Special Report

The Worst States For Lyme Disease

Source: mdgmorris / Getty Images

6. Delaware
> Avg. new Lyme disease cases per year: 53.2 confirmed cases per 100,000 people
> Total cases in 2019: 641 (619 confirmed, 22 probable)
> Worst year in last decade: 2011; 84.6 confirmed cases per 100,000 people
> Physically active adults: 72.7% (8th lowest)
> Uninsured rate: 6.6% (16th lowest)

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.

Source: SeanPavonePhoto / Getty Images

5. Rhode Island
> Avg. new Lyme disease cases per year: 56.1 confirmed cases per 100,000 people
> Total cases in 2019: 971 (527 confirmed, 444 probable)
> Worst year in last decade: 2018; 62.5 confirmed cases per 100,000 people
> Physically active adults: 76.5% (18th lowest)
> Uninsured rate: 4.1% (3rd lowest)

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.

Source: HaizhanZheng / E+ via Getty Images

4. Pennsylvania
> Avg. new Lyme disease cases per year: 62.3 confirmed cases per 100,000 people
> Total cases in 2019: 8,998 (6,763 confirmed, 2,235 probable)
> Worst year in last decade: 2017; 72.2 confirmed cases per 100,000 people
> Physically active adults: 78.0% (23rd highest)
> Uninsured rate: 5.8% (10th lowest)

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.

Source: DenisTangneyJr / Getty Images

3. New Hampshire
> Avg. new Lyme disease cases per year: 73.6 confirmed cases per 100,000 people
> Total cases in 2019: 1,710 (1,106 confirmed, 604 probable)
> Worst year in last decade: 2013; 100.0 confirmed cases per 100,000 people
> Physically active adults: 79.2% (17th highest)
> Uninsured rate: 6.3% (14th lowest)

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.

Source: Sean Pavone / Getty Images

2. Vermont
> Avg. new Lyme disease cases per year: 90.8 confirmed cases per 100,000 people
> Total cases in 2019: 1,064 (706 confirmed, 358 probable)
> Worst year in last decade: 2019; 113.1 confirmed cases per 100,000 people
> Physically active adults: 81.6% (7th highest)
> Uninsured rate: 4.5% (5th lowest)

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.