Composting aquatic plant battles parasite, boosts incomes in Senegal

ITHACA, N.Y. – Turning aquatic vegetation near agricultural land into compost simultaneously eradicates habitat for disease-carrying snails while improving agricultural output and increasing incomes in northern Senegal, Cornell University researchers have found.

Combining highly detailed biological and microeconomic modeling, the team’s finding has the potential to aid rural residents of the West African nation, who are often caught in a vicious cycle of poverty and disease.

“Modeling How and Why Aquatic Vegetation Removal Can Free Rural Households From Poverty-disease Traps,” published Dec. 17 in Proceedings of the National Academy of Sciences.

Chris Barrett, professor of applied economics and management at Cornell, is the paper’s senior author.

The researchers show analytically, using data from a previous study, that removal of aquatic vegetation reduces habitat for snails, which carry the infectious helminth (a parasitic worm), while also returning soil nutrients that leach into surface water via runoff to agricultural land. The result, the researchers wrote, is “healthier people, more productive labor, cleaner water, more productive agriculture and higher incomes.”

The helminth schistosomiasis, also known as bilharzia, infects hundreds of millions of people worldwide and has been termed the second-most socioeconomically devastating parasitic disease, after malaria, by the World Health Organization.

The researcher’s modeling of both the economics and the disease ecology was painstaking, but produced valuable information.

“These sorts of models are very sensitive,” Barrett said. “There’s so much feedback that they can blow up very quickly if you don’t calibrate them right. That’s one of the reasons why people commonly don’t attempt this level of granular interactions between the biology and the social science: It’s hard to get it right.”

Barrett said this work can be adapted to other diseases and vectors. And with a changing climate, where and how people become infected will change, too.

“Dengue fever, malaria – these are diseases that are very clearly affected by how humans manage natural landscapes,” he said. “We should not assume that the range of these diseases is going to stay static, and we’re going to have to think carefully about how and where to intervene in ways that don’t upset the stability of the system.”

This research was supported by grants from the National Science Foundation and the Indiana Clinical and Translational Sciences Institute.

For additional information, see this Cornell Chronicle story.

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