June 30 (UPI) -- While cases of diarrhea in children often increase after heavy rains and flooding, new research suggests a link between extended droughts and the at-times deadly illness for those under age 5, especially in poorer countries.
This is an especially "ominous" sign as the world continues to get warmer due to climate change, said researchers at the Yale School of Public Health, whose study was published Thursday in Nature Communications.
Diarrhea, though preventable and treatable, is the second leading cause of death in children under 5, the World Health Organization says.
Globally, the illness, which can arise from exposure to contaminated food or water, animal feces, or another infected person, kills about 525,000 children under age 5 annually.
The Yale scientists found the problem worsened in households that had to travel long distances for water or lacked water and soap for handwashing. But they said even adequate sanitation did not compensate for diarrhea risk associated with drought.
They described their findings as yet another call to action on climate change.
"You cannot fully eliminate drought's impact on diarrhea risk, especially under a climate that will have more drought in the future," Kai Chen, an assistant professor in the Yale School of Public Health's Department of Epidemiology, and a senior author of the study, said in a news release.
"We need to reduce greenhouse gas emissions," Chen added.
According to the researchers, their study is the largest to explore the effects of long-term drought on diarrhea risk in children living in low- and middle-income countries. And they described it as "the first of its kind to use a new measure of drought that takes both water supply and demand into account."
Specifically, the study's authors analyzed international health surveys and climate data, measuring drought "at a 10-square-kilometer resolution with a metric called the standardized precipitation evapotranspiration index."
They reviewed data on bouts of diarrhea collected between 1990 and 2019 by the Demographic and Health Surveys, a collaboration among USAID and dozens of countries.
The surveys covered 1.3 million-plus children under 5 living in 51 countries in sub-Saharan Africa, South and Southeast Asia, Latin America and the Caribbean.
Across all of the surveyed countries, 14.4% of children had experienced diarrhea in the past two weeks; risk was highest for babies and toddlers aged six months to 23 months.
The most affected country was Niger, where about 36.4% of children had recently had diarrhea, according to the study. Other heavily affected countries included Bolivia, Liberia, the Central African Republic, Burundi, Malawi, and Haiti, where about one in five young children had recently been affected.
Young children's risk of getting the illness increased when dry conditions lasted longer, the researchers also found.
Living in drought conditions for six months raised the risk of diarrhea by 5% if the drought was mild, they said, and 8% if the drought was severe.
Researchers explained that drought may increase the concentration of dangerous bacteria and viruses in water sources. And in times of scarcity, drinking water takes priority over using it for personal hygiene.
Diarrhea prevention calls for straightforward measures such as access to safe drinking water and sanitary facilities, they said.