What is Cholera?

Overview

Cholera is an acute diarrhoeal infection that occurs when the small intestine is infected with the bacterium Vibrio cholerae. Cholera primarily spreads through the faecal-oral route, where infected food or water is ingested. When infected, this waterborne disease presents it self through acute watery diarrhoea, which can become fatal if left untreated. 

Fortunately, due to modern sewage and effective water treatments, cholera has been virtually eradicated in most developed countries. Unfortunately, it is still present in some resource-limited  regions such as Africa, Southeast Asia and island nations such as Haiti and is estimated to affect up to 4 million people annually. However, despite cholera being relatively easy to treat through prompt rehydration therapy, it sadly still results in 140,000 deaths every year. 

Causes of cholera

The bacterium Vibrio cholerae causes cholera. The acute watery diarrhoea associated with cholera results from a toxin produced by the bacterium. This toxin causes the cells lining the intestine to abnormally secrete large volumes of water, resulting in the rapid loss of fluids and electrolytes through diarrhoea.^.  

Typically, cholera is spread through the faecal-oral route, where contaminated food or water is ingested. 

Potential sources of cholera include: 

• Surface or well water. Drinking from contaminated sources of water is a frequent source of cholera outbreaks 
• Seafood. Cholera is present in coastal waters. Eating seafood that is raw or undercooked puts you at risk of being exposed to V. cholerae
• Raw fruits and vegetables. Particularly those washed or watered with contaminated surface or well water
• Grains. In areas where cholera is prevalent, grains can become dangerous after cooking and when stored at room temperature, as they can promote the growth of V. cholerae bacteria 

Signs and symptoms of cholera

Most people infected with V. cholerae bacteria do not ever exhibit any symptoms. However, the bacteria are shed in infected individuals’ faeces for anywhere between 1 to 10 days after infection. During this period, they could unknowingly infect other individuals.  

Some people will experience mild to moderate symptoms. The onset of cholera symptoms typically takes between 12 hours to 5 days after ingesting the contaminated food or water.¹ Unfortunately, with most cases of cholera, it is difficult to distinguish it from other causes of diarrhoea. 

However, according to the CDC, around 10% of people infected with cholera will go on to experience severe symptoms. At an early stage, these can manifest as: 

• Watery diarrhoea (known as rice water stools)
• Nausea and vomiting 
• Thirst 
• Leg cramps
• Restlessness or irritability
• Dehydration

Dehydration and cholera 

The minority that develops severe acute watery diarrhoea can experience dangerous fluid loss, resulting in severe dehydration if left untreated. Symptoms of cholera dehydration include:

• Rapid heart rate
• Loss of skin elasticity 
• Dry mucous membranes
• Low blood pressure 

Individuals who experience severe dehydration due to cholera can develop symptoms such as muscle cramps and shock. These result from an electrolyte imbalance caused by the rapid loss of bodily fluids. These symptoms need to be dealt with immediately by a doctor or they can be fatal. 

Management and treatment for cholera

Because of the fast-acting nature of the disease, it is vital to seek immediate treatment. The CDC reports that if left untreated, 25-50% of severe cholera cases prove to be fatal.  

Prompt rehydration therapy is the key to effectively managing cholera. This can be done using oral rehydration salts (ORS). ORS should be offered to cholera patients frequently in small amounts. You can calculate the approximate amount of ORS that should be administered over 4 hours by using the following equation: 

Amount of ORS (ml) = patient’s weight (kg) x 75

However, ORS can be expensive and difficult to acquire in remote locations. Therefore, there are some homemade recipes that you can make. One oral rehydration solution recommends mixing 1 litre of clean drinking or boiled water with six teaspoons of sugar, half a teaspoon of salt, and a mashed banana for potassium. 

The importance of rehydration is best demonstrated by fatality dropping from almost 50% to less than 1% with rehydration treatment. If you have severe dehydration, you may require intravenous fluids in order to restore lost fluids and salts promptly. 

