In the 1990s and 2000s, Costa Rica and Panama experienced spikes in malaria cases. The massive loss of amphibians in the region to a deadly fungal disease may have contributed to the resurgence of this human disease.
The spread of the fungal disease chytridiomycosis has been a slow-motion disaster, driving a decades-long wave of amphibian decline around the world. From the 1980s to the 2000s, the wave moved northwest to southeast across Costa Rica and Panama, hitting different locations at different times. An analysis of local ecological surveys, public health records and satellite data suggests a link between amphibian mortality and an increase in human malaria cases as the wave passed, researchers report in the month of ‘october. Environmental Research Letters.
Unraveling the ways in which biodiversity loss “ripples”[s] through ecosystems and affect[s] humans” can help make the case for preemptive action in the face of other ecological threats, says Michael Springborn, an environmental economist at the University of California, Davis.
On average, each county in Costa Rica and Panama recorded 0.8 to 1.1 additional cases of malaria per 1,000 people per year for about six years, beginning a few years after the amphibian losses, Springborn and his colleagues found. colleagues.
Other research suggests that amphibians serve as important controls on mosquito populations. Amphibian larvae eat mosquito larvae and the animals compete for resources, such as places to live.
So missing frogs, toads, and salamanders may have resulted in more mosquitoes and potentially more malaria transmission. But it’s unclear if mosquito populations actually increased during that time, Springborn says, because that data doesn’t exist.
Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis Where comics, led to the greatest recorded loss of biodiversity due to disease. It has caused the decline of at least 500 species worldwide (SN: 03/28/19). Ninety of these species are presumed extinct. Frogs and toads in the Americas and Australia have suffered the greatest declines. The international amphibian trade has spread the fungus globally.
Springborn and his colleagues wondered if the impacts of amphibian losses also extended to humans. The researchers turned to Costa Rica and Panama, where the fungus moved through ecosystems somewhat evenly along the narrow strip of land the two countries sit on, Springborn says. This meant that researchers could determine when the fungus arrived at a given location. The team also looked at the number of malaria cases in these locations before and after the amphibian die-offs.
During the first two years after the decline of the animals, cases of malaria began to increase. For the next six years or so, cases stayed high, then started to drop again. Researchers do not yet know what is behind the eventual fall.
Studies of the links between biodiversity loss and human health could “help motivate conservation by highlighting the direct benefits of conservation to human well-being,” says Hillary Young, a community ecologist at the University of California in Santa Barbara, which did not participate in the work.
“Humans are causing wildlife to disappear at a rate similar to other major mass extinction events,” she says. “We are increasingly aware that these losses can have major impacts on human health and well-being – and, in particular, the risk of infectious diseases.”
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