Trouble from a tiny tick
Health experts are urging people who spend time outdoors to be on the lookout for disease-causing deer ticks this spring.
Formally known as black-legged ticks, the tiny ticks are less than half the size of a common wood tick and are known carriers of Lyme disease, an illness that's become more frequent in Minnesota in recent years but remains relatively uncommon in North Dakota.
Dave Neitzel, an epidemiologist for the Minnesota Department of Health, said Lyme disease cases in the state have increased steadily since the mid-1980s and have averaged about 1,000 cases annually the past three or four years.
The record was 1,239 cases in 2007, he said, and the numbers for 2009 will be out in a couple of weeks.
"What we've noticed over the last few years is that the risk of tick-borne disease is heading farther north and west in Minnesota," Neitzel said.
Why that is, he said, is hard to say for sure.
"We certainly had a string of warmer winters, which may help tick survival," Neitzel said. "But it may be over time, we're detecting the spread, and they've just finally made it into the areas and survived."
Still, he said, deer ticks need wooded country to thrive, and the lay of the land will limit their prevalence in the Red River Valley.
"They're closely tied to wooded and brushy habitat, and there are extensive areas of (northwestern Minnesota) that we'll never see populations of these black-legged ticks," Neitzel said. "The open ag areas, the Red River Valley area there's going to be very little potential."
That likely explains why North Dakota, historically, has documented very few cases of Lyme disease. According to Tracy Miller, senior epidemiologist for the North Dakota Department of Health, the state recorded only 30 to 35 cases, total, in the five or six years before last year. But preliminary numbers indicate the state had 10 to 14 cases of Lyme disease in 2009.
"So, obviously there are some cases," she said. "Not in large numbers but more than we've seen."
Hunting for ticks in N.D.
In an effort to shed more light on what's happening, Miller said the department this summer is conducting a study with student researchers from UND and North Dakota State University to sample ticks in the eastern part of the state.
The study, which will involve students dragging white sheets across test areas and identifying all of the ticks that appear on the sheets, is scheduled to begin sometime next month. The Centers for Disease Control is funding the study, Miller said. Considering North Dakota's proximity to Minnesota, which has high numbers of deer ticks and Lyme disease, the study promises to produce some good information, Miller said.
"We're getting anecdotal reports, but we don't have any good documentation of what ticks are out there that's fairly recent," Miller said. "Several decades ago, there might not have been (deer) ticks, but that's not saying that is the case anymore."
And if the study does produce significant populations of disease-causing ticks, Miller said the department can better inform the public to reduce the risks.
Besides Lyme disease, deer ticks can transmit diseases such as anaplasmosis and babesiosis.
"If we do have the ticks out there, we're going to try to do some testing to see if they're carrying any illness," she said. "This is my first opportunity to work with the colleges, so I'm really excited to get going and get started."
For ticks of any kind, prevention is the best way to minimize the risk. Neitzel of the Minnesota Health Department said the agency recommends repellants containing up to 30 percent DEET or Permethrin. The latter, he said, is for use only on clothing but is very effective at keeping ticks at bay. Permethrin also kills the ticks and remains effective through at least two clothes-washing cycles.
Neitzel said people in tick country should be especially diligent from mid-May through mid-July because the nymph ticks, which are most apt to carry diseases, are out in force. If a deer tick bites, the bulls-eye rash that typically indicates Lyme disease usually appears within three to 30 days.
And if the thought of the ticks makes your skin crawl, imagine being Neitzel, who makes a career of looking for the critters; he said he encounters "several hundred" deer ticks a year.
"It's my job to look for these things, so I know exactly when I get into good tick habitat to start checking pant legs right away," Neitzel said. "I know from experience the nymph stage of the black-legged tick, it's very difficult to even feel them crawling on you.
"But certainly with adult black-legged ticks and regular wood ticks, you can feel those walking on you."
Tales from the outdoor experts
Stuart Bensen, a conservation officer for the Department of Natural Resources who lives just south of Erskine, Minn., knows that feeling well.
"At my farm, there are more deer ticks than dog ticks," Bensen said. Bensen has been bitten and infected by a deer tick. He developed the classic bull's-eye rash behind his knee. Antibiotics took care of the problem.
"It's when you get bit and can't see the rash develop, like in your hair, that's scary," he said.
Bensen's farm contains a trail system he maintains and uses for hunting.
"It's gotten to the point now where I'm reluctant to walk back there in the thicker woods."
He's worn knee-high rubber boots ("ticks don't like rubber") but has switched to high leather boots treated with Permethrin.
The locals in the Erskine area know deer ticks have become common. The pests started showing up 11 years ago.
In 2000 -- a warm winter weather year -- Bensen's cats brought deer ticks into the house every month of the year. He treats his pets with Frontline, a tick repellent. He gets his dog vaccinated every year, too.
"I've poked around the rivers around East Grand Forks and Crookston and haven't found any deer ticks yet," he said.
Still, the little buggers are so small, "they're tough to detect on your clothes, on your skin, in your hair."
The common DNR website map that shows high-risk deer tick habitat in Minnesota is outdated, he said. "They're about 50 miles short there" in the northwest, Bensen said.
Gary Rankin is another law enforcement officer who spends much of his time outside. He's a game warden based in Larimore, N.D. He's unaware of any reports of deer ticks west of the Red River and hasn't heard of anyone who's had Lyme disease. Like Bensen, though, he's experienced being infected and had to be treated with antibiotics. He thinks he picked up the tick while camping in north-central Minnesota.
On the pet front
Even though the Red River Valley isn't in a traditional Lyme disease area, veterinarian Kyle Peterson says his practice is seeing an increasing number of pets who've contracted the disease. Peterson practices in East Grand Forks.
Most of the dogs that have been infected belong to clients who take them east to lake areas, such as Union and Sarah.
Peterson expects to see more Lyme cases in the future as the tick population expands in the state.
Pet owners have a choice to have pets tested for Lyme during the heartworm testing procedure. But there's widespread disagreement in the veterinarian community -- and human medical community -- about how accurate the test is. That's because the test produces a lot of false positives, leaving doctors wondering how to treat those dogs.
Peterson chooses not to administer the tests; other vets do.
One of the better ways of keeping Lyme at bay in pets is by vaccination.
"We vaccinate dogs who are exposed to ticks in general: farm dogs, hunting dogs, especially if you hunt in Minnesota tick country," Peterson said.