The Worst States For Lyme Disease

With more than 10 confirmed cases for every 100,000 people from 2010 to 2015, Massachusetts is one of 16 high-incidence states, including Washington D.C., identified by the CDC. However, Lyme disease infection rates have declined precipitously in the state over the last few years. The average infection rate between 2017 to 2019 was just 1.7 per 100,000 people, well below the decade high of 57.0 per 100,000 in 2013. There were a total of only six confirmed cases of the disease in the state in 2019.

Public health officials in Massachusetts dispute the figures reported by the CDC, claiming that the actual number of cases has not declined by over 90%, but rather remained steady in recent years. The disparity may be linked to the CDC’s standard of requiring both a clinical diagnosis and a positive lab test for a case of the disease to be counted — a standard state officials claim is overly burdensome.

There are an average of 8.4 confirmed cases of Lyme disease in the District of Columbia annually — a higher infection rate than in all but 14 states. The worst year for the disease over the last decade was 2015, when there were 11.6 confirmed cases per 100,000 people.

Unlike many states with high Lyme infection rates, D.C. is an urban area with relatively little green space. Still, the spring and summer humidity in the area provides ideal conditions for ticks, which can still be found in backyards and parks in the city and pass the disease from mice, rather than deer, as is the case in the Northeastern U.S.

Virginia is one of several states in the mid-Atlantic region with a relatively high incidence rate of Lyme disease. There are an average of 10.1 cases in the state for every 100,000 people annually, 14th highest among states. Peak transmission in the state occurs in May and June, and residents who spend time in heavily wooded areas are at increased risk.

The state’s infection rate rose slightly in 2019 to 9.2 cases per 100,000 people from 8.7 the previous year. Still, infections remain below the decade high of 13.1 per 100,000 recorded in 2015.

The average incidence rate of Lyme disease in New York state of 14.9 cases per 100,000 people annually is the 13th highest among states. There were 2,847 confirmed cases in 2019 and another 1,396 probable cases that were not factored into the infection rate.

While much of New York is forested and rural — areas that many associate with higher risk of Lyme disease — those in urban parts of the state still face some risk. Over 40% of the state’s population live in New York City, where parks and backyards can be an ideal habitat for disease-carrying ticks. There have been as many as 1,000 confirmed cases in a single year in New York City.

As is the case across the United States, Lyme disease is the most common tick-borne disease in Maryland. There are an average of 15.9 confirmed cases of Lyme disease in the state annually for every 100,000 people, the 12th highest rate among states.

Mid-Atlantic states such as Maryland tend to have warm and humid spring and summer seasons, which are ideal conditions for blacklegged ticks. However, cases of Lyme disease appear to be becoming increasingly less common across Maryland. The incidence rate of Lyme has fallen each year since hitting a decade peak of 21.2 cases per 100,000 people in 2016. There were only 13.3 confirmed cases per 100,000 people in the state in 2019.

Minnesota is one of only two Midwestern states classified as high-incidence for Lyme disease by the CDC — meaning it has had at least 10 confirmed cases per 100,000 people for three reporting years. Over the last three years, there have been an average of 19.5 confirmed cases of Lyme in the state for every 100,000 people, the 11th highest rate among states.

Not only do parts of Minnesota offer blacklegged ticks a suitable habitat, but residents of the state appear more likely to come into contact with disease-carrying ticks by engaging in outdoor activities. Over 80% of adults in the state are regularly physically active, one of the higher shares among states.

Wisconsin has the highest incidence rate of Lyme disease in the Midwest and the 10th highest of any state nationwide. There are an average of 23.7 known cases of the disease for every 100,000 people per year.

As is the case in much of the country, cases are becoming less common in Wisconsin. There were only 20.9 cases for every 100,000 people in the state in 2019, less than half the 10-year high of 44.0 per 100,000 reported in 2010.

Lyme disease was first identified in Connecticut in the 1970s, and today, the state remains one of the hotspots for the disease. There are an average of 32.1 new infections for every 100,000 people annually in Connecticut, more than four times the national incidence rate.

Encouragingly, the disease appears to be becoming less common in the state. There were only 22.3 cases of Lyme reported for every 100,000 people in Connecticut in 2019, the lowest infection rate in the last decade and less than half the 10-year high of 58.7 incidents per 100,000 people reported in 2013.

