An Epidemiological Investigation of Leptospirosis Outbreak in Shimoga District of Karnataka, India

Leptospirosis is considered as one of the most widespread zoonotic diseases in the world. It is apparently emerging rapidly as a significant public health problem in developing countries including India. Various programs have been implemented to improve the surveillance and early initiation of control measures to contain such outbreaks. Here we describe an outbreak of leptospirosis in the densely forested Western Ghats foot hills of Karnataka.

The study was conducted in the villages coming under the 3 PHCs belonging to Thirthahalli taluk of Karnataka during middle of January 2011. A total of 286 cases were reported in the outbreak. Information about potential risk factors, clinical features, treatment history was collected by interviewing the cases using a structured questionnaire.

Age of the patients ranged from 3 to 62 yr. there was no significant differences in sex and age distribution. The epidemic spread along 3 PHC area involving 32 villages. It took 4 days to reach the peak and declined gradually over a period of 2 weeks. The disease was more common among agriculture workers and those working in forestry and fisheries.

The epidemiological investigation team mobilized at short notice, conducted an epidemiological investigation, and arrived at a probable diagnosis of leptospirosis. The factors that had a significant association were agricultural practices, factors relating to house and environment, animals in house and rat infestation, working in logged water for paddy cultivation. We emphasize the importance of an effective surveillance system in detecting and responding to outbreaks (IDSP), especially in case of outbreaks of emerging disease. In this context, a strong laboratory support is important to give direction to the epidemiological investigation.