Climate change driving expansion of Lyme disease in the US

From AGU

Posted by Lauren Lipuma

Tick on a blade of grass. Credit: National Parks Service.

Tick on a blade of grass. Credit: National Parks Service.

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.

Black-legged tick, also known as the deer tick (ixodes scapularis) on a leaf. Credit: Scott Bauer/U.S. Department of Agriculture.

Black-legged tick, also known as the deer tick (ixodes scapularis) on a leaf. Credit: Scott Bauer/U.S. Department of Agriculture.

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.

Full post here.

Advertisements

98 thoughts on “Climate change driving expansion of Lyme disease in the US

  1. Until about ten years ago the government of Manitoba did not allow testing for Lyme disease and their website clearly stated there was no problem in Manitoba. They would even harass any doctor who wanted to treat someone suffering from it. Manitobans were not allowed to get blood tests and had to travel to the USA at their own expense to get testing and treatment. The odd case that did turn up was explained away as obviously caused by people traveling to the USA and getting infected there, even among those who had never been south. However when vets in the province began routine screening and discovered a huge number of dogs and cats had been exposed to the Lyme disease bacteria and some animals were getting sick who had never left home, the government finally finally had to respond. And guess what? Lyme disease exists in several areas of Manitoba! Many who had been told they were having psychological problems finally got diagnosed and treated for Lyme disease. Yet the climate change loons blame the “sudden increase” in Lyme disease in Manitoba on climate change. The government of Manitoba eagerly grabbed the climate change story to cover their own incompetence that left left Manitobans untreated for decades. They don’t look at ‘ascertainment bias’ because that doesn’t fit the narrative. Climate change is a very handy get out of jail free card.

    • It is just criminally negligent that this disease got diagnosed as “psychological” also here in Europe.
      Partly as it takes careful antibody checks – even experienced GP’s are fooled. One local GP actually died of it.
      The damned bacteria apparently can camouflage or alter its signature, and gets into bones where antibiotics cannot reach. So better diagnosis give the false positive sudden jump in cases. How many people were chronically “bed-ridden” because of that bacteria?

      Worse than criminal is the attempt to blame CO2, and thus neighbor’s autos, for it.

      I can only think of Lord Bertrand Russell bemoaning the lack of wars, and pestilence. Prince Philip openly declares a wish to be reborn as a deadly virus to “do something about population”. The odd thing is that tick usually carries, along with Lyme, Tetanus and the encephalitis virus – a Royal coincidence, or made to order?

      • My cat got lyme disease, which is very unusual but not unheard of. He was suffering from intermittent fever and couldn’t jump properly without falling over and he was staggering about when not sleeping. He was drooling constantly. Fortunately for the cat, the vet had seen lyme disease in dogs before so she knew what it was. She did the blood test for lyme, it was positive, and the cat was put on a six week course of antibiotics. The vet had to do an on line search to figure out how to treat him because feline lyme disease is so rare. The poor cat was suffering so much I considered putting him down. However, he made a full recovery by the fourth week. It was devastating to watch him. Anyone suffering with this horrific disease has my deepest sympathy. I seriously doubt my cat’s condition was psychological due to some feline neurosis.

    • This is exactly right Justin. There was deliberate under diagnosis of Lyme and not just in Manitoba. Lyme has been with us all along and the infected have been told they were imagining things. I have a friend and associate whose wife finally succumbed to the disease after suffering for years with chronic Lyme. As well a close relative in the Carolinas suffered with Lyme for years before being diagnosed properly so it wasn’t just in Canada.
      I don’t deny that climate is changing and that it could effect the frequency of the disease but there is absolutely no support for this thesis of significant climate effect on the disease until there has been correction for under diagnosis.

    • Ditto in Quebec. I know someone who had to go to the US for diagnosis and treatment because there was “no Lyme disease in Canada.”

    • Everyone on this site misses the most important point. We wouldn’t have nearly this problem if we kill the ticks. Bring back DDT and the problem will likely go away.

  2. Correlation does not equal Causation.
    The climate has been warming since the last ice age, on a 20,000 year time scale, and since the “Little Ice Age” on a 200 year time scale. What else is new.

    The biggest cause in Lyme disease in humans, I would allege, is the overabundance of White Tailed Deer in the North East United States. Their population has exploded, due to restrictions on hunting, and removal of hunting lands due to development. They are a major Lyme vector.

      • Some time ago now, mid/late 1990’s, MNF Mendocino National Forest CA, had zones identified with ‘hot spot’ Lyme disease carriers. Black Tail deer, rats, mice, rodents, birds to be carriers(ticks) of Lyme in these zones. Most frequent were Chaparral and other brush dominate places.

      • Gary, thank you for that!

        My wife was bitten on her back by one of these ticks, and developed the bullseye ring of Lyme disease – though she’s still in denial that she was infected (she was treated with antibiotics very quickly, and never became symptomatic).

        Many months later, I was sitting in my office in Federal Aviation Administration Headquarters, and suddenly felt a tremendous bite on my right wrist. When I finally got reading glasses strong enough to see the culprit, I found it to be the same tiny tick that had bitten my wife. I, too, quickly developed the bullseye, but antibiotics stopped it. Nevertheless, it took forever for that damn bite to heal.

        I couldn’t imagine how the tick had invaded my office. The one that got my wife was easy to explain. She had laid her jacket on the grass while working in her greenhouse, grass that’s visited by deer in great numbers. We didn’t have any deer in FAA HQ, to my knowledge.

        It turns out, however, that we had mice. I learned that a month or so after the fact, and recommended a more aggressive extermination campaign.

    • White tail deer are not sickened by ticks and can carry thousands of them, happily feeding away. Wherever white tail deer have invaded, ticks follow. This is devastating not only to humans but to horses, moose and related ungulates, who are sickened by the ticks. No doubt the climate change alarmists loons will blame the spread of invasive white tail deer on climate change as well. The animal rights loon are already hard at work trying to stop any culling of these pests.

    • The subject is the US.

      Rough estimates of global warming in past centuries are irrelevant.

      For the US, let’s considered NAAO temperatures for the 48 contiguous states:

      — USCRN network of rural stations — no warming since it’s creation in 2008, and probably this is the most relevant measurement for areas where deer live

      — USHCN network — no warming since 1995

      2019, from January through August, was the coldest January though August on record (records since 1895) based on maximum daily temperatures
      (USHCN data)

    • You have the problem correct. It is the deer population, specifically in relation to an expanding human population and specifically in areas like my town near Lowell, MA where you can’t hunt, but there’s loads of river flood plains, loads of deer, and a growing coyote population due to the deer……and lots of Lyme. Deer populations are up all over.

      However, the deer are not the vector for the disease…..at all. The deer tick is the vector. The deer are important for adult female ticks to feed on before laying thousands of eggs and dying. That’s it.

      The Lyme host is mainly the white-footed mouse.

      Also to note, there are at least 4 other known diseases carried by the same ticks. Babesiosis, ehrlichiosis, Powassan virus, deer tick virus…

      -former Lyme researcher

    • John Pickens – you are correct that the White-tailed Deer population explosion is related to the rise in Lyme Disease in people, but ‘vector’ has a specific meaning in epidemiology. A vector transmits the disease-causing microbes to a new host: Ixodes ticks are the vectors of Lyme Disease. You don’t get Lyme Disease from a deer bite (not as far as I know anyway).

      What White-tailed Deer do, as Justin Burch points out below, is amplify the tick population many fold over what it was when deer were rare. Most likely, Lyme Disease has always been around, and may have been common (if undiagnosed) in Colonial Times, but as deer populations were reduced by over-hunting and land use change (e.g. farming) it would have gotten rarer because there would have been fewer tick vectors (the ticks need mice and deer to complete their lifecycle – we are not good hosts). The booming deer populations as farmland returned to woods and hunting pressure dropped off during the 1900s explain the resurgence of Lyme Disease without any need to invoke climate change.

