Tick associated with red meat allergy in humans suspected in lakes country
The tick associated with triggering a rare allergy to red meat in humans has been found in at least two North Dakota counties, but no cases of the allergy are known to state health officials.
The lone star tick was found last year in Dunn County in western North Dakota and in Dickey county in the eastern part of the state, said Laura Cronquist, an epidemiologist for the state Department of Health.
This year, a lone star tick was removed from a dog in Cass County, but the family reported travel to North Carolina in the two weeks before the tick's discovery.
"Unfortunately, we have no way to determine whether the tick was from North Dakota or North Carolina," she said Thursday, July 5.
But no cases of the allergy to red meat, which is not a reportable condition, are known to state health officials, she said.
The rare allergy has afflicted people in the lakes country and north woods of Minnesota, but the tick has not been found.
It appears that the tick, which is found throughout most eastern and southern states, and the allergic response it creates are creeping toward the area.
Cases of allergies to red meat believed to be caused by tick bite were first reported in Minnesota over the last two or three years. The rare allergy is caused when a tick bites a non-primate mammal and acquires a sugar, known as alpha-gal, and then transmits it to a person. In some, the body's immune system produces antibodies, which cause an allergic reaction when the person eats red meat, which also contains the sugar.
A Sanford allergist based in Fargo, who also treats patients at clinics in Detroit Lakes, Bemidji and Thief River Falls in Minnesota, has encountered the rare red meat allergy.
"I've diagnosed a handful of cases," said Dr. Chris Cleveland. "This is a relatively new diagnosis." Although relatively new to parts of the Midwest, the lone star tick is well established in the South and East.
"It is something that's coming up," Cleveland said. "We're finding it more and more often."
Dave Neitzel, supervisor of vector-borne diseases for the Minnesota Department of Health, said the allergy is not a reportable condition, so state officials don't formally track it.
"It's kind of a newly reported condition," he said. "I can't say with any confidence how often these allergies have been reported in Minnesota."
There have been about 50 confirmed cases of the tick-transmitted red meat allergy, which tends to occur in scattered pockets, Neitzel said. "It's always been kind of one here, one there," he said.
A Centers for Disease Control map depicting the approximate range of the lone star tick shows it as a concern in most of Iowa and much of eastern Nebraska, but does not indicate the lone star tick is yet a concern in Minnesota, North Dakota or South Dakota.
Unlike most food allergies, which cause obvious reactions almost immediately, the tick-transmitted red meat allergy causes a reaction hours later. If someone eats a steak dinner at 6 p.m., for instance, the reaction, typically starting as itchy skin, then hives and can escalate to difficulty breathing, might not happen until hours later, when the person is in bed, Cleveland said.
"A classic food allergy happens right away," he said.
People with the allergy to red meat can eat poultry and fish with no problem, but must strictly avoid red meat. Cleveland monitors his patients, having them come in once a year for testing.
If they lack the antibody to alpha-gal, they can try to eat small amounts of red meat to test for a reaction. In some cases, they can return to a normal diet.
But there is always a risk they could get the condition again from another tick bite, Cleveland said.
Meanwhile, the black-legged tick, more commonly called the deer tick, which spreads Lyme disease and other tick-borne diseases, continues to expand its territory in Minnesota, Neitzel said.
The tick recently has been found in the northwest corner of Minnesota, and state health officials plan to look for it in Clay County in 2019 or 2020, he said. But the black-legged tick is found close by, including Becker and Otter Tail counties.
In North Dakota, deer ticks have been found this year in Grant, Grand Forks, Rolette, Walsh, Ranson, Ramsey, Burleigh, Richland, War, Morton, Traill, Steele, Emmons, Towner, Dunn, Pembina and Cass County, Cronquist said.
There have been no deaths from tick-borne diseases in North Dakota the past two years, she said. "There were quite a few hospitalizations, though. I think people are becoming more aware of them and the seriousness of the diseases."