Climate change will bring infectious diseases to new regions says study

By now most people are aware that climate change means an increase in the number of invasive species. As land and water temperatures warm, some species will naturally seek out climates more to their liking. However, the most dangerous of invasive species are too small to be noticed until they are found in a patient by medical professionals.

According to Daniel Brooks of the Laboratory of Parasitology at the University of Nebraska-Lincoln, the appearance of diseases in new places and new hosts will be par for the course as the climate continues to change. We have already seen this to an extent with diseases such as West Nile virus and Ebola, but those won’t be the last.

In an article published in a special issue of the Philosophical Transactions of the Royal Society B, Brooks wars that man more illnesses will emerge in the future as climate shifts, animals and vegetation move and people are exposed to pathogens they they have never been exposed to before.

“It’s not that there’s going to be one ‘Andromeda Strain’ that will wipe everybody out on the planet. There are going to be a lot of localized outbreaks putting pressure on medical and veterinary health systems. It will be the death of a thousand cuts,” said Brooks in a statement, referring to the 1971 science fiction film about a deadly pathogen.

Eric Hoberg, co-author of the paper, is a zoologist with the U.S. National Parasite Collection of the USDA’s Agricultural Research Service. Brooks and Hoberg have both directly observed the impact of climate change on ecosystems. Hobart’s work has primarily been in the arctic and Brooks’ in the tropics.

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

As an example, Brooks points to Costa Rica; in regions where capuchin and spider monkeys were hunted out of existence, the parasites that used to infect them immediately switched to howler monkeys. In the Canadian Arctic, some lungworms have moved north and switched hosts from caribou to muskoxen.

For more than 100 years it was assumed that because animals and parasites evolved together over many generations that the parasites could not easily jump from one host to another. Unfortunately, according to the researchers, recent history has disproved that assumption.

Hobart and Brooks call for a “fundamental conceptual shift” recognizing the fact that pathogens retain “ancestral genetic abilities” which allow them to quickly acquire new hosts.

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

Worse still, because they have not built up an immunity, new hosts are more susceptible to infections and get sicker from it according to Brooks.

“West Nile Virus is a good example – no longer an acute problem for humans or wildlife in North America, it nonetheless is here to stay,” he said.

Brooks and Hobart are calling for greater collaboration between public health officials, veterinary health communities and museum biologists who study and classify life forms and their evolution.

In addition to treating human diseases and developing vaccines, it will be important for scientists to know which non-human species are likely to carry pathogens according to Brooks.

“We have to admit we’re not winning the war against emerging diseases. We’re not anticipating them. We’re not paying attention to their basic biology, where they might come from and the potential for new pathogens to be introduced,” said Brooks.

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