Cholera in Mozambique, Variant of<i>Vibrio cholerae</i>

To the Editor: Cholera outbreaks caused by toxigenic Vibrio cholerae serogroup O1 frequently occur in many sub-Saharan African countries. The serogroup O1 is classified into two biotypes, classical and El Tor. The seventh and current pandemic of cholera is caused by the El Tor biotype; the classical biotype is believed to be extinct. The classical and El Tor biotypes of V. cholerae O1 are closely related in their O-antigen biosynthetic genes but differ in other regions of the genome. The genomic structure of the CTXΦ filamentous phage (1), in which the cholera toxin genes are contained, differs between the classical and El Tor biotypes. CTXclassΦ is found in classical strains, CTXETΦ is present in El Tor and O139 strains, and…