When my husband and I hike the woods surrounding our cabin near Bemidji, he strides confidently ahead through brush while I perform all sorts of contortions to avoid branches and fern fronds, and stop every few minutes to check for ticks. Having spent summers at the cabin his whole life, he refuses to acknowledge danger lurking in the forest. His optimism comes at a price. He’s been felled by tick-borne illnesses—including the two most common in Minnesota, Lyme disease and human anaplasmosis—several times and endured days of misery before recovering.
The arachnids I scout for are deer ticks, otherwise known as blacklegged ticks, which are the size of poppy seeds, have no eyes, and attach themselves via nasty barbed drinking spikes (the more-familiar wood tick is several times larger). These minuscule vampires are a growing menace in Minnesota and spread illnesses that often bring the sort of high fever, chills, and headache associated with a bad flu and typically send the afflicted crawling to the doctor for antibiotics. Symptoms have the potential to become quite severe, especially if left untreated. One rare virus can cause brain swelling, seizures, and death.
Last summer, the Centers for Disease Control and Prevention acknowledged it had been dramatically undercounting Lyme cases in the United States and increased its estimate tenfold, to 300,000 annual infections. Minnesota, one of the more heavily affected states outside of New England, officially counts between 1,000 and 1,300 Lyme cases yearly and hundreds more of anaplasmosis. Those numbers represent dramatic increases from a decade ago, yet the real totals are likely much higher.
Rising infection rates concern Dave Neitzel, an epidemiologist and blacklegged-tick expert at the Minnesota
Department of Health. But he’s also alarmed by the new illnesses these ticks carry—and the fact that they are invading new territories. A map of infections reveals a bright swath running directly through Minnesota’s cabin country. “Most troubling to us is we continue to see tick-borne illnesses happening in other parts of the state where we hadn’t seen them before, like in the north and northwest,” he says.
That could be due to rising northern temperatures related to climate change, as well as thriving herds of white-tailed deer, which blacklegged ticks feed on and travel aboard. Generally, ticks pick up diseases from white-footed mice; as adults, in order to reproduce, they attach to large mammals. As someone who has watched her husband curled up on the floor of an urgent-care clinic because he was too sick to sit in a chair—when I see a deer in the woods these days, I don’t think Bambi.
The CDC suggests that tick-borne illnesses should be dealt with more aggressively. But that’s hard to do, given the enemy’s diminutive size and the enormity of its habitat. Mass applications of pesticides are problematic and expensive, and can harm beneficial insects such as bees. And the lone vaccine for humans against Lyme was pulled from the market a decade ago due to weak demand and questionable efficacy.
Hikers have a single course of action, which is to avoid being feasted upon in the first place. The blacklegged tick is most active from May to early July and again from mid-September through November. They desiccate easily—yes, much like vampires—and tend to favor brushy areas. Neitzel recommends using a spray containing the long-lasting pesticide permethrin to thoroughly mist a pair of light-colored pants (not bare skin), preferably tucked unfashionably into white socks; or, DEET can be applied to skin.
In the course of his job, Neitzel picks up hundreds of ticks each summer. “I check my pants every few yards to see if anything is walking up,” he says. He hikes in the same enjoyment-killing way I do. And, like me, he has yet to be infected.