Posted by Lauren Lipuma
By Lara G. Streiff
Warmer winter temperatures are leading to an increase in cases of Lyme disease in the United States, according to new research.
A new study finds increasing average winter temperatures are driving up reported Lyme disease cases in the Northeast and Midwest, especially near the outer limits of tick habitats where warmer winters boost tick survival rates and ability to find hosts. Public health officials are even seeing the disease spread to parts of Canada, in areas where it has never been seen before.
“There’s a lot of prior evidence that climate, in particular temperature and moisture conditions, affect different parts of the lifecycle of the tick that transmits Lyme disease,” said Lisa Couper, an ecologist at Stanford University who presented the work last week at the 2019 American Geophysical Union Fall Meeting in San Francisco. “But what is less clear is how that actually translates to effects on cases of Lyme disease.”
Lyme disease is a bacterial infection that presents much like the flu and is transmitted by a tick bite. Headaches, stiffness, joint-pain and a tell-tale bulls-eye rash are just some of the unpleasant symptoms caused by a Lyme-infected black-legged tick. These tiny transmitters are approximately the size of a sesame seed as adults, though according to the Centers for Disease Control and Prevention, most people who contract the disease are infected by an immature teenage tick the size of a poppy seed.
Lyme disease cases have increased over the past several decades, but scientists are unsure what is driving this, and whether climate change is a factor. It is evident that climate change is drying out summers, lowering average winter temperatures and increasing spring showers in parts of the U.S. These changes can affect ticks by expanding their habitats, increasing their survival rates and shifting their strategies for finding hosts.
In the new study, Couper looked into how closely climate variations have influenced Lyme disease cases over the past two decades across seven regions in the continental U.S. She employed statistical analysis to separate the effects of climate change from non-climate related factors that might also cause increasing rates of the disease.
The results show warmer winter temperatures were an important factor in the increase in Lyme disease cases, though increasing spring rains and dry summers were not. Higher spring precipitation did result in fewer cases of Lyme disease in the Northeast and Midwest, but Couper mostly attributes this to people being less likely to go outside and pick up a tick, rather than climate effects on tick ecology.
Ticks can be sensitive to drying out, so hot dry days, especially in the Southwest, could also impact Lyme disease cases. However, instead of hurting tick survival rates and subsequently lowering reported infections, ticks simply seem to have adapted to drier conditions by shifting strategies for finding hosts over the past couple of decades, according to Couper.
A spritely young tick seeking a new host to cling to is “questing.” To avoid drying out in hot conditions, ticks just quest differently. When they sense a host coming, most ticks will emerge from the leaf litter, climb up a blade of grass and sway at the end waving their arms with the hopes of hooking onto a passer-by. According to the CDC, most ticks need to attach to their hosts for at least 36 hours to pass on the responsible bacterium, Borrelia burgdorferi, that causes Lyme disease.
“When it’s too hot, they don’t want to expose themselves, so they’ll actually just stay on the ground,” Couper said. In the Southeast and southern California, researchers have seen this to be true. Ticks are still successfully surviving on alternate hosts and reproducing without effect on their range.
“That’s a huge reason why Lyme disease risk is a lot lower in the Southeast…It’s just that ticks are not actively getting on people because they’re not really coming up from the ground,” Couper said.
Although Couper tested these climate variables nationwide, Lyme disease cases were only driven up in two regions—the Northeast and Midwest—where ticks’ habitat range is currently geographically limited by temperature. But that doesn’t mean neighbors up north can breathe a sigh of relief. “It’s really expanding into southern Canada. They’re starting to see Lyme disease cases where they never have before,” Couper said.
Understanding climate effects on this disease can help predict future cases as well. Couper modeled two greenhouse gas emissions scenarios to anticipate what the future of Lyme disease will look like in the U.S.
Mang climastrology is confusing, even to the climastrologists. When it causes everything, they can’t keep up with what the new normal is. After last year’s record precipitation, that was supposed to be the new normal, not drying out summers like the new normal from years prior. It was even supposed to be the year of tickaghedon because of the wet and cooler weather, but that didn’t materialize.
