Alpha-gal syndrome (AGS) is a rare, potentially life-threatening allergy caused by a sensitivity to a sugar called galactose-α-1,3-galactose, or alpha-gal. This allergy can lead to severe reactions not just to red meat, but also to some medications and medical products derived from mammalian tissues.
Historically, scientists believed that this allergy was primarily transmitted by bites from the lone star tick (Amblyomma americanum), a species found mainly in the southern and eastern U.S. However, new research indicates that other tick species, such as the black-legged ticks (Ixodes), also play a role in spreading this allergy across a wider geographical range.
Black-Legged Ticks Identified as Potential Alpha-Gal Syndrome Carriers Across U.S. Regions
While the lone star tick had been predominantly linked to AGS in the U.S., case reports now suggest that black-legged ticks, such as the deer tick (Ixodes scapularis) in the eastern U.S. and the western black-legged tick (Ixodes pacificus) on the West Coast, can also trigger the allergy.
These findings indicate that people across a broader region of the U.S. may be at risk of developing alpha-gal syndrome. Despite this, experts, including Dr. Johanna Salzer from the Centers for Disease Control and Prevