Climate change expected to worsen effects of parasites

Climate change is often blamed for shifts in seasonal patterns and extreme weather disasters. But many people may overlook the possiblity that climate change is able to empower parasites. That’s according to a new study, showing that frogs suffered more infections from a fungus when exposed to unexpected swings in temperatures.

Parasites include tapeworms. Those are the tiny organisms that cause malaria and funguses. Scientists say these parasites may be more clever at adapting to climatic shifts, than the animals they live on. That’s because these organisms are smaller and grow more quickly.

Thomas Raffel is with Oakland University in the United States. He led this particular study with colleagues at the University of South Florida. He told Reuters that, “Increases in climate variability are likely to make it easier for parasites to infect their hosts. We think this could exacerbate the effects of some disease.”

For the study, researchers exposed Cuban treefrogs to varying temperatures and infections of a particular fungus — in 80 lab incubators. This fungus, Batrachochytrium dendrobatidis, is often deadly for the amphibians. In one experiment, frogs kept at a temperature of 25 degrees Celsius for four weeks suffered far more infections when they were shifted to incubators at 15C and exposed to the fungus than frogs already used to living at 15°C.

In another test, frogs that were exposed to predictable daily temperature variations between 15° and 25° Celsius, typical of shifts from night to day, were much better at resisting the fungus. Based on factors including their size, life expectancy and factors such as their metabolisms, the scientists said frogs probably took 10 times as long as fungus to get used to unexpected temperature changes. This process is known as acclimation.

However, Raffel says more tests were needed of other parasites and hosts to confirm his team’s findings. This particular study was only done on a single tropical frog species.

The U.N. has a panel of experts dedicated to the study of global warming. The group says global warming is expected to add to human suffering — through more heatwaves, floods, storms and droughts. It, too, agrees global warming may be able to spread the ranges of some diseases.

Photo by Gilles San Martin