Lyme disease – the most common tick-borne disease in the U.S. – is on the rise. One important part of this trend is the expanding geography of Lyme disease. Once believed to be confined to the Northeastern U.S., Lyme disease has spread into the Upper and Lower Midwest, the West Coast, and the Southern U.S. That means Lyme disease is cropping up in states where it hasn’t been seen – or at least been common – before.
Below, learn about some of the more surprising places you’ll find Lyme disease both inside and outside the U.S. Then read on to learn about why cases of Lyme and other tick-borne diseases are increasing and what you can do to protect yourself.
Where is Lyme disease most common?
The majority of cases of Lyme disease in the U.S. still occur in the Northeast and Upper Midwest. Specifically, most cases are found in the following 15 states, plus Washington D.C.:
- Connecticut
- Delaware
- Maine
- Maryland
- Massachusetts
- Minnesota
- New Hampshire
- New Jersey
- New York
- Pennsylvania
- Rhode Island
- Vermont
- Virginia
- West Virginia
- Wisconsin
However, this doesn’t paint a full picture of the geography of Lyme disease in the U.S. In addition to the high incidence states listed above, it’s well established that Lyme is also present on the West Coast (California, Oregon, and Washington) as well as some Lower Midwest states. In fact, Lyme disease has been found in all 50 states.
As you can see, Lyme disease prevalence is spreading further west and south. Read on to learn where.
7 places you wouldn’t expect to find Lyme (but do)
1. Arizona
According to a 2018 study, Arizona is the number 1 state for increases in Lyme disease cases – followed by two Southern states further down on this list. While most people associate ticks with humid, forested areas like those in the Northeast and mid-Atlantic, this new research confirms that even the arid Southwest isn’t immune to the spread of tick-borne disease.
2. Florida
Florida was the second state listed in the study mentioned above, with a whopping 77% increase in Lyme cases between 2015 and 2017.
3. Georgia
Georgia comes in at number 3 on the list of states with the highest increase in rates of Lyme in the U.S.
4. Ohio
The number of incidences of Lyme disease in this Midwestern state has increased every single year since 2010, when there were 21 confirmed cases. In 2018, there were 243.
5. Texas
Another southwestern state, Texas is probably better known for its wild hog problem than for tick-borne diseases. However, the CDC reports Lyme disease cases in the double digits in the Lone Star State going back to 2009.
6. Alaska
According to CDC data, there has been at least one reported case of Lyme disease in Alaska every year since 2009, hitting a peak in 2013 with 14 confirmed cases. However, it’s suspected that most of these cases were contracted outside the state.
7. Mexico
A 2007 report described four patients with confirmed Lyme disease in Mexico. The patients had never traveled outside of Mexico and had most likely contracted the disease while camping in or visiting forests in Mexico, suggesting that B. burgdorferi – the bacteria that causes Lyme disease – is endemic to the North American country. Recent research has found people infected with not only B. burgdorferi but other Lyme and Tick Borne Relapsing Fever borreliae.
Why are Lyme and other tick-borne diseases spreading?
Experts point to a few reasons for the expansion of Lyme and other tick-borne illnesses in the U.S. and beyond, most of which intersect with each other and with climate change.
Warming temperatures
Rising temperatures associated with climate change mean longer summers and warmer year-round temperatures. This affects Lyme and other tick-borne diseases in several ways:
- Increase in animal reservoirs and tick hosts – Warmer weather makes it easier for animal reservoirs of Lyme borreliae, including but not limited to burgdorferi – such as the white-footed mouse – to survive and spread. Ditto for tick hosts such as deer, which ticks depend on for survival. Greater animal reservoir and host populations means greater tick populations.
- Warmer weather expands tick geography – As temperatures rise, ticks (and their hosts) can survive farther north than before.
- Warmer weather extends tick seasonality – Climate change is creating longer summers, extending the period of time when ticks are most active.
Basically, warming temperatures allow ticks, the animals they depend on, and the animals that spread disease through them to multiply and expand geographically.
Ticks spreading
The number of ticks and tick-borne illnesses in the United States is increasing. No longer is the blacklegged tick, Ixodes scapularis (or Ixodes pacificus on the West Coast), which transmits Lyme disease, the only tick that should be of concern. And no longer do tick-borne illnesses affect only people living in certain areas of the country. The problem is spreading.
Two prime examples of this spread include the new Longhorned tick – which was first found in New Jersey in 2017 in sheep and has spread to 10 states in the East in two years – as well as the Lone Star tick (see map below), which originated in Texas and has spread north and east into New England.
Globalization
People travel more today than ever before. This means they can contract a tick-borne illness in one region before traveling back to their home region and getting a diagnosis. Though tick-borne diseases don’t spread from human to human, it’s important for travelers to remember that it only takes one tick bite to contract a tick-borne disease. Just because you don’t live in a tick-endemic area doesn’t mean you can’t get Lyme disease.
Land use changes
Experts have cited reforestation and suburbanization in the Northeastern U.S. as causes for an increase in physical proximity between ticks, animal hosts, and people. That leads to an increase in overall rates of tick-borne disease.
Other developments to note
It’s not just changes in geography that the public should be aware of. The CDC also notes that researchers are currently uncovering new disease-causing germs as well as new tick species. These developments underscore an ever increasing need for better education, tick prevention, and diagnostic testing for Lyme disease and other tick-borne diseases.
The importance of tick awareness and prevention
Conventional wisdom about ticks – such as that they’re only a risk in heavily forested areas or during the summer months – no longer suffices to keep the public safe. The data shows that Lyme and other tick-borne diseases are a risk to anyone, anywhere, any time of year.
Practice good tick prevention no matter where you live in the U.S., including performing tick checks after outdoor activity – even daily tasks such as gardening or yard work. To learn more, read the Tick Talk blog How to Prevent Lyme Disease & Avoid Tick Bites: A Guide.
And while the risk is much higher in certain regions, you should never ignore Lyme-like symptoms, even if you don’t live in a tick-endemic area. Feel free to use the IGeneX Symptom Checker if you feel you may be at risk of a tick-borne illness, and don’t delay medical treatment.
