Diarrhoeal Diseases (Human)

Unique identifier / Notation

BI0028

Synonyms

Not identified.

Diarrhoeal diseases are infectious diseases, contaminants and other causes of diarrhoea. Diarrhoea is defined as the passage of three or more loose or liquid stools per day, or more frequently than is normal for the individual (WHO, no date). This includes the three clinical types of diarrhoea: acute watery diarrhoea – lasts several hours or days, and includes cholera; acute bloody diarrhoea – also called dysentery; and persistent diarrhoea – lasts 14 days or longer (WHO, 2017).

Primary reference(s)

WHO, no date. Diarrhoea. World Health Organization (WHO). Accessed 20 September 2020.

WHO, 2017. Diarrhoeal disease. World Health Organization (WHO). Accessed 20 September 2020.

Additional scientific description

Diarrhoeal disease is the second leading cause of death in children under five years old. It is both preventable and treatable. Each year diarrhoea kills around 525,000 children under five. A significant proportion of diarrhoeal disease can be prevented through the provision of safe drinking-water and adequate sanitation and hygiene. Globally, there are nearly 1.7 billion cases of childhood diarrhoeal disease every year.

Diarrhoeal diseases can be caused by infectious disease, malnutrition, contaminated water and food, and other causes:

Infection: Diarrheal diseases are usually a symptom of gastrointestinal infection, which can be caused by a variety of bacterial, viral and parasitic organisms, most of which are spread by faeces-contaminated water or from person to person as a result of poor hygiene. Infection is more common when there is a shortage of adequate sanitation and hygiene and safe water for drinking, cooking and cleaning. Rotavirus and Escherichia coli are the two most common etiological agents of moderate-to-severe diarrhoea in low-income countries. Other pathogens such as Cryptosporidium and Shigella species may also be important. Location-specific etiologic patterns also need to be considered (WHO, 2017).

Malnutrition: Children who die from diarrhoea often suffer from underlying malnutrition, which makes them more vulnerable to diarrhoea. Each diarrhoeal episode, in turn, makes their malnutrition even worse. Diarrhoea is a leading cause of malnutrition in children under five years old (WHO, 2017).

Source: Water contaminated with human faeces, for example, from sewage, septic tanks and latrines, is of particular concern. Animal faeces also contain microorganisms that can cause diarrhoea (WHO, 2017).

Other causes: Diarrhoeal disease can also spread from person-to-person, aggravated by poor personal hygiene. Food is another major cause of diarrhoea when it is prepared or stored in unhygienic conditions. Unsafe domestic water storage and handling is an important risk factor. Consumption of fish and seafood from polluted water may also contribute to diarrhoeal disease (WHO, 2017).

Diarrhoea can last several days and can leave the body without the water and salts that are necessary for survival. Severe diarrhoea leads to fluid loss, and may be life-threatening, particularly in young children and people who are malnourished or have impaired immunity. In the past, for most people, severe dehydration and fluid loss were the main causes of diarrhoea deaths. Now, other causes such as septic bacterial infections are likely to account for an increasing proportion of all diarrhoea-associated deaths. Children who are malnourished or have impaired immunity as well as people living with human immunodeficiency virus (HIV) are most at risk of life-threatening diarrhoea (WHO, 2017).

Metrics and numeric limits

Not applicable.

Key relevant UN convention / multilateral treaty

International Health Regulations (2005), 3rd ed. (WHO, 2016).

Examples of drivers, outcomes and risk management

The World Health Organization (WHO) recommends the following key measures to prevent diarrhoea: access to safe drinkingwater; use of improved sanitation; hand washing with soap; exclusive breastfeeding for the first six months of life; good personal and food hygiene; health education about how infections spread; and rotavirus vaccination (WHO, 2017).

The WHO provides the key measures to treat diarrhoea which include the following (WHO, 2017):

Rehydration with an oral rehydration salts solution. This is a mixture of clean water, salt and sugar. It costs a few cents per treatment. The oral rehydration salts solution is absorbed in the small intestine and replaces the water and electrolytes lost in the faeces.
Zinc supplements reduce the duration of a diarrhoea episode by 25% and are associated with a 30% reduction in stool volume.
Rehydration with intravenous fluids in cases of severe dehydration or shock.
Nutrient-rich foods: the vicious circle of malnutrition and diarrhoea can be broken by continuing to give nutrient-rich foods – including breast milk – during an episode, and by giving a nutritious diet – including exclusive breastfeeding for the first six months of life – to children when they are well.
Consulting a health professional, in particular for management of persistent diarrhoea or when there is blood in the stool or if there are signs of dehydration.

The WHO also works with Member States and other partners to: promote national policies and investments that support case management of diarrhoea and its complications as well as increasing access to safe drinking-water and sanitation in developing countries; conduct research to develop and test new diarrhoea prevention and control strategies in this area; build capacity in implementing preventive interventions, including sanitation, source water improvements, and household water treatment and safe storage; develop new health interventions, such as the rotavirus immunisation; and help to train health workers, especially at community level (WHO, 2017).