The Ultimate Lyme Disease Map — So Far

This is the ultimate Lyme Disease map for the Eastern United States — so far, that is. Those scary red blots keep swelling, and swelling, and swelling…

But at least this latest charting of the risk to humans means we’re keeping better track of Lyme Disease, a tick-borne illness whose symptoms can range from a rash and fever to long-term neurological effects.

(Better track in most places, anyway. Please ignore the apparent Lyme-free zone on Cape Cod above. It’s just an artifact of limits on the data.)

The map and its analysis are just out in the American Journal of Tropical Medicine and Hygiene. I spoke today with Maria Diuk-Wasser, an assistant professor of epidemiology at the Yale School of Public Health and lead author on the paper, “Human Risk of Infection with Borrelia burgdorferi, the Lyme Disease Agent, in Eastern United States.” I pressed her to apply a superlative to the study, and she offered that this is “the largest field-based, standardized effort to describe the risk for Lyme Disease.”

In concrete terms, that means that about 100 people — she eventually lost count — went “tick-dragging” all over for the ticks that carry Lyme Disease. They were trained and sent out onto a given territory with a “drag cloth,” a one-meter-square swath of corduroy. They would walk along and drag the cloth behind them, and every 20 meters they would lift it up, pick up all the ticks attached to it with tweezers, preserve them in alcohol and ultimately send them in to Dr. Diuk-Wasser’s team for analysis.

It will be news to few Massachusetts residents that the state is a hotbed of Lyme Disease, and we’ve written about it before. But the survey further crystallizes the disease’s geography, and Dr. Diuk-Wasser says that one of its findings may also help inform clinical practice: Almost everywhere that the draggers found young ticks, the usual culprits in spreading Lyme Disease, about one in five of the ticks actually carried the Lyme Disease bacterium.

That finding could simplify clinical guidelines because doctors may no longer need to consider how widespread the Lyme bacteria is among local ticks, she said. They may be able to simply make a general presumption that if there’s Lyme Disease around and a tick has been on a patient at least 36 hours — long enough to transmit the bacteria — the patient’s risk of Lyme Disease is about one in five.

Back to the broader geography: Why might Lyme Disease have spread in such a distinctive pattern of two huge red spots?

It’s not entirely clear, Dr. Diuk-Wasser said, but it’s known that in the Northeast, at the turn of the last century there was very little forest, virtually no deer, and no ticks. “Back then, it made the paper if you saw a deer,” she said. The tick population and Lyme Disease had pretty much receded to a few islands. But it has been expanding outwards again since perhaps the 1920s or 1930s; “Following re-forestation, deer invaded, ticks came, and Lyme Disease followed.”

Similarly in the Midwest, she said, it’s believed that the deer and tick population had retreated to virtual islands — areas where they had never been exterminated — and has more recently been expanding back outward from Minnesota. The two “expansion fronts may actually merge and we may have it all through Ohio,” she said.

From the study’s press release:

Band of tick hunters gathered evidence for most extensive field study ever conducted. Given frequent over- and under-diagnosis of Lyme disease, map offers officials new tool for assessing risk and tracking disease spread

Deerfield, Ill. — A new map pinpoints well-defined areas of the Eastern United States where humans have the highest risk of contracting Lyme disease, one of the most rapidly emerging infectious diseases in North America, according to the U.S. Centers for Disease Control and Prevention.

As part of the most extensive Lyme-related field study ever undertaken, researchers found high infection risk confined mainly to the Northeast, Mid-Atlantic and Upper Midwest and low risk in the South. The results were published in the February issue of the American Journal of Tropical Medicine and Hygiene. Given frequent over- and under-diagnosis of Lyme disease, the new map could arm the public and health officials with critical information on actual local risk.

