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ANCHORAGE, Alaska – As the world’s climate warms, pest-borne wildlife diseases will shift north, with animals in the cold far north and high-altitude regions expected to experience the most dramatic increases, warns a study published Friday in the journal. Science.
The study projects increase the spread over the next five decades of wildlife diseases caused by infectious bacteria, fungi, viruses and worms. There are serious implications for humans, said co-author Jason Rohr of the University of Notre Dame in Indiana.
“We know that 75 percent of emerging infectious diseases have a wild origin,” said Rohr, who runs an ecology and public health laboratory at Notre Dame. “We should be concerned about our health when we see studies that suggest there could be an increase in infectious diseases in wildlife.”
Climate change is already causing an increase in wildlife disease, the study notes. And people have already been infected with diseases from wildlife, including COVID-19, Rohr said.
The study supports the “thermal mismatch” theory of wildlife diseases, finding that cold-adapted species are at greatest risk when their habitats are warm and heat-adapted species are at greatest risk when their habitats cool.
It is based on records of 7,346 wildlife populations that include 1,381 species of freshwater and terrestrial, from small insects to large mammals on all seven continents. It uses past climate records and variable scenarios for future climate conditions over the next five decades to calculate trends for pests that spread wildlife diseases.
According to the study, at current rates of carbon dioxide emissions and warming, the prevalence of these parasites will increase “sharply” in high latitudes and high altitudes, some nearly doubling by 2070 in many boreal and mountain locations.
If warming is slowed down, however, there will be “much, much smaller increases in infectious disease in wildlife,” Rohr said.
At greatest risk are cold-blooded animals – including amphibians, fish and insects – who cannot regulate their body temperature to adapt to heating conditions, Jeremy Cohen of the University of Wisconsin, the first author of the study, said via email .
Mammals in cold climates can partially compensate for heat stress by regulating their body temperature, said Cohen, who began his research with Rohr at the University of South Florida. However, parasites such as ticks that infect mammals with diseases will develop faster and reproduce more in warming conditions, Cohen said.
“Therefore, the warm weather creates the perfect storm for pest proliferation in the northern areas, where they may not have previously been able to thrive,” he said.
The study does not break down the risks by animal species. This is the topic of ongoing research, Rohr said. The study does not consider marine ecosystems; There is too little information available on marine systems to use in the disease spread model, Rohr said.
Arleigh Reynolds, head of the Center for One Health Research at the University of Alaska Fairbanks, said the study likely underestimates the model.
“I think the scale of the problem is even greater,” he said, noting study sites like Alaska North Slope, where new animal diseases are appearing.
Dr Richard Ostfeld, a disease ecologist who was not involved in the study, said that while the study’s “huge data sets” were admirable, they were limited to studying the effects of temperature.
Climate change also affects rainfall, increasing the frequency of extreme events, which also affects the prevalence of infectious diseases, said Ostfield, with the Cary Institute of Ecosystem Studies in Millbrook, New York.
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