Risk factors associated with rural and urban epidemics of leptospirosis in Tiruchirappalli district of Tamilnadu, India

Aim: The study sought to determine the risk factors involved in Leptospira infection in rural settings and the relative severity of the disease in comparison with the urban environment in Tiruchirappalli district, Tamil Nadu, India. Subject and methods: During an upsurge of leptospirosis, 621 suspected blood samples were obtained from patients and screened by MAT and IgM ELISA. To set up an age-matched case control study, 1,230 seronegative control samples were also included in the study. The case-control analysis was carried out using unconditional logistic regression and all P-values were two-sided. Results: From 621 suspected cases, 214 (74%) from rural and 196 (59%) from urban settings had a laboratory-confirmed diagnosis of leptospirosis. The highest antibody titres were identified against Leptospira interrogans serovar Canicola both in rural (35%) and urban (38%) settings. Increased infection risk was observed for cases in the age group of 20-40 years and 10-40 years in rural and urban settings respectively. In rural settings, the risk of leptospiral infection was found to be significantly (P<0.0001) associated with people having cattle at their house and those involved in wet cultivation. Among urban cases, building workers and people living in house dwelling near water bodies were significantly (P<0.0001) associated with leptospiral infection. Conclusion: The findings of the present study identified ideal niches for the transmission of leptospires in the rural and urban settings. Identification and understanding the potential risk factors in different environments would help to identify the source of contamination. This also identifies the need for more public health assistance.