Tick bite triggers life-threatening allergy, changing diet for Finnish woman

Merit Kuusniemi experienced a life-threatening anaphylactic shock during a car trip, initially suspecting a mosquito bite due to itching on her neck. The reaction quickly spread, causing hives on her neck, shoulders, and back, and a strange sensation in her throat. She drove to Jorvi hospital's emergency room, where medical staff prioritized her condition.

Months later, in January 2022, Kuusniemi received a diagnosis of alpha-gal allergy. She suspects her symptoms may have begun as early as 2015, with severe digestive issues that doctors couldn't explain through endoscopies or imaging. A new symptom emerged in January 2019 when she woke up with hives in Lapland after eating game meat. At the time, she didn't connect the reaction to food or the numerous tick bites she had received over the years.

Kuusniemi believes she contracted the allergy in Suvisaaristo, an area where she spent significant time after returning to Finland from the United States in 2014. The vicinity of her holiday home had many ticks, and she recalls finding up to ten attached to her skin during the summer. She doesn't recall finding ticks anywhere else.

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I can't say exactly when and which tick bit me.

The allergy is caused by a sugar molecule called alpha-gal, found in the saliva of certain tick species. A tick bite can sensitize the immune system to alpha-gal. When the body encounters this molecule again, the immune system can trigger an allergic reaction. Alpha-gal is present in the tissues of many mammals but not humans. While often called a meat allergy, reactions can occur from beef, pork, or lamb, and also from other mammal-derived products like dairy and gelatin.

"There has been no study in Finland measuring alpha-gal allergy antibodies in the population and then investigating the symptoms of those who tested positive," says specialist physician Johanna Mandelin from HUS Skin and Allergy Hospital. "Therefore, we do not know how common alpha-gal sensitization is in Finland." At HUS, alpha-gal has been studied for years in connection with unexplained allergic reactions and abdominal pain, with a few dozen patients identified.

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There has been no study in Finland measuring alpha-gal allergy antibodies in the population and then investigating the symptoms of those who tested positive. Therefore, we do not know how common alpha-gal sensitization is in Finland.