Distribution of phage type of Vibrio cholerae O1 biotype ElTor in Indian scenario (1991-98).

During the period 1991-98, distribution of biotype, serotype and phage type of V. cholerae O1 strains isolated from different parts of the country and referred to the National Institute of Cholera and Enteric Diseases, Calcutta were studied. Of the 8101 strains received, 5613 (69.2%) were subjected to phage typing. All these strains belonged to the biotype ElTor and Ogawa was the predominant serotype (96.08%). The strains were clustered into only two types--types 2 and 4 and around 10 per cent strains remained untypable. However, using the new scheme, all these strains were found to be typable and 8 major types were recognized of which type number 27 was the predominant type (66.12%). The distribution of a common type throughout the country suggests that a particular clone of V. cholerae O1 is probably circulating all over India. A constant monitoring through phage typing is necessary to observe the emergence of any new clone of V. cholerae O1 in India.