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Diarrheal diseases and cholera

  • Page updated onMarch 16, 2025
Cholera and other diarrheal diseases
Photo: Bruno Abarca

Diarrhea is one of the greatest threats to public health in humanitarian emergencies and one of the leading causes of morbidity and mortality among children. Each year, there are over 1.7 billion cases and more than 400,000 deaths among children under five. Most of these deaths could be prevented with well-known measures. These include both preventive measures related to water, sanitation, hygiene, and vaccination, as well as rehydration with additional zinc supplements. However, some pathogens require specific treatment with antibiotics.

Some diarrheal diseases have significant epidemic potential, such as cholera and dysentery, making them particularly alarming in humanitarian contexts, where fecal-oral transmission may also be easier.

Importance of diarrheal diseases in humanitarian settings

Diarrhea is characterized by the increased frequency of stools with less consistency than usual or watery stools, which can last for several days. This is often a symptom of gastrointestinal infections caused by various bacteria (such as Escherichia coli, Salmonella, Shigella, Campylobacter, or Vibrio cholerae), viruses (such as rotavirus, hepatitis A, and norovirus), and parasites (such as Giardia and Entamoeba). Vaccines are available for some of these pathogens that can play a key role in their prevention.

The transmission of diarrheal infections is mainly feco-oral

Most infectious diarrhea is transmitted through contact with feces and contaminated elements such as dirty hands, flies, crops, food, or water. The pathogens expelled in the feces of an infected person are eventually ingested by another person, who becomes infected and continues the transmission. Even when the number of microorganisms is low, their multiplication upon reaching raw or poorly cooked food can be very rapid.

Fecal-oral transmission is exacerbated when sanitation conditions are poor, there is insufficient access to water (or the water is not safe for consumption), and there is poor hygiene. All these factors worsen in humanitarian emergencies, but this does not mean that there is an increased risk of any diarrheal infection in these contexts. For a specific type of infection (such as cholera) to occur, the pathogen causing it must be endemic or at least imported from another endemic area, which does not always happen.

Diarrheal diseases can have very serious consequences

The main complication of diarrhea is the loss of fluids and electrolytes, which can result in dehydration. This dehydration can be fatal, especially in young children.

Diarrhea also leads to a deficit in nutrient absorption. Therefore, it can be both a cause and a consequence of malnutrition. A malnourished child is at greater risk of falling ill with diarrhea, which in turn worsens their nutritional status. In some middle- and low-income countries or those affected by humanitarian crises, children under 5 years old may experience multiple episodes of diarrhea throughout the year. This can also lead to chronic malnutrition and delays in growth and child development.

Sometimes certain pathogens cause inflammation of the colon, resulting in the presence of mucus and blood in the stools. This diarrhea, known as dysentery, can lead to severe cases that require antibiotic treatment. In some cases, certain diarrheal diseases can even result in sepsis.

Water, sanitation and hygiene help prevent diarrhea

Given that the fecal-oral route is the primary transmission pathway for these infections, it makes sense to think that the disease burden in humanitarian contexts could be reduced with WASH programs (water, sanitation, and hygiene).

Access to water is a determining factor

Sometimes, the water supply network is destroyed in conflicts, or it is even the target of deliberate attacks by combatants who do not respect international humanitarian law. In other cases, people are displaced by a complex emergency to areas where access to water is not guaranteed. This threatens the survival of families for many reasons, including the increased risk of infections.

Due to this, a fundamental priority in humanitarian responses is to ensure the provision of a sufficient amount of water for drinking, covering essential basic needs, and guaranteeing the survival and dignity of people. The Sphere standards propose a minimum of 15 liters per person per day (depending on the context), distributed across multiple points. This way, no family should have to walk more than 500 meters or wait more than 30 minutes to access water. This is sometimes achieved by rehabilitating the water supply infrastructure. However, in other cases, water must be distributed using tank trucks, as well as tanks or containers for storage, and jars or buckets for transport and use. Drinking water should also be treated in the network, at the point of access, or at the point of use. There are different ways to do this.

Adequate sanitation is necessary for maintaining hygiene

Sanitation includes the proper management and disposal of waste, wastewater or contaminated water, and solid waste. It is essential for maintaining the hygiene of the environment and the places where people live their lives.

