Question:medium
All of the following statements about El Tor vibrios are true, except:
All of the following statements about El Tor vibrios are true, except:
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Cholera toxin binds GM1 on enterocytes only, not on other tissues.
Updated On: Jun 24, 2026
- Humans are the only reservoir
- Can survive in ice cold water for 2 to 4 weeks
- Killed by boiling for 30 seconds
- Enterotoxin can have direct effects on tissues other than intestinal epithelial cells
Show Solution
The Correct Option is D
Solution and Explanation
El Tor is one biotype of $Vibrio$ $cholerae$, the cause of epidemic cholera, and this item wants the single wrong statement.
Reservoir: Cholera is a purely human disease. There is no maintained animal host, so people are the only reservoir. Statement A matches the facts.
Environmental survival: Cholera vibrios persist in clean cold water for weeks. Survival in ice cold water for 2 to 4 weeks is well described and supports its spread through contaminated water supplies, so statement B is correct.
Heat killing: These organisms are not heat resistant. A brief boil, about half a minute, kills them, which is the basis of advising boiled drinking water during outbreaks. Statement C is correct.
Toxin target: Cholera toxin works only at the gut. Its B subunit attaches to the GM1 ganglioside on enterocytes, then the A subunit drives a rise in cyclic AMP and a flood of fluid into the lumen, producing rice water stools. It has no direct action on tissues outside the intestinal lining. Therefore the statement that the toxin acts directly on other tissues is wrong.
The false option is D.
\[\boxed{\text{Enterotoxin acting on tissues other than intestinal epithelium}}\]
Reservoir: Cholera is a purely human disease. There is no maintained animal host, so people are the only reservoir. Statement A matches the facts.
Environmental survival: Cholera vibrios persist in clean cold water for weeks. Survival in ice cold water for 2 to 4 weeks is well described and supports its spread through contaminated water supplies, so statement B is correct.
Heat killing: These organisms are not heat resistant. A brief boil, about half a minute, kills them, which is the basis of advising boiled drinking water during outbreaks. Statement C is correct.
Toxin target: Cholera toxin works only at the gut. Its B subunit attaches to the GM1 ganglioside on enterocytes, then the A subunit drives a rise in cyclic AMP and a flood of fluid into the lumen, producing rice water stools. It has no direct action on tissues outside the intestinal lining. Therefore the statement that the toxin acts directly on other tissues is wrong.
The false option is D.
\[\boxed{\text{Enterotoxin acting on tissues other than intestinal epithelium}}\]
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