Overview

Cholera is an acute diarrhoeal infection caused by ingesting food or water contaminated by the bacterium Vibrio cholerae.

It is a water-borne disease, and the risk of transmission is higher in areas that lack adequate sanitation facilities and/or a regular supply of clean water.

According to World Health Organization, Cholera is a global threat to public health and an indicator of inequity and lack of social development.

It is often preventable and can be eliminated where good hygiene practices are ensured continually, and there is access to clean water and sanitation facilities.

History

Cholera is an ancient disease. First records from Hippocrates (460-377 BC) and India Peninsula described an illness that might have been Cholera, but its discovery in 1883 was accredited to Robert Koch, a German bacteriologist.

The spread of Cholera started across the world from the Ganges delta in India in 1817.

With six subsequent pandemics, this killed millions of people across the globe from 1817-1923.

The current (seventh) pandemic beginning at South Asia in 1961, has affected more continents than the previous six; it reached Africa in 1971 and the Americas in 1991.

A new strain of Cholera, V cholerae serogroup O139 (Bengal), occurred in Bangladesh 1992 and India in 1993 and has affected more than 11 countries.

However, Cholera has been less common in industrialized nations for the past century but is still very much available in the Indian subcontinent and sub-Saharan Africa.

Cholera is now endemic in many countries of the world.

Causes

Cholera is caused by a bacterium known as Vibrio cholerae, which is usually found in food or water that is contaminated by faeces from an individual with the infection.

The common sources include:

Surface or well water: Contaminated public wells are common sources of large-scale cholera outbreaks, and risk is higher in people living in crowded conditions without adequate sanitation.

Seafood: Eating raw or undercooked seafood, like imported shellfish, can expose a person to cholera bacteria. Recent cases of Cholera in the United States have been linked to seafood from the Gulf of Mexico.

Raw fruits and vegetables: These include unpeeled and raw fruits and vegetables. For instance, in developing countries, farm produce in the field are commonly contaminated by manure fertilizers (not composted) or irrigation water containing raw sewage.

Grains: In regions where Cholera is widespread, grains such as rice and millet that are contaminated after cooking and kept at room temperature for several hours can grow cholera bacteria.

Others include ice made from municipal water, food and drinks street vendors sell.

Symptoms

The severity of cholera infections occurs in only 1 in 20 cases, with no symptoms in most. For those showing symptoms, it is between 12 hours and five days following exposure and ranges from mild or asymptomatic to severe.

The symptoms usually include:

– Large volumes of explosive watery diarrhoea, sometimes referred to as “rice water stools” because it can look like water that has been used to wash rice

– Vomiting

– Weakness

– Leg cramps

– Severe dehydration and shock can occur

Shock can lead to a collapse of the circulatory system.

It is a life-threatening condition that requires a medical emergency.

Children with Cholera usually have the same symptoms as adults but may also experience severe drowsiness, fever, convulsions and coma.

Pathophysiology

Cholera is an acute diarrheal illness caused by Vibrio cholerae.

It can negotiate with the normal flora of the small intestine through its O1 and serogroup strains.

In the small intestine, the bacteria produce an enterotoxin that promotes the secretion of fluid and electrolytes into the lumen of the small intestine.

Therefore, the ability to cause disease mainly depends on the mode of administration.

If V. cholerae is ingested with water, a higher dose of organisms is required to cause illness, whereas when ingested with food, fewer organisms are required to produce disease.

The enterotoxin is a protein molecule with subunits responsible for binding to a receptor known as ganglioside (monosialosyl ganglioside, GM1) located on the surface of the cells that line the intestinal mucosa.

The part of the subunit activates an enzyme called adenylate cyclase to cause an increase in cAMP (cyclic adenosine monophosphate). Increased cAMP blocks the absorption of sodium and chloride by the microvilli and promotes the secretion of chloride and water by the crypt cells.

The result is watery diarrhoea with electrolyte concentrations isotonic to those of plasma.

Fluid loss originates in the duodenum and upper jejunum; the ileum is less affected.

The colon is usually in a state of absorption because it is relatively insensitive to the toxin.

However, the large volume of fluid produced in the upper intestine overwhelms the absorptive capacity of the lower bowel, resulting in severe diarrhoea.

Unless the lost fluid and electrolytes are replaced adequately, the infected person may develop shock from profound dehydration and acidosis from loss of bicarbonate.

The enterotoxin acts locally and does not invade the intestinal wall. As a result, few neutrophils are found in the stool.

Also, Cholera infection is known to be increased with the use of antacids, histamine receptor blockers, and proton pump inhibitors, as well as in patients who had undergone gastrectomy or patients with chronic gastritis because of reduced gastric acidity.

Transmission

A person can get Cholera by drinking water or eating food contaminated with cholera bacteria.

In an epidemic, the source of the contamination is usually the faeces of an infected person that contaminates water or food.

The disease can spread rapidly in areas with inadequate sewage and water treatment.

