London School of Hygiene & Tropical Medicine

The role of pathogens in childhood diarrhoea has been significantly underestimated, with bacteria, viruses and fungi responsible for nearly twice as many cases than previously thought, according to a study in The Lancet.

The research, led by the University of Virginia, USA analysed the stool samples of over 10,000 children from countries including India, Bangladesh, Kenya and Mali found that just six pathogens were responsible for 77.8% of all diarrhoea cases. The most prevalent pathogen was Shigella, but the researchers discovered that amongst children with a diarrhoea-causing pathogen, approximately half of them had more than one infection.

The researchers reanalysed samples from the original Global Enteric Multicenter Study published in 2013. Those results suggested that just 51.5% of cases were linked to pathogens but for this study, the researchers were able to make use of new detection techniques.

Diarrhoea remains the second leading cause of mortality in under-fives across the world and is responsible for around half a million deaths per year. It can be difficult to pinpoint the cause in individual cases, but it is often from infections that spread between people via contaminated food and water. Patients are usually treated by supportive care alongside rehydration and zinc supplements.

So how significant is this study to support our understanding of diarrhoea? How much more needs to be done in developing countries to curb infant mortality from this area? Professor Val Curtis, Director of the Environmental Health Group at the London School of Hygiene & Tropical Medicine explains:

"This study is a game changer. It ushers in an era where we can no longer say that we largely don't know what is the cause of the second biggest killer of children in the world today. Instead of only being able to find a specific pathogen in the stools of about a half of children with diarrhoea, we can now find one in some 80% of cases.

 "Such molecular diagnostic methods need to become widespread and cheap enough for use in developing countries. They need to be used to understand the transmission routes of these killer pathogens. Finally, the results underscore how we have shockingly ignored the study of diarrhoea. Neglecting to eradicate it by improving environmental conditions, such as sanitation, water and hygiene, in developing countries, is a scandal."

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