There were more than 26,000 confirmed cases of Lyme disease in the United States in 2016. Humans contract the disease when a blacklegged tick infected with the bacterium Borrelia burgdorferi bites them and stays attached for 36 to 48 hours.
Lyme disease has a wide range of symptoms. Shortly after the tick bites, a rash can develop at the site, though not in all cases. Other early signs include flu-like symptoms such as fevers, headaches, and joint pain. The disease can be treated with antibiotics. If left untreated, later symptoms can include neck stiffness, inflammation of the brain and spinal cord, pain and numbness in the extremities, and even short-term memory loss.
Due to under reporting, the Centers for Disease Control and Prevention believes that more than 300,000 people actually contract Lyme disease annually. However, the incidence of Lyme disease differs widely between states.
The disease is currently concentrated in the northeastern U.S., but that could be changing. Dr. Daniel Cameron, an expert in Lyme disease, said tens of millions of ticks attach themselves to migratory birds and move throughout North America. “Ticks going in all directions due to the birds are making all the old assumptions about where the worst states are kind of redundant and a little bit old fashioned,” Dr. Cameron said.
24/7 Wall St. reviewed CDC data on the reported incidence of Lyme disease in each state to determine the worst states for Lyme disease.
> Incidence of Lyme disease: 11.6 per 100,000 residents
> Confirmed cases: 976 (9th highest)
> Pct. population rural: 24.5% (22nd least)
> Pct. adults physically active: 77.7% (23rd highest)
The number of confirmed Lyme disease cases in Virginia fell from 1,102 in 2015 to 976 in 2016. Still, the state still had one of the highest incidences of Lyme disease anywhere in the country. Blacklegged ticks, the only kind that carries Lyme disease, are found in wooded and grassy areas. Even though most states have a higher percentage of their populations living in rural areas than Virginia, the state still ranks among the worst for Lyme disease.
13. New York
> Incidence of Lyme disease: 13.3 per 100,000 residents
> Confirmed cases: 2,623 (3rd highest)
> Pct. population rural: 12.1% (12th least)
> Pct. adults physically active: 74.6% (13th lowest)
Though a low percentage of New York’s population lives in rural areas where ticks are likely to be found, the state is in the center of the blacklegged ticks’ habitat in the Northeast. New York state had over 2,600 reported cases of Lyme disease in 2016, accounting for more than 10% of all cases nationwide.
12. West Virginia
> Incidence of Lyme disease: 16.2 per 100,000 residents
> Confirmed cases: 297 (14th highest)
> Pct. population rural: 51.3% (3rd most)
> Pct. adults physically active: 70.8% (6th lowest)
More than half of West Virginia’s residents live in rural areas, where Lyme disease-carrying ticks are likely to be found. The number of confirmed Lyme disease cases in West Virginia has risen significantly in the last few years, increasing from 112 in 2014 to 243 in 2015 and to 297 in 2016.
> Incidence of Lyme disease: 21.2 per 100,000 residents
> Confirmed cases: 1,274 (6th highest)
> Pct. population rural: 12.8% (13th least)
> Pct. adults physically active: 77.8% (22nd highest)
Maryland had 1,274 confirmed cases of Lyme disease in 2016, the most in the state since 2009. Some 21.2 Maryland residents per 100,000 had a confirmed case of the disease in 2016, though just 12.8% of the population lives in a rural area where ticks are more likely to be found.
> Incidence of Lyme disease: 23.6 per 100,000 residents
> Confirmed cases: 1,304 (5th highest)
> Pct. population rural: 26.7% (25th most)
> Pct. adults physically active: 80.2% (9th highest)
More than 80% of adults in Minnesota report getting some physical activity in their leisure time, one of the higher rates in the nation. As the Land of 10,000 Lakes, Minnesota has lots of space for outdoor activities in rural areas. It is likely that many Lyme disease cases in the state came from people spending their leisure time outdoors.
