Atypical El Tor: new Vibrio cholerae O1 biotype causing epidemic cholera

Abstract

Toxigenic strains of Vibrio cholerae serogroup O1 and O139 are causative agents of deadly diarrheal disease named cholera. Vibrio cholerae O1 is traditionally divided into two biotypes, classical and El Tor, which are different in phenotypic as well as genotypic traits. Since 1961, classical strains of Vibrio cholerae O1 serogroup has become obsolete as the cause of epidemic and pandemic cholera and replaced by El Tor strains. Since 2002, atypical O1 El Tor strains possessing the traits of classical strains have been increasingly recognized as the cause of cholera in many countries across the world. This article focuses on the genetic traits of O1 classical and El Tor strains. Furthermore, an overview of emergence of atypical O1 El Tor strains and their genetic traits is presented