Research has shown that using antibiotics can reduce the duration of illness and cholera-related diarrhoea. However, the CDC only recommends the use of antibiotics in critical cholera cases. 

Zinc supplements have also been shown to be effective in reducing diarrhoea and improving cholera symptoms in children.

FAQs

How is cholera diagnosed?

Because of the similarity between cholera symptoms and other pathogens that produce acute watery diarrhoea, it is difficult to be certain of a cholera diagnosis without testing a stool sample. Although a cholera diagnosis won’t change how a clinician would treat your symptoms, it is fundamental in preventing an outbreak. 

Lab cultures

The use of lab cultures to isolate and identify V. cholerae is currently considered the gold standard for the diagnosis of cholera. A stool sample is spread onto the selective thiosulfate-citrate-bile salts agar (TCBS). This medium is the ideal choice for the isolation of V. cholerae. When left to incubate for 18-24 hours, V. cholerae will produce large, flattened yellow colonies. Further testing can confirm the presence of the bacteria. 

Cholera dipstick test 

In epidemic situations, rapid cholera dipstick tests allow doctors to identify cholera in areas where labs are not readily available. However, because of the fast-acting nature of the disease, treatment is often administered without confirmation of the diagnosis. 

How can I prevent cholera?

If you are planning on visiting an area where cholera is widespread then you should take the following steps to reduce your risk of cholera transmission.

• Drink and use safe water. Don’t drink tap water. Use bottled water. If bottled water isn’t available, you should use water that you have boiled and treated with a chlorine product. Don’t add ice to drinks unless it has been prepared by you and make sure to wipe down the outside of bottled or canned drinks
• Wash your hands. Always wash your hands before preparing food and after going to the toilet. A guide on effective hand washing can be found here. If you aren’t able to access soap and safe water, use an alcohol-based gel
• Only use fruit and vegetables that you have peeled yourself
• Use toilets. If you cannot access a toilet, try to get rid of faeces away from any body of water, especially wells
• Vaccine. You can get a vaccine for cholera if you are going to a remote area where there is limited access to medical care. Aid workers may also receive a vaccine if they are in an area where cholera is widespread. The vaccine is given as a drink 

Who is at risk of cholera?

Anyone can become sick with cholera, however, there are some factors which make you more susceptible to cholera transmission and more likely to get seriously ill.  

Risk factors for cholera include: 

• Unclean conditions. Individuals living in places with poor sanitary conditions are more likely to become infected with V. cholerae. According to the WHO, at-risk areas include peri-urban slums, refugee camps, and areas affected by famine, war or natural disasters
• Reduced stomach acid. Stomach acid acts as a natural defence against infection with V. cholerae. However, some individuals, such as children, elderly people and those taking antacids, have reduced protection against cholera
• Living or visiting an area where cholera is widespread
• Type O blood. For reasons that are not very well understood, individuals with Type O blood are 2x more likely to develop cholera
• People who are immunocompromised
• Those without access to rehydration therapy. Individuals without access to rehydration therapy are more likely to develop severe symptoms of cholera. Severe dehydration can result in death within hours 

How common is cholera?

Cholera remains a global threat, with up to an estimated 4 million cases annually. 

When should I see a doctor?

If you suspect you have contracted cholera, you should immediately seek medical attention. This is important not only for your personal health but in preventing a cholera outbreak.

The NHS advises you to see a doctor if you have been in an area where cholera is widespread and are experiencing the following: 

• Severe watery diarrhoea and vomiting
• Symptoms of dehydration

Summary

Cholera is an infection of the intestines by the bacterium Vibrio cholerae, which remains a global threat to public health. Transmission primarily occurs through the faecal-oral route, where infected food or water is ingested. 

Whilst many do not experience any symptoms, some individuals will experience severe watery diarrhoea, resulting in dehydration. This symptom can be treated relatively easily if diagnosed at an early stage by administering an oral rehydration solution. Therefore, it is crucial to seek out medical attention as soon as possible, if you believe you may have contracted cholera. 

Additionally, notifying health organisations is vital as early identification of cholera can help prevent widespread outbreaks in communities.