Climate change's effect on emerging diseases, Lyme disease - Outbreak News Today | Outbreak News Today Outbreak News Today
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Two articles/studies published in the journal, Philosophical Transactions of the Royal Society B, discuss how climate change and warmer temperatures are affecting infectious diseases and their affect on us.

Black-legged tick

Ixodes scapularis, a Black-legged tick/CDC

First, an article by Harold W. Manter Laboratory of Parasitology at the University of Nebraska-Lincoln affiliated zoologist, Daniel Brooks warns that humans can expect more such illnesses to emerge in the future, as climate change shifts habitats and brings wildlife, crops, livestock, and humans into contact with pathogens to which they are susceptible but to which they have never been exposed.

Brooks and his co-author, Eric Hoberg, a zoologist with the U.S. National Parasite Collection of the USDA’s Agricultural Research Service, have personally observed how climate change has affected very different ecosystems. During his career, Brooks has focused primarily on parasites in the tropics, while Hoberg has worked primarily in Arctic regions.

“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.”

Changes in habitat mean animals are exposed to new parasites and pathogens.

For example, some lungworms in recent years have moved northward and shifted hosts from caribou to muskoxen in the Canadian Arctic. Scientists also have observed that climate shifts in the late Pliocene and Quaternary periods resulted in new species of pocket gophers, with the lice that infect them following suit.

But for more than 100 years, scientists have assumed parasites don’t quickly jump from one species to another because of the way parasites and hosts co-evolve.

Brooks calls it the “parasite paradox.” Over time, hosts and pathogens become more tightly adapted to one another. According to previous theories, this should make emerging diseases rare, because they have to wait for the right random mutation to occur.

But it turns out such jumps 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.

“We have to admit we’re not winning the war against emerging diseases,” Brooks said. “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.”

In addition, the journal features a study by researchers at the Cary Institute of Ecosystem Studies in Millbrook, NY, which demonstrate that in the northeastern United States, warmer spring temperatures are leading to shifts in the emergence of the blacklegged ticks that carry Lyme disease and other tick-borne pathogens. At the same time, milder weather is allowing ticks to spread into new geographic regions.

Cary Institute ecologist and co-author of the study, Dr. Richard S. Ostfeld notes, “Nearly two decades of data revealed climate warming trends correlated with earlier spring feeding by nymphal ticks, sometimes by as much as three weeks. If this persists, we will need to move Lyme Disease Awareness Month from May to April.”

Risk of tick-borne illness is shaped by complex interactions among pathogens, ticks, and host animals. Take the case of Lyme disease: blacklegged ticks acquire the bacterium that causes Lyme when they feed on small mammals that harbor Borrelia burgdorferi. Ticks seek a single blood meal at each life stage: larva, nymph, and adult. Larval ticks are born free of the Borreliabacterium. Tiny infected nymphs pose the greatest threat to people.

Dr. Taal Levi of Oregon State University led the emergence analysis; he performed the work while a Postdoctoral Associate at the Cary Institute. Levi explains, “Understanding when ticks are active, and at what life stage, is essential to predicting tick-borne disease spread. Pathogens that cause a lasting host infection, such as the Lyme disease bacterium, benefit from a lag between nymphal and larval feeing. The same might not be true of other pathogens, like Powassan virus, that are transmitted when larvae and nymphs feed simultaneously.”

“Results suggest that significant climate warming may reduce risk of anaplasmosis and the Powassan virus, but increase Lyme disease risk, particularly in the Upper Midwest where tick feeding patterns are likely to become more asynchronous,” Levi said.

With Ostfeld emphasizing, “Here in the Northeast, warming is already having an effect, and people need to be tick-vigilant before May, as potentially infected nymphal ticks are searching for their blood meals earlier and earlier.”

1 Comment

  1. Don Culo says:

    New data shows that the “vanishing” of polar ice is not the result of runaway global warming

    When future generations look back on the global-warming scare of the past 30 years, nothing will shock them more than the extent to which the official temperature records – on which the entire panic ultimately rested – were systematically “adjusted” to show the Earth as having warmed much more than the actual data justified.

    Two weeks ago, under the headline “How we are being tricked by flawed data on global warming”, I wrote about Paul Homewood, who, on his Notalotofpeopleknowthat blog, had checked the published temperature graphs for three weather stations in Paraguay against the temperatures that had originally been recorded. In each instance, the actual trend of 60 years of data had been dramatically reversed, so that a cooling trend was changed to one that showed a marked warming.

    This was only the latest of many examples of a practice long recognised by expert observers around the world – one that raises an ever larger question mark over the entire official surface-temperature record.

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    Following my last article, Homewood checked a swathe of other South American weather stations around the original three. In each case he found the same suspicious one-way “adjustments”. First these were made by the US government’s Global Historical Climate Network (GHCN). They were then amplified by two of the main official surface records, the Goddard Institute for Space Studies (Giss) and the National Climate Data Center (NCDC), which use the warming trends to estimate temperatures across the vast regions of the Earth where no measurements are taken. Yet these are the very records on which scientists and politicians rely for their belief in “global warming”.

    Homewood has now turned his attention to the weather stations across much of the Arctic, between Canada (51 degrees W) and the heart of Siberia (87 degrees E). Again, in nearly every case, the same one-way adjustments have been made, to show warming up to 1 degree C or more higher than was indicated by the data that was actually recorded. This has surprised no one more than Traust Jonsson, who was long in charge of climate research for the Iceland met office (and with whom Homewood has been in touch). Jonsson was amazed to see how the new version completely “disappears” Iceland’s “sea ice years” around 1970, when a period of extreme cooling almost devastated his country’s economy.

    One of the first examples of these “adjustments” was exposed in 2007 by the statistician Steve McIntyre, when he discovered a paper published in 1987 by James Hansen, the scientist (later turned fanatical climate activist) who for many years ran Giss. Hansen’s original graph showed temperatures in the Arctic as having been much higher around 1940 than at any time since. But as Homewood reveals in his blog post, “Temperature adjustments transform Arctic history”, Giss has turned this upside down. Arctic temperatures from that time have been lowered so much that that they are now dwarfed by those of the past 20 years.

    Homewood’s interest in the Arctic is partly because the “vanishing” of its polar ice (and the polar bears) has become such a poster-child for those trying to persuade us that we are threatened by runaway warming. But he chose that particular stretch of the Arctic because it is where ice is affected by warmer water brought in by cyclical shifts in a major Atlantic current – this last peaked at just the time 75 years ago when Arctic ice retreated even further than it has done recently. The ice-melt is not caused by rising global temperatures at all.

    Of much more serious significance, however, is the way this wholesale manipulation of the official temperature record – for reasons GHCN and Giss have never plausibly explained – has become the real elephant in the room of the greatest and most costly scare the world has known. This really does begin to look like one of the greatest scientific scandals of all time.

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