In Half of U.S. Counties, Talking Ticks Is a Must for Health

I’ve done it: I’ve just picked my first upward-traveling tick of 2018 off my pants leg. The poppy seed-sized nymphs of black-legged ticks searching for a meal of my blood are as sure a sign of spring as blooming flowers and new leaves on trees. It’s creepy to have things crawling on you, but since ticks can carry diseases like Lyme, they also present a real public health problem. With April as ticks’ springtime debut, I concur with the experts who are saying April should be Lyme Disease Awareness Month, instead of May.

I live in New York State, one of the 37 states where the blacklegged tick is found. In 2015, 95 percent of confirmed Lyme disease cases came from 14 states in the Northeast and upper Midwest. Another 6 western states are home to the western blacklegged tick that can also carry Lyme. The blacklegged tick has seen a population explosion in the eastern United States, doubling the number of counties in which it’s established, in less than 20 years. The number of counties in northeastern and midwestern United States considered “high-risk” for Lyme has increased more than four-fold since the 1990s, and the number of reported cases has tripled.

I’ve had more than one Lyme infection—with the characteristic chills, headache, and bullseye rash—and considered myself quite lucky to know I’d been bitten: I could go get diagnosed and treated with a course of antibiotics. But 20 to 30 percent of people with Lyme infections don’t develop symptoms, and for them an untreated Lyme infection can develop into much more serious neurological problems.

It’s been estimated that U.S. tickborne Lyme infections may be ten times more common than reported, meaning upwards of 300,000 or more cases each year.

The continuing spread of Lyme disease is due to many factors, including climate change. First there’s contact: warmer temperatures mean that people stay active outdoors longer. And as people build more homes at edges of forests and fields, they come into closer contact with ticks and the warm-blooded animals ticks use as hosts: mice, chipmunks, and deer. Then there’s timing: ticks are active longer over the course of the year if temperatures are milder. One study in Dutchess County, New York showed that springtime now arrives three weeks earlier than it used to 19 years ago—and that the peak questing activity of tick nymphs is also earlier. Projected warming by the 2050s is expected to advance the timing of average nymph activity by another 8–11 days. Tickborne infection risks could come earlier and earlier each year. And there’s geography: warmer temperatures allow ticks to move into new areas or higher altitudes that were once inhospitably cold. A large portion of the United States east of the Rocky Mountains has experienced their warmest average spring temperatures in the past seven years. The westward and northward march of ticks may not be done yet.

Why more Lyme cases in the Northeast? It may be that Northeastern nymphs of the blacklegged tick are bolder and more active in questing—when they seek out one of their three lifetime blood meals.

Ticks can also carry other pathogens, and people can be “co-infected” with more than one tickborne illness. Different tick species can carry a whole range of other serious infectious diseases including anaplasmosis, babesiosis, ehrlichiosis, Powassan disease, Rocky Mountain spotted fever, Colorado tick fever, tularemia, tickborne relapsing fever; and outside the borders of the United States, other tickborne diseases abroad.

What can we do to protect ourselves?

The first thing is to know where you might encounter ticks. These two maps show the range of two ticks that can carry Lyme:

Source: CDC (2015), National Center for Emerging and Zoonotic Infectious Diseases, Division of Vector Borne Diseases

The second thing is to avoid getting bitten. It pays to take these precautions if you visit or live in an area where ticks are found:

  • Avoid thick vegetation and leaf litter in woodlands;
  • Get used to wearing longer socks and pull your socks up over your pants;
  • Wear long sleeves;
  • Use insect repellent;
  • Bathe after hiking, and put your clothes in a dryer on high for 10 minutes (not washer) – ticks don’t like dry heat;
  • Do “tick checks” of you and your pets, especially if they sleep with you;
  • And mainly, start your tick checks earlier in the year. Really. Especially if April (and not May) should be annual Lyme Awareness Month.

Ticks and the illnesses they carry aren’t reason enough to stop enjoying the outdoors. By practicing these precautions, you can keep enjoying the outdoors and all its benefits for your well-being.

About the Authors

Kim Knowlton

Senior Scientist and Deputy Director, Science Center

Join Us

When you sign up you'll become a member of NRDC's Activist Network. We will keep you informed with the latest alerts and progress reports.