Twin outbreak of cholera in rural North Karnataka, India

BACKGROUND & OBJECTIVES: Successive outbreaks of acute watery diarrhoea occurred in Talikoti and Harnal, located in Bijapur District of the southern Indian State of Karnataka, in July and August 2012, respectively. These outbreaks were investigated to identify the aetiology and epidemiology. METHODS: Information was collected from the local population and health centres. Stool and water samples were collected from the admitted patients and their drinking water sources. Standard microbiological and PCR techniques were employed for isolation and characterization of the pathogen. RESULTS: While 101 people (0.38%) were affected in Talikoti, 200 (20.94%) were affected in Harnal which is a small remote village. All age groups were affected but no death occurred. While the outbreak was smaller, longer and apparently spread by person to person contact in Talikoti, it occurred as a single source flash outbreak at Harnal. A single clone of toxigenic Vibrio cholerae O1 Ogawa biotype El Tor was isolated from the two stool samples obtained from Talikoti and subsequently from three of five stool samples obtained from Harnal indicating village to village spread of the aetiological agent. Striking similarity in antibiotic resistance profiles of these isolates with a particular strain isolated from the city of Belgaum, 250 km away, in 2010, prompted tracking the lineage of the V. cholerae isolates by DNA fingerprinting. Random amplified polymorphic DNA (RAPD) fingerprinting assay helped confirm the origin of the incriminating strain to Belgaum. INTERPRETATION & CONCLUSIONS: Our study reported the first twin outbreak of cholera in two remote areas of Bijapur district, Karnataka, south India. It also indicated the need for immediate preparedness to deal with such emergencies.