How prevalent is Lyme disease where you live? Find out with this interactive map.

Rashes. Fatigue. Swollen joints.

These are not the ingredients for a happy summer day. But they are the most common symptoms of Lyme disease, a tick-borne illness transmitted by deer ticks that have been infected with the bacteria Borrelia burgdorferi.

Mosquito, flea, and tick-borne illnesses in the United States tripled from 2004 to 2016, according to a new report from the Centers for Disease Control and Prevention. Massachusetts is one of the 14 states where, according to CDC, 95 percent of Lyme disease cases were reported in 2015. Experts estimate that 87,000 people per year in Massachusetts are infected with the bacteria Borrelia burgdorferi, which causes Lyme disease.

Thanks to increasing urban and suburban sprawl, forests are being parceled into smaller pockets of vegetation, said Northeastern University Distinguished Professor of Biology Kim Lewis, who directs Northeastern’s Antimicrobial Discovery Center. Parks and backyards in the suburbs are now the perfect size to sustain mice, but not quite large enough to sustain foxes. That means mice can run rampant with no natural predators to keep their population at bay. And with mice, come ticks.

“The sprawling of suburbia is a fairly recent phenomenon,” Lewis said. “You get more hosts for the ticks, and of course, you get more ticks.”

As the clock ticks closer to summer and the height of tick season approaches, check out our interactive map to see the prevalence of Lyme disease in your state.

The darker the red, the more lyme disease per county
Select year to change the map
Select a county to see Lyme cases in 2016
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Lyme cases per 1 thousand people →
Lyme cases in Massachusetts decline, but other places peak.
Select a state to view its counties
States are in order by total Lyme cases in 2016, from highest to lowest.
Select a county
Counties are ordered alphabetically.
Select a line to highlight
Data sources
Lyme disease data sourced from Centers for Disease Control and Prevention. Population data sourced from United States Census Bureau: County Intercensal Datasets: 2000-2010, County Population Totals and Components of Change: 2010-2016.