Organism That Transmits Cholera
Cholera is caused by the bacterium Vibrio cholerae, specifically the toxigenic strains of serogroups O1 and O139, which produce cholera toxin responsible for the disease's lethal symptoms. 1
Bacterial Characteristics
- Vibrio cholerae is a Gram-negative bacterium that produces a potent enterotoxin (cholera toxin) when it infects the human small intestine 2
- Only toxigenic strains (those producing cholera toxin) of V. cholerae O1 or O139 cause epidemic cholera and should be reported as cholera cases; non-toxigenic strains do not constitute cholera 3
- The O1 serogroup has two biotypes: classical and El Tor, each with two major serotypes (Ogawa and Inaba) and the extremely rare Hikojima 2
Mechanism of Disease
- The cholera toxin is an oligomeric complex composed of six protein subunits: one A subunit and five B subunits connected by a disulfide bond 1
- Once the B subunit binds to intestinal surface membranes, the toxin is internalized and the A subunit is released, initiating processes that increase adenylate cyclase activity and cAMP levels 1
- This results in massive fluid and electrolyte efflux into the intestinal lumen, causing the characteristic profuse watery diarrhea 1
Transmission Routes
- The disease is transmitted primarily through ingestion of fecally-contaminated water by susceptible persons 4, 5
- Food serves as an important secondary vehicle for transmission, particularly seafood (fish, shellfish, crabs, oysters, clams), contaminated rice, millet gruel, vegetables, fruits, poultry, meat, and dairy products 4, 6
- Foods become contaminated during preparation, particularly by infected food handlers in unhygienic environments, or through contact with contaminated water 4, 6
Critical Clinical Points
- The incubation period ranges from several hours to 5 days 5
- Symptoms include profuse watery diarrhea, vomiting, abdominal cramps, and rapid dehydration that can progress to hypovolemic shock 1, 5
- Case fatality rate exceeds 50% without proper treatment but drops below 1% with prompt rehydration and antibiotics 5, 7