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Definition: diarrhoea from Philip's Encyclopedia

Frequent elimination of loose, watery stools, often accompanied by cramps and stomach pains. It arises from various causes, such as infection, intestinal irritants or food allergy. Mild attacks can be treated by replacement fluids.

Summary Article: Diarrhea
From Encyclopedia of Global Health

This year, over one billion people around the world will suffer from diarrhea. The disease is particularly prevalent in the developing world, where a combination of poor sanitation practices and limited access to clean drinking water act together to spread many causative organisms. Diarrhea is often ignored as a routine irritation of the gastrointestinal system, but it can rapidly progress to cause profound and life-threatening dehydration, especially in children.

According to the World Health Organization (WHO), 500 million children worldwide have at least one episode of diarrhea every year. Two million of these children die, making it the second most common cause of childhood death after respiratory infections. In fact, 20 percent of all childhood deaths (under 5 years old) are caused by diarrhea-induced dehydration, making it a leading concern for global healthcare practitioners.


Diarrhea, defined as excessively liquid or frequent evacuation of feces, can be caused by numerous conditions. Infectious diseases make up the vast majority of causative factors, although diarrhea can also be caused by contaminated food, as a medication side effect (particularly antibiotics), as a symptom of colorectal cancer, and as a sign of hormonal abnormalities.

Infectious organisms causing diarrhea include viruses (rotavirus being the most common), bacteria (e.g., E. coli), and parasites (e.g., Giardia). The gastrointestinal system, particularly the small and large intestines, are naturally populated by hundreds of different strains of nonharmful bacteria, many of which help with digestion. Infectious diarrhea can be caused either when a harmful, nonnative, biological agent colonizes the intestines or when one particular strain of native bacteria is favored over the others and takes over. This second pathway is exemplified by cases of bacterial overgrowth following the administration of antibiotics. The ingested antibiotics kill off most of the natural bacterial “flora” of the gut allowing a single disease causing variety to take over and proliferate.

The principle pathway of infectious diarrhea however, occurs through the spread of dangerous organisms through the environment. Infected individuals without access to latrines or a safe sanitation system inadvertently contaminate their own supply of water, spreading the disease to other members of their communities and creating a cycle of illness. Even with access to a clean water supply, organisms in improperly disposed of human waste can be spread to food by “vectors” like mosquitoes and other insects.


Diarrhea by itself is often ignored by patients and considered by many to be a temporary nuisance. However, it is important to distinguish associated symptoms that indicate a more serious condition. Fever, abdominal pain, blood or mucous in the stool, nausea, and vomiting are all reasons to seek urgent medical attention. If the nausea and vomiting are severe, the patient’s ability to maintain wellhydrated is at risk.

Dehydration is the biggest danger to deal with during severe episodes of diarrhea. Signs and symptoms of dehydration include lethargy, weakness, sunken eyes, an increased heart rate (greater than 110 beats per minute for a 5-year-old), and decreased urine output.

Chronic low-level diarrhea may also lead to malnutrition in children, who are unable to absorb the nutrients they need for normal growth and development.


The main treatment of diarrhea is rehydration therapy, either oral or intravenous. Oral fluids should be provided to the patient in a slow and steady manner, 15 ml per 15 minutes. In the 1960s, scientists invented oral rehydration salts (ORS), comprised of sugar, sodium, and other electrolytes, which are added to water to increase the intestinal absorption of the fluid. ORS saw their first widespread use in Bangladesh after the refugee crisis resulting from the 1971 India-Pakistan war. Since then, they have become widely available throughout the developing world and the therapy is thought to have saved millions of children’s lives. ORS is available for purchase in sachets manufactured under the supervision of the WHO and the United Nations Children’s Fund (UNICEF). Caregivers can also be taught the following simple home recipe to make a similar solution at home: one liter of water, one fist of sugar, and one pinch of salt. Oral rehydration should continue until the diarrhea runs its natural course. Children who cannot tolerate oral intake due to nausea and vomiting should be hospitalized for intravenous fluid therapy.

Mothers should continue feeding their children during diarrhea episodes. The diet should include breast milk for breastfeeding infants, or bananas, rice, and lentils for children used to solid food. The diet should be advanced slowly, and fluid hydration should be prioritized over solid foods.

In rare cases, antibiotics may be required to treat certain strains of bacterial diarrhea. The decision to use antibiotics and the choice of agent should be left to a health practitioner, whose decision can be guided by an in-depth history of the illness and laboratory analysis (stool culture, stool analysis for ova and parasites, etc.).

The majority of diarrhea episodes can be prevented via personal and public sanitation practices. Individuals should wash their hands after using the bathroom and before cooking and eating. Where municipal water is unavailable, water should be boiled or filtered. Municipal governments can prevent diarrhea by providing a clean supply of water and by building public latrines.

Despite the consensus regarding diarrhea prevention and the ready availability of ORS, diarrhea remains a leading cause of child mortality in the developing world. Unhygienic bathroom practices and a limited access to clean water account for the continued prevalence. ORS is still used by caregivers only about 50 percent of the time to treat diarrhea.

Diarrhea prevention should include increasing access to safe water, improved hygiene, and ORS promotion. The idea must be made clear to target populations that ORS is a treatment for dehydration, not diarrhea, and that it should be used as long as the diarrhea persists.

In recent years, research has focused on developing a vaccine for rotavirus (two vaccines, rotateq and rotarix, are currently in clinical trials), which could prevent 500,000 child deaths and 2 million hospitalizations a year.

  • Constipation; Digestive Diseases; Drinking Water; E. Coli Infections; Giardia Infections; Infectious Diseases; Nausea and Vomiting; Travel Medicine; Traveler’s Health.

  • David A. Ahlquist; Michael Camilleri, “Diarrhea and Constipation,” in Harrison’s Principles of Internal Medicine, 15th ed. (McGraw-Hill Professional, 2001).
  • Centers for Disease Control and Prevention, Richard E. FryeDiarrhea,” eMedicine,, (Cited February 2006).
  • The Rehydration Project
  • World Health Organization
  • Amit Chandra, MD, M.Sc.
    New York Hospital Queens
    Copyright © 2008 by SAGE Publications, Inc.

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