Diarrheal diseases are the third leading cause of child mortality globally. The World Health Organisation has stated that diarrheal diseases are “both treatable and preventable”.1 So, why are so many children still dying from them?
In 2017, almost 1.6 million people died from diarrheal diseases globally and, as the visualization below shows, one-third were children under five years old. For most of the past three decades under-5s have accounted for the vast majority of deaths from diarrheal diseases – back in 1990 it killed 1.7 million children.
Half a million of the 5.4 million children that died in 2017 died from diarrheal disease – it was the cause of every tenth child’s death. Diarrheal diseases are the third leading cause of child mortality globally, after Pneumonia (and other lower respiratory diseases) and preterm birth complications.
The majority of deaths from diarrheal diseases occur in poorer countries: we see this in the chart below, which shows the relationship between the diarrheal disease death rates and a country’s income. The rates of death from diarrheal diseases are high in the poorest countries and they decline as incomes rise; very few people die of diarrheal diseases in high-income countries.
The relationship between income and the prevalence of diarrheal diseases is also clear when we look at the map of death rates from diarrheal diseases across the world. At lower levels of income risk factors for diarrheal diseases such as lack of access to clean water, rotavirus vaccine availability, undernutrition, stunting and others are most prevalent.2
Understanding the cause of disease is important so that we can set our priorities on the interventions and treatments that would save most lives, e.g. developing vaccines against the main agents for diarrhea and using antibiotic treatments only when they are appropriate.
Diarrheal diseases are caused primarily by viral and bacterial pathogens. The visualization below shows the major pathogens responsible for diarrhea in children; the area of each box indicates the number of deaths from diarrhea in 2016 that can be attributed to each pathogen. While bacterial pathogens (shown in red) are the major group of organisms responsible for diarrheal diseases, rotavirus is the single largest causative agent. 3
There are two main reasons why the number of children dying from diarrhea is still so large – the prevalence of diarrhea-associated risk factors and the lack of access to essential treatment.
The figure below shows the major risks factors associated with the development of diarrheal diseases: unsafe drinking water, poor sanitation and malnutrition are responsible for the largest portion of deaths. Since 1990 we have made a lot of progress in reducing these major risks; you can read more in our Hunger and Undernourishment and Water Use and Sanitation entries. But continued progress is still needed.
In addition to reducing exposure to risks factors, increasing access to oral rehydration solution (ORS), therapeutic zinc use and the coverage of rotavirus vaccines were all shown to be essential for reducing the burden of diarrheal diseases in children.4
Diarrheal diseases are both ‘preventable and treatable’, as the WHO says, because we already know how to deal with many of the risk factors that may lead to diarrhea and, if diarrhea cannot be avoided, we know how to treat it.
The table below lists the range of interventions available for the treatment of diarrhea we have today.5 Some of these interventions, such as ORS, breastfeeding and improvements in sanitation broadly target all-causes of diarrhea, whereas, vaccination and antibiotic use are specifically directed against the causative agents of the disease.
Water, sanitation and hygiene (WASH) interventions are the best way to prevent diarrheal diseases. Hand washing with soap, better water quality and better sanitation have been shown to reduce the risk of diarrheal infections by 47%, 17% and 36%, respectively.6
Educating mothers about the importance of breastfeeding is also important. Breastfeeding allows for the transfer of maternal immunity to the child – in developing countries infants that are not breastfed are six times more likely to die from infectious diseases, such as those causing to diarrhea, in the first 2 months of their lives.7
Another way to prevent diarrheal diseases is vaccination. Until relatively recently, there were few vaccines available to prevent diarrheal diseases. Cholera vaccine has been licensed since 1991 but it is primarily given to travelers and used as an outbreak control measure. This is because targeted immunization combined with other sanitary measures is more cost-effective than immunizing every individual with a vaccine that only provides a few years of protection.8 In 2006, however, new vaccines against rotavirus – the leading cause of childhood diarrhea as the treemap above shows – have been introduced. The most recent studies show that, while the effectiveness of the new rotavirus vaccines vary across different countries, it works well in protecting children against rotavirus disease.9 We will explore the success, potential and limitations of rotavirus vaccines in an upcoming post.
When preventative measures fail, several options for the treatment of diarrheal diseases are available, including nutritional interventions and antibiotic use when necessary. But the single best treatment for diarrheal diseases is a surprisingly simple mixture of water, salt and sugar: otherwise known as the oral rehydration solution.10 The estimates of ORS effectiveness vary by source, with some suggesting that the current use of ORS helps to prevent 69% of diarrheal deaths and, if its coverage would be increased close to 100%, 93% of diarrheal deaths could be prevented.11
We will look in more detail at the specific prevention and treatment measures against diarrheal diseases in upcoming posts. This should help to make clear what is possible and effective in preventing and treating one of the leading causes of death in children.
Potential of interventions to prevent the burden of diarrheal diseases in childhood12
|Intervention||Estimate of the effect size|
|Handwashing with soap||48% risk reduction|
|Improved water quality||17% risk reduction|
|Excreta disposal (improved sanitation)||36% risk reduction|
|Breastfeeding education||43% increase in exclusive breastfeeding rates at day 1, 30% increase until 1 month, and 90% increase from 1-6 months|
|Preventive zinc supplementation||13% reduction in diarrhea incidence, but no effect on mortality|
|Therapeutic zinc supplementation||46% reduction in all-cause mortality and 23% reduction in hospitalization due to diarrhea|
|Rotavirus vaccines||74% effectiveness against very severe rotavirus infection; 61% against severe; 47% reduction in hospitalization|
|Cholera vaccines||52% effective against cholera infection|
|Oral rehydration solution (ORS)||69% reduction in diarrhea-specific mortality|
|Dietary management for diarrhea||47% reduction in diarrhea treatment failure and 47% reduction in treatment failure|
|Antibiotics for cholera||63% reduction in clinical failure rates|
|Antibiotics for Shigella||82% reduction in clinical failure rates|
|Antibiotics for cryptosporidiosis||52% reduction in clinical failure rates|
|Community-based interventions (home visits and healthcare promotion)||160% increase in ORS use and 80% increase in zinc use. 9% increase in seeking care for diarrhea and 75% reduction in inappropriate antibiotic use|