Climate change will have varying effect on disease transmission, study finds

A recent study found that climate change may have unanticipated effects on host-pathogen interactions due to drastic temperature variations.

The study was published in the journal eLife, and conducted by researchers at the Carl von Ossietzky University of Oldenburg in Germany and Trinity College in Ireland. Their investigation set out to discover how classic environmental transmission is affected by temperature changes. To do so, scientists observed how a small crustacean know as Daphnia magna and its gut parasite, Odospora colligata responded to differing temperatures.

Researchers exposed the crustaceans and the parasites to three sets of temperatures—a constant temperature, a temperature that fluctuated daily below or above three degrees Celsius, and a three-day heatwave that was six degrees Celsius above ambient temperature. After exposure, the researchers determined the lifespan, fertility, infection status, and the amount of parasite spores within the guts of the three groups of crustaceans.

The study’s results showed in comparison to the control group, the crustaceans that were exposed to fluctuating temperatures had both reduced infection and spore levels. Infection rates among crustaceans exposed to the heat wave were similar to the control group. The heatwave did increase spore burden in the crustaceans at 16 degrees Celsius an optimum temperature for the parasite. However, temperatures beyond 16 degrees Celsius were shown to reduce spore burden. Overall, the fitness and the reproductive health of the crustaceans exposed to either the heatwave, fluctuating temperatures, or parasite spores were decreased.

“Our findings show that temperature variation alters the outcome of host-pathogen interactions in complex ways,” said the paper’s co-author Pepijn Luijckx, PhD in a statement. “Not only does temperature variation affect different host and pathogen traits in a distinct way, but the type of variation and the average temperature to which it is applied also matter.”

The study’s researchers concluded that these results suggest the effect that future extreme weather will have on disease transmission will be profound yet largely unpredictable. Integrative practitioners may want to consider this study while treating patients at high risk for developing disease living in areas with high exposure to extreme temperatures.