> Incidence of Lyme disease: 26.0 per 100,000 residents
> Confirmed cases: 1,504 (4th highest)
> Pct. population rural: 29.8% (19th most)
> Pct. adults physically active: 78.9% (16th highest)
Wisconsin is one of two Midwestern states to have a higher than average incidence of confirmed Lyme disease cases, along with Minnesota. The incidence of Lyme disease per 100,000 people increased from 22.7 in 2015 to 26.0 in 2016. The increase of 3.3 cases per 100,000 was one of the largest in the country.
> Incidence of Lyme disease: 34.6 per 100,000 residents
> Confirmed cases: 1,238 (7th highest)
> Pct. population rural: 12.0% (11th least)
> Pct. adults physically active: 79.6% (13th highest)
Connecticut — the first U.S. state to have documented cases of Lyme disease — had one of the largest drops in incidence, but still surpassed all but seven other states in contraction rates. The reported cases of Lyme disease dropped from 52.2 confirmed cases per 100,000 people in 2015 to 34.6 per 100,000 the following year. That drop was second only to Massachusetts, where incidence fell by more than 40 cases per 100,000 people, knocking it off the list of the worst states for Lyme disease.
7. New Jersey
> Incidence of Lyme disease: 37.3 per 100,000 residents
> Confirmed cases: 3,332 (2nd highest)
> Pct. population rural: 5.3% (2nd least)
> Pct. adults physically active: 76.7% (25th highest)
Some 5.3% of New Jersey residents live in rural areas, the second smallest rate of any state. Yet state residents were still among the most likely to contract Lyme disease, with 37.3 residents per 100,000 diagnosed with the disease in 2016. Still, this was a notable improvement from 2015, when 43.9 residents for every 100,000 contracted Lyme disease.
> Incidence of Lyme disease: 41.1 per 100,000 residents
> Confirmed cases: 391 (13th highest)
> Pct. population rural: 16.7% (18th least)
> Pct. adults physically active: 73.9% (10th lowest)
Delaware’s incidence of confirmed Lyme disease cases increased significantly in 2016, from 35.3 cases per 100,000 residents in 2015 to 41.1 cases per 100,000 residents — one of the sharpest increases nationwide. The increase may have been the result of Delaware’s campaign to increase public awareness of the disease. If previously some people who contracted the disease were unaware and never diagnosed, many more are now better informed of the symptoms and more likely to be correctly diagnosed.
5. Rhode Island
> Incidence of Lyme disease: 50.6 per 100,000 residents
> Confirmed cases: 535 (11th highest)
> Pct. population rural: 9.3% (7th least)
> Pct. adults physically active: 75.9% (19th lowest)
Rhode Island is just one of a handful of states on this list in which the incidence of Lyme disease dropped from 2015 to 2016. In those years, Rhode Island’s incidence rate declined from 53.4 cases to 50.6 cases per 100,000 people. For comparison, the overall U.S. incidence of reported Lyme disease cases declined from 8.9 cases per 100,000 in 2015 to 8.1 per 100,000 in 2016.
4. New Hampshire
> Incidence of Lyme disease: 51.8 per 100,000 residents
> Confirmed cases: 691 (10th highest)
> Pct. population rural: 39.7% (11th most)
> Pct. adults physically active: 79.4% (14th highest)
No state had a greater increase in the incidence of Lyme disease than New Hampshire. There were 51.8 reported cases per 100,000 residents in 2016, 19.0 more cases per 100,000 residents than the year before. The total number of Lyme disease cases increased from 436 to 691 in that timeframe, a more than 50% increase.
> Incidence of Lyme disease: 70.3 per 100,000 residents
> Confirmed cases: 8,988 (the highest)
> Pct. population rural: 21.3% (20th least)
> Pct. adults physically active: 76.0% (21st lowest)
Pennsylvania had 8,988 confirmed cases of Lyme disease in 2016, by far the highest total of any state. That figure is higher than the next four highest states combined. Pennsylvania accounts for more than one-third of total confirmed Lyme disease cases in the United States. However, due to Pennsylvania’s relatively high population, it ranks behind two other states in incidence rate of the disease, at 70.3 per 100,000 residents in 2016.
