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7 Point Plan

Diarrhoeal diseases: The basics

Diarrhoeal diseases: The basicsDiarrhoea is defined as having loose or watery stools at least three times per day, or more frequently than normal for an individual. Though most episodes of childhood diarrhoea are mild, acute cases can lead to significant fluid loss and dehydration, which may result in death or other severe consequences if fluids are not replaced at the first sign of diarrhoea.

What causes diarrhoea?

Diarrhoea is a common symptom of gastrointestinal infections caused by a wide range of pathogens, including bacteria, viruses and protozoa. However, just a handful of organisms are responsible for most acute cases of childhood diarrhoea.8 Rotavirus is the leading cause of acute diarrhoea, and is responsible for about 40 per cent of all hospital admissions due to diarrhoea among children under five worldwide.9 Other major bacterial pathogens include E. coli, Shigella, Campylobacter and Salmonella, along with V. cholerae during epidemics (Box 1). Cryptosporidium has been the most frequently isolated protozoan pathogen among children seen at health facilities and is frequently found among HIV-positive patients (Box 2). Though cholera is often thought of as a major cause of child deaths due to diarrhoea, most cases occur among adults and older children.

How are diarrhoea pathogens transmitted?
Most pathogens that cause diarrhoea share a similar mode of transmission – from the stool of one person to the mouth of another. This is known as faecal-oral transmission. There may be differences, however, in the number of organisms needed to cause clinical illness, or in the route the pathogen takes while travelling between individuals (for example, from the stool to food or water, which is then ingested).

Box 1 - In humanitarian crises, diarrhoea is a major cause of death

What are the main forms of acute childhood diarrhoea?
There are three main forms of acute childhood diarrhoea, all of which are potentially life-threatening and require different treatment courses:
  • Acute watery diarrhoea includes cholera and is associated with significant fluid loss and rapid dehydration in an infected individual. It usually lasts for several hours or days. The pathogens that generally cause acute watery diarrhoea include V. cholerae or E. coli bacteria, as well as rotavirus.
  • Bloody diarrhoea, often referred to as dysentery, is marked by visible blood in the stools. It is associated with intestinal damage and nutrient losses in an infected individual. The most common cause of bloody diarrhoea is Shigella, a bacterial agent that is also the most common cause of severe cases.
  • Persistent diarrhoea is an episode of diarrhoea, with or without blood, that lasts at least 14 days. Undernourished children and those with other illnesses, such as AIDS, are more likely to develop persistent diarrhoea. Diarrhoea, in turn, tends to worsen their condition.

Why are children more vulnerable?
Children with poor nutritional status and overall health, as well as those exposed to poor environmental conditions, are more susceptible to severe diarrhoea and dehydration than healthy children (Figure 5). Children are also at greater risk than adults of life-threatening dehydration since water constitutes a greater proportion of children’s bodyweight. Young children use more water over the course of a day given their higher metabolic rates, and their kidneys are less able to conserve water compared to older children and adults.

How is diarrhoea prevented?
Reducing childhood diarrhoea requires interventions to make children healthier and less likely to develop infections that lead to diarrhoea; clean environments that are less likely to transmit disease; and the support of communities and caregivers in consistently reinforcing healthy behaviours and practices over time.

Reference Reference Reference Reference Box 2 - The links between diarrhoea and HIV

Many well-known child survival interventions are critical to reducing child deaths from diarrhoea. They work in two ways: by either directly reducing a child’s exposure to the pathogens that cause diarrhoea (through the provision of safe drinking water, for example) or by reducing a child’s susceptibility to severe diarrhoea and dehydration (through improved nutrition and overall health).

Improvements in access to safe water and adequate sanitation, along with the promotion of good hygiene practices (particularly handwashing with soap), can help prevent childhood diarrhoea. In fact, an estimated 88 per cent of diarrhoeal deaths worldwide are attributable to unsafe water, inadequate sanitation and poor hygiene.14

Water, sanitation and hygiene programmes typically include a number of interventions that work to reduce the number of diarrhoea cases. These include: disposing of human excreta in a sanitary manner, washing hands with soap, increasing access to safe water, improving water quality at the source, and treating household water and storing it safely.

