Cholera causes

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editors-In-Chief: Priyamvada Singh, MBBS [2]

Overview

Cholera is a severe diarrheal disease caused by the bacterium Vibrio cholerae.[1]. Persons infected with cholera have massive diarrhea. This highly liquid diarrhea, which is often compared to "rice water," is loaded with bacteria that can spread under unsanitary conditions to infect water used by other people.

Causes

  • Cholera (or Asiatic cholera or epidemic cholera) is a severe diarrheal disease caused by the bacterium Vibrio cholerae.[1]
  • V. cholerae is a Gram-negative bacteria which produces cholera toxin, an enterotoxin, whose action on the mucosal epithelium lining of the small intestine is responsible for the characteristic massive diarrhea of the disease.[1]
  • The major reservoir for cholera was long assumed to be humans, but some evidence suggests that it is the aquatic environment.
    • Vibrio cholera is not dependent on humans for its propagation.
    • Vibrio cholera can grow inbrackish estuaries, coastal seawaters (in close association with copepods or other zooplankton), and water of lower salinity when it is warm and adequate organic material is available.[2]

Pathogenicity

  • Following the ingestion the cholera pass through stomach (low pH is known to lower the infectious dose in the infected individuals)
  • After passage through the stomach, Vibrio cholera has the capacity to survive and colonize in the small intestine with the help of the toxin coregulated pili (TCP) by following mechanisms:[3][4]
    • Mediating bacterium–bacterium interactions and enabling microcolony formation
    • Protection against toxic factors produced in the intestine
    • promote attachment to the intestinal epithelium
  • Following colonizing in the small intestine, Vibrio cholera secretes cholera toxin (CT), the AB 5 subunit type protein toxin that causes the secretory diarrhea that is characteristic of cholera.

Serogroups

  • Vibrio cholerae has many different types or serogroups
  • Only two of which can cause epidemic cholera if they also produce the cholera toxin. Those two serogroups include:
    • Serogroup O1
    • Serogroup O139 (found only in Asia)
  • Serogroups which can cause a less severe diarrheal disease and does not have epidemic potential include:
    • Non-O1 and non-O139 Vibrio cholerae (third most commonly reported group of Vibrio bacteria)

Infections are seasonal with a peak in the late summer and early fall, coinciding with the warmest water temperatures.

References

  1. 1.0 1.1 1.2 Ryan KJ, Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. pp. 376&ndash, 7. ISBN 0838585299.
  2. Wilcox, Bruce A., and Rita R. Colwell. "Emerging and reemerging infectious diseases: biocomplexity as an interdisciplinary paradigm." EcoHealth 2.4 (2005): 244-257.
  3. Taylor RK, Miller VL, Furlong DB, and Mekalanos JJ: Use of phoA gene fusions to identify a pilus colonization factor coordinately regulated with cholera toxin. Proc Natl Acad Sci U S A 1987; 84: pp. 2833-2837
  4. Taylor, Ronald K., et al. "Use of phoA gene fusions to identify a pilus colonization factor coordinately regulated with cholera toxin." Proceedings of the National Academy of Sciences 84.9 (1987): 2833-2837.
  5. 5.0 5.1 5.2 5.3 5.4 5.5 5.6 "Public Health Image Library (PHIL)".


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