Part of the confusion comes from relying on government statistics. Many things don’t exist, according to the government, that clearly do, like mountain lions in Nebraska and Kansas. You’d be a fool to think that something doesn’t exist just because an alphabet agency refuses to acknowledge it, but they tend to make the best climastrologists.
Whenever I see something attributed to global cooling/warming/climate change/weirding my first reaction is always “what is it really?” and “what is being avoided?” by so doing.
It’s like the middle ages and demons.
The worlds gone mad!
Yes. If psychosis is separation from reality, then those who take the results of unproven climate models as evidence of coming change in the real world are psychotic….or at least a little mad.
Science requires theories to be tested against real world data to be confirmed or nullified. The set of climate models embraced by the IPCC in the 1990’s generated predictions with which the real world refused to cooperate. The models said that with rising CO2 temps would rise rapidly. The CO2 has been rising. The temps in the US and elsewhere are either flat or have risen minimally, nothing like the models and their apocalyptic proponents predicted. The real world says no accelerated warming above the baseline coming out of the Little Ice Ace of the 1600-1700’s. The models are nullified. The proponents seem not to have noticed.
This study confuses expansion of the vector (deer ticks) with expansion of the disease. The disease has been expanding out of Connecticut for 20 years or more. This has nothing whatever to do with climate change — it is a biological problem — it has a lot to do with the expansion of deer herds, wildlife control, increase of numbers of people interacting with wildlife, expansion of human habitation into deer territory, etc.
This is more of the silliness that claims dengue, yellow fever, malaria, etc will spread into areas in the US because of climate change — when they only consider ifthe habitat might become suitable for the vector — ignoring the disease itself.
Kip
I have probably mentioned this to you before, but there is evidence that the blue belly lizard found in California can kill or neutralize the spirochete that is responsible for Lyme. That is probably why it isn’t more widespread in California, despite an abundance of ticks and warm Winters. It is possible that other potential vectors have a defense against Lyme.
fascinating read about the lizards and the unidentified protein … I have several family members and friend suffering the ill effects of Lyme. Perhaps they should eat some lizards from California. As we know, nature always provides the cure to any illness.
Clyde ==> Lyme disease is just that — a disease — caused by a germ. “Lyme disease is classified as a zoonosis, as it is transmitted to humans from a natural reservoir among small mammals and birds by ticks that feed on both sets of hosts ” (wiki).
The infection first has to exist in the natural environment in small mammals and birds. Then it has to be picked up my a tick biting the infected animal. Only then can it be transmitted to a human, who must be bitten by an infected tick.
Lyme is not transmitted tick-to-tick — it is not a disease of ticks. It is like many zoonotic diseases that ae passed to humans — it first has be to found in the animal hosts.
This map from the CDC shows the disease spreading from its origin in Conn. (It appears that Massachusetts doesn’t report Lyme).
Kip
I think that you missed the point. Blue belly lizards that are fed on by ticks don’t get the disease and apparently also kill the spirochetes in the ticks. Thus, the reservoir of infected ticks is reduced.
http://www.anapsid.org/lyme/sceloporus.html
Clyde ==> That is an interesting report. However, there is little subsequent support for the idea in available literature on Lyme.
Kip
There is no shortage of literature supporting the idea that blue belly lizards cleanse ticks of the LD spirochete. Most importantly, I have not found any studies that call that conclusion in the original 1998 study into question.
http://calag.ucanr.edu/Archive/?article=ca.v052n02p4
https://www.smcmvcd.org/post/lizards-ticks-and-lyme-disease
https://aspenn.com/could-lizards-be-spreading-lyme-disease/
https://yankeebarbareno.com/2012/03/31/ticks-lizards-and-lyme-disease/
https://www.murraysussermd.com/lyme-disease-and-lizards-los-angeles/
There is, however, a study that suggests that the mechanism isn’t a protein, but rather a robust immune system in a creature that regularly eats ticks.
https://reneeadavis.com/2017/06/01/take-western-fence-lizard-tincture-lyme-disease/
You forgot to mention the increased reporting of West Nile virus victims in the U.S.
