Diarrheal Diseases: Causes, Impact, and Prevention

Diarrheal diseases remain one of the most preventable yet deadly health threats worldwide. Each year, approximately 443,832 children under age five die from diarrheal diseases, making it the third leading cause of death in this age group. Despite significant medical advances, millions of families still face this challenge due to unsafe water, poor sanitation, and inadequate hygiene practices. Understanding what causes diarrheal diseases and how to prevent them can save countless lives.

What are diarrheal diseases? 🔗

Diarrheal disease occurs when a person passes three or more loose or liquid stools per day. While this might seem like a simple digestive issue, the consequences can be severe. The condition results from infections in the intestinal tract caused by various pathogens including bacteria, viruses, and parasites. Globally, there are nearly 1.7 billion cases of childhood diarrheal disease every year, affecting communities across all income levels but disproportionately impacting low and middle-income countries.

The disease can manifest in three clinical forms: acute watery diarrhea lasting several hours or days, acute bloody diarrhea (also called dysentery), and persistent diarrhea that continues for 14 days or longer. Each type poses different risks, but all can lead to dangerous dehydration if not properly managed.

The hidden burden on children 🔗

Children under five years old bear the heaviest burden of diarrheal diseases. In 2021, diarrheal diseases caused 1.2 million deaths worldwide, with children under five having the highest mortality rate among all age groups. The impact extends beyond immediate mortality. Each diarrheal episode deprives children of essential nutrients needed for growth and development, creating a vicious cycle where diarrhea leads to malnutrition, and malnourished children become more susceptible to future infections.

Regional disparities remain stark, with sub-Saharan Africa experiencing the highest mortality rates. While high-income countries see fewer than one death per 100,000 children, some regions in sub-Saharan Africa record more than 150 deaths per 100,000 children under five.

The pathogens behind the disease 🔗

Bacterial causes 🔗

Several bacteria can trigger diarrheal infections, with Escherichia coli (E. coli) being among the most common. Not all E. coli strains are harmful-many live harmlessly in our intestines. However, pathogenic strains cause significant illness. Six types of E. coli cause diarrheal illness, including enterotoxigenic E. coli (ETEC), which is the leading cause of traveler’s diarrhea.

Shiga toxin-producing E. coli (STEC) can cause severe complications, including hemolytic uremic syndrome, which damages the kidneys and blood. Other bacterial culprits include Salmonella, Shigella, and Campylobacter species, all transmitted primarily through contaminated food and water.

Viral infections 🔗

Rotavirus stands out as the single most significant viral cause of severe diarrhea in young children worldwide. Before widespread vaccination, it was responsible for hundreds of thousands of child deaths annually. The virus spreads easily among infants and young children, causing fever, vomiting, and watery diarrhea that can quickly lead to severe dehydration.

Other viral pathogens include norovirus, adenovirus, and astrovirus. These viruses spread through the fecal-oral route, often in settings where many children gather, such as daycare centers and schools.

Parasitic infections 🔗

Parasites like Cryptosporidium, Giardia, and Entamoeba species also cause diarrheal diseases, particularly in children aged three to five years. These parasites often contaminate water sources and can survive in conditions that kill many bacteria and viruses.

How diarrheal diseases spread 🔗

Understanding transmission pathways is crucial for prevention. Infection spreads through contaminated food or drinking water, or from person to person due to poor hygiene. Water contaminated with human feces-from sewage, septic tanks, or open defecation-poses particular danger. Animal feces also contain pathogens capable of causing human disease.

Transmission occurs through the fecal-oral route via contaminated food or water, person-to-person contact, contact with animals or their environment, and swimming in untreated water. In many cases, food becomes contaminated during preparation or storage in unhygienic conditions.

The danger of dehydration 🔗

Dehydration represents the most severe threat from diarrheal disease. During episodes, the body loses water and critical electrolytes-sodium, chloride, potassium, and bicarbonate-through liquid stools, vomit, sweat, and breathing. When these losses aren’t replaced, dehydration occurs rapidly, especially in young children.

Severe dehydration manifests through lethargy or unconsciousness, sunken eyes, inability to drink, and skin that returns very slowly when pinched. This condition requires immediate medical attention and can be fatal if untreated. Historically, severe dehydration and fluid loss caused most diarrhea deaths, though bacterial infections now account for an increasing proportion of fatalities.