Improvements in sanitation reduce the transmission of pathogens that cause diarrhoea by preventing human faecal matter from contaminating environments. Improving sanitation facilities has been associated with an estimated median reduction in diarrhoea incidence of 36 per cent across reviewed studies.15 (A recent survey in the British Medical Journal showed that their readers believed sanitation to be the most important medical milestone since 1840.16) However, a major challenge in this regard is scaling up sanitation facilities to the point where they are used by an entire community (‘total sanitation’). Use of such facilities by all community members is necessary to significantly reduce diarrhoeal disease transmission (Box 3).17

Figure 5 - Nutrition, health and environmental factors all play a role in preventing and treating childhood diarrhoea


Reference Box 3 - Increasing demand to stop community-wide open defecationWashing one’s hands with soap is another important barrier to transmission (Box 4), and has been cited as one of the most cost-effective public health interventions.19 A number of studies have shown that handwashing with soap can reduce the incidence of diarrhoeal disease by over 40 per cent.20 Accessible and plentiful water has also been shown to encourage better hygiene, handwashing in particular, although the extent to which access to improved water sources reduces diarrhoea rates often depends on the type of water source available (such as public taps or standpipes, protected dug wells or boreholes).21

Interventions to improve water quality at the source, along with treatment of household water and safe storage systems, have been shown to reduce diarrhoea incidence by as much as 47 per cent.22 Proven and field-tested household water treatment options that are currently being promoted include chlorination, filtration, combined flocculation and disinfection, boiling, and solar disinfection. Household water treatment could potentially be scaled up quickly and inexpensively in both development and emergency situations. It has even become common practice in large cities where homes are connected to a municipal water supply, since water is often polluted between the source and the point of use.


Undernourished children are at higher risk of suffering more severe, prolonged and often more frequent episodes of diarrhoea. Repeated bouts of diarrhoea also place children at a greater risk of worsening nutritional status due to decreased food intake and reduced nutrient absorption, combined with the child’s increased nutritional requirements during repeated episodes.

Diarrhoea often leads to stunting in children due to its association with poor nutrient absorption and appetite loss. The risk of stunting in young children has been shown to increase significantly with each episode of diarrhoea,23 and diarrhoea control, particularly in the first six months of life, may help to reduce stunting prevalence among children.24

Box 4 - Handwashing with soap: A high-impact, cost-effective interventionBREASTFEEDING
Breastmilk contains the nutrients, antioxidants, hormones and antibodies needed by a child to survive and develop. Infants who are exclusively breastfed for the first six months of life and continue to be breastfed until two years of age and beyond develop fewer infections and have less severe illnesses than those who are not, even among children whose mothers are HIV-positive. This protection has been shown to be higher where maternal literacy is lower and where sanitation is worse.25 Infants who are not breastfed have a sixfold greater risk of dying from infectious diseases in the first two months of life, including from diarrhoea, than those who are breastfed.26

Vitamin A supplementation is a critical preventive measure, and studies have shown mortality reductions ranging from 19 per cent to 54 per cent in children receiving supplements.27 This reduction is associated in large part with declines in deaths due to diarrhoeal diseases and measles. Vitamin A supplementation has also been shown to reduce the duration, severity and complications associated with diarrhoea.28

Adequate zinc intake among children is critical for normal growth and development. Recent supplementation trials have shown that adequate zinc leads to a substantial reduction in childhood diarrhoea cases.29

Immunizations help reduce deaths from diarrhoea in two ways: by helping prevent infections that cause diarrhoea directly, such as rotavirus, and by preventing infections that can lead to diarrhoea as a complication of an illness, such as measles.

