Tick talk - part one
BAXTER — Tick tock.
With one in three blacklegged ticks carrying one or more diseases, the chances of getting bit by an infected tick may be just a matter of time.
“We are seeing more and more cases,” said David Neitzel, epidemiologist, acute disease investigation and control, with the Minnesota Department of Health.
But there are ways to protect from tick illnesses even in the high-risk zone of central Minnesota, which includes Cass, Crow Wing, Morrison, Mille Lacs and Aitkin counties.
Prevention of tick diseases and updates on the prevalence in the lakes area were part of community health panel discussion Monday at the Northland Arboretum.
Neitzel said Crow Wing, Cass and Aitkin counties have been at the center of the high-risk area ever since the state gained knowledge of tick diseases back in the 1980s.
A panel of specialists in health and safety from the state health department, the Department of Natural Resources, Crow Wing County and Essentia Health-St. Joseph’s Medical Center and UrgentCare, participated in the panel. About 120 people packed into the meeting room for the presentation.
Neitzel said Lyme disease is still the most common tick-transmitted disease, but human anaplasmosis is gaining. In 2010, anaplasmosis was the most common tick-borne illness in Crow Wing County. Babesiosis, described as a version of malaria, is less common.
Now among the mix, although more rare, are human ehrlichiosis and Powassan encephalitis (which is compared to the West Nile virus). Both are transmitted by blacklegged ticks or deer ticks. Also rare here is Rocky Mountain spotted fever, one of the few illnesses transmitted by the common wood tick.
But not only are tick diseases increasing, so are the kinds of ticks found here. Neitzel said ticks, such as the lone star tick — recognizable by the white star on its back — which once were localized to the nation’s south, are starting to be found here and seem to be expanding to Minnesota.
Minnesota has 11 species of ticks, some are so single-minded that coming in contact with them would mean holding a fox or being near a fox den. Tick diseases are most commonly reported between May and August, related to the tick’s life cycle and the nymph stage. The small ticks are so difficult to see, people are often bitten by one but never realize it. A nymph may be the size of poppy seed. Immature stages of the blacklegged tick are dark and small. Blacklegged tick larvae are about the size of the period on the end of this sentence. An engorged female is the size of a water melon seed.
Blacklegged ticks, which become infected after feeding on infected hosts such as a white-footed mouse, have no white markings and the adult females have orange backs. Female blacklegged ticks may live two years and lay up to 3,000 eggs. Ticks don’t travel great distances, which Neitzel said is why stepping into an area where the eggs have recently hatched may find a person quickly covered with 200 to 300 ticks.
“So it can be pretty unsettling,” Neitzel said.
He said the ticks don’t have eyes but crawl up out of their home in the leaf litter on the forest floor a few inches, perhaps a foot or so. They crawl up on vegetation and wait for a host to come by. Once a host is detected, by body heat and carbon dioxide, the tick sticks out its legs. If the host is close enough to brush by, the tick clings to clothing and then seeks a place to attach itself, perhaps the back of a person’s knee. Once bitten by an infected tick, a person may begin to feel symptoms in three to 30 days. The diseases can be life-threatening.
Since 1996, there have been steady increases in Lyme disease cases from 200 to 300 per year to 1,200 per year now. Where there may have been a single babesiosis case in a year, now there are 70. “The trend is up in all of our tick-borne diseases,” Neitzel said.
Lyme affects all age groups, while middle-aged people to the elderly appear more likely to get human anaplasmosis or babesiosis. Neitzel, based out of St. Paul but a field biologist at heart, has been doing field research for the last few years and watching the numbers of infested ticks.
Studies find if three blacklegged ticks are found on a person, one of the ticks is likely infected.
“That’s a pretty alarming percentage in my mind,” Neitzel said.
Gwen Anderson, registered nurse, Crow Wing County public health manager, said a county risk assessment identified tick diseases as the second highest risk, second only to a tornado. Anderson said the goal is to have people consider applying tick repellent the way they think of sunscreen or seat belts.
Coming Wednesday in the Dispatch look for part two, more information on prevention of tick-borne illnesses, symptoms and when to seek medical assistance. The community health panel is hosting a second presentation from 8:30 a.m. to 10 a.m. Tuesday, July 17, at the Northland Arboretum.