Beware hikers, turkey hunters, and other brush-country and wilderness travelers: Black-legged tick season is here, and the tiny bloodsuckers are looking for a host.
“It’s that time of year,” said Dave Neitzel, supervisor of the vectorborne disease unit at the Minnesota Department of Health in St. Paul. “The bottom line is this: If you’re in a woodsy, brushy area, you’re at risk.”
And maybe never more so: Minnesota has seen a dramatic increase in the number of counties reporting established tick populations.
Commonly referred to as deer ticks, black-legged ticks might be tiny, but they pack a significant bite. They carry and transmit Lyme disease, which manifests with several symptoms from extreme fatigue to fever to muscle aches. Transmission of Lyme disease, which has no vaccination and is treated with antibiotics, is often marked at the spot of the bite with a small bull’s-eye rash. Protecting public health, Neitzel said, hinges on minimizing encounters with infected ticks. “Minnesotans are active and like to get out in the woods, especially in spring after a long winter,” he said. “But precautions need to be taken.”
More than 300,000 people are diagnosed with Lyme disease each year in the United States, a number that has increased steadily since the tick-borne illness was discovered in the 1970s. That’s because black-legged tick infestations across the country, including Minnesota, have spiked in recent years. In 2015, for example, 45 of Minnesota’s 87 counties reported established black-legged tick populations (a previous study from 1996 showed only nine).
A recently released federal study by the Centers of Disease Control and Prevention (CDC) compared tick infestations data tallied in 1996 and 2015. Last year across the nation, black-legged ticks were documented in 1,531, or 49 percent, of counties in 43 states. In the 1996 study, 1,058 counties in 41 states reported the presence of deer ticks.
As deer tick populations have spread, Neitzel said, incidences of Lyme disease have increased. In Minnesota, the median number of Lyme disease cases each year from 1996 to 2005 was 464, according to the Minnesota Department of Health. From 2006 to 2014, the median rose to 1,065. Lyme disease information for 2015 is not yet available.
“Lyme disease cases can fluctuate from year to year based on weather conditions,” said Neitzel. “When it’s drier, deer ticks are less active. In warmer years with more humidity, ticks are more active and looking for hosts.”
What’s the best way to prevent deer-tick exposure? Neitzel said there are three factors for outdoor travelers to consider and understand:
The “when” part
Black-legged ticks have three life-cycle stages: larva, nymph and adult. Neitzel said they’re most active during the nymph, or immature, stage, which runs from about mid-May to mid-July. “That’s the highest-risk time of year,” said Neitzel, adding that adult ticks are active now and can transmit Lyme disease.”
People can start to show Lyme disease symptoms during any month of the year. However, mid-May through mid-July is when most people are bitten and infected by ticks. The rest are infected in early spring and in the fall when the adult ticks are most prevalent. A deer tick nymph is about the size of a poppy seed — difficult to detect. “They’re very hard to spot, that’s for sure,” Neitzel said.
The “where” part
Neitzel said black-legged ticks live in wooded, brushy areas that provide food and cover for white-footed mice, deer and other mammals. Such habitat provides the humidity deer ticks need to survive and thrive. “This is the heart of risk area,” said Neitzel. The ticks search for hosts from the tips of low-lying vegetation and shrubs, not from trees. “Deer ticks don’t jump or fly — they typically grab onto people when they brush against vegetation and then crawl up to find a place to bite,” said Neitzel. “That’s why I tell people when they’re hiking to stay in the middle of the trail. That will decrease your risk to exposure.”
The “final” part
If you’re working or playing in tick-infested areas, Neitzel said take precautions. Use a “good” repellent on skin and clothing.
Neitzel recommended DEET-based products containing no more than 30 percent DEET, the most common active ingredient in insect repellent. Do not use DEET on infants under 2 months. Products containing permethrin, which are used on clothing and should not be applied to skin, are especially recommended for people who spend a lot of time in tick habitat. “Permethrin lasts a long time and kills ticks on the treated surface,” Neitzel said. He said to follow label instructions for each repellent to the letter. To detect ticks more easily and reduce exposure, Neitzel said to wear light-colored, long-sleeved shirts and long pants. “You can create a tick barrier by tucking your pants into the top of your socks or boots,” he said. “Deer ticks are very good at finding exposed skin. They don’t have eyes, but they do have great sensory organs.”
Lastly, if you find an embedded deer tick, remove it immediately, Neitzel said. If possible, use a pair of tweezers to grasp the tick’s head close to the skin. Pull the tick outward slowly, gently and steadily. Apply antiseptic on the bite. See a doctor if you’ve been bit or exhibit systems of Lyme disease.
“You can never be too careful,” Neitzel said.