“There has been a lot of discussion of whether Lyme disease exists outside of the Northeast and the upper Midwest, but our sampling of tick populations at hundreds of sites suggests that any diagnosis of Lyme disease in most of the South should be put in serious doubt, unless it involves someone who has traveled to an area where the disease is common,” said Dr. Maria A. Diuk-Wasser, Assistant Professor at the Yale School of Public Health and the lead author of the study.

“We can’t completely rule out the existence of Lyme disease in the South,” she added, “but it appears highly unlikely.”

The Lyme disease risk map was developed by researchers at the Yale School of Public Health in collaboration with Michigan State University, University of Illinois and University of California, Irvine, through a cooperative agreement with the CDC, which is seeking a better understanding of where Lyme disease poses a public health menace.


Current geographical assessments of Lyme disease risk are heavily reliant on reports of human infections, which the study notes can be a poor predictor of risk. The researchers point out that using human cases to determine areas of risk can be misleading due to the high level of “underreporting and misdiagnosis” of Lyme disease. They also note that where someone is diagnosed with the disease is not necessarily where they contracted it.

In addition, the study found that infected I. scapularis ticks may colonize a region long before they actually infect a human with Lyme disease, which means risk can be significant even without a confirmed case.

“A better understanding of where Lyme disease is likely to be endemic is a significant factor in improving prevention, diagnosis and treatment,” Diuk-Wasser said. “People need to know where to take precautions to avoid tick bites. Also, doctors may be less likely to suspect and test for Lyme disease if they are unaware a patient was in a risky area and, conversely, they may act too aggressively and prescribe unneeded and potentially dangerous treatments if they incorrectly believe their patient was exposed to the pathogen.”

The study notes that “accurate and timely” diagnosis is crucial to initiating antibiotic treatments that can help patients avoid the more serious complications of Lyme disease. At the same time, the authors point out that incorrectly suspecting Lyme disease has its own consequences, including potentially life-threatening complications from the antibiotics typically used to treat infections. (While the laboratory test for Lyme disease can produce both false-positives and false-negatives, false-positives are far more likely in non-endemic areas.)

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  • Matt

    My wife and daughter have both tested positive for Lyme in the last month my daughter can not eat any meat without being doubled up in upper stomach pain. My wife has been going to doctors for over a year with all the classic Lyme symtoms and only til I raised hell at our family doctors office would they even agree to test her for Lyme. Low and behold she was positive and then I had my daughter tested and so was she I’m being tested on June 17 2013 . We live in west central florida where the map shows we are at low risk I know of 15 other people in our county that also have been positive and a lot more that are sick and who are going to get tested. The ticks in our area are horrible and have been for several years and no one wants to hear it not the local health dept. so I hope someone will take a better look at Florida .

  • Rick
  • Robert Butler

    Lyme Disease is in every State and spreading faster than we can imagine. The disease is not only transmitted from an infected tick. My adult daughter is completely disabled due to Lyme. Prior to her knowledge that she had the illness she became pregnant – her baby was born with Lyme. Now age 7 he like his Mother suffer daily. Now we have discovered her husband has Lyme – never been bitten. Lyme is sexually transmitted as well. The Lyme bacteria is cousin to syphillis. Just as dibilitating, just as deadly. Early detection is essential. My daughter had no bullseye, no illness and no symptoms for eight years after being bitten. The pregnancy triggered the bacteria bringing it out of dormancy. Inform yourself of this illness. It is not to be taken lightly. Watch “Under Our Skin” by Openeye Pictures. It’s a documentary worth watching. It could save a life. Visit my website for more information  and help get the word out. Stay safe.

  • Daisyduke011

    I live in the city part of Washington County, Pennsylvania and keep getting various different facts about Lyme’s Disease being either a low-risk or high-risk. No one that I know here as got bitten by a deer tick. Am I at a low-risk area due to living in the city or should I be worried?

    • Robert Butler

      Lyme is not only passed through a tick bite. It is also tranferred during sex. It is cousin to syphillis. It also passes inutero. My grandson was born with it as his Mother has Lyme and was unaware that it could be passed to the baby. Now 7yrs old her son suffers like she does each and every day.

