PROPERTIES OF VIBRIO CHOLERAE STRAINS ISOLATED IN ASIA AND THEIR RELATIONSHIP TO THE STRAINS CIRCULATING IN OTHER CONTINENTS DURING THE SEVENTH CHOLERA PANDEMIC

Abstract

The review deals with the properties of Vibrio cholerae (classical, El Tor, 0139, non-01/non-0139 strains) circulating worldwide during the seventh cholera pandemic. Particular attention is given to the variability in the cholera pathogen: the replacement of classical Vibrio cholerae by the El Tor biotype and subsequently the emergence of serogroup Vibrio cholerae 0139 and genetically altered El Tor Vibrio cholerae; the causes giving rise to these changes and spread of Vibrio cholera in the countries of the Asian continent. A large genetic variability found in Asian strains suggests that there is a real possibility of the emergence of new clones with new properties, including those with an epidemic potential. The Vibrio cholerae strains, that periodically appear in Asia and have an epidemic potential and new properties, spread over all continents, by causing cholera infection. The cholera pathogen adapts to new existence conditions in some cases, by altering some properties and, by having been rooted in a certain area, causes mainly sporadic cases of the disease. These Vibrio cholerae strains, unlike the Asian strains (the pathogens of the seventh pandemic), may be virulent, by preserving the virulence genes in the genome; however, they are, in most cases, non-endemic and unable to spread widely.