The infection is not likely to spread directly from one person to another. Therefore, casual contact with an infected person is not a risk factor for becoming ill.

Treatment

Cholera can be simply and successfully treated by immediately replacing the fluid and salts lost through diarrhoea.

Patients can be treated with oral rehydration solution (ORS), prepackaged sugar and salts mixed with 1 litre of water and taken in large amounts.

This solution is used throughout the world to treat diarrhoea.

Severe cases also require intravenous fluid replacement. With prompt appropriate rehydration, fewer than 1% of cholera patients die.

Antibiotics shorten the course and diminish the severity of the illness, but they are not as important as rehydration.

Persons who develop severe diarrhoea and vomiting in countries where Cholera occurs should seek medical attention promptly.

Zinc is an important adjunctive therapy for children under 5, which also reduces the duration of diarrhoea and may prevent future episodes of other causes of acute watery diarrhoea.

Prevention

5 Simple Steps To Prevent Cholera

1. Wash hands frequently with soap.
2. Avoid street food.
3. Do not eat raw or half-cooked meat.
4. Drink treated purified water.
5. Maintain good sanitation.

Epidemiology

According to a recent NCDC Cholera Situation Report, eleven states reported suspected Cholera cases in 2023. They include Abia, Bayelsa, Benue, Cross River, Ebonyi, Kano, Katsina, Niger, Ondo, Osun, Sokoto and Zamfara.

Of the suspected cases since the beginning of the year, 51% are males, and 49% are females, while the age group 0-5 years is the most affected age group for males and females.

Cross River (242 cases), Ebonyi (86 cases), Niger (38 cases), Abia (35 cases), and Ondo (10 cases) account for 96% of all cumulative cases.

Fifteen LGAs across nine states reported more than 5 cases each this year – Ebonyi (4), Cross River (3), Ondo (2), Bayelsa (1), Abia (1), Katsina (1), Sokoto (1), Niger (1) and Zamfara (1).

Outbreak In Nigeria

Cholera is an endemic and seasonal disease in Nigeria, occurring mainly during the rainy season and often in areas with poor sanitation, with the first series of cholera outbreaks reported between 1970 and 1990.

Major epidemics also occurred in 1992, 1995-1996, and 1997.

Between January and October 2010, The Federal Ministry of Health reported 37,289 cases and 1,434 deaths, while 22,797 cases of Cholera had 728 deaths, and a case fatality rate of 3.2% was recorded in 2011.

Also, there were recorded outbreaks in 2018, with Nigeria Centre for Disease Control (NCDC) reporting 42,466 suspected cases and 830 deaths with a case fatality rate of 1.95% from 20 out of 36 states from the beginning of 2018 to October 2018.

In 2022, 2,187 confirmed cases of Cholera were reported from 31 states and 233 deaths were recorded from January 1 to September 25, 2022.

As of January 29 2023, 429 suspected cases including 17 deaths have been reported from 11 states.

Most Recent Cholera Research, Reports & Resources

• Cholera – Global situation | World Health Organisation
• UNICEF sounds alarm over fast-spreading cholera outbreaks in Africa | United Nations News
• Data and Statistics on Global Cholera | Centre for Disease Control and Prevention
• Cholera | The Lancet
• Epidemiology of cholera | Sciencedirect
• Prevention and control of Cholera with household and community water, sanitation and hygiene (WASH) interventions: A scoping review of current international guidelines | PLOS ONE

References

• Cholera – Public Health. https://www.publichealth.com.ng/cholera/.

• Cholera WHO https://www.who.int/news-room/fact-sheets/detail/cholera.

• Cholera Webmd https://www.webmd.com/a-to-z-guides/cholera-faq Written by Mary Anne Dunkin, Medically Reviewed by Nayana Ambardekar, MD on July 25, 2021.

• Cholera. Medically reviewed by Debra Sullivan — Updated on January 31, 2022 https://www.healthline.com/health/cholera.

• Cholera Mayo clinic. https://www.mayoclinic.org/diseases-conditions/cholera/symptoms-causes/syc-20355287#:~:text=A%20bacterium%20called%20Vibrio%20cholerae,fluids%20and%20salts%20(electrolytes).

• Cholera Medscape (2021). Sajeev Handa. https://emedicine.medscape.com/article/962643-overview?reg=1.

• Centre for disease control and prevention. Department of health and human services 2022 https://www.cdc.gov/cholera/general/index.html#:~:text=A%20person%20can%20get%20cholera,of%20sewage%20and%20drinking%20water.

• Everything you need to know about Cholera. Medically reviewed by University of Illinois — By Sy Kraft on January 11, 2018 https://www.medicalnewstoday.com/articles/189269.

• Nigeria Centre for Disease Control. https://ncdc.gov.ng/diseases/factsheet/50..

• Updated global burden of Cholera in endemic countries. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4455997/.

Written by Marindoti Damilola and Adetoyinbo Anjolaoluwa.

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