Cholera is caused by toxin-producing strains of Vibrio cholerae, with the most common serogroups being O1 and O139. Humans are the only reservoirs for the bacteria and contaminate food and water sources when they are shed in their stool during infection. Like all species of Vibrio, the bacteria reside in warm brackish, estuarine or marine water. Cholera-like illness can also be caused by other toxin-producing serogroups and species of Vibrio.
Cases of cholera are rare in the United States, with the majority being acquired while visiting endemic countries or attributed to the consumption of contaminated food. Endemic countries include those within Asia, Africa and South America, and are commonly associated with poor sanitation, untreated waste water, overcrowding and poverty.
Cholera is transmitted via the consumption of fecally contaminated water or food. During large epidemics and in endemic countries, human fecal waste can contaminate local water supplies. If left untreated, contaminated waste water causes illness when it is used for drinking water, making ice, and to wash and prepare various foods. Fish, shellfish and different types of plankton can act as reservoirs and vehicles for transmission and can cause illness when eaten raw or undercooked.
The infection may be asymptomatic or can range from a mild to acute gastrointestinal illness. The incubation period can be a few hours to 5 days, with 2-3 days being the average.
- Profuse painless watery diarrhea, described as ‘rice-water stool’ (due to the mucosal layer of the intestine being stripped away by the toxin)
- Nausea and vomiting
If left untreated:
- Rapid and severe dehydration – dry mucous membranes and loss of skin elasticity
- Electrolyte imbalances
- Muscle cramps, restlessness and irritability
- Low blood pressure and rapid heart rate
- Circulatory collapse, shock and renal failure
- Coma and death
The profuse levels of watery diarrhea contain large numbers of Vibrio cholerae bacteria and can be a serious source of secondary transmission and contamination of water and food.
The risk of cholera in endemic countries, even during epidemics, is very low when proper precautions are taken. The risk in the United States is even lower, with most cases being imported from endemic countries.
General recommendations for avoiding Cholera in endemic countries:
- Drink safe water such as bottled water with unbroken seals or water that has been boiled for at least 1 minute.
- Avoid ingestion of tap water in endemic countries – tap water, ice, water served in mixers or drinks at eating establishments and using tap water when brushing teeth. Do not swallow water when bathing or swimming.
- Avoid cross contaminating drinking water and food with unsafe water sources, such as tap water, water used in the bathroom or in the laundry.
- Only eat foods that you have been peeled by yourself, or that have been boiled or cooked (ie. Avoid salads and fresh produce that may have been rinsed or prepared with contaminated water).
- Avoid food and beverages from street vendors as unsafe water may have been used for their preparation (ie. water used for rice).
- Only eat thoroughly cooked seafood and shellfish until they are steaming hot. Do not eat any raw seafood.
- Practice hand washing hygiene, wash with soap and safe water often:
- Before you handle, prepare or eat food
- Before feeding your family, children or others
- After using the restroom or cleaning a diapered child
- After taking care of anyone with diarrhea
Recent Texas Trends
In the last 5 years there have been 1-2 annual cases of cholera in Texas.