The work was conducted both in The Applied Genomics Laboratory, Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa, Israel and The Wellcome Trust Research Laboratory, Department of Gastrointestinal Sciences, Christian Medical College, Vellore, India.
Environmental monitoring of Vibrio cholerae using chironomids in India
Article first published online: 21 DEC 2009
© 2009 Society for Applied Microbiology and Blackwell Publishing Ltd
Environmental Microbiology Reports
Special Issue: Vibrio Ecology. Editors: Carla Pruzzo, Balakrish Nair, Jim Oliver and Rita Colwell
Volume 2, Issue 1, pages 96–103, February 2010
How to Cite
Raz, N., Danin-Poleg, Y., Broza, Y. Y., Arakawa, E., Ramakrishna, B. S., Broza, M. and Kashi, Y. (2010), Environmental monitoring of Vibrio cholerae using chironomids in India. Environmental Microbiology Reports, 2: 96–103. doi: 10.1111/j.1758-2229.2009.00109.x
- Issue published online: 8 FEB 2010
- Article first published online: 21 DEC 2009
- Received 19 August, 2009; accepted 19 October, 2009.
Environmental Vibrio cholerae strains belonging to the non-O1/non-O139 serogroups are natural inhabitants of freshwater including estuarine environments. Recent findings indicated that chironomids (Diptera: Chironomidae), the most widely distributed insects in freshwater, serve as a natural reservoir of these bacteria. Here we study the role of chironomids, particularly exuviae as carriers and as a monitoring tool for the distribution of V. cholerae in the environment. During a survey conducted in India (June 2006), 326 V. cholerae non-O1/non-O139 isolates were isolated from chironomid egg masses, larvae and exuviae. In addition, a heat-stable enterotoxin (nag-st) positive strain was isolated from exuviae during the local cholera outbreak. We identified 62 different strains in a subset of 102 isolates by analysis of variable number of tandem repeats (VNTR), demonstrating a high variation of V. cholerae on hosting chironomids. Our results show that chironomids can both maintain and distribute this overwhelming diversity of environmental V. cholerae strains, including toxigenic ones. Exuviae proved to be an efficient tool for the monitoring of environmental V. cholerae, offering simple, direct and practical access for on-shore collection. Finally, finding toxigenic V. cholerae on chironomids in endemic areas, together with molecular typing, may potentially improve monitoring of cholera in the future.