Sustained Local Diversity of Vibrio cholerae O1 Biotypes in a Previously Cholera-Free Country

Abstract

Although the current cholera pandemic can trace its origin to a specific time and place, many variants of Vibrio cholerae have caused this disease over the last 50 years. The relative clinical importance and geographical distribution of these variants have changed with time, but most remain in circulation. Some countries, such as Mexico and Haiti, had escaped the current pandemic, until large epidemics struck them in 1991 and 2010, respectively. Cholera has been endemic in these countries ever since. A recent retrospective study in mBio presents the results of more than 3 decades of V. cholerae monitoring from environmental and clinical sources in Mexico (S. Y. Choi et al., mBio 7:e02160-15, 2016, http://dx.doi.org/10.1128/mBio.02160-15). It reveals that multiple V. cholerae variants, including classical strains from the previous pandemic, as well as completely novel biotypes, have been circulating in Mexico. This discovery has important implications for the epidemiology and evolution of V. cholerae.

Simultaneous Quantification of Vibrio metoecus and Vibrio cholerae with Its O1 Serogroup and Toxigenic Subpopulations in Environmental Reservoirs

“…Lack of species specificity and the presence of multiple copies in single cells make quantitative estimates unreliable. Furthermore, given that a single lineage of V. cholerae is responsible for all major outbreaks [phylocore genome/pandemic generating (PG) V. cholerae ] [ 8 , 44 ] ( Supplementary Figure S1 ), detection of other, mostly harmless, genotypes can be misleading in evaluating the risk of outbreaks. Attempts to accurately quantify toxigenic V. cholerae using the cholera toxin (CT) gene ctxA have been made; while the reference El Tor strain N16961 carries a single copy of this gene, other V. cholerae strains carry several copies of this element and it is also occasionally found in other Vibrio species [ 41 , 45 , 46 , 47 ].…”

Evolutionary Model of Cluster Divergence of the Emergent Marine Pathogen Vibrio vulnificus : From Genotype to Ecotype

“…cholerae, where all strains capable of causing cholera belong to a single clade, a comparison between V. vulnificus strains reveals a more complex pattern in the distribution of its clinical strains (24–27). Clinical V.…”

Sequential displacement of Type VI Secretion System effector genes leads to evolution of diverse immunity gene arrays in Vibrio cholerae

“…Among them are a few human pathogens of relevance, including Vibrio cholerae, the causative agent of the sometimes dramatic and lethal cholera diarrhea. More specifically, a single lineage of the V. cholerae species, comprised primarily of O1 and O139 serogroup strains 3 , has adapted to effectively colonize the human gastrointestinal tract and is responsible for all known cholera pandemics 4 . Pandemic V. cholerae strains harbor the horizontally acquired genetic elements VPI-1 and CTX-Φ, encoding the toxin co-regulated pilus and cholera toxin respectively.…”