Prevention through water, sanitation, and hygiene 🔗

The solution to diarrheal diseases lies largely in improving water, sanitation, and hygiene-collectively known as WASH. Studies estimate that inadequate water, sanitation, and hygiene cause approximately 842,000 diarrhea deaths annually, accounting for 58% of all diarrheal disease burden.

Safe water access 🔗

Water quality interventions can reduce diarrhea incidence by 19% after 12 months of implementation. Access to safe drinking water-through piped connections, protected wells, or household water treatment-forms the foundation of prevention. However, billions still lack this basic necessity.

Improved sanitation 🔗

Sanitation interventions can reduce diarrhea incidence by 36%. Proper disposal of human waste prevents contamination of water sources and food. Improved sanitation facilities include flush toilets connected to sewage systems, ventilated improved latrines, and composting toilets.

Hand hygiene practices 🔗

Perhaps the most cost-effective intervention is also the simplest. Hand washing with soap can reduce diarrhea risk by 47%. Yet, only about 19% of the world’s population washes hands with soap after contact with excreta. Promoting handwashing at critical times-after toilet use and before food preparation-could prevent nearly half of all diarrheal infections.

The power of vaccination 🔗

Rotavirus vaccines are safe, effective, and recommended for all infants, with two types available that are given orally in multiple doses. These vaccines have dramatically reduced severe rotavirus infections. Seven out of ten babies completing the vaccine series are protected from all rotavirus infections, while nine out of ten are protected from severe disease.

The global implementation of rotavirus vaccination has prevented hundreds of thousands of deaths and hospitalizations, demonstrating how targeted interventions can transform public health outcomes.

Treatment approaches that save lives 🔗

When prevention fails, prompt treatment becomes critical. Oral rehydration solution (ORS)-a simple mixture of clean water, salt, and sugar-remains the cornerstone of treatment. This inexpensive intervention can prevent up to 93% of diarrheal deaths when widely available and properly used.

Zinc supplementation reduces diarrhea duration by 25% and decreases stool volume by 30%. For severe dehydration, intravenous fluids become necessary. Continued feeding with nutrient-rich foods, including breast milk for infants, helps break the cycle between malnutrition and diarrhea.

A preventable tragedy 🔗

The persistence of diarrheal diseases as a major killer reflects not a lack of solutions but a failure to implement known interventions at scale. We possess the knowledge and tools to prevent most cases-safe water systems, sanitation infrastructure, hygiene education, effective vaccines, and simple treatment protocols. About 88% of diarrheal deaths among children under five are attributable to inadequate water, sanitation, and hygiene, making these issues fundamentally preventable.

Progress has occurred. Global diarrheal mortality has decreased by 60% since 1990, driven by improvements in WASH infrastructure, nutrition programs, vaccine introduction, and increased access to oral rehydration therapy. However, vast disparities persist between and within countries, with the poorest and most marginalized communities bearing the greatest burden.

What do you think? How can communities without access to improved water and sanitation facilities implement practical hygiene measures to reduce diarrheal disease risk? What role should governments and international organizations play in ensuring universal access to basic WASH services as a fundamental human right?

References

1. https://www.who.int/news-room/fact-sheets/detail/diarrhoeal-disease
2. https://www.healthdata.org/news-events/newsroom/news-releases/diarrheal-diseases-remain-leading-killer-children-under-5-adults
3. https://data.unicef.org/topic/child-health/diarrhoeal-disease/
4. https://www.cdc.gov/ecoli/about/kinds-of-ecoli.html
5. https://my.clevelandclinic.org/health/diseases/16638-e-coli-infection
6. https://www.mayoclinic.org/diseases-conditions/rotavirus/symptoms-causes/syc-20351300
7. https://wwwnc.cdc.gov/travel/yellowbook/2024/infections-diseases/escherichia-coli-diarrheagenic
8. https://www.who.int/publications-detail-redirect/9789241564823
9. https://www.who.int/tools/elena/bbc/wsh-diarrhoea
10. https://www.cdc.gov/rotavirus/vaccines/index.html
11. https://doh.wa.gov/you-and-your-family/immunization/diseases-and-vaccines/rotavirus
12. https://www.cdc.gov/global-water-sanitation-hygiene/about/index.html