Malaria spike linked to amphibian die-off

Dozens of species of frogs, salamanders and other amphibians quietly disappeared from parts of Latin America in the 1980s and 2000s, with little notice from humans outside of a small group of ecologists. Yet the amphibian decline had direct health consequences for people, according to a study by researchers at the University of California, Davis and other institutions.

The U.S. National Science Foundation-supported work, published in the journal Environmental Research Letters, links an amphibian die-off in Costa Rica and Panama with a spike in malaria cases in the region. Frogs eat insects, including the mosquitoes that carry malaria.

At the peak of the amphibian die-off, more than three times as many people contracted malaria than normally would have, the researchers found. "This study shows the unpredictable ways change in one part of nature can harm seemingly unconnected parts, especially people," said Sam Scheiner, a program director in NSF's Division of Environmental Biology.

"Stable ecosystems underpin all sorts of aspects of human wellbeing, including regulating processes important for disease prevention and health," said lead author Michael Springborn of UC Davis. "If we allow massive ecosystem disruptions to happen, they can substantially impact human health in ways that are difficult to predict and hard to control."

Researchers were motivated to conduct the study by concerns about the future spread of diseases through international wildlife trade. For instance, Batrachochytrieum salamandrivorans, or "Bsal," threatens to invade ecosystems through global trade markets.

Springborn said measures that could help prevent the spread of pathogens to wildlife include updating trade regulations to better target species that host such diseases as our knowledge of threats evolve.

"The cost of putting those protective measures in place is immediate and evident, but the long-term benefits of avoiding ecosystem disruptions are harder to assess but potentially massive," Springborn said.