To ensure the proper disposal of human waste, the Sphere standards recommend that, in rapid emergency responses, there should be a minimum of 1 communal latrine for every 50 people. As soon as possible, this should be increased to 1 for every 20 people. Latrines should be located in safe, well-lit areas, segregated by sex, and at least 50 meters away from living quarters. Additionally, they must have water available for cleaning and hand hygiene, be designed to facilitate proper menstrual hygiene, and be installed in a way that does not pose a risk of contaminating water sources. To accommodate the needs of all individuals, there should be at least 1 latrine with improved accessibility for every 250 people. Once installed, it is also necessary to ensure their maintenance and management, including periodic sludge removal (dislodging).

Community mobilization and hygiene promotion

The promotion of hygiene is also necessary to ensure that everyone is aware of the risks associated with poor hygiene. These actions should also help to promote the recommended practices and measures to reduce those risks. Additionally, there is a need for the distribution of hygiene items such as soap, containers, menstrual hygiene products, or items for the hygiene of young children. These distributions should be followed by monitoring to ensure that the products are appropriate and are distributed in sufficient quantities. Occasionally, this need can be addressed with multipurpose cash transfers if markets are functioning.

An adequate promotion of hygiene requires a good strategy for community mobilization and communication. This is not only important for addressing the key factors for behavior change. Community participation is essential for the effectiveness of other water and sanitation actions. For example, families and communities should be consulted about the design of interventions and the location of water access points and community latrines. Additionally, it is recommended to establish community committees that have an active role in their management and cleaning.

More and better scientific evidence on WASH and diarrheal diseases is needed

There is substantial scientific evidence regarding the effectiveness of these types of interventions in improving water quality or other indicators of sanitation and hygiene. However, unfortunately, there are hardly enough studies that demonstrate the impact of these actions on health outcomes, such as the incidence of diarrheal infections (or their severity and duration) in humanitarian contexts.

Recent studies in Kenya, Zimbabwe and Bangladesh have shown mixed results. There was no effect in either Kenya or Zimbabwe. In Bangladesh there was a substantial improvement, but neither water treatment nor the combination of different WASH actions had a significant effect. This suggests the need for more comprehensive and ambitious WASH approaches to reduce exposure to microorganisms affecting the digestive tract.  

Importance of oral rehydration in the treatment of diarrhea

It may seem to us that the current 400,000 annual deaths from diarrhea in children under five are many. They are. However, we must not forget that until 1980, the annual number of childhood deaths from diarrhea exceeded four and a half million. What was the factor that led to such a drastic reduction in this figure? The introduction of oral rehydration therapy in 1979 and the multiplication of its production and use in the following years. Of course, this was not the only factor. There were also advances in water, sanitation, promotion of breastfeeding, and the widespread use of vitamin A and the measles vaccine, among others. However, the introduction of oral rehydration therapy was possibly the most significant.

Oral rehydration salts are a mixture of sodium and potassium salts with carbohydrate powders for dissolution in water. They are used to increase the intake of fluids (and electrolytes) and so to compensate for losses caused by diarrhea. This simple "low-tech" therapy, which is also inexpensive and easy to use, may reduce diarrhea-related dehydration and mortality by more than 90%. Therefore, oral rehydration therapy is today the cornerstone of diarrhea treatment, in combination with zinc supplements that reduce the number of diarrhea episodes and their duration. The use of antibiotics or intravenous rehydration is thus reserved for specific types of diarrhea and complicated cases.

Importance and approach to cholera in humanitarian crises

Cholera is a diarrheal bacterial disease with high epidemic potential transmitted through the fecal-oral route. It is one of the major public health threats in many humanitarian crises. Cholera can cause such severe watery diarrhea that it is capable of causing death from dehydration in just a few hours.

The 1994 cholera epidemic in Rwanda marked the history of this disease

In April 1994, a terrible genocide of Hutus against Tutsis began in Rwanda. In July of the same year, the Patriot Front (Tutsi) defeated the Hutu government and took control of the country. As a result, between July 14 and 17, 1994, more than half a million Rwandan refugees fled to North Kivu and its capital, Goma. Barely a month later, by August 14, nearly 50,000 of these people had died from an outbreak of cholera (followed by an outbreak of dysentery). The humanitarian response, which intensified in the second week after the outbreak began, only began to have an impact in the third week.

