Common Cholera Misconceptions

Cholera is a bacterial infection, which can cause severe diarrhoea.¹ It is caused by eating or drinking food or water contaminated with Vibrio cholerae bacteria.² After consumption of contaminated food or water, it usually takes between 12 hours and 5 days for symptoms to appear in an affected person. The symptoms of cholera include: profuse watery diarrhoea, vomiting, thirst, leg cramps, and restlessness or irritability.³ Cholera can lead to severe dehydration, characterised by symptoms such as rapid heart rate, loss of skin elasticity, dry mucous membranes and low blood pressure. If severe dehydration is not treated in a timely manner, it can lead to shock, coma, and even death within hours.³

Cholera can infect both children and adults and it can kill within hours, if left untreated.² According to WHO, it is estimated that there are 1.3 to 4.0 million cases, and 21,000 to 143,000 deaths annually, due to the infection of cholera, all around the world.

There are a lot of misconceptions surrounding cholera and it is important to address them in order to provide correct information to improve prevention and treatment of it.

Misconception no.1: cholera is caused by contaminated food

Cholera is caused by a coma-shaped, rod-like, motile Gram-negative bacterium named Vibrio cholerae.⁴ While there are over 200 serogroups of cholera, only two serogroups have been identified to cause outbreaks: O1 and O139.⁵ V. cholerae releases an exotoxin called cholera toxin. Cholera toxin attaches itself to the mucosa of the small intestine, which causes fluid and electrolyte loss (diarrhoea).⁵

V. cholerae has two main reservoirs: humans and water (both freshwater and seawater). In water reservoirs, V. cholerae can persist for a long time and it can undergo genetic changes, which means that the elimination of cholera is not easy to achieve, if not impossible. Humans are usually infected through contaminated water used for drinking or preparing foods, and when symptomatic, they keep shedding the bacteria with faeces for about 1 to 2 weeks, which can in turn infect other people.⁶ Quite often, large epidemics are related to faecal contamination of water supplies or street-vendor foods.⁷ While most infections are caused by drinking or preparing food with contaminated water, it can also be caused by eating certain contaminated foods. V. cholerae can easily attach themselves to chitin-containing shells of crabs, shrimps, and other shellfish, and these can be a source of infection if eaten raw or undercooked.⁷

This highlights the importance of having proper water and sanitation infrastructure as well as good cooking practices.

Misconception no.2: cholera is only found in developing countries

It is believed that cholera originated in Asia, specifically in the Ganges River Delta in India.^5,6 Cholera spread all over the world from its initial reservoir in the Ganges Delta in India during the 19^th century. Subsequently, six pandemics have occurred since then, which have killed millions of people globally. The current (seventh) pandemic initially started in South Asia in 1961, made it to Africa in 1971, and then the Americas in 1991.⁸

Cholera is now endemic, which is defined as an area with confirmed cases detected over the past 3 years, in Asia, Latin and Central America, and sub-Saharan Africa.⁵ In December 2023, 50,440 new cholera cases, including 483 new deaths, had been reported globally, with 5 countries with the most reported cases being Afghanistan, Syria, Zimbabwe, Sudan, and Mozambique.

While most cholera cases occur in developing countries, there have been cases reported in developed countries recently as well. However, cases in EU/EEA countries and the USA are very low and they are due to international travel.^7,9 In 2019, 25 cases were reported in EU/EEA countries, none were reported in 2020, 2 were reported in 2021 and in 2022, 29 cases were reported in nine of the EU/EEA countries.⁷ Meanwhile, the occurrence of cholera in the US ranges from 0 to 5 cases annually.⁹ While the risk of catching cholera abroad is low, the Advisory Committee on Immunization Practices (ACIP) recommends cholera vaccine for both paediatric and adult travellers, who are visiting areas of active cholera transmission.¹⁰

Misconception no.3: cholera is always fatal

Cholera is not always fatal. Most of the people, who get infected with cholera bacteria, have no symptoms or only have mild or moderate symptoms, which can be easily and effectively treated with a simple oral rehydration solution.⁸ However, a minority of less than 20% of patients will develop acute watery diarrhoea with moderate or severe dehydration, which can lead to death if not treated in time.¹¹ The average mortality rate for cholera is about 1.9% (2.9% in Africa) globally, however, if left untreated, the mortality rate is about 25 to 50% for severe cholera cases.^7,11

Having said that, the mortality rate can be reduced to less than 1% if adequate treatment is provided in a timely manner.¹¹ As severe patients are at risk of shock, they need to be rapidly treated with administration of intravenous fluids. Additionally, the most severely ill patients will be given antibiotics to reduce the length of diarrhoea, however, it is not recommended to carry out mass administration of antibiotics as it has not been proven to have an effect on the spread of cholera and it may play a part in increasing antimicrobial resistance.⁸

It is important to note that it is believed that a large number of cases are not reported, particularly in countries with the highest burden. It is estimated that only around 5-10% of cases are actually reported.⁶ Many cases are not being recorded because of limitations in surveillance systems and fear of negative effects on trade and tourism.⁸

Misconception no.4: cholera vaccines provide complete protection

At the moment, there are 3 oral cholera vaccines, which have been pre-qualified by WHO: Dukoral®, Shanchol™, and Euvichol-Plus®. All of these vaccines require 2 doses for full protection.⁸ These vaccines are not 100% effective in preventing cholera disease. The estimate percentages of the effectiveness in preventing disease ranges from around 60 to 80% with these vaccines.^{12, 13} These vaccines also do not provide life-long protection. On average, the duration of protection ranges from 2 to 3 years.⁸ In addition, both doses of the vaccine need to be administered, otherwise, one dose only provides a short-term protection.⁸

Currently, the worldwide supply of oral cholera vaccine is not enough to meet all the demand for two doses of preventive vaccination. Because of this, on 20 October 2022, the International Coordinating Group members (IFRC, MSF, UNICEF, and WHO) took a hard decision to temporarily limit all active cholera vaccine campaigns to one single dose.¹¹

Because the current vaccines are not 100% effective in preventing the disease and because the current demand for the vaccine is higher than the supply, the cholera vaccine cannot be solely relied on to provide complete protection against cholera.

