cLYMEate change.

Pennsylvania has led the nation in confirmed cases of Lyme disease for the last decade, according the Centers for Disease Control and Prevention. In fact, in 2018—the last year for which data are avail-able—the incidence of Lyme in the Commonwealth was more than six times that of Connecticut, home to the town for which the tick-borne infection was named.

Illustration: Alexander Lebron

While the numbers are not surprising given that Pennsylvania is a large state both in population and acreage, the steady increase in diagnosed cases every year—and the climate-based explanation for the uptick—has health officials and outdoor enthusiasts concerned.

Since the early 20th century, Pennsylvania has increased in temperature more than 1.8° F. Winter temperatures have risen faster, at a rate of 1.3° F per decade from 1970 to 2000. In addition, annual precipitation has increased about 10 percent during the past century.

Ticks prefer warm weather (above 45°F) and they thrive in areas with at least 85 percent humidity.

“As the climate changes, we have seen a significant increase in the number of ticks in the state, and the diseases those ticks carry,” Pennsylvania Secretary of Health Dr. Rachel Levine said. “Ticks can be found in every county in Pennsylvania, and the warmer winters are causing them to be more active for longer periods of time.”

In fact, the correlation between climate change and the spread of Lyme disease is so significant, that the Environmental Protection Agency monitors the spread of Lyme disease as an indicator of climate change in the U.S.

The state Department of Health offers these tips for preventing Lyme infections:

• Treat clothing and gear with products containing 0.5 per-cent permethrin.

• Check clothing, gear, and pets for ticks after going indoors.

• Shower within two hours of being outdoors.

• Check your entire body for ticks and immediately remove any that you find.