Two women who mysteriously developed vomiting, diarrhea, difficulty breathing and a life-threatening allergic reaction were found to be suffering from a rare tick-borne illness.
Neither woman, one from Maine and one from Washington, had any history of food allergies but began experiencing reactions after eating red meat.
Taking a patient history revealed both women had been bitten by a tick within the last month and blood testing confirmed they had developed alpha-gal syndrome (AGS).
AGS is triggered when a person is bitten by a tick – most commonly the lone star tick – that carries the alpha-gal sugar. When the tick bites someone it injects the sugar into the person’s body and causes the immune system to develop antibodies that attack it.
Alpha-gal molecules are also found in the meat of most mammals, including pork, beef, venison and other red meats, as well as milk, gelatin or other animal products.
When a person eats these foods, the body detects the alpha-gal and attacks it. This immune response can lead to a life-threatening allergic reaction.
Health officials have said they are not aware of any confirmed deaths from AGS, but have rising concerns over the spread of the condition.
Between 2017 and 2022, the CDC reported about 90,000 suspected cases of AGS – and the number of new suspected cases increased by approximately 15,000 each year. The agency estimates as many as half a million Americans have AGS.
Alpha-gal syndrome (AGS) is triggered when a person is bitten by a tick – most commonly the lone star tick (pictured above) – that carries the alpha-gal sugar.
Cases were predominantly in southern, midwestern and mid-Atlantic regions of the US, but recent testing on human and tick samples suggests millions more Americans could be at risk because the tick that causes AGS is spreading to new geographical areas.
Additionally, it’s been found the condition is increasingly being passed on to humans by new species of ticks.
A new case study from the CDC detailed a 61-year-old woman from Washington state who experienced two allergic reactions – one requiring hospitalization – after bitten by an unknown tick about one to two months earlier.
Her first allergic reaction occurred 29 days after the bite and she developed hives and lip swelling.
After taking an allergy medication her symptoms improved, but a month later, the woman experienced itching in her groin and hives on her back.
Her tongue began to swell and she had difficulty speaking. She called 911 and was rushed to the hospital.
Enroute her symptoms worsened and she experienced difficulty breathing, spreading hives and worsening tongue swelling. Her blood pressure dropped dangerously low and her heartrate sped up.
She was given epinephrine – the typical treatment for allergic reactions – but her symptoms worsened and her throat began to close.
The woman was then given steroids and by the time she arrived at the hospital her condition began to improve.
While she originally reported no significant event preceding either allergic reaction, in later interviews she said about a month before the first episode she had been bitten by a tick and was treated with an antibiotic.
The above map shows where alpha-gal syndrome cases have been reported in the US between 2017 and 2022
Additionally, she revealed she had eaten six beef tacos before the first episode and consumed a pork sausage and ham sandwich before the second episode took place.
Alpha-gal levels are measured in the blood in kilounits per liter (kU/L) to detect AGS. The woman’s blood tests revealed her alpha-gal levels were 27.4 kU/L. Any result over 0.1 kU/L is considered positive for AGS, experts say.
She was advised to stop eating red meat and avoid milk and gelatin. While avoiding the foods she experienced no other allergic reactions and her alpha-gal levels fell to about 7 kU/L.
About three years later in April 2020, however, she was bitten by a western black-legged tick. Three days after the bite her alpha-gal levels were 0.72 kU/L. A month later they rose to 20 kU/L.
Another two years later she was bitten by another western-black-legged tick. Shortly after discovering the bite her alpha-gal levels were 0.89 kU/L. Those rose to 18.8 kU/L four weeks later.
The case report authors credit her vegetarian diet for preventing any dangerous allergic reactions she would have suffered from eating red meat because of her elevated alpha-gal levels.
The second new case study released by the CDC Thursday detailed a 45-year-old woman from Maine who found a deer tick on her arm in May 2022.
The tick was removed and while she was left with slight swelling and redness, the woman experienced no other immediate side effects.
However, about 10 days later, the woman consumed roasted rabbit and about two hours later developed abdominal pain and fatigue that lasted three hours.
Over the next two weeks she had recurrent similar symptoms every time she ate red meat.
About three weeks after the tick bite, she experienced a ‘severe’ episode of diarrhea and vomiting after eating beef, prompting her to go to her doctor.
Blood test results revealed her alpha-gal levels were more than 100 kU/L – greater than the maximum limit of detection.
Doctors advised the woman to avoid pork, beef and lamb. She was able to tolerate small amounts of dairy but foods like ice cream caused nausea and cramping.
Following the avoidance diet, her symptoms resolved but she found two more ticks within two months of the initial episode.
When she tried to eat bacon three months later and steak seven months after that she experienced heartburn.
However, 10 months after her first tick bite, she was able to eat steak and roast beef with no symptoms and she returned to eating red meat.
About a year after her first testing, her alpha-gal levels declined to 16 kU/L and at two years they were 4.6 kU/L.
Authors of both case reports stressed the importance of increased surveillance of AGS and the types of ticks people acquire the condition from as ticks and states that historically have not posed the risk of AGS are increasingly being traced as the source.