Nevertheless, it is worth mentioning that additional vaccines are available to travellers, such as Vaxchora vaccine, a single-dose, oral vaccine, which has been approved by FDA in the United States. It has been reported that vaccination with Vaxchora results in reduction of the risk of moderate and severe diarrhoea by 90% at 10 days after vaccination and by 80% at 3 months after vaccination. However, it is not known how long people are protected beyond 3–6 months after vaccination.¹⁴

Misconception no.5: cholera outbreaks are solely due to poor hygiene

It is true that cholera thrives in situations where there is poor personal and environmental hygiene due to not having access to safe and clean water as well as inadequate disposal of human waste.⁴ However, poor hygiene is not the only factor that affects the spread of the disease. According to WHO, there are several factors that contribute to outbreaks of cholera:¹¹

• Humanitarian crises, political instability, conflict, and a lack of development are increasing cases of humanitarian crises. This puts people at an increased risk of cholera. Nine countries of the ones that have reported outbreaks are facing conflicts and unrest in the affected areas.
• Climate change: Many of the countries that have reported recent cholera outbreaks in 2022 are suffering from natural disasters such as cyclones (Mozambique, Malawi), flooding (Pakistan, Nigeria), and drought (Horn of Africa countries). Severe flooding events and above-normal hurricane seasons can damage water and sanitation infrastructure, causing contamination of water sources and poor sanitation conditions, which then increase the risk of transmission. The above-normal hurricane season in the Americas is impacting multiple countries in the Caribbean and Central America and is causing major flooding. Post-monsoon season is often associated with an increase in cholera cases in South Asia. Furthermore, some countries experienced droughts, resulting in cholera because of a lack of safe water
• Several ongoing outbreaks: Multiple countries with cholera outbreaks are also suffering from other outbreaks of diseases such as monkeypox, dengue, chikungunya and measles. This makes it even harder to respond to cholera outbreaks, especially when resources are limited
• Inadequate surveillance: Inadequate surveillance can negatively affect response. There are several reasons why surveillance might be sub-optimal such as lack of data sharing, failure of surveillance system due to humanitarian crises and political unrest, and incapacity to accurately confirm cholera cases
• Limited availability of medical supplies and healthcare resources: the supply of cholera kits globally can be insufficient, and suppliers may struggle to meet the demand. Delays or shortages of medical products can increase the number of preventable deaths. Additionally, the number of outbreaks, multiple ongoing outbreaks and humanitarian crises can stretch the resources and reduce the capacity to respond to cholera outbreaks.
• Availability of oral cholera vaccine: The global demand for cholera vaccines exceeds the supply, this decreases the number of people who can get two doses of vaccine in affected areas.

Misconception no.6: cholera can be diagnosed based solely on symptoms

It is true that the diagnosis of cholera is often based on clinical signs and symptoms, particularly in countries where resources are limited and appropriate laboratory facilities are not available.⁵ The hallmark symptom of cholera is acute watery diarrhoea, sometimes described as “rice-water stools”, which can be accompanied by other symptoms such as vomiting, thirst, and symptoms of dehydration.³ However, it is not possible to distinguish between cholera and other diseases, which cause acute watery diarrhoea, based on symptoms alone.

To actually confirm cholera infection, a stool sample needs to be collected and cultured to isolate and identify V. cholerae serogroup O1 or O139. This is a gold-standard test. However, as these are often not readily available in endemic areas, an alternative - the Crystal® VC dipstick rapid test can be used. Unfortunately, rapid tests are not as accurate as laboratory tests and it is recommended that in case these tests are positive, then the sample should be tested in the lab to confirm it.¹⁵

Summary

Cholera is a bacterial infection that can cause acute watery diarrhoea. Most of the cases are caused by drinking or preparing food with contaminated water, however, it can also be caused by eating certain contaminated foods, such as raw or undercooked seafood. Cholera can result in severe dehydration, which can lead to shock, coma, and even death within hours if left untreated. Cholera has a high mortality rate if not managed properly, however, the rate can be immensely reduced through fast and effective treatment. While there are several cholera vaccines available, none of them provide 100% protection against cholera and only offer fairly short-lived protection of 2-3 years.

Cholera mostly affects developing countries, however, there have been cases reported in developed countries as well, due to international travelling. There are many factors that contribute to outbreaks of cholera such as inadequate water and sanitation infrastructure, humanitarian crises, climate change, and limited medical supplies and healthcare resources. While in most affected areas cholera is diagnosed based on the symptoms, it is not an effective way to diagnose it as it is similar to other diarrhoeal diseases. To accurately diagnose cholera, a lab test should be performed. Accurate diagnosis of cholera is important for an adequate surveillance system of the outbreaks. In turn, surveillance of the outbreaks can help improve the response to them and help with the management, reducing the severity of them.