      • Daisyduke011

        I see. Thank you for letting me know but should I still be worried? I live in the city and don’t go into high grass or the woods because of my severe sinus condition.

  • Kaguirre

    Just stumbled across this website looking for research and information- I just pulled 12 black ticks of various sizes out of our pet dog, and we live in the california desert- I have never seen ticks in or around my property before, and we have been here 30 years- so this is a first- I have heard they are nearby, but usually in the more mountainous regions. I am in the  Antelope Valley desert in the  Lake LA vicinity. Just wanted to add to the data base.

  • Sueb123

    That’s a scary map. Have to watch the kids when they are out.

  • Nick Knight

    I wish it where a world map.  I am interested to see where it has spread outside of the USA. 

  • Jon Nixon

    As a practitioner with  25+ years of primary care experience in rural northern Virginia, I have seen very few cases of Lyme disease with the classic presenting symptoms of rash, fever, joint pain in the setting of a recent tick bite. I have seen a single case of Lyme- related heart conduction disease which required a pacemaker in an otherwise healthy adolescent. I have also seen many, many patients who have a variety of chronic problems, usually fatigue and generalized pain, who have been given a diagnosis of “chronic Lyme disease”, usually based on very little, if any,hard evidence. Their symptoms seems to be no different from those with the diagnosis of fibromyalgia or CFS. The fad of giving people prolonged treatment with potent intravenous antibiotics based on a “borderline positive” blood test has fortunately fallen from popularity after studies have shown no difference from placebo in terms of symptom relief, and the risk of aquiring serious ( even deadly) antibiotic- related GI infections. Something, God knows what, causes people to feel sick and tired, and there are multiple causes, Lyme disease being only one of them. (It is great business for the “natural supplement” industry, BTW.) If there aren’t ticks with LD in your area, then common sense says you can’t get it, for Pete’s sake……….           

    • Matt

      Perhaps Lyme is misdiagnosed sometimes but what I found that on the West Coast MD were deeply ignorant about Lyme research.  I had classic symptoms and was told it didn’t exist on the West Coast.  I also had been bitten on the Cape the same year.  This was 1994.  After a couple years, one MD put me on a nearly year long course of antibiotics and my symptoms went away.  The shorter course did not work.  What I found is that most MDs use probability as the basis for a lot of their diagnosis.  If you have a 1 in 10 chances of a particular illness, they treat it as 0 in 10, leaving 10% undiagnosed.  

  • Cathy

    More misleading information about the “attachment” time of ticks.  These guidelines of how long the tick is attached assumes that the tick has not had a blood meal (attachment to another human or dog, for example) in the previous 24 or 36 hours, depending on who is offering the information. The bacteria, which lives in the abdomen of the tick, takes a long time to travel to the saliva glands, from which it is transmitted during a bite. Ticks have been shown to transmit  not only Lyme, but especially the insidious co-infections in as little as 15 minutes of attachment to a human.  Perhaps the ticket was feeding on another host in the last half hour, and was dislodged.  The bacteria is already present at the saliva glands. These gross generalizations are dangerous and mislead people into thinking they couldn’t possibly be infected.  And then, of course, it is too late.
    Get your info straight.

    • Carey Goldberg

      Dear Cathy — Would you have an official source on this? We plan to cover Lyme Disease extensively and if there’s wrong information out there, I’m very eager to correct it. Thank you for writing and all best — Carey

    • Robert Butler

      Thanks for the post. Getting the information is so important. While I’m sure there are many people who think they have Lyme and don’t I’m certain there are just as many who think they don’t and really do. There are several case where the autopsies showed Lyme was the cause of death when the patient was actually diagnosed and treated for the obvious symptoms they had shown. Lyme is the Great Immitator and has fooled many professionals through the years. It’s a wicked illness that steals your life from you slowly. I hate watching my daughter and grandson deteriorate. The little guy is only 7 years old and has never been bitten by a tick. He was born with it after the doctors assured my daughter that Lyme can only be from an infected tick. He sure was wrong and my grandson is the proof.

