Cholera (Vibrio cholerae Infection)

What is cholera?

Cholera is the bacterial infection of small bowel caused by Vibrio cholerae. Patients with cholera typically complain of excessive watery and frequent stool, often described as explosive diarrhea. Cholera occurs as a result of consuming water or food contaminated with the fecal material of cholera-infected person. Treatment is essential because if left untreated cholera patients may be life threatening due to dehydration. Oral rehydration solution is the mainstay of treatment along with antibiotics. In some serious cases intravenous fluid replacement may be necessary.

Cholera Symptoms

Most of the people who become infected with the cholera bacteria may not produce the symptoms of the disease. It is estimated that for every patient with typical symptoms of cholera there are about 3 to 100 asymptomatically infected people. Even if a person is not exhibiting symptoms, they can still excrete the bacteria in their stool for approximately 7 to 14 days after contracting the infection.

The symptoms of cholera include :

  • Excessive, painless diarrhea (approximately 10 to 20 liters), known as “rice water stool”, which may have a characteristic fishy smell.
  • Nausea and vomiting.
  • Diarrhea due to cholera causes excessive fluid loss leading to symptoms of dehydration, namely :
    - Lethargy, fatigue
    - Dryness of mouth, excessive thirst
    - Sunken eyes
    - Reduced skin elasticity
    - Reduced urine volume
    - Fainting, blackout due to low blood pressure
    - Increased heart rate
    - Loss of electrolytes (sodium, potassium with water) may lead muscle cramps, confusion, convulsion (seizure)

Cholera patients without any fluid replacement will progress to a state of shock and will eventually die.

Causes of Cholera

Vibrio cholerae infection leads to symptoms of cholera. There are two sources of cholera infection, namely contaminated water and contaminated food. Ingestion of about 100 million cholera bacteria is required for infection in a healthy adult. After ingestion, few of the bacteria survive the gastric acidity and reach the small intestine. Here cholera bacteria produce a toxin which prevents the absorption of water and electrolytes (sodium, potassium, chloride, bicarbonate) through the intestine leading to profuse diarrhea and dehydration.

Contaminated water

Fecal matter of cholera-infected persons (both symptomatic and asymptomatic) may contaminate drinking water due to inadequate sanitary conditions. The bacteria can remain in dormant state in water for long periods. Public wells contaminated with cholera bacteria are afrequent source of cholera outbreak in developing countries.

Contaminated food

Transmission of cholera through contaminated food is largely due to it being contained, treated or cleaned with contaminated water. This includes seafoods (shell fish), raw vegetables and grains (rice or millet) mainly in developing countries.

Cholera Risks

Although cholera bacteria can affect any person, some factors increase the chance of cholera infection.

  • Inadequate sanitary condition.
  • Reduced acid production in the stomach: gastric acidity destroy most of the ingested bacteria. Therefore reduction of gastric acid production (commonly due to intake of drugs like antacids and proton pump inhibitors) may increase the risk of cholera infection.
  • Family members suffering from cholera.
  • O blood group (two times more risk).
  • Eating raw and undercooked seafood or raw vegetables from questionable sources.

Treatment of Cholera

The treatment of cholera is simple and essential to prevent fatal outcome. Cholera cause over 100,000 deaths per year throughout the world. This is largely due to inadequate medical attention and ignorance about the proper measures to prevent and treat dehydration as a result of the infection.


Replacing the fluids and electrolytes lost through diarrhea and vomiting is essential to avoid life threatening complications.

  • ORS (oral rehydration salt) powder can be mixed with drinking water to treat fluid and electrolyte loss.
  • IV (intravenous) fluid is administered in severe cases of dehydration when the patient is unable to drink or keep down the ORS.


Symptomatic patients with severe diarrhea that is not easing and where there is a risk of dehydration should be treated with medication.

  • Antibiotics eradicate the bacteria from the gut. The diarrhea may still continue thereafter until the normal intestinal flora (bacteria) is restored either naturally or with probiotics. Antibiotics can reduce the duration of diarrhea and the severity of symptoms.
  • Zinc supplements have been shown to reduce the severity and duration of diarrhea in cholera. However, zinc should not be used as a means to replace antibiotics. Instead it should be used along with antibiotics.

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