Study links malaria outbreak to amphibian extinction


A recent study connects a die-off of amphibians in Costa Rica and Panama with an increase in malaria incidence. The study reveals how crucial biodiversity is to maintaining human health.

An increase in malaria cases in Costa Rica and Panama is associated with an amphibian die-off, according to a study that was published in the journal Environmental Research Letters. The study discovered that at the height of the increase, up to 1 person per 1,000 annually developed malaria, which they ordinarily wouldn’t have if the amphibian die-off hadn’t happened.

According to senior author Michael Springborn, a professor in the UC Davis Department of Environmental Sciences and Policy, “Stable ecosystems underpin all sorts of facets of human wellbeing, including regulating mechanisms critical for disease prevention and health.” Massive ecosystem changes “may have a significant influence on human health in ways that are hard to foresee in advance and hard to regulate after they’ve started.”

A fatal fungal pathogen known as Batrachochytrium dendrobatidis, or “Bd,” spread over Costa Rica from the early 1980s to the mid-1990s, decimating frog populations. Through the 2000s, this amphibian chytrid fungus continued to spread over Panama to the east. At least 90 amphibian species were eliminated by the disease globally, while at least 500 other species saw a reduction.

Both Costa Rica and Panama saw an increase in malaria incidence shortly after the amphibian mass extinction.

Every day, certain frogs, salamanders, and other amphibians consume hundreds of mosquito eggs. Malaria is spread through mosquitoes. Could the decline in amphibians have contributed to the surge in malaria cases, pondered scientists?

The researchers used this natural experiment to combine their understanding of amphibian ecology with newly digitised public health record data and data analysis techniques created by economists.

The study’s co-author, Joakim Weill, a Ph.D. candidate at UC Davis at the time, said, “We’ve known for a while that intricate interactions occur between ecosystems and human health, but evaluating these relationships is still exceedingly hard.” “By combining technologies and data that don’t typically mix, we were able to arrive there. Before working with a herpetologist, I had no idea what they studied!”

According to the findings, there is a direct correlation between the expansion of the fungus-causing disease and the rise in malaria cases at specific times and places. Despite the fact that they cannot completely rule out another confounding factor, the researchers remark that they did not discover any indication of any more factors that might both cause malaria and follow the same pattern of die-offs.

Though not nearly as strongly as the loss of amphibians, the loss of tree cover was also linked to an increase in malaria occurrences. Comparatively to the amphibian die-off, typical levels of tree canopy loss increase annual malaria incidence by up to 0.12 cases per 1,000 people.

Threats to trade

Concerns about the potential spread of such diseases through international animal trading spurred researchers to perform the study. For instance, the “Bsal,” or Batrachochytrieum salamandrivorans, similarly poses a threat to ecosystems through international trading markets.

Adapting trade laws to better target animals that harbour these diseases as our understanding of dangers changes, according to Springborn, is one step that could help reduce the spread of pathogens to wildlife.

The costs of implementing those preventative measures are upfront and obvious, but as this article demonstrates, the long-term benefits of preventing ecosystem upsets like this one might be enormous.