In the 1990s and 2000s there were spikes in cases of malaria in Panama and Costa Rica. A deadly fungal disease that killed thousands of amphibians in the region may have contributed to this rise in human malaria cases.
The slow-motion spread of the fungal disease, chytridiomycosis, led to decades of amphibian declines worldwide. From the 1980s through the 2000s, the wave moved northwest to southeast through Costa Rica, Panama, and hit different places at different points. A study of satellite data, public health records, and local ecological surveys suggests that the wave moved from northwest to southeast across Costa Rica and Panama. A link exists between amphibian death and an increase of human malaria casesResearchers reported in the October that the wave had passed. Environmental Research Letters.
Teasing out ways that biodiversity loss “ripple[s]Through ecosystems and affect[s] humans” can help make a case for preventive actions in the face of other ecological threats, says Michael Springborn, an environmental economist at the University of California, Davis.
Springborn and colleagues discovered that the average number of cases of malaria in Costa Rica or Panama per 1,000 inhabitants was 0.8 to 11.1 per year. This is approximately six years before the amphibian loss.
Research suggests that amphibians are important mosquito control agents. The amphibian larvae consume mosquito larvae.
Therefore, the loss of salamanders (frogs), toads, and toads may have contributed to more mosquitoes. This could also lead to increased malaria transmission. But it’s unclear whether mosquito populations actually increased during this time, Springborn says, because those data don’t exist.
Chytridiomycosis is caused by the fungus Batrachochytrium dendrobatidis Oder Bd,It has been a catalyst for the The largest loss of biodiversity ever recorded due to a virus. It’s caused the Globally, at least 500 species are in decline (SN: 3/28/19). Ninety percent of these species have been declared extinct. The most significant declines have occurred in Australia and the Americas, which has seen the largest losses of frogs and toads. International trade in amphibians is what has spread the fungus around the world.
Springborn and his colleagues wondered if amphibian deaths had an impact on humans. Springborn says that the researchers looked at Panama and Costa Rica, where the fungus was moving in an uneven manner through the ecosystems. The researchers were able to determine when the fungus reached a particular place. The researchers also examined the numbers of malaria cases in the areas before and after the amphibian die-offs.
In the first couple of years after the animals’ decline, malaria cases started to rise. Over the next six years, cases rose again, but then dropped. The researchers aren’t sure yet what was behind the eventual drop.
Studies on the connections between biodiversity loss and human health might “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 was not involved in the work.
“Humans are causing wildlife to be lost at a rate similar to that of 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, on risk of infectious disease.”