  3. It is the most prevalent tick-transmitted infection in temperate areas of Europe, North America and Asia … link

    The disease doesn’t seem to spread to warm areas. Why would anyone think global warming would cause it to spread?

    • Coming after a series of abnormally cold winters, this discovery could use some quantitative data. I don’t see any.

  4. The explanation for the spread of it has always been simple. Suburban sprawl into once rural areas and the explosion of the white tailed deer as pointed out by John Pickens.

  5. Here in New England we see the greatest number of ticks on the animals (and are reminded to check ourselves!) in mid-spring and late fall, before steady hard freeze. The reason is the ticks’ peak activity occurs when the temperature difference is greatest between them and their hosts–damp, cool weather and a nice warm critter walks by. Once the summer heat and dryness occurs, or the ground freezes hard in December–done for the season. BTW, personal observation is far FEWER ticks the last 2 years in spite of supposedly mild winters.

  6. Urbanization and habitat destruction are the leading causes of increased Lyme. Its pretty basic stuff. Nothing to do with weather or climate. The continuous overreach to blame everything on the BS Climate Change is getting to the point of needing someone to hit the reset button.

  7. Lyme disease has always been around, probably at the same level of infection as is seen today. The difference is that there are diagnostics and doctors are more aware of it. That’s the way it is with almost all diseases. Better detection allows us to identify the cause of the symptoms that were, otherwise, written off as something else.

    • Mark from the midwest,

      I think you are right that Lyme disease has probably always been with us, and only more attentive medicine has identified it in current times. I had it four times. I used to walk my dog near a river in Virginia. There was high grass at the river bank. Once the dog became old we stopped visiting the river and we never got Lyme disease again. The now deceased dog tested positive in one of his vet visits. In past generations people probably just lived with the undiagnosed disease.

      The treatment is a simple antibiotic for a few weeks and in our cases a rapid and complete cure. Those who are never treated can develop more severe symptoms which could require longer term treatments. If one inspects legs, hair and limbs after a walk in the woods the ticks can be removed before the disease develops. They are small ticks and could be well hidden on the back of a leg for example. Run a comb through the hair.

      Many in the medical community think it is probably psycho-somatic, an illness of chronic complainers. As a layman my internet reading seems to show it is a problematical diagnosis–lots of false positives and false negatives. The symptoms appeared real to me.

  8. Tony Heller shows USHCN Peak temperatures on a slow linear decline since the 1930’s USHCN Peak Temperature Era. Same for the Number of USHCN Days in the 100’s, the 90’s and 80’s…all are also in a slow linear decline.

    It’s the extreme temperatures that stress species. Extreme temperatures and the number of extreme temperature days are declining. Maybe it’s the milder climate that is bolstering pest populations (if that is in fact the case).

  9. A couple of comments, above, right on the money. How does a researcher isolate cause and effect in the natural world, you know, like to maintain the scientific process? “employed statistical analysis…” is a telling declaration in this report. There are so many natural processes possible, that the need to isolate the key elements affecting the possible spread of lyme disease (I say possible, maybe there is just better identification?), i s nearly impossible. I am in favor of medical research trying to identify and treat this problem, because it is a serious illness, but throwing in the global warming bogey.man is nonsense.

  10. I’ve lived in the same spot in west central Colorado for 27 years. Lots of scrub oak, sage brush and Ponderosa pine. For the first two decades I could expect to find 3-5 ticks per day on my clothes after the spring thaw until mid-June when it dried out. Then, we had six years of zero, no ticks what-so-ever. Then last year I saw two or maybe three ticks total, which was odd since we didn’t dry out until mid-July. I would have expected more with the moisture lasting so late, but the season started late with late freezes as well. More ticks, nope.

  11. My wife suffered from Lyme. In Oregon, she could not get a diagnosis, was told it’s fibromyalgia , or in her head or poor diet. Took us many years and much money (putting us into big debt issues,)
    Finally we found a Doctor in Idaho who was not a quack, who through several years of antibiotics and natural herb remedies, got her clear.
    The the problem is too many blasted deer. Period.