Hi Kip – Spot on, as usual, and saves me from having to do any handwaving. Lyme Disease is a complex and interesting story. I had to write it up for a book chapter a few years ago, but I haven’t kept up since then. One wonders what effect the Borrelia have on the ticks – they don’t spontaneously generate, so they must be eating some tick to increase, and do pass from the larval tick to the nymph and adult (although B. burgdorferi doesn’t pass into the eggs of the next generation, although B. myiamotoi apparently does). Also, one wonders why anyone would think that small changes in average seasonal temperature or rainfall would have an observable effect on Lyme Disease prevalence? The ticks have to survive the extremes of the weather, as do we, and minor variations in the average seem epidemiologically unimportant.
Anyway, the drought in Queensland is extreme, haven’t seen a Monarch for weeks and there are no live larval host plants anywhere on my land, and it looks like I am going to have to purchase an ‘unprecedented’ second haul of tank water. I haven’t had to cut the grass for over 6 months, so one blessing. Happy New Year from Oz.
The increase in the deer tick population is obviously from the increase in the deer population and this study is absurdly non scientific.
The areas that have the worst infestations are some of the coldest, with the warmer regions of the country not seeing tick populations increase.
They say that ticks can adapt to the increase in hot/dry conditions but are telling us that they can’t adapt to the cold by stating that less cold means more ticks(it doesn’t).
This study is consistent with most of the others, applying the new rule for life on this planet that was created several decades ago, in tandem with the hijacking of climate science and rewriting climate history for the political agenda.
Good life always suffers adversity from climate change/global warming: humans, polar bears, honey bees, butterflies, frogs, crops, birds, fish……etc……
Bad life always thrives from climate change/global warming: ticks, fleas, mosquitoes, rats, roaches, bacteria, virus’s, weeds……..etc…….
Incredible how the exact same conditions have the complete opposite affect on life(in all these studies) based on whether humans think of it as bad life or good life.
Life and biology are based on authentic science………not whether humans consider that life good or bad. Clearly bias and politics are interfering in the ability of scientists to be objective in observing and analyzing the authentic science.
Maybe it’s a stupid question, but do states west of the Mississippi have any mountain lion populations left? (Florida may be the exception – what’s the Lyme disease prevalence there?)
https://emammal.si.edu/wildlife-your-watershed/blog/mountain-lions-eastern-united-states
If the deer tick is the carrier, it would seem sensible to re-establish the natural predator that can cull out the sick deer in areas where Lyme is spreading. This is a solution that most ecologists would endorse.
I lived in Northern Virginia for a few years and it appears that deer, turkey vultures, SUVs and auto insurers have become the new “Circle of Life”.
https://discardstudies.com/2017/12/04/consider-the-vulture-an-ethical-approach-to-roadkill/
Shortage of predators, not climate change, is the problem.
west of the Mississippi —- meant to say “east of the Mississississ…” never mind.
Bill – I’ve seen reports of male cougars wandering east of the Mississippi, even one in Chicago if memory serves (and it wasn’t hype), but no breeding females (except FL of course). Not sure mountain lions would be the best biocontrol: automobiles seem to kill quite a few more deer than lions would and having a cougar for a neighbour is a bit unsettling – see David Barron’s ‘The Beast in the Garden’.
DIY “tick tubes ” may be useful in some situations .
The insecticide doesn’t kill the rodents , just the ticks and fleas .
DIY because the marketed version is fantabulously expensive and particularly for the coverage density required to be effective.
American toilet paper tubes with Permethrin infused cotton batting. 100’s per acre.
In the UK ticks carry Red Water Disease fatal to cattle. I’m not sure how much sheep dipping is carried on these days which used to control parasites to a certain extent 40 years ago.
There is a book titled “Lab 257: The Disturbing Story of the Government’s Secret Plum Island Germ Laboratory” where the author Michael C Carroll thinks that both Lyme disease and West Nile virus originated at Plum Island Germ Laboratory near Long Island.
Lyme disease was named after Old Lyme Connecticut where a outbreak in the 1970 occurred.
https://www.amazon.ca/Lab-257-Disturbing-Governments-Laboratory/dp/0060011416
What’s about tick-borne encephalitis (TBE) ?
All of the Tick Borne Diseases are becoming more prevalent. The controversy is to better detection and reporting or expanding ranges.
See ProMEDmail.org by the Int’l Society for Infectious Diseases.
Very few physicians “report” acute Lyme disease in endemic areas, even though it is technically a “reportable” disease. Most of them just treat it clinically based on classical symptoms, exposure history, and (usually) a typical rash.
Lab tests take months to turn positive, and are rarely done when a patient with acute clinical Lyme disease presents for care.
Actual incidence of Lyme is MUCH higher than officially reported.
Your ‘lab test’ comment is wrong. Indeed, there is a specific lab-on-a-chip that may be available this season.
The worst area for ticks that I have ever experienced is around Bratsk in Siberia where winters are regularely below -40. And indeed Siberia is notorious for TBE (tick-borne encephalitis).
So I’ve never believed this “climate change” story, though a recent increase in tick infestation in Sweden is, of course, blamed on climate. Though, oddly, climate change apparently only affects areas where there are lots of roe deer.
We have a house in the Swedish countryside, Halland province, where we used to get 100s of ticks among family members. Roe deer is the most likely vector, but boar, hare and hedgehog are also likely bearers.
After the very dry 2018 summer, there has been a significant decrease of ticks. Hardly any in 2019.
We’ve had cold, warm, snowy and snowfree winters without any effect on the number of ticks.
So dry, warm late spring and summer is in my experience the most effective limiting factor to ticks. Which I’d at least call warming, CAGW and any other flavor.
And yes we’ve had Lyme disease many times. I even had to argue with a doctor on my daughter’s round ring being that. He kept claiming it was another tick born disease, but not which one! (The ring was slightly atypical and mostly red)
Ixoides ticks primary abiotic mortality is starvation and then desiccation. About 90% starve and, of them, 90% desiccate. An egg laden adult carries about 3000 eggs to be dropped where the final vector – usually a ‘deer’ – travels. Stay away from deer trails.
An Ixoides tick can travel only tens of meters on its own in its lifetime, and most of those are spent 100 mm at a time retreating to detritus to rehydrate and back to the questing site.
Landscaping is the best defense. Short grass << 100 mm. Fences. Abrupt transitions from manicured to dense scrub that people avoid.
The ‘bullseye rash’ is diagnostic of Borrelia infection and Lyme is only one of the Borrelioses. All are treated the same with prompt presumptive treatment essential. Then do the confirmatory tests.
It is argued that Ixoides evolved in the Paleartic Siberia.
How does the summary statement, “But what is less clear is how that actually translates to effects on cases of Lyme disease.” translate into the headline?
https://dearcrissy.com/diy-tick-tubes/
k i ll fleas and ticks .
😉
The USCRN rural station network is the most relevant for Lyme disease bug and deer environment and it shows no warming since 2008. The USHCN Peak temperature record is on a slow linear decline since the 1930 decade. Where are the bugs getting this warmer winter weather from?
Plum Island and Lyme disease
“Climate change driving expansion of Lyme disease in the US”
Charles: There should be a “?” at the end of titles like this.
Uggh. The comments are a dog’s breakfast.
On topic; climate change may be driving the expansion of the prevalence of Lyme Disease, but the predicate is the expansion of the vectors and not of the Ixoides ticks. Ixoides ticks are quite unaffected by the environment, they don’t freeze or hibernate. They are sensitive to degree-days of warmth and will actively quest when conditions are right.
Dog’s breakfast indeed. Not the least of which is the abuse of the tick’s Generic name:
It is Ixodes, not Ixoides. The black legged tick is Ixodes scapularis, formerly referred to as Ixodes dammini (now a junior synonym).
Apologies for not italicizing or underlining the Generic and specific names.
Climate change is resulting in the graying of America…you can plot US median age and see how it’s being driven by climate change…it’s scary. If we don’t stop climate change we’ll all die from age related issues…
And sadly, climate change is creating more political havoc…the number of presidential impeachment’s has doubled in the last hundred years…we can expect to see even more impeachments in the future…
As one still recovering (4 years) from “Chronic Lyme Disease”, I am all too familiar with all the partial facts and extreme complexity of the issues. How silly to have not simply added it to the convenient “caused by global warming” list!
I do however wonder if perhaps a “Green-inspired” misdeed is a factor: Stop burning leaves and instead compost them (say the Greens) – providing warm overwintering piles for ticks and chipmunks – ready to emerge against nearby humans come spring.