Veterinarians in northern Minnesota say the number of dogs contracting Lyme and other tick-borne diseases has skyrocketed, an increase also seen in humans.
Indeed, it's not just dogs who are becoming sick. The number of Minnesotans who grew ill from tick diseases jumped to record levels last year. Statewide, there were nearly 1,300 cases of Lyme disease. That's up 21 percent from 2009.
Doctors also have seen a dramatic increase in a lesser known tick-borne illness called human anaplasmosis, which affected more than 700 people last year. In the hotspot region of north central Minnesota, anaplasmosis is now more common than Lyme disease.
Reported cases of tick-borne illnesses in Minnesota have increased tenfold since the 1990s.
Deer ticks carrying the disease have been spreading slowly from the eastern United States. Tick-borne diseases appeared in north central Minnesota in about 2005.
Since then, case numbers in dogs have quadrupled, said Eric Thorsgard, a veterinarian at Animal Care Clinic in Bemidji. This time of year, he diagnoses dogs with Lyme disease almost daily.
"It came here fast," Thorsgard said. "The first year we saw Lyme disease, we probably saw 100 cases, and then the next year, 200 cases. We're up there, 300, 400 cases a year that we see."
One of the dogs Thorsgard recently diagnosed is named Suka, a chocolate Labrador that looked healthy but wasn't feeling well. The dog was listless, had been vomiting and had diarrhea.
Suka had Lyme disease last year, and on a recent visit, Thorsgard suspected that she may have picked it up again.
Thorsgard ran tests to check for Lyme disease and two other diseases spread by the black-legged tick, also known as the deer tick -- a small insect about the size of a sesame seed.
After a blood test came back positive for Lyme disease, Thorsgard put the dog on 30 days of antibiotics. He expected her to improve in a few days.
Reported cases of tick-borne illnesses in Minnesota have increased tenfold since the 1990s, and as summer tick season nears its end state officials say this could be another record year.
In Beltrami and Hubbard counties, for example, Lyme disease cases doubled, while cases of anaplasmosis roughly tripled from 2009 to 2010.
The rapid rise of tick-borne illnesses means people are becoming increasingly aware of the importance of prevention, said RaeAnn Mayer, community health manager at St. Joseph's Area Health Services in Park Rapids.
"So it means not only that we're using the tick repellant such as deet, and the clothing that we need when we're outdoors, but also protecting our animals," she said.
There are a variety of reasons tick-borne illnesses are on the rise, said David Neitzel, a Minnesota Department of Health epidemiologist who specializes in tick-borne diseases. Neitzel said deer ticks are spreading, but the number of cases also is rising because there is more awareness among doctors and more effective testing available.
Neitzel said the numbers may also be up because of the way people live in northern Minnesota.
"There's a lot of people who ride their ATVs back way deep in the wooded areas," he said. "Back in the 1970s, nobody did anything like that. It's just one example of a change in behavior, so as people change the way they interact with wooded areas that may increase or decrease the risk of coming into contact with ticks, too."
Scientists also point to climate change as a factor in the spread of tick-borne illnesses. Among them is Bemidji State University biology professor Patrick Guilfoile, who has studied disease-transmitting ticks.
"To the extent that global warming ... might in the future contribute to higher temperatures in our area during the winter, I would expect that it would increase the likelihood of the ticks surviving in northern Minnesota," Guilfoile said. "That may well be responsible, at least in part, for some of their broader distribution in our part of the state."
The highest risk for tick diseases is from mid-May through mid-July. But state health officials warn that deer ticks are active again late in the fall, from mid-September through November.