ESSENTIALS OF DIAGNOSIS
History of travel in endemic area or contact with infected person.
Voluminous diarrhea (up to 15 L/day).
Characteristic “rice water stool.”
Rapid development of marked dehydration.
Positive stool cultures.
Cholera is an acute diarrheal illness caused by certain serotypes of Vibrio cholerae. The disease is toxin-mediated, and fever is unusual. The toxin activates adenylyl cyclase in intestinal epithelial cells of the small intestines, producing hypersecretion of water and chloride ion and a massive diarrhea of up to 15 L/day. Death results from profound hypovolemia. Cholera occurs in epidemics under conditions of crowding, war, and famine (eg, in refugee camps) and where sanitation is inadequate. Infection is acquired by ingestion of contaminated food or water. For over a century, cholera was rarely seen in the Western Hemisphere until an outbreak occurred in Peru, starting in the early 1990s and ending by 2001; the outbreak resulted in almost 400,000 cholera cases and more than 4000 deaths. The most recent outbreak of cholera in the Western Hemisphere occurred in Haiti in late 2010, when there was a massive earthquake followed by a cholera outbreak that resulted in thousands of deaths.
Cholera is characterized by a sudden onset of severe, frequent watery diarrhea (up to 1 L/hour). The liquid stool is gray; turbid; and without fecal odor, blood, or pus (“rice water stool”). Dehydration and hypotension develop rapidly. Stool cultures are positive, and agglutination of vibrios with specific sera can be demonstrated. Rapid antigen and PCR-based testing is also available.
Treatment is primarily by replacement of fluids. In mild or moderate illness, oral rehydration usually is adequate. A simple oral replacement fluid can be made from 1/2 teaspoon of table salt and 6 level teaspoons of sugar added to 1 L of water. Intravenous fluids are indicated for persons with signs of severe hypovolemia and those who cannot take adequate fluids orally. Lactated Ringer infusion is satisfactory.
Antimicrobial therapy will shorten the course of illness and is indicated for severely ill patients. Antimicrobials active against V cholerae include tetracycline, ampicillin, trimethoprim-sulfamethoxazole, fluoroquinolones, and azithromycin. Multidrug-resistant strains exist, so susceptibility testing, if available, is advisable. A single 1 g oral dose of azithromycin is effective for severe cholera caused by strains with reduced susceptibility to fluoroquinolones, but resistance is emerging to this drug as well.
Oral cholera vaccines are available that confer short-lived, limited protection and may be required for entry into or reentry after travel to some countries. One live attenuated oral vaccine is approved for use in the United States for persons traveling to areas of active cholera transmission, but supplies may be limited or unavailable.
Vaccination programs are expensive and not effective in ...