  • Pam

    Your map is WAY off. I have Lyme and live in Florida, where I know many others with it. I also run a popular Lyme website and get hundreds of requests for help from folks in almost every state,  especially in the Eastern half of the US.. Lyme is also rampant on the West Coast. 

    • Scott

      Oh, you run a popular website? Well, that’s enough for me. Forget science.

      • Pam

        Scott, don’t let scientists pull wool over your eyes. Believe me, i’d love to agree with the results of this report. While their red, highest risk areas may be accurate, their not indicating any risk in the rest of the Eastern US is patently wrong. You must not have Lyme or know anyone who does. If you did, and they lived in any of the supposedly safe, green areas, you’d be raising an eyebrow at these results instead of browbeating the thousands of us who do have Lyme and related illnesses that come with it and don’t live in or near red areas.

        • 7LeagueBoots

          Pam, if you re-read the map legend you’ll see that the green is “low risk” not no risk.  That indicates that lyme disease is indeed present, but that the risk of contracting it is relatively low, especially compared with high risk areas.  According to the map they provided, everywhere in the US has the potential for lyme disease.

        • Robert Butler

          Best wishes to you in your fight against Lyme. My daughter and grandson are also victims and it is heartbreaking. My grandson was never bitten by a tick – he was born with it. So much for the doctors assurance that the bacteria could not pass to the fetus. I think science need to do some catching up on the facts. Not sure why they don’t consult with the Lyme community. They are the ones with the first hand knowledge.

      • Robert Butler

        You need to broaden your science material and you will see that every State has Lyme and it’s spreading quickly. It is the fastest growing infectious disease today. Do more research. Arm yourself with knowledge about Lyme and how it is spread. Ticks aren’t the only culprit. My 7 year old grandson was never bitten by a tick – he was born with it after the doctors gave their assurance it could not be passed to the fetus – they were dead wrong and he will now suffer like his mother for the rest of his life and supposedly we live in a safe State. My State told me when I tried to report the Lyme that they don’t keep records on Lyme cases as  that sort of thing would harm tourism. Visit a Lyme blog and listen to the people who’s lives have been totally destroyed by this illness. It’s a real eye opener. Better yet watch the documentary Under Our Skin, you’ll quickly become an advocate to get the word out about this illness. Knowledge is power. Arm yourself.

  • Tristramdammin

    Nantucket, the Vineyard ,and the Cape are not colored as high risk- incorrect. . 

    • Careyg

      Right — as I note in the text, that green color for the cape and islands is just an artifact of the limits on the data, which came from NASA and tends to cut off coastal areas, so please ignore! I’ve heard of many reports of Lyme in those areas…As for Florida and other states, I don’t know, but perhaps it’s an effect of the specific method used? Clearly it’s not totally exhaustive — but seems to be an improvement over what we had…

      • Pam

        Florida and the rest of the Southern states have plenty of Lyme, sorry to report.

        • Guest

          Florida has plenty of people that *think* they have Lyme.

          • Neko

            The East Coast has plenty of doctors that adhere to the CDC’s guidelines of reading the Western Blot blood test for Lyme titers which is currently being debated in the medical community.

          • Guest

            there’s a great new test by NeuroScience called My lyme Immune ID.  check it out if you have a negative western blot.

      • Robert Butler

        I personally believe the map is inaccurate. My daughter and grandson both have Lyme and when we tried to report it to our State health department they claimed they do not take such reports. I was actually told that if records of this sort were on file the State would see tourism drop significantly. So much for dependable data.

        • Lisamarieprice76

           Robert, This map isn’t of reported cases.  They actually went out and caught the ticks and tested them.  This is a much more accurate way of detecting the prevalence of Lyme disease since diagnosing it in humans is problematic.  I suffered with chronic Lyme disease for 11 years.