> Incidence of Lyme disease: 78.1 per 100,000 residents
> Confirmed cases: 488 (12th highest)
> Pct. population rural: 61.1% (2nd most)
> Pct. adults physically active: 80.5% (8th highest)
Vermont has a large rural population, and is known for its outdoor activities, such as hiking, camping, and backpacking. This, and the fact that the state is in the midst of the blacklegged ticks’ habitat, means state residents are among the most likely in the country to contact Lyme disease.
> Incidence of Lyme disease: 86.4 per 100,000 residents
> Confirmed cases: 1,151 (8th highest)
> Pct. population rural: 61.3% (the most)
> Pct. adults physically active: 78.6% (17th highest)
Maine’s incidence of confirmed Lyme disease cases of 86.4 per 100,000 residents in 2016 was by far the highest of any state. It was also more than 10 times higher than the national incidence rate of 8.1 cases per 100,000 residents. As the state with the greatest share of rural residents, many people in Maine are likely to be close to grassy and wooded areas where disease-carrying blacklegged ticks tend to live.
Detailed findings & methodology:
Lyme disease is relatively new as far as diseases go. While it likely began thousands of years earlier, it was first properly recorded in the United States in the summer of 1975. Dozens of children came down with symptoms that at first appeared to be juvenile arthritis. Two years later, a doctor at Yale published a paper outlining the new tick-borne disease, then called Lyme arthritis.
Lyme disease is concentrated mainly in the Northeastern and mid-Atlantic United States — the blacklegged ticks’ main habitat area. That area comprises a dozen of the 14 states on this list. The Midwest also has a few states with higher than average incidences of Lyme disease.
On the West Coast, particularly northern California, the western blacklegged tick carries Lyme disease. However, no state that is entirely west of the Mississippi River has an above average incidence of Lyme disease.
24/7 Wall St. ranked the states by incidence of Lyme disease, which is based on confirmed reported cases. However, there are several limitations to the data. As the CDC notes, the disease is likely under-reported due to two main reasons. First, because the symptoms of Lyme disease can be so general, and because the current test are more reliable a few weeks after contracting the disease, Lyme disease can be difficult to diagnose. Second, not all states have similar procedures for reporting Lyme disease to the CDC.
Lyme disease tends to affect either children ages 6-9, or adults ages of 40-50, though it is difficult to know why. Dr. Daniel Cameron, an expert on Lyme disease, said the disparity may come from teenagers and young adults underreporting their symptoms. “I’m concerned teenagers don’t always share how sick they are with their parents. … I think they get overlooked.”
There is a huge gap between the states on this list and those that are not. Virginia, the state with the lowest incidence on our list, had 11.6 confirmed cases per 100,000 residents in 2016. The next highest state, Iowa, had just 2.4 cases per 100,000 residents. For context, the overall U.S. incidence of Lyme disease in 2016 was 8.1 cases per 100,000 residents, down from 8.9 cases per 100,000 in 2015. The state with the highest incidence of Lyme disease, Maine, had 86.4 cases for every 100,000 residents. The 14 states on this list account for nearly 95% of the total reported Lyme disease cases in the U.S.
Many factors impact the prevalence of blacklegged ticks in a given year. The number of animals like mice and deer that the ticks feed on can affect the population. Weather also is a major driving force behind the blacklegged tick population, and by extension the incidence of Lyme disease. Ticks are inactive during the colder seasons, but if temperatures fail to drop in the winter, the ticks will stay active longer.
To determine the worst states for Lyme disease, 24/7 Wall St. reviewed Lyme disease data from the Centers for Disease Control and Prevention. The data included the incidence of Lyme disease in every state in 2016, the most recent year available, and the total number of confirmed cases by state. The share of the state population that lives in rural areas and the percentage of adults who are physically active are both for 2017 and come from County Health Rankings & Roadmaps, a Robert Wood Johnson Foundation and University of Wisconsin Population Health Institute joint program.
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