Diarrhoeal Diseases

Key facts

• Diarrhoeal disease is the second leading cause of death in children under five years old. It is both preventable and treatable.
• Diarrhoeal disease kills 1.5 million children every year.
• Globally, there are about two billion cases of diarrhoeal disease every year.
• Diarrhoeal disease mainly affects children under two years old.
• Diarrhoea is a leading cause of malnutrition in children under five years old.

Diarrhoeal disease is the second leading cause of death in children under five years old, and is responsible for killing 1.5 million children every year. Diarrhoea can last several days, and can leave the body without the water and salts that are necessary for survival. Most people who die from diarrhoea actually die from severe dehydration and fluid loss. Children who are malnourished or have impaired immunity are most at risk of life-threatening diarrhoea.

Diarrhoea is defined as the passage of 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. Diarrhoea is usually a symptom of an infection in the intestinal tract, which can be caused by a variety of bacterial, viral and parasitic organisms. Infection is spread through contaminated food or drinking-water, or from person-to-person as a result of poor hygiene. Diarrhoeal disease is treatable with a solution of clean water, sugar and salt, and with zinc tablets.

There are 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.

Scope of diarrhoeal disease

Every year there are about two billion cases of diarrhoeal disease worldwide.

Diarrhoeal disease is a leading cause of child mortality and morbidity in the world, and mostly results from contaminated food and water sources. Worldwide, around 1 billion people lack access to improved water and 2.5 billion have no access to basic sanitation. Diarrhoea due to infection is widespread throughout developing countries.

In 2004, diarrhoeal disease was the third leading cause of death in low-income countries, causing 6.9% of deaths overall. In children under five years old, diarrhoeal disease is the second leading cause of death – second only to pneumonia. Out of the 1.5 million children killed by diarrhoeal disease in 2004, 80% were under two years old.

In developing countries, children under three years old experience on average three episodes of diarrhoea every year. Each episode deprives the child of the nutrition necessary for growth. As a result, diarrhoea is a major cause of malnutrition, and malnourished children are more likely to fall ill from diarrhoea.

Dehydration

The most severe threat posed by diarrhoea is dehydration. During a diarrhoeal episode, water and electrolytes (sodium, chloride, potassium and bicarbonate) are lost through liquid stools, vomit, sweat, urine and breathing. Dehydration occurs when these losses are not replaced.

The degree of dehydration is rated on a scale of three.

Early dehydration – no signs or symptoms.<

Moderate dehydration:

• thirst
• restless or irritable behaviour
• decreased skin elasticity
• sunken eyes

Severe dehydration:

• symptoms become more severe
• shock, with diminished consciousness, lack of urine output, cool, moist extremities, a rapid and feeble pulse, low or undetectable blood pressure, and pale skin.

Death can follow severe dehydration if body fluids and electrolytes are not replenished, either through the use of oral rehydration salts (ORS) solution, or through an intravenous drip.

Causes

Infection: Diarrhoea is a symptom of infections caused by a host of bacterial, viral and parasitic organisms, most of which are spread by faeces-contaminated water. Infection is more common when there is a shortage of clean water for drinking, cooking and cleaning. Rotavirus and Escherichia coli are the two most common causes of diarrhoea in developing countries.

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.

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.

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. Water can contaminate food during irrigation. Fish and seafood from polluted water may also contribute to the disease.

Prevention and treatment

Key measures to prevent diarrhoea include:

• access to safe drinking-water
• improved sanitation
• exclusive breastfeeding for the first six months of life
• good personal and food hygiene
• health education about how infections spread
• rotavirus vaccination

Key measures to treat diarrhoea include the following.

• Rehydration: with intravenous fluids in case of severe dehydration or shock and/or oral rehydration salts (ORS) solution for moderate or no dehydration. ORS is a mixture of clean water, salt and sugar, which can be prepared safely at home. It costs a few cents per treatment. ORS is absorbed in the small intestine and replaces the water and electrolytes lost in the faeces.
• Zinc supplements: zinc supplements reduce the duration of a diarrhoea episode by 25% and are associated with a 30% reduction in stool volume.
• 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 worker if there are signs of dehydration.

WHO response

WHO works with Member States and other partners to:

• promote current policies for the management of diarrhoea in developing countries
• conduct research to develop and test new health delivery strategies in this area
• develop new health interventions, such as the rotavirus immunization
• help to train health workers, especially at community level.