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Diarrheal diseases and cholera in humanitarian crises: WASH, oral rehydration and vaccines

  • Page updated onJune 29, 2026
Cholera and other diarrheal diseases
Text and photo: Bruno Abarca

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

Some diarrhoeal diseases have significant epidemic potential, such as cholera and dysentery, and are therefore particularly concerning in humanitarian crises, where the risk of faecal-oral transmission is also heightened.

Why diarrheal diseases are a critical threat in humanitarian emergencies

Diarrhoea consists of an increase in the number of stools with less consistency than usual or liquid stools, which may last several days. This is often a symptom of infections of the digestive tract caused by different 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) (WHO, 2024). Vaccines exist for some of these pathogens and 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.

Faecal-oral transmission is heightened when sanitation conditions are poor, access to sufficient water is lacking or it is unsafe for consumption, and hygiene is inadequate (UNHCR, 2026). All these factors worsen in humanitarian emergencies, but this should not lead to the assumption that there is an increased risk of any diarrhoeal infection in these contexts. For a particular type of infection to occur (such as cholera), the causative pathogen must be endemic or at least have been imported from another endemic area, which does not always happen (GTFCC, 2024a).

Diarrheal diseases can have very serious consequences

The main complication of diarrhoea is the loss of fluids and electrolytes, which can result in dehydration. This dehydration can be fatal, particularly in young children (WHO, 2024).

Diarrhoea also causes a deficit in nutrient absorption. It can therefore be both a cause and a consequence of malnutrition. A malnourished child faces a higher risk of falling ill with diarrhoea, which in turn worsens their nutritional status. In some low- and middle-income countries or those affected by humanitarian crises, children under 5 may suffer many episodes of diarrhoea throughout the year. This can also result in 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 (WASH) to prevent diarrhea in emergencies

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

On occasion, water supply networks are destroyed in conflicts, or even become the target of deliberate attacks by combatants who do not respect international humanitarian law. In other cases, the population is displaced by a complex emergency to places where access to water is not guaranteed. This threatens the survival of families for many reasons, among which is the increased risk of infection.

For this reason, a fundamental priority in humanitarian responses is to ensure an adequate supply of water for drinking, meeting essential basic needs, and guaranteeing people's survival and dignity. The Sphere standards propose a minimum of 15 litres per person per day (depending on the context), distributed across multiple points (Sphere Association, 2017). In this way, no family should have to walk more than 500 metres or wait more than 30 minutes to access water.

This is sometimes achieved by rehabilitating the supply network infrastructure. In other cases, water must be distributed by tanker trucks, along with tanks or jerricans for storage and jugs or buckets for transport and use. Drinking water must also be treated at the network level, at the point of access, or at the point of use. There are different ways of doing this (Sphere Association, 2017).

Adequate sanitation is necessary for maintaining hygiene

Sanitation encompasses 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 (Sphere Association, 2017).

For the correct disposal of human excreta, the Sphere standards propose that, in rapid emergency response, a minimum of 1 communal latrine per 50 people be established. As soon as possible, this should be increased to 1 per 20 people. Latrines must be located in safe and well-lit areas, segregated by sex and at least 50 metres from dwellings. They must also have water available to facilitate cleaning and hand hygiene, be adapted to allow proper menstrual hygiene, and be installed in such a way that they do not pose a risk of contaminating water sources. To take into account the needs of all people, there must be at least 1 per 250 people with improved accessibility. Once installed, it is also necessary to ensure their maintenance and management, including, for example, periodic sludge emptying (dislodging).

Community mobilisation and hygiene promotion

Hygiene promotion is also necessary to ensure that all people are aware of the risks associated with poor hygiene (GTFCC, 2024b). These actions must also help to promote the recommended practices and measures for reducing those risks. In addition, the distribution of hygiene items such as soap, containers, menstrual hygiene products and items for the hygiene of young children is required. These distributions should be followed by monitoring to ensure that the products are appropriate and distributed in sufficient quantities. In some cases, this need can be addressed through multipurpose cash transfers, where markets are functioning (Sphere Association, 2017).

Effective hygiene promotion requires a sound strategy of community mobilisation and health communication. This is not only important for addressing the key drivers of behaviour change. Community participation is necessary for the remaining water and sanitation actions to be effective. For example, families and communities should be consulted on the design of interventions and the location of water access points and communal latrines. It is also recommended to establish community committees with an active role in their management and cleaning.

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

There is extensive scientific evidence on the effectiveness of these types of interventions for improving water quality or in relation to other sanitation and hygiene indicators. However, unfortunately, there are barely enough studies demonstrating the impact of these actions on health outcomes, such as the incidence of diarrhoeal infections (or their severity and duration) in humanitarian contexts.

Recent studies in Kenya, Zimbabwe and Bangladesh have shown mixed results (Cumming et al., 2019). Neither Kenya nor Zimbabwe showed any effects. Bangladesh did show a substantial improvement, but without water treatment or the combination of different WASH actions having a significant effect. This suggests the need for more comprehensive and ambitious WASH approaches to reduce exposure to microorganisms affecting the digestive tract.

🧠 Let's pause and reflect

What explains why well-implemented WASH interventions do not always reduce the incidence of diarrhoeal diseases, and what are the implications for the design of humanitarian responses?