    • Here is Rockefeller himself explaining the true purpose of the CC/AGW scam. It seems he was not shy about admitting it.
      David Rockefeller’s 1991 Speech Outs the Useful Idiots in the Media

      • Tis article also states:

        It is evident that climate change is drying out summers, lowering average winter temperatures and increasing spring showers in parts of the U.S.

        The contradictions continue to grow.

  12. This Lyme-Disease card (like many such cards) has been overplayed countlessly. No, it isn’t “climate change”, you imbecilic grant-seekers, it’s your culture’s anti-hunting mindsets and the resulting explosive over-population of deer. My area in autumn looks like a war-zone w/their blood & guts strewn along the roads & most every incident results in a badly-damaged or totaled car/truck and possibly a human injury or worse.

    • Right about wild animals. Mother was driving early one night & a deer jumped out from side off road landing somehow onto her Ford passenger car’s front. Animal died ending up across hood & smashing the windshield. Fortuntely mother was not injured & in her way coped with the incident; didn’t bring home road kill.

    • The worst animal/vehicular accidents in the US are caused by moose. They tend to be much higher than the vehicle which strikes them and then fall over and into the vehicle’s windshield. Both moose and driver are then trapped inside, the moose ends up kicking the unfortunate occupant to death.

  13. The area that a person live in has a strong relationship with who acquires Lyme disease. Forty years ago a good friend and coworker was identified as having Lyme disease. He lived in Simsbury CT and worked in Windsor CT. Both his home and workplace were surrounded by heavy woodlands and near a state forest. It was common to see deer almost daily and for someone to hit a deer almost daily. Same for the area where Lyme disease got its name – Lyme CT. Look at Lyme and Old Lyme CT on any satellite map. When you zoom in closely you will see that there are homes in that area that at first looks like a state/national forest. And as others have said above more and more people are moving further out into these heavily wooded lands and more and more deer are populating these lands and their population has forced them into the surrounding developments. As a child, when I rode in a car along the interstates there were pastures or crops growing on either side. Today thes farms have been replaced with developments that are surrounded with woodlands. When a deer from these woodlands walks by the decorative landscaping surrounding a home the tick is brushed off onto the shrub, tree, etc., waiting to jump onto the human, pet, or other animal that walks by. And the disease spreads.

  14. I just did my own research and found that, according to the US Climate Reference Network, the minimum temperature anomaly for the contiguous States has not changed, or has declined slightly since the network began working in 2005.

    So much for climate change.

  15. It has nothing to do with the rapid growth of human populations in areas where Lyme disease exists.
    It must be do to warmer temperatures that no thermometer is able to detect.

  16. This Lyme thing is getting over used. I suppose young researchers need to publish.

    Anyway, rumor has it that alcohol kills ticks.
    Thus, maintain a goodly consumption of wine, whisky, and beer.
    I can verify that this works.

  17. If you’re going out into the woods, treat your clothes with a 0.5% solution of permethrin. Watch any ticks that fall onto your clothing drop off immediately. Check yourself for ticks when you get back indoors.

    Keep permethrin soaked clothing away from cats until the clothing is dry. Wet permethrin will kill your cat.

    • Yes, one of my cats gets the deer-ticks often. From what I’ve read, a cat’s metabolism usually prevents significant problems from Lyme disease (unlike people). I know a number of people nearby that have had problems from the disease, and I myself have been checked and results suggested I had been exposed a long time ago.

  18. “Of these two species, in Manitoba, only the blacklegged tick is of medical importance. The blacklegged tick is a known vector of Borrelia burgdorferi, the causative agent of Lyme disease, along with microbes that cause human granulocytic anaplasmosis and babesiosis.”

    I was born (1930s) and grew up in Manitoba and ticks were a well-known resident. Here’s from the same article:

    “Ticks are just a fact of life here in Manitoba; they come with spring, just like pollen and allergies.

    http://wallisroughley.ca/ticksurveillance.html

    More fake news. It is clearly not temperature! The record breaking cold in Chicago and in Ohio last year is a normal mid winter day in Manitoba. The vector is deer and possibly other animals. The cold is not a factor.

