Cholera – Causative organism, mode of transmission, symptoms, control and treatment

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Causative organism

Vibrio cholerae is the causative organism of cholera. It is a gram-negative bacterium that infects the small intestine. It produces the toxin choleragen also abbreviated as CTX, which is responsible for the colossal diarrhoea characteristic of cholera disease.

Vibrio cholerae is naturally found in brackish or salt water. As a facultative anaerobe, it is able to respire and produce ATP when oxygen is present, and when oxygen is absent, it undergoes normal anaerobic respiration. When ingested, this bacterium can cause severe diarrhoea and vomiting within a few hours to 2-3 days after ingestion.

Cholera facts

Before we look at the mode of transmission of this disease, let’s digest some of its facts as shared by the World Health Organisation:

  • Cholera is a disease that can kill within hours if left untreated.
  • There are about 1.3 – 4 million cases of cholera yearly, which translates to about 21000 – 143000 deaths yearly.
  • Interestingly, up to about 80% of cholera cases can be successfully treated with Oral rehydration solution.
  • Surprisingly, about 75% of people infected with Vibrio cholerae 01 do not show any symptom, and among people infected with cholera, 80% show moderated to mild symptoms.
  • Risk areas or places most susceptible to cholera are the peri-urban slums with poor access to safe drinking water.
  • Surveillance is the most important action in order to prevent disease outbreak in vulnerable areas.
  • There are now safe and effective cholera vaccines endorsed by the WHO that can provide up to 65% protection against cholera for about 5 years.
  • Cholera can be easily prevented, on the condition that safe drinking water and proper sanitation are registered.
  • Fast access to treatment should be provided in cases of outbreak in order to reduce loss of lives.
  • Today, there is absolutely no country that demands cholera vaccination proof as a condition for entry.

 

Mode of transmission

This deadly disease has a faecal-oral transmission route. It happens when someone ingests the faeces of an infected individual through contaminated food or water. A research has shown that the transmission of cholera in developed countries is mostly through food, and in developing countries it is more of water (2004). This is because a considerable number of the overall population in developing countries still lack access to a clean and healthy source of water, unlike developed countries where clean water is available, with susceptibility cornered through the consumption of contaminated food.

People suffering from cholera are associated with a massive diarrhoea, and disease transmission mostly occurs when this extremely liquid stool comes in contact with the water used by others. The watery diarrhoea discharged by cholera patients must not be allowed to get into waterways, drinking water supplies, or even the ground water. When their untreated discharge is allowed into the above sources of water, a potential cholera outbreak looms around the corner, as drinking or eating anything from the water can cause contraction of cholera disease.

 

Symptoms

The most common symptom of cholera is severe watery diarrhoea accompanied by vomiting, which are the two most important causes of dehydration associated with this disease. The symptoms of cholera can begin to manifest as early as a few hours upon ingestion of bacteria or even longer than 3 days after infection.

The following are the major signs and symptoms of this deadly disease:

  • Severe watery diarrhoea
  • Vomiting
  • Rapid heartbeat
  • Nausea
  • Severe dehydration, which is accompanied by sunken eyes, dry mouth, high thirst, low blood pressure, muscle cramps, and decreased skin tugor.

 

Control and prevention

Although cholera is among the deadliest diseases on earth, its prevention is on the contrary very easy as long as proper sanitation practices are in place. Even the almighty World Health Organisation recommends the use of cholera vaccines along with preventive control measures as long as you are in risk of contracting it. Although cholera vaccines are easily available, it is best to prevent this hazardous disease through the use of certain control mechanisms. Most of these vaccines do not provide 100% protection against cholera. For the first 6 months after vaccination, they are said to provide about 85% protection, and the level of protection decreases as time goes on. So, in essence it is best to adhere to the following control mechanisms:

  • Prevention of contamination of water by infected urine and faeces.
  • Drinking water and food should be thoroughly boiled and cooked to kill all potential cholera causing bacteria that may be present.
  • Although cholera only affects humans and there is no animal reservoir or insect vector, a research published in 2001 emphasized the vector potential of houseflies (Musca domestica) in the transmission of Vibrio cholerae in India. Due to this, measures should be taken to eliminate any potential vector of the disease.
  • Food should always be covered to prevent potential vectors from contaminating it, especially in developing countries where a considerable percentage of inhabitants eat or sell food in places where houseflies are rampant.
  • Water purification should be adopted to kill off cholera causing bacteria. Whether used for cooking, drinking, or washing, water should be purified using various methods such as boiling, chlorination, ultraviolet light sterilization and so on.
  • Another important preventive measure is surveillance, and it involves reporting any case to proper authorities in order to prevent outbreak or contain the epidemic. This is especially important in endemic countries where cholera occurs as seasonal disease usually during the rainy season.
  • Lastly, vaccination is also a good way to prevent cholera. However, it is best not to rely on it alone. One must supplement it with proper control measures.

 

Treatment

Hydration is the major way to treat cholera disease, and this can be achieved through the prompt administration of oral rehydration solution (ORS). Most people have been treated successfully using this method. The WHO has an ORS standard sachet which can be dissolved in a litre of clean and purified water. Adult patients may require a whooping 6 litres of ORS in order to treat moderate dehydration on the first day.

Depending on how severe the dehydration is, treatment may also include intravenous solutions to replenish lost fluids. Antibiotics are also used to reduce the severity of the disease symptoms, shorten its duration, and reduce fluid requirements. Most people recover without the use of antibiotics and the WHO recommends their use only in severe cases of dehydration.

Note: The information provided here is for educational purposes only, and it’s not intended to provide any form of medical assistance.

 

 

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abbati
abbati
Abbati is a student from the department of Biological sciences, Ahmadu Bello Univeristy, Zaria. He loves learning about the medicinal properties of foods, and the need to explore them!

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