Cholera Outbreaks in the El Tor Biotype Era and the Impact of the New El Tor Variants

Abstract

Vibrio cholerae O1, the causative agent of the disease cholera, has two biotypes namely the classical and El Tor. Biotype is a subspecific taxonomic classification of V. cholerae O1. Differentiation of V. cholerae strains into biotype does not alter the clinical management of cholera but is of immense public health and epidemiological importance in identifying the source and spread of infection, particularly when V. cholerae is first isolated in a country or geographic area. From recorded history, till date, the world has experienced seven pandemics of cholera. Among these, the first six pandemics are believed to have been caused by the classical biotype whereas the ongoing seventh pandemic is caused by the El Tor biotype. In recent years, new pathogenic variants of V. cholerae have emerged and spread throughout many Asian and African countries with corresponding cryptic changes in the epidemiology of cholera. In this chapter, we describe the outbreaks during the seventh pandemic El Tor biotype era spanning more than five decades along with the recent advances in our understanding of the development, evolution, spread, and impact of the new variants of El Tor strains.

PaxVax CVD 103-HgR single-dose live oral cholera vaccine

“…Since the 1960s, the world has experienced the progressive dissemination of a seventh pandemic, this one due to El Tor [5]. More recently, 'El Tor hybrid strains' have appeared consisting of V. cholerae O1 El Tor expressing classical cholera enterotoxin and sometimes also exhibiting classical biotype toxin co-regulated pili (TCP), the protein organelles on the vibrio surface that foster colonization of the human proximal small intestine [6,7].…”

Estimation of Vibrio Species Incidences and Antibiotic Resistance in Diarrhea Patients.

“…In the past few years, increased incidences of Vibrio have been reported from various parts of the globe [25] with coastal regions more prone to this infectious disease [18,25]. Historically, Vibrio has caused many pandemic and epidemics along with several explosive outbreaks which continue to thrive in regions with contaminated water and suboptimal hygiene practices [26][27][28]. Diarrhea-associated morbidity and mortality rates are quite higher in Indian sub-continent than the rest parts of world [1,26], and many parts of country are endemic for cholera disease.…”

“…Historically, Vibrio has caused many pandemic and epidemics along with several explosive outbreaks which continue to thrive in regions with contaminated water and suboptimal hygiene practices [26][27][28]. Diarrhea-associated morbidity and mortality rates are quite higher in Indian sub-continent than the rest parts of world [1,26], and many parts of country are endemic for cholera disease. In Southeast Asian region, India and Bangladesh have reported highest Vibrio infections, and in the past few years, threefold increase in infection rates has been reported [25].…”

Estimation of Vibrio Species Incidences and Antibiotic Resistance in Diarrhea Patients.

“…In the past few years, increased incidences of Vibrio have been reported from various parts of the globe [25] with coastal regions more prone to this infectious disease [18,25]. Historically, Vibrio has caused many pandemic and epidemics along with several explosive outbreaks which continue to thrive in regions with contaminated water and suboptimal hygiene practices [26][27][28]. Diarrhea-associated morbidity and mortality rates are quite higher in Indian sub-continent than the rest parts of world [1,26], and many parts of country are endemic for cholera disease.…”

“…Historically, Vibrio has caused many pandemic and epidemics along with several explosive outbreaks which continue to thrive in regions with contaminated water and suboptimal hygiene practices [26][27][28]. Diarrhea-associated morbidity and mortality rates are quite higher in Indian sub-continent than the rest parts of world [1,26], and many parts of country are endemic for cholera disease. In Southeast Asian region, India and Bangladesh have reported highest Vibrio infections, and in the past few years, threefold increase in infection rates has been reported [25].…”