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Warmer Temps Trigger More Disease

  • Joe DeCapua

FILE - Undated file photo provided by the U.S. Forest Service shows egg masses of the hemlock woolly adelgid. Scientists say climate change is a contributing factor.

FILE - Undated file photo provided by the U.S. Forest Service shows egg masses of the hemlock woolly adelgid. Scientists say climate change is a contributing factor.

Climate change is often associated with extreme weather events, melting glaciers and rising sea levels. But it could also have a major impact on human, animal and plant health by making it easier for diseases to spread.

Various germs and parasites may find the coming years a time to live longer and prosper. Rising temperatures are changing environments and removing some of their natural impediments.

Sonia Altizer is an associate professor at the University of Georgia’s Odum School of Ecology and lead author of the study. She said it’s a review of research done over the past 10 years to see what trends and new information on climate change have emerged.

“One of the big themes that has emerged is that there’s a lot of diseases, especially in natural systems, where there as a pretty clear signal that either the prevalence or severity of those diseases has increased in response to climate change.”

She said some of those natural systems where the signal is strongest are in the arctic and in warmer oceans.

“So in the arctic there are parasitic worms that affect muskox and reindeer, for example, that are developing faster and becoming more prevalent and expanding their ranges. And then in tropical oceans, like Caribbean coral reefs, there’s a large amount of evidence that has mounted that shows that warming interferes with the symbiosis of corals – makes them more vulnerable to disease and at the same time increases the growth rate of some lethal bacteria,” she said.

But a second theme emerged indicating that sometimes climate change may have no effect at all.

“The other main point that we focused on is that knowing why different pathogens respond differently to climate change is what’s needed to help us predict and ultimately manage disease outbreaks in people and animals and plants,” she said.

Some countries will be much better prepared to handle the disease threat than others, like those in Europe and North America.
“Surveillance, vector control, modern sanitation, drugs, vaccines can be deployed to prevent outbreaks of a lot of diseases, especially vector borne disease or diarrheal disease that are much more problematic in the developing world. And so these can counter the effects of climate change and make it hard to detect increases in those pathogens,” said Altizer.

Controlling vectors means controlling such things as mosquitos and ticks, which can carry malaria or dengue fever.

In developing countries, pathogens affecting agriculture and wildlife could adversely affect food security and the livelihoods of indigenous peoples.

So how concerned should health officials be? Altizer said there’s no simple answer.

“I think that the answer to it really depends on the location. So where, when and what pathogen? So I think we’re at a stage now where in the next five to ten years scientists will be able to move towards a predictive framework that will be able to answer questions about where in the world and what pathogens are responding and will continue to respond most strongly to climate change.”

Altizer says the effects of climate change will unfold over decades. So it’s vital to follow long-term standardized data for many diseases and pathogens. She said crop management may be a good example to follow. It has a long history of tracking disease outbreaks, forecasting potential threats and responding to those threats early.