Haitian ctxB producing Vibrio cholerae in Karnataka, India: Emphasis on molecular epidemiology and laboratory networking system

Abstract

Cholera, a primeval waterborne, severe dehydrating diarrheal disease, caused by V.cholerae , with a considerable health burden especially in developing countries. Due to lack of laboratory based evidences of an etiological agent many  outbreaks are recorded as diarrhea outbreaks and cholera as well as V.cholerae El Tor biotype may remain unrecognized.    The present report is an effort to trace the circulating strain in the community with the support  of  laboratory networking system and the aid of molecular techniques in epidemiology. Under Integrated Disease Surveillance Programme [IDSP], Dept of Microbiology Bangalore Medical College and Research Institute is recognized as a state referral laboratory for investigation of outbreaks in linked districts .In the month of July 2016   a total of 06 representative stool samples randomly collected  in Cary Blair media  from suspected cases of cholera were received  for isolation and identification of etiological agent. All stool specimens were processed according to standard protocol and V.cholerae isolates were sent to National Institute for Cholera and Enteric Diseases [NICED] for molecular characterization. V. cholerae  was isolated from 05 out of 06 samples tested.  Serological tests revealed that all 05 isolates belonged to  V.cholerae strain O1 serotype Ogawa. PCR based study from NICED confirmed all the V.cholerae strains contain Haitian ctxB. This molecular epidemiological study under the laboratory networking system revealed the circulation of Haitian variants of V.cholerae in some regions of Karnataka. Since the mortality and morbidity is high with Haitian genotypes than the El tor biotype coordinated and vigilant monitoring of V.cholerae is essential.