CHANGING EPIDEMIOLOGICAL TREND OF CHOLERA IN WEST BENGAL: THE GIANT IS BACK

Cholera is a devastating diarrheal disease caused by V. cholera.Two biotypes of V. cholerae O1, classical and El-Tor, are distinguished.Each biotype is further subdivided into two serotypes, termed Inaba and Ogawa.As large deltaic areas of the Ganges and Brahmaputra rivers are considered to be the homeland of cholera, objective of our study was to detect the circulating strain of Vibrio causing Cholera outbreaks in different pockets of West Bengal.Water samples collected from the water sources of the affected areas and stool samples and or rectal swabs of suspected cases were tested according to standard bacteriological protocol.In July 2008, Cholera outbreak was caused by Vibrio cholerae O1 El-Tor Inaba serotype in Darjeeling district affecting 176 persons.Mean age of the affected people was 15years.Thereafter in the June, 2010, there was an outbreak of Vibrio cholerae El Tor Ogawa affecting 87 people in Maldah.Mean age of the cases was 25years.Similar type of Vibrio cholerae O1 El-Tor Ogawa strain was isolated in the outbreak of June to September 2012 in Maldah with lower mean age of cases i.e.7years.A total of 93 patients suffered from Cholera during this outbreak.Cholera outbreak in West Bengal was caused by classical Vibrio cholerae O1 Ogawa serotype affecting 803 people in North 24 Paragana in October, 2013.Mean age of the patients was 31year.As classical Vibrio causes more severe disease than El-Tor, its reemergence with multidrug resistant properties is no doubt an upcoming threat. INTRODUCTION:Cholera is a devastating diarrheal disease caused by V. cholerae that has been responsible for seven global pandemics and much suffering over the past two centuries.It is an acute diarrheal disease that can, in a matter of hours, result in profound, rapidly progressive dehydration and death.Accordingly, cholera gravis (the severe form of cholera) is a much-feared disease, particularly in its epidemic presentation.Epidemic cholera remains a significant public health concern in the developing world today.The species V. cholerae is classified into more than 200 serogroups based on the carbohydrate determinants of their lipopolysaccharide (LPS) O antigens.Although some non-O1 V. cholerae serogroups (strains that do not agglutinate in antisera to the O1 group antigen) have occasionally caused sporadic outbreaks of diarrhea, serogroup O1 was, until the emergence of serogroup O139 in 1992, the exclusive cause of epidemic cholera.Two biotypes of V. cholerae O1, classical and El Tor, are distinguished.Each biotype is further subdivided into two serotypes, termed Inaba and Ogawa.Cholera is native to the Ganges delta in the Indian subcontinent.Since 1817, seven global pandemics have occurred.The seventh pandemic-the first due to the El Tor biotype-began in Indonesia in 1961 and spread throughout Asia as V. cholerae El Tor displaced the endemic classical