They were a physically weakened population after a long journey on foot, with a prevalence of acute malnutrition around 20%, and a very high rate of untreated water consumption. They settled in an overpopulated area, with very poor living conditions and no latrines (with soil that made it difficult to dig them). Additionally, the few available health centers were completely overwhelmed by the enormous influx of people.

Although the cholera outbreak in Goma in 1994 has unfortunately not been the only one to occur in humanitarian contexts, none have had such high crude mortality rates as that one. Nevertheless, there have been significant subsequent outbreaks, such as those in Haiti (with around 800,000 cases and 10,000 deaths between 2010 and 2019) or Yemen (with approximately 2,500,000 cases and 4,000 deaths between 2016 and 2021). Additionally, between 2021 and 2024, cholera has resurfaced in numerous humanitarian contexts (along with many other infectious diseases).

Importance of rehydration in cholera management

In most cases, cholera is asymptomatic (although it greatly depends on the studies and the level of endemicity). However, among symptomatic cases, it is estimated that 20% develop severe acute watery diarrhea that can lead to dehydration. Studies show that nearly half of these patients with severe diarrhea and dehydration may die if they do not receive treatment.

The treatment for symptomatic patients mainly involves administering oral rehydration solution after each liquid stool. This compensates for fluid loss until the diarrhea stops. Oral rehydration should be complemented with zinc for children, if they were not already taking it for the treatment of acute malnutrition.

Treatment with oral rehydration solution can be administered at home. However, during an outbreak, community distribution and oral rehydration points and cholera treatment centers are often established. In these facilities, patients can be continuously monitored, intravenous rehydration therapy and antibiotics can be administered in the most severe cases, strict hygiene, disinfection, and personal protective measures can be ensured, and proper disposal of stools and other potentially contaminated waste can be maintained. It is estimated that, with appropriate treatment, the cholera case fatality rate can be reduced to 1%.

Cholera is a vaccine-preventable disease

Currently, we have several vaccines available against cholera: Dukoral, Shanchol, Euvichol-Plus, and, since April 2024, Euvichol-S. The latter has a simplified formulation that is less complex, more cost-effective, and equally effective as Euvichol-Plus. All of these are inactivated and safe vaccines. Among them, Shanchol and Euvichol are the vaccines available in the global stockpile and are used in outbreak control. Both require the administration of two doses (separated by 14 days). They produce a protective immune response starting one to two weeks after the last dose, which typically lasts for at least three years before it begins to wane. When only one dose is administered, the level of protection achieved may be similar but of shorter duration (about six months).

The oral cholera vaccine can be used where cholera is endemic, in humanitarian crises with high risk, and in outbreak response, in combination with other prevention and control strategies. The decision to use this vaccine should be made after assessing the risks of infection and the feasibility of vaccine use. This requires an analysis of its availability, its actual usefulness considering the time it takes to administer two doses and generate protection, and the possibility of using a single dose to provide protection for a shorter period of time. Other contextual factors should also be examined.

Vaccination should never be an excuse to reduce the emphasis on the main measures for the prevention and control of outbreaks. These include proper treatment, primarily based on the use of oral rehydration solution, access to water and sanitation, hygiene promotion, and community mobilization.

What strategies are available for cholera control?

The global strategy for cholera control outlines several key objectives to prioritize. These include early detection and rapid response for outbreak control, multi-sectoral collaboration, and proper coordination through the Global Task Force on Cholera Control, its technical groups, its country support group, and the National Cholera Control Programs.

For the control of cholera outbreaks, it is crucial to strengthen health systems beforehand. This includes enhancing a good system of epidemiological surveillance, adequately preparing the health personnel, and ensuring pre-positioning sufficient quantities of oral rehydration salts, other treatments, disinfectants, and personal protective equipment.

Experience also demonstrates the importance of community mobilization within national control and response plans. This mobilization enables community members to understand the risks and the importance of preventive measures, and to trust the use of vaccines and treatment for the disease. Additionally, these individuals should be able to participate in all stages of the response, amplifying its impact, and they can assist humanitarian actors in understanding what determines local knowledge, attitudes, and practices.

At times, it is recommended to establish community outbreak response teams to implement Case-Area Targeted Interventions (CATI) around a case once an outbreak has been declared. This model can be useful when there are few cases, at the onset of an outbreak, or in a second stage after a mass intervention (as a complementary measure). It allows for quick action in priority areas, requiring fewer resources than other approaches.

Infectious diseases

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