West Virginia recently became a high-incidence state for Lyme disease after reporting more than 10 cases for every 100,000 people in 2015, 2016, and 2017. Cases of the disease have continued to increase in the years since, and in 2019, the state reported a 10-year high of 39.2 cases for every 100,000 people.

In light of the recent increase, researchers at West Virginia University are working on developing a vaccine to protect against Lyme disease with the help of a $1.9 million grant from the National Institute of Allergy and Infectious Diseases.

The humidity common in much of the mid-Atlantic region allows tick populations to thrive. In New Jersey, 2,400 people were infected with Lyme disease by blacklegged ticks, and an additional 1,219 people were likely infected in 2019. Over the last three years, there have been an average of 33.2 confirmed cases of Lyme disease for every 100,000 people in the state annually, the seventh highest infection rate of any state.

Encouragingly, cases of the disease are becoming less common in the state. The 2019 infection rate of 27 cases for every 100,000 people is the lowest it has been in New Jersey in at least a decade.

Delaware is one of only six states with an annual Lyme disease infection rate greater than 50 per 100,000 people. There have been an average of 53.2 confirmed cases for every 100,000 people in the state over the last three years.

Though infections have been identified in each of the state’s three counties, cases tend to be concentrated in New Castle, the state’s northernmost county that sits across the Delaware River from New Jersey and shares a border with Maryland and Pennsylvania — three other states that are also considered high-incidence by the CDC.

The Northeastern United States — particularly the New England region — is a hotspot for Lyme disease. Each of the five states with the highest annual incidence rate of the disease is located in the Northeast, and Rhode Island is one of them. There are an average of 56.1 known cases of the disease for every 100,000 people per year in the state.

Cases have climbed considerably in Rhode Island over the last 10 years, from just 10.9 cases per 100,000 people in 2010 to 49.7 per 100,000 in 2019. Infection rates in the state over the last decade peaked in 2018, when there were 62.5 cases for every 100,000 people.

The average incidence rate of Lyme disease in Pennsylvania of 62.3 cases per 100,000 people annually is the fourth highest among states. There were 6,763 confirmed cases of the disease in the state and another 2,235 probable cases, which were not factored into the infection rate, in 2019 alone.

The type of tick that carries Lyme disease was virtually nonexistent in Pennsylvania as recently as the 1960s. Experts attribute its prevalence today to climate change, change in human and animal behavior that may bring ticks closer to population centers, and the regrowth of timber that was initially cut around 1900 that is now providing a habitat for tick populations.

There are an average of 73.6 cases of Lyme disease in New Hampshire for every 100,000 people annually. The state, bordered by Vermont, Massachusetts, and Maine, which are classified as high-incidence by the CDC, reported 1,106 confirmed cases and another 604 probable cases in 2019.

The incidence rate of the disease in 2019 of 81.3 per 100,000 people is the state’s second highest annual rate in the last decade, trailing only 2013, when there were 100 cases per 100,000 people.

Cases of Lyme disease have skyrocketed in Vermont over the last 30 years. In the early 1990s, there a dozen or fewer cases a year. In 2019, there were 706 confirmed cases, or 113.1 for every 100,000 people, the most in at least the last decade. The year’s infection rate does not include another 358 probable cases reported in the state. The state’s average annual infection rate of the last three years stands at 90.8 per 100,000, the second highest of any state.

Though Vermonters have been diagnosed with Lyme disease in every county in the state, the disease tends to be concentrated in the southern half of the state — particularly in Bennington, Rutland, and Windham counties.

Maine is the only state with a Lyme disease infection rate greater than 100 per 100,000 people. There have been an average of 103.6 confirmed cases for every 100,000 people in the state over the last three years, over 13 times higher than the national average. There were 1,629 confirmed cases in 2019, or 121.2 for every 100,000 people, the most in at least the last decade. The infection rate does not include another 538 probable cases reported in the state that year.

Maine is one of the most rural and sparsely populated states in the country, and Mainers are likely to be close to grassy and wooded areas where disease-carrying blacklegged ticks tend to live. According to the Maine Center for Disease Control and Prevention, Lyme disease is found in every county in the state, and children ages 5 to 14 are at especially high risk for the disease.