Introduction
According to WHO diarrhea is defined as the passage of three or more loose or liquid stools per day, or more frequent bowel movements than an individual’s norm. It occurs due to disruptions in the normal absorption and secretion processes of the intestines, leading to excess water in the stool.
Globally, it accounts for around 1.7 billion childhood episodes yearly and is the third leading cause of death among children aged 1–59 months, causing around 443,800 deaths annually. In 2019, global mortality totaled approximately 1.53 million deaths.
Types
According to WHO, there are three main clinical types of diarrhoea:
- Acute Watery Diarrhoea: Lasts several hours or days and includes cholera.
- Acute Bloody Diarrhoea: Also called dysentery.
- Persistent Diarrhoea: Lasts 14 days or longer.
Causes
- Infectious: Diarrhoea is a manifestation of infections caused by a host of bacterial, viral and parasitic organisms. Among children under 5 years of age, the most common pathogens are:
- Viruses: Rotavirus, Norovirus, Adenovirus and Astrovirus.
- Bacteria: Escherichia coli, Salmonella spp., Shigella spp., and Campylobacter spp.
- Parasites: Cryptosporidium, Giardia, and Entamoeba spp.
- Malnutrition: Underlying malnutrition makes children more vulnerable to diarrhoea. Each diarrhoeal episode, in turn, makes malnutrition even worse.
- Contaminated Source: Water contaminated with human faeces, eg. from sewage, septic tanks and latrines, is of particular concern. Animal faeces also contain microorganisms that can cause diarrhoea.
- Medications: Antibiotics, chemotherapy, magnesium-containing antacids.
- Food intolerances: Lactose, fructose, artificial sweeteners.
- Chronic GI diseases: IBS, IBD (Crohn’s/ulcerative colitis), celiac disease, SIBO.
- Other causes:
- Spread from person-to-person.
- Poor personal hygiene.
- Food prepared or stored in unhygienic conditions.
- Unsafe domestic water storage and handling.
- Fish and seafood from polluted water.
Risk Factors
- Young children (especially <5 years) and the elderly.
- Weakened immune system (due to chemotherapy, HIV/AIDS, etc.).
- Frequent antibiotic use and hospitalization.
- Travelers to high‑risk (developing) regions.
Signs & Symptoms
- Frequent loose or watery stools.
- Urgency and abdominal cramping.
- Nausea, bloating.
- Signs of Dehydration: thirst, dry mouth, sunken eyes, dark urine, dizziness, lethargy.
- In inflammatory diarrhea: mucus or blood in stools, high fever, intense abdominal pain.
Complications
- The most dangerous complication is dehydration, which can lead to electrolyte imbalance, kidney injury, malnutrition and even death, especially in children.
- Malnutrition and weight loss if chronic.
- Pathogen-specific complications include:
- E. coli: Hemolytic-uremic syndrome
- Campylobacter: Bacteremia, meningitis.
- Shigella: Seizures, HUS, reactive arthritis, sepsis.
- C. difficile: Pseudomembranous colitis, toxic megacolon, perforation, sepsis.
Prevention
Key measures to prevent diarrhoea include:
- Water, sanitation & hygiene: Access to safe drinking-water, use of improved sanitation, hand washing with soap.
- Exclusive Breastfeeding for the first 6 months of life
- Food safety & traveler precautions: Avoid raw/unwashed produce, drink bottled water, avoid street food.
- Health education about how infections spread.
- Rotavirus Vaccination for infants.
Home Remedies
Key measures to treat diarrhoea include the following:
- Rehydration with oral rehydration salts (ORS) solution. 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.
- 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 6 months of life – to children when they are well.
- Probiotics can help restore gut flora; potential benefit in antibiotic-associated diarrhea but evidence varies.
When to Seek Medical Attention
Seek medical care if you observe:
- Signs of dehydration: Dizziness, extreme thirst, dry mouth, little to no urination, rapid heartbeat.
- Diarrhea lasting more than 2 days in adults or immediately in infants and young children.
- High fever, bloody or black stools.
- Severe abdominal pain or persistent vomiting.
- If diarrhea follows antibiotic use to rule out Clostridioides difficile infection.
- Chronic or recurrent diarrhea indicating possible underlying disease.
Bibliography
[1] https://www.who.int/news-room/fact-sheets/detail/diarrhoeal-disease/
[2] https://www.ncbi.nlm.nih.gov/sites/books/NBK448082/
[3] https://www.mayoclinic.org/health/diarrhea/DS00292
[4]: https://www.worldgastroenterology.org/guidelines/acute-diarrhea/acute-diarrhea-english
[5] https://www.ncbi.nlm.nih.gov/books/NBK551643/
[6] https://www.ncbi.nlm.nih.gov/books/NBK470525/
[7] https://www.mayoclinic.org/diseases-conditions/diarrhea/symptoms-causes/syc-20352241
[8] https://www.niddk.nih.gov/health-information/digestive-diseases/diarrhea/symptoms-causes