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Climate change having an impact on pathogens

February 27, 2015

In the fight against bloodborne pathogens it's important to identify all factors that may be contributing to their exposure and spread. For many hospitals, clinics and medical organisations this mainly involves infection control practices and practices related to sharps safety. This has been recently demonstrated by the Ebola epidemic that has swept across West Africa.

A new report has suggested that climate change is having an impact on the proliferation of infectious diseases. Daniel Brooks, a noted zoologist from the University of Nebraska-Lincoln, said that this will cause a number of new infections to emerge in the future.

In his article, which was published in a special issue of the Philosophical Transactions of the Royal Society, he said that climate change can cause a shift in habitats, which exposes people to pathogens that they haven't been exposed to before. This means they come into contact with pathogens that they are vulnerable to because they have never been exposed to them before.

He said that it will not be that there's a single strain that will wipe out everything on the planet, like something from a science-fiction film, but more that there will be a higher number of localised outbreaks. This, Brooks argues, will put pressure on medical and veterinary health systems, which will "be the death of a thousand cuts".

Along with his co-author, Eric Hoberg, a zoologist with the US National Parasite Collection of the USDA's Agricultural Research Service, Brooks has observed how climate change has affected different ecosystems.

Both of them have observed the arrival of species that hadn’t previously lived in that area and the departure of others, Brooks said.

“Over the last 30 years, the places we’ve been working have been heavily impacted by climate change,” Brooks said in an interview last week. “Though I was in the tropics and he was in the Arctic, we could see something was happening.”

For more than a century, scientists have assumed parasites don’t quickly jump from one species to another because of the way parasites and hosts co-evolve, which the authors call the “parasite paradox”.

Over time, hosts and pathogens become more tightly adapted to one another, which should make emerging diseases a rare occurrence as they have to wait for the right mutation to happen. However, such jumps can happen more quickly than anticipated. 

Even pathogens that are highly adapted to one host are able to shift to new ones under the right circumstances. The authors call for a “fundamental conceptual shift” to recognise that parasites and pathogens retain genetic capabilities that allow them to quickly shift to new hosts.

“Though a parasite might have a very specialised relationship with one particular host in one particular place, there are other hosts that may be as susceptible,” Brooks said.

In fact, the new hosts are more susceptible to infection and get sicker from it, Brooks said, because they haven’t yet developed resistance.

This information could eventually help people better combat infections such as Ebola, and even prevent them from occurring.

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