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Oral rehydration (ORS) saved millions of lives and remains essential today

The current 400,000 annual deaths from diarrhoea in children under five may seem like an enormous number. They are. However, we must not forget that until 1980 the annual number of child deaths from diarrhoea exceeded four and a half million. What was the factor that brought about such a dramatic reduction in this figure? The introduction of oral rehydration therapy in 1979 and the rapid scale-up of its production and use in the years that followed. It was not the only factor, of course. There were also advances in water and sanitation, the promotion of breastfeeding, and the wider use of vitamin A and the measles vaccine, among others. However, the introduction of oral rehydration therapy was arguably the most significant (Victora et al., 2000).

Oral rehydration salts are a mixture of sodium and potassium salts with carbohydrates in powder form for dissolution in water. They are used to increase fluid (and electrolyte) intake and thereby compensate for the losses caused by diarrhoea. This simple "low-technology" therapy, which is also affordable and easy to use, can reduce dehydration and diarrhoea-related mortality by more than 90% (Santosham et al., 2010). Oral rehydration therapy is therefore today the cornerstone of diarrhoea treatment, in combination with zinc supplements that reduce the number and duration of diarrhoeal episodes. The use of antibiotics or intravenous rehydration is reserved for specific types of diarrhoea and complicated cases.

Cholera in humanitarian crises: from the Goma outbreak to global control

Cholera is a diarrhoeal bacterial disease with high epidemic potential, transmitted via the faecal-oral route. It is one of the major public health threats in many humanitarian crises (Stoddard et al., 2023). Cholera can produce such acute watery diarrhoea that it is capable of causing death from dehydration within just a few hours.

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

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

This was a population physically weakened after a long journey on foot, with a prevalence of acute malnutrition of around 20%, and an extremely high rate of untreated water consumption. They settled in a territory that became severely overcrowded, with very poor shelter conditions and no latrines (the ground making it difficult to dig them). In addition, the few health facilities available were completely overwhelmed by the massive influx of people (Goma Epidemiology Group, 1995).

Although the 1994 Goma cholera outbreak has not (unfortunately) been the only one to occur in humanitarian contexts, none has had such high crude mortality rates as those. Even so, there have been major subsequent outbreaks, such as those in Haiti (with around 800,000 cases and 10,000 deaths between 2010 and 2019) and Yemen (with around 2,500,000 cases and 4,000 deaths between 2016 and 2021). Between 2021 and 2024, moreover, cholera has resurged in numerous humanitarian contexts (alongside many other infectious diseases) (Stoddard et al., 2023).

Importance of rehydration in cholera management

In the majority of cases, cholera is asymptomatic (although this varies greatly depending on the studies and the level of endemicity). However, among symptomatic cases it is estimated that 20% develop severe acute watery diarrhoea that can lead to dehydration. Studies show that almost half of these patients with severe diarrhoea and dehydration may die if left untreated.

Treatment for symptomatic patients consists primarily of administering oral rehydration solution after each liquid stool (GTFCC, 2024a). This compensates for fluid loss until the diarrhoea stops. Oral rehydration should be supplemented with zinc in the case of children, if they were not already receiving it for the treatment of acute malnutrition.

Oral rehydration solution treatment can be administered at home. However, when an outbreak occurs, community oral rehydration distribution and administration points and cholera treatment centres are often established (GTFCC, 2024a). These allow for continuous patient monitoring, the administration of intravenous rehydration therapy and antibiotics in the most severe cases, the enforcement of strict hygiene, disinfection and personal protection measures, and the safe disposal of stools and other potentially contaminated waste. 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 (WHO, 2017). The decision whether or not to use this vaccine must be made after analysing the risks of infection and the feasibility of vaccine use. This requires an analysis of its availability, the practical utility taking into account the time needed to administer two doses and for them to generate protection, and the possibility of using a single dose to provide protection over a shorter period of time. Other contextual factors must also be considered.

Vaccination should never be used as an excuse to reduce the emphasis on the main measures for outbreak prevention and control (WHO, 2017). These measures include appropriate treatment, based primarily on the use of oral rehydration solution, access to water and sanitation, hygiene promotion and community mobilisation.

🧠 Let's pause and reflect

In what cases might the availability of cholera vaccines lead to underestimating the importance of water, sanitation and hygiene interventions?

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What strategies are available for cholera control?

The global strategy for cholera control sets out several main objectives to prioritise. These are early detection and rapid response for outbreak control, multi-sectoral collaboration, and effective coordination through the Global Task Force on Cholera Control, its technical groups, its country support group, and National Cholera Control Programmes (GTFCC, 2019).

For the prevention and control of cholera epidemics, health system strengthening is key. This includes reinforcing a sound epidemiological surveillance system, the adequate training of health staff, and the prepositioning of sufficient quantities of oral rehydration salts, other treatments, disinfectants and personal protective equipment.

Experience likewise demonstrates the importance of community mobilisation within national control and response plans (GTFCC, 2024b). This mobilisation is what can enable community members to understand the risks and the importance of preventive measures, and to trust in the use of the vaccine and disease treatment. Furthermore, these individuals must be able to participate in all stages of the response, multiplying its impact, and can help humanitarian actors understand what shapes local knowledge, attitudes and practices.

Community outbreak response teams are sometimes recommended to implement Case-Area Targeted Interventions (CATI) around a case once an outbreak has been declared. This model can be useful when case numbers are low, at the start of an outbreak, or as a complementary approach in a second phase following a mass intervention. It allows rapid action in priority areas, requiring fewer resources than other approaches (Bulit & Ramos, 2020).

References

Infectious diseases

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How to cite this page

Abarca, B. (June 29, 2026). Diarrheal diseases and cholera in humanitarian crises: WASH, oral rehydration and vaccines. Salud Everywhere. https://saludeverywhere.com/en/health-in-humanitarian-crises/diarrheal-diseases-and-cholera/

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