More Trees in Watersheds Tied to Less Diarrheal Disease in Children

A new study led by the University of Vermont (UVM) finds that children whose watersheds have greater tree cover are less likely to experience diarrheal disease.

Diarrhea is a leading cause of illness and death among children under five living in low- and middle-income countries. Research has shown that frequent diarrhea during the first two years of life is associated with poor cognitive development and early school performance.

The new study, which involved 300,000 children in 35 nations, is the first to verify the connection between watershed quality and individual health outcomes of children on a global scale.

“Looking at all of these diverse households in all these different countries, we find the healthier your watershed upstream, the less likely your kids are to get this potentially fatal disease,” says Taylor Ricketts of UVM’s Gund Institute for Environment.

In fact, the researchers predict that a 30 percent increase in upstream tree cover in rural watersheds would have a comparable effect to improved water sanitation, such as the addition of indoor plumbing or toilets.

“This suggests that protecting watersheds, in the right circumstances, can double as a public health investment,” says Brendan Fisher of UVM’s Gund Institute and Rubenstein School of Environment and Natural Resources. “This shows, very clearly, how ‘natural infrastructure’ can directly support human health and welfare.”

The study is also the first to use a massive new database that will allow researchers to use “big data” approaches to study links between human health and the environment, globally. The database holds 30 years of USAID (United States Agency for International Development) demographic and health surveys, with 150 variables for 500,000 households, including spatial data on the environment.

“We are not saying trees are more important than toilets and indoor plumbing,” says Diego Herrera, who led the paper as a UVM postdoctoral researcher, and is now at Environmental Defense Fund. “But these findings clearly show that forests and other natural systems can complement traditional water sanitation systems, and help compensate for a lack of infrastructure.”

The researchers hope the new findings will help inform governments and development agencies around the world and lead to healthier living environments. They add that more research is needed to understand exactly how watershed forests impact the risk of diseases like diarrhea, which has many causes, including waterborne pathogens.

The research involved 35 nations across Africa, Southeast Asia, South America and the Caribbean, including Bangladesh, Philippines, Nigeria, Colombia, and the Democratic Republic of the Congo.

According to the World Health Organization (WHO), 361,000 children die of diarrheal disease every year because of poor access to clean water, sanitation, and hygiene.

The findings are published in the journal Nature Communications.

Source: University of Vermont