In the 1990s and 2000s, Costa Rica and Panama experienced spikes in malaria cases. The massive loss of amphibians in the region due to a deadly fungal disease may have contributed to the uptick in this human disease.
The spread of chytridiomycosis, a fungal disease, was a slow-motion disaster, leading to a decades-long wave of amphibian declines around the world. From the 1980s to the 2000s, the wave moved from northwest to southeast across Costa Rica and Panama, hitting different places 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 October issue Environmental investigation letters.
Unravel ways in which biodiversity loss “spreads[s] through ecosystems and affect[s] humans” can help make the case for preventive action against other ecological threats, says Michael Springborn, an environmental economist at the University of California, Davis.
On average, each county in Costa Rica and Panama had an additional 0.8 to 1.1 cases of malaria per 1,000 people per year for about six years, starting a couple of years after the amphibian losses, Springborn and his colleagues found. colleagues.
Other research suggests that amphibians serve as an important control of mosquito populations. Amphibian larvae eat mosquito larvae, and the animals compete with each other for resources, such as places to live.
So the missing frogs, toads and salamanders may have led to more mosquitoes and potentially more malaria transmission. But it’s not clear whether mosquito populations actually increased during this time, Springborn says, because such data doesn’t exist.
Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis either bb, has led to largest recorded loss of biodiversity due to disease. has caused the decline of at least 500 species globally (Serial number: 03/28/19). Ninety of those species are presumed extinct. Frogs and toads in the Americas and Australia have suffered the largest declines. The international amphibian trade has spread the fungus globally.
Springborn and his colleagues wondered if the impacts of amphibian losses extended to humans as well. The researchers turned to Costa Rica and Panama, where the fungus moved through ecosystems in a somewhat uniform fashion along the narrow strip of land that the two countries sit on, says Springborn. This meant that the researchers could determine when the fungus arrived at a certain location. The team also looked at the number of malaria cases in those places before and after the amphibian die-off.
In the first couple of years after the animals’ decline, malaria cases began to increase. For the next six years or so, cases remained high and then began to decline again. Investigators are still not sure what was behind the eventual fall.
Studies of the connections 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, Santa Barbara, who did not participate in the study. to work.
“Humans are causing wildlife loss at rates similar to other major mass extinction events,” she says. “We are increasingly aware that these losses can have a major impact on human health and well-being and, in particular, the risk of infectious diseases.”