  19. All. Deer populations are a host-vector species for the tick species that transmit Lyme. Deer density increases when people build homes in the rural-suburban fringe (deer in rural settings are low in density as they are culled/hunted). The deer shed ticks and the resulting nymphs wait to feed on an infected rodent. Lyme-permissive rodent species also increase due to the free food that is provided by humans (trash, bird feeders, kid’s birthday party on the lawn and scattered hot dogs, etc.). Because more people are exposed to Lyme infected ticks, there are more Lyme infections. Because the diagnostic tests are more sensitive, and more people are infected, the result is many more people are diagnosed. I recognize that this is a simplistic model, but the influences of marginally warmer (or colder) climate has a negligible effect on the Lyme infections. Don’t be fooled by idiots with a PhD.

  20. Lisa Couper, an ecologist at Stanford University is probably an idiot. She claims that she can think like a tick! Ohh … those ticks know how to survive!

    There have been a couple of posts here on WUWT that discussed ticks. I think Kip Hanson was active in the discussion as well as myself a couple of years ago. Greater awareness and testing is most likely the cause for more diagnosis of the disease.

    • eyesonu,
      Can Lisa Couper ‘see CO2’ also, like reGretable Thunberg? These modern seers have amazing ‘talents’!

      • She sees ticks everywhere around her at Stanford University and other universities, in government offices, under her bed, and in the mirror! She wins a “Participation Trophy”.

  21. I’ve seen convincing evidence that Lyme is spreading due to a change in forestry practice in Eastern American hardwoods, following investment in land/Forest post the financial crash, where the new ownership don’t manage the forest and allow invasive shrub layer which is ideal for ticks…

    Article somewhere in ‘the long read’ site, if I recall correctly

    • There are dozens of reasons for the increase, population, medical diagnosis advances, public awareness, forestry changes, feral animals, movement corridor confinement and probably last on that list would be climate change.

  22. Absolutely fascinating, except that according to this CDC reference, Lyme disease has not increased in the US from 2009-2018. How inconvenient.

    At the same site, the recent incidence maps show that lyme disease is primarily centered in areas which get cold in the winter. It’s much rarer where winters are milder. That’s inconvenient too.

    Finally, the author of the the post is Lara G. Streiff, who:

    is a current student in the UC Santa Cruz Science Communication Program

    The post references a paper presented to the 2019 American Geophysical Union Fall Meeting in San Francisco by Lisa Couper, an ecologist at Stanford University. The methodology:

    Couper modeled two greenhouse gas emissions scenarios to anticipate what the future of Lyme disease will look like in the U.S.

    Her projections indicate that without climate mitigation, Lyme disease cases in the Northeast will likely increase further. “But interestingly, that only happens under the high emission scenario,” she said. If the current climate trend continues with moderate mitigation, her research suggests numbers of disease cases will remain stagnant, though Couper feels that warming trend is rather optimistic.

    So, Lyme disease in the US has the highest incidence in the NorthEast US (above the Mason-Dixon line) and in the upper midwest (Wisconsin, Minnesota), and overall infection rates are not increasing. So while the risk of Lyme disease is greater in colder states, global warming will somehow make it worse.

    But the computer models and a university science communication student think we should be scared anyway.

    • And no analysis of how much it will be reduced on the southern side of the current “high incidence” areas?

      Seems that every Alarmist analysis fails to point out that if their claims of lost crop area, dead coral reefs, lost habitat were accurate, the crop areas, reefs and habitats will simply extend into new areas. It seems none of them have more than a 5th grade education. Maybe that’s why they all look up to St. Greta.

    • “At the same site, the recent incidence maps show that lyme disease is primarily centered in areas which get cold in the winter. It’s much rarer where winters are milder. That’s inconvenient too.”

