Lyme disease is a debilitating, sometimes deadly infection, transmitted to humans through bites of blacklegged ticks, commonly known as deer ticks. Lyme disease typically induces flu-like symptoms, including sore joints, and headaches. According to Centers for Disease Control and Prevention estimates, 300,000 Americans are infected with Lyme disease each year.

In the last 10 years, Lyme disease has been diagnosed in every state except for Hawaii. However, 96% of all confirmed cases of Lyme were isolated to only 14 states in 2014. 24/7 Wall St. reviewed CDC data on confirmed cases of the disease to determine the worst states in the country for Lyme disease. In Maine, there were 87.9 confirmed cases of Lyme disease for every 100,000 state residents, the most of any state and more than 11 times the nationwide diagnosis rate of 7.9 cases per 100,000 Americans.

In an interview with 24/7 Wall St., Candice Hoffmann, a spokesperson with the CDC, explained that what is now known as Lyme disease “was described in Europe in the early 20th century,” but not identified in the United States until the 1970s. The first known cases in the U.S. were in Lyme, Connecticut when children experienced flu-like symptoms in the summer months. Since then, the disease has been widely studied and diagnosed in nearly every state.

Click here to see the 12 worst for lyme disease.

According to Hoffmann, various types of blacklegged ticks that carry the disease are found in humid areas. In certain parts of the country, such as the Midwest and Northeast, “ticks feed upon small mammals and birds that have the Lyme disease bacteria in their blood” and then “spread the bacteria to humans.”

Given the geographic location of the disease’s namesake, it is perhaps not surprising that Lyme disease cases are most common in New England. All six of the New England states are among the seven worst states in the country for Lyme disease. Other states with the highest incidences of Lyme disease are either Mid-Atlantic or Midwestern states.

Lyme disease is contracted from blacklegged ticks that typically live in wooded areas. “Highly urbanized settings generally are not considered to present high risk of Lyme disease because of the lack of suitable tick habitat,” said Hoffman. By contrast, Lyme-carrying ticks are relatively common in rural areas. As a result, those who spend time in these areas are at greater risk of infection. Maine and Vermont, the two states with the highest infection rates, are also home to the largest share of residents living in rural areas.

However, not every state with the highest Lyme disease incidence are especially rural. People are also likely to come into contact with infected ticks in suburban environments “whether in backyards, public parks, or hiking trails,” Hoffmann said.

The incidence of Lyme disease is on the rise in the United States. Hoffmann noted that due largely to climate change, the geographic regions suitable to ticks are getting larger. While the factors involved are very complex, Hoffmann added this will likely continue in future decades. The diagnosis has rate has gone up by 8% across the U.S. in the last 10 years.

Diagnoses of the disease have spiked even more dramatically in certain states. However, according to Hoffmann, the increases may be due largely to reporting methods. “Surveillance data are subject to each state’s abilities to capture and classify cases, which are dependent upon budget and personnel and varies not only between states, but also from year to year within a given state,” Hoffmann said. Some of these especially dramatic increases may not actually represent a true change in disease incidence.

While the disease is widespread and public awareness is increasing, there is much to be learned about Lyme disease. People are often misdiagnosed as symptoms can vary from patient to patient. For example, while many associate a bull’s eye-shaped rash with the disease, such a rash does not always appear. Even blood tests that check for the presence of antibodies are not always an accurate diagnostic tool. While the disease is often curable with a regimen of antibiotics, in some patients, symptoms can linger for months and even years.

In order to determine the 12 worst states for Lyme disease, 24/7 Wall St. reviewed CDC data on the number of confirmed cases in each state for every 100,000 residents in 2014. States were ranked in order from the lowest incidences to the highest, and only those states with a confirmed infection rate more than double the national rate were ranked. We also reviewed the total number of confirmed cases, along with the incidence rate, for each of the previous 10 years. The number of probable cases in 2014 also came from the CDC. Supplemental data, including the percent of physically active adults, percentage of a population with access to places for physical activity, and the percentage of the population living in rural areas came from County Health Rankings & Roadmaps, a Robert Wood Johnson Foundation and University of Wisconsin Population Health Institute joint program.

These are the worst states for Lyme disease.