Rotavirus is estimated to cause about 40 per cent of all hospital admissions due to diarrhoea among children under five years of age worldwide30 – leading to some 100 million episodes of acute diarrhoea each year that result in 350,000 to 600,000 child deaths.31 Introduction of rotavirus vaccine in countries with the greatest diarrhoea burdens, especially in Asia and Africa, must be accelerated on a priority basis. Global rotavirus vaccine introduction has recently been recommended by the World Health Organization (WHO).32

Measles is an acute viral infection that is often self-limiting. But some children, particularly those who are undernourished or have compromised immune systems, may experience serious side effects, including diarrhoea. Diarrhoea is one of the most common causes of death associated with measles worldwide.

Immunizations help reduce deaths from diarrhoea in two ways


How is diarrhoea diagnosed?
Guidelines for the diagnosis and treatment of childhood diarrhoea are set out in the Integrated Management of Childhood Illness handbook.33 Diagnosis is based on clinical symptoms, including the extent of dehydration, the type of diarrhoea exhibited, whether blood is visible in the stool, and the duration of the diarrhoea episode. Treatment regimens differ based on the outcomes of this clinical assessment. Microbiological culture and microscopy are not necessary to diagnose diarrhoea and initiate treatment, even in high-income countries, although these tools can help identify specific pathogens for outbreak investigations.

It is important that caregivers recognize the symptoms that require immediate attention from appropriate health personnel, including trained community health workers. These symptoms include dehydration, blood in the stool, profuse and persistent diarrhoea and repeated vomiting.

How is diarrhoea treated?
The latest recommendations for treating childhood diarrhoea in the developing world are set out in a UNICEF and WHO joint statement34 issued in 2004. These interventions are proven, affordable and relatively straightforward to implement.

Since the 1970s, oral rehydration therapy has been the cornerstone of treatment programmes to prevent life-threatening dehydration associated with diarrhoea (Box 5). Fluid replacement should begin at home and be administered by the caregiver at the start of the diarrhoea episode. A solution made from oral rehydration salts (ORS) is the ‘gold standard’ of oral rehydration therapy, and a new formula has been developed (known as low-osmolarity ORS) that improves overall outcomes when compared to the original version (Box 6). UNICEF and WHO recommend that all children with diarrhoea have access to this new ORS formula; making it widely available to children in need will require innovative delivery strategies.

When ORS are not available, other fluids will also work to prevent dehydration among children with diarrhoea, although they are not as effective in treating children who have become dehydrated. Such fluids (which many countries have designated as ‘recommended homemade fluids’) can be prepared at home using readily available and low-cost ingredients. Examples of rehydrating fluids include cereal-based drinks made from a thin gruel of rice, maize, potato or other readily available low-cost grain or root crop the family has at home. Breastmilk is also an excellent drink for fluid replacement and should continue to be given to infants with diarrhoea simultaneously with other oral rehydration solutions.

Why is Rehydration so import and how it works to save childrens lives Reference Box 5 - Oral rehydration salts: One of the most important medical advances of the 20th century

Box 6 - Low-osmolarity ORS: A life-saving remedy just got better

If ORS or other appropriate fluids are not available, increased amounts of almost any fluid could also help to prevent dehydration. Continuing to feed the child during the diarrhoea episode, while providing oral rehydration therapy, further supports the absorption of fluids from the gut into the bloodstream to prevent dehydration. Children receiving food during the diarrhoea episode are also more likely to maintain their nutritional status and their ability to fight infection.

A recent and important development in diarrhoea treatment is the addition of zinc to the regimen. Box 7 details the added value of zinc in diarrhoea treatment, and its effectiveness in reducing both the duration and severity of diarrhoea episodes as well as reducing stool volume and the need for advanced medical care. Children receiving zinc often have greater appetites and are more active during the diarrhoea episode; its use has also been associated with increased ORS uptake. The provision of zinc tablets by health workers may also reduce the demand from caregivers for other less effective drugs, such as antibiotics and antidiarrhoeal medications, which should not be routinely administered.

Box 7 - Zinc: Critical to diarrhoea treatment, but largely unavailable in developing countries