1. What is the mechanism of transmission of Vibrio cholerae?

Major reservoir is humans. Transmitted through ingestion of contaminated food and water.  Large inoculum (108 - 1010) required to establish infection with normal gastric acidity.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2. What host factors increase the likelihood of infection with V. cholerae

A- or hypochlorhydria.

 

 

 

 

 

 

 

 

 

 

 

 

 

3. Describe the mechanism of action of cholera toxin.

The A1 portion of the cholera toxin catalyzes the ADP-ribosylation of the Gs (stimulatory) regulatory protein, "locking" it in the active state. 

Gs acts to return adenylate cyclase to its active state resulting in persistent activation of AC. 

Accumulation of cAMP results in active secretion of Na, K, Cl, HCO3, and water into the intestinal lumen.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4. Besides toxin production, what other virulence determinant is essential for the development of cholera?

The ability to adhere to the mucosa. Nonadherent mutants are avirulent.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5. How would you manage the dehydration? Why can oral rehydration fluid be used in many cases of cholera?

For severely ill persons, IV fluids containing approximately isotonic concentrations of Na and Cl with super-physiologic concentrations of K and bicarbonate (or lactate). 

Taking   advantage of a glucose-linked sodium absorptive mechanism that is not affected by cholera toxin, less ill persons can maintain hydration with glucose containing oral solutions of electrolytes.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6. What advice would you provide to other travelers to Rwanda concerning avoidance of cholera?

Drink only bottled water or beverages, no ice, and eat only freshly prepared cooked foods. 

Wash hands after using the lavatory and before eating

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7. List three public health solutions to the global problem of epidemic cholera.