% were Leptospira grippotyposa. Patients were in the age group of 1-86 years, with a median age of 43.5 years. 50% positive cases were in the age group of 10-35 years. Majority of the Leptospira infected cases were males (62.98%) than females (37.02%). Conclusion: Leptospirosis occurs in Chennai throughout the year although the number and positivity of cases increased during the monsoon season.