Smith Collection/Gado(NEW YORK) — The number of children who die from diarrhea worldwide fell by a third between 2005 and 2015, researchers have found.

But mortality rates remain highest in some of the world’s poorest countries, with diarrhea killing almost half a million children under 5 years old globally each year, according to a new study published in The Lancet.

The study found that diarrhea is responsible for more than 8 percent of all deaths of young children, making it the fourth leading cause of death. More than 40 percent of these deaths occur in India and Nigeria alone.

“Diarrheal diseases disproportionately affect young children,” said lead author Dr. Ali Mokdad of the Institute for Health Metrics and Evaluation (IHME) at the University of Washington. “Despite some promising reductions in mortality, the devastating impact of these diseases cannot be overlooked. Immediate and sustained actions must be taken to help low-income countries address this problem by increasing health care access and the use of oral rehydration solutions.”

The study estimates that there were 2.3 billion episodes of diarrheal disease globally in 2015, with 957 million of these being in children. A decade later, there were a total of 1.3 million deaths, including 499,000 child deaths.

Diarrheal diseases are most common in low-income countries with poor access to clean water, sanitation and urgent medical care, as well as a frequent cause of hospitalization in high-income nations.

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