Diarrhoeal diseases

Diarrhoeal diseases are the second leading cause of death in children under five years old. They are responsible for killing around 525,000 children every year globally (WHO data from 2017) and a leading cause of malnutrition in children under five years old. Diarrhoeal diseases are often a major concern in emergency situations, where WASH infrastructure may be damaged and access to health services impacted because they are transmitted through the faecal oral route.

The following are standard case definitions to allow national health authorities to interpret data in an international context. However, during an outbreak case definitions may be adapted to the local context and the Red Cross Red Crescent should use those agreed/established by national health authorities. NB: Consider that during community-based surveillance, volunteers should use broad (simplified) case definitions (referred to as community case definitions) to recognize most or all possible cases, provide relevant risk communication and appropriate actions and encourage them to seek care. Other actors such as healthcare workers or investigators studying the cause of a disease, on the other hand, can use more specific case definitions that may require laboratory confirmation.

• Diarrhoea is defined as three or more loose or liquid stools per day (or more frequent passage than is normal for the individual).
• Frequent passing of formed stools is not diarrhoea, nor is the passing of loose, "pasty" stools by breastfed babies.

WHO case definition source of information here.

Above the threshold based on historical data.

• Water contaminated with human faeces, for example from sewage, septic tanks and latrines, is a source of infection. Animal faeces also contain microorganisms that can cause diarrhoea.
• Poor personal hygiene and inadequate access to clean water and sanitation facilities.
• Food when prepared or stored in unhygienic conditions. Raw fruits and vegetables that are not appropriately washed. Seafood taken from contaminated water and eaten raw or not sufficiently cooked.
• Unsafe domestic water storage and handling.
• Household members and close neighbours of patients with diarrhoeal disease are often at increased risk in the days immediately following the person’s illness if there are difficulties following necessary hygiene measures (e.g. if there is a lack of appropriate sanitation facilities or limited access to potable water).
• Typical at-risk areas include peri-urban slums where minimum requirements of clean water and sanitation are often not met.
• Humanitarian crises can increase the risk of diarrhoeal disease, through disruption of water and sanitation systems, or through the displacement of populations to inadequate and overcrowded camps.

Attack rates will vary from one outbreak to another. In case of an outbreak, consult the latest information provided by health authorities.

The attack rate depends among others on the infectious agent, the settings and the demographic and socioeconomic aspects of the region concerned.

E.g. shigella : median range : 1–33 per cent.

• Malnutrition: malnourished children are more vulnerable to diarrhoea. Each diarrhoeal episode, in turn, makes their malnutrition even worse.
• Young children under five years old.
• Immunosuppressed persons such as those receiving chemotherapy, transplant recipients or HIV carriers.
• People with chronic diseases such as renal disease, cancer, chronic lung disease, and diabetes.
• Individuals without ready access to rehydration therapy and health services.

Diarrhoeal disease can be caused by virus (Rotavirus, Adenovirus, Norovirus), by bacteria (e.g. Shigella, Cholera, Campylobacter, E. coli, Salmonella, Clostridium difficile) and protists (Cryptosporidium, Amoebiasis).

Rotavirus and Escherichia coli (E. coli), are the two most common infectious agents of moderate-to-severe diarrhoea in low-income countries. Other pathogens such as Cryptosporidium and Shigella species may also be important. Location-specific causes and age specific pathogens also need to be considered.

For more information and user-friendly mapping of the data, please visit: Diarrheal diseases - Our World in Data.

For some infectious agents: only humans (e.g. the most important rotaviruses, Shigella, etc.).

For other infectious agents: animals and humans (e.g. E. coli, Cryptosporidium).

Faecal oral transmission: pathogens in faecal particles pass from one person to the mouth of another person through contaminated hands, surfaces, objects, utensils or water. Ingestion of contaminated food and water that have been handled by a person who is shedding the pathogen through the faeces, or sewage  getting into the water used for drinking or washing food are both common transmission mode. Flies and other insects can mechanically transfer the organism to food, where the pathogens then multiply to achieve an infective dose.

Depends on the agent. For example, less than 48 hours for rotaviruses, 3—8 days for E. coli, 2—10 days for Cryptosporidia, 1—3 weeks for Shigella.

Depends on the  infectious agents

• Adults excrete E. coli for approximately one week or less; in children it can be longer.
• Persons infected with Rotaviruses shed large quantities of virus in their faeces beginning two days before the onset of diarrhoea and for up to ten days after the onset of symptoms. Rotavirus may be detected in the stool of immunodeficient persons more than 30 days after infection.

• Three or more loose or liquid stools over a period of 24 hours.
• Possible stomach pains, fever, nausea and vomiting.
• Severe diarrhoea can cause dehydration, sepsis and death.
• Liquid stools can be watery diarrhoea (lasts several hours or days), and includes cholera, bloody diarrhoea (also called dysentery) and chronic diarrhoea (lasts 14 days or longer).

Diarrhoeal diseases include cholera, Shigella, Rotavirus, Adenovirus, Campylobacter, E. coli, Clostridium difficile, Salmonella, Cryptosporidium, Amoebiasis, among others.

• Stool sample for faecal leukocytes test.
• Faecal lactoferrin assays.
• Stool culture (E. coli, Campylobacter, Shigella, Salmonella, Yersinia).
• Antigen testing (Cryptosporidium, Giardia).
• Toxin testing (C. difficile).

Please refer to the appropriate local or international guidelines for clinical management. All clinical management including the administration of any treatment or vaccine should be conducted by health professionals.

• Rehydration with Oral Rehydration Solution (ORS): ORS is a mixture of clean water, salt and sugar. It costs a few cents per treatment. ORS is absorbed in the small intestine and replaces the water and electrolytes lost in the faeces. In severe cases intravenous rehydration is necessary.
• Zinc supplementation for children.
• 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.
• If pathogen is bacterium intake of antibiotics.
• In severe dehydration cases hospitalization is required.
• Preventive vaccines are available against Rotavirus. Today, they are four oral rotavirus vaccines recommended for use by the World Health Organization (WHO).

Agent specific.

Randomized controlled trials have shown that both monovalent and pentavalent rotavirus vaccines are 80—90 per cent efficacious against severe rotavirus gastroenteritis (RVGE) in countries with very low, or low child and adult mortality. They are also 40—60 per cent efficacious in countries with high child mortality and high, or very high adult mortality. In most cases, vaccination in infancy provides protection against severe RVGE for at least two years.