      Not really.
      Nothing to do with being colder in winter.
      Everything to do with being cool (but still not too dry) in summer.
      Ticks in those conditions do not hide away, and are close to where humans are (eg on branches at arms height).

      https://www.sciencedaily.com/releases/2017/01/170112110732.htm

      “Absolutely fascinating, except that according to this CDC reference, Lyme disease has not increased in the US from 2009-2018…..”

      It has in this communication, actually giving numbers of overall cases…

      https://www.ucsf.edu/news/2018/05/410401/lyme-disease-rise-expert-explains-why

      “Earlier this month, the U.S. Centers for Disease Control and Prevention (CDC) reported that cases of tickborne diseases had more than doubled from 2004 to 2016, from 22,000 to 48,000, and that Lyme disease accounted for 82 percent of tickborne diseases.”

      That looks like an increasing trend to me (>x2).

      • Anthony Burton:

        The numbers in the link you provided simply do not agree with the Historical Data provided by the CDC which I linked to. The CDC table does not go back to 2004; it starts in 2009. So it’s possible there has been a doubling since 2004 in as much as the disease was first identified in 2000.

        But the specific number in your link:

        Earlier this month, the U.S. Centers for Disease Control and Prevention (CDC) reported that cases of tickborne diseases had more than doubled from 2004 to 2016, from 22,000 to 48,000, and that Lyme disease accounted for 82 percent of tickborne diseases.

        “This month” presumably refers to the publication date of the article, which is May 16, 2018, so I don’t know why the CDC wouldn’t have used more current data in whatever report is referenced in that article (the link just goes to a generic CDC site). In any case, the value of 48,000 cases appears nowhere in the 2009-2018 data which shows the maximum value of 29,959 in 2009 and a decrease to 23,558 for 2018. But I don’t see any evident trend.

        Dr. Chiu also says:

        In terms of reported cases, there are about 80 to 100 a year in the state. Residents in or travelers to the northwestern coastal counties – Trinity, Humboldt, and Mendocino – are at highest risk. But because of underreporting, the actual number of Lyme disease cases likely exceeds 1,000 cases a year, simply because most cases of Lyme disease are not reported.

        I see no increase in diagnosed cases; is he talking about increases in “likely” cases? I can’t tell.

        There’s ample ground to speculate from the data in the CDC table. The biggest standout for me is Massachusetts, which was reporting case incidence in line with neighboring New Hampshire, New York and Connecticut from 2009 to 2015 (> 40 cases / 100,000 population), but then from 2016-2018 reported cases plummeted to less than 5 cases / 100,000 population and in 2018 it was 0.2. None of the other high-incidence (> 10 cases / 100K population averaged over 3 years) states showed anything like a similar decline.

        There is a warning in the table about changes in reporting methodology, but I couldn’t see anything that would explain the Massachusetts data. It seems unlikely MA rolled out a Lyme disease program that effective while public health officials in neighboring states remained unaware of it. Maybe MA is simply underreporting, but most other high-incidence states show either no increase or an actual decrease.

        Dr. Chiu is speaking specifically about California, but there is no trend there either.

        Pennsylvania is a clear exception there with 2018 incident rate 57% higher than 2009 (61.8 vs. 39.3) Connecticut, where the disease was first identified, showed a reduction of 55% in the same years (35.5 vs. 78.2).

        But taken all together, there is no increase. The national incidence rate was 9.8 in 2008 and 7.2 in 2018.

        If climate change has a hand here, it’s for the better.

  23. It is evident that climate change is drying out summers, lowering average winter temperatures and increasing spring showers in parts of the U.S. …
    It is evident that climate change is drying out summers, lowering average winter temperatures and increasing spring showers in parts of 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.

  24. 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.

  25. 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.

    • 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.

  26. 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.

        • 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’.

  27. 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.

  28. 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.

    • 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.

  29. 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.

  30. 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.

  31. 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?

  32. 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?

  33. “Climate change driving expansion of Lyme disease in the US”

    Charles: There should be a “?” at the end of titles like this.

  34. 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.

  35. 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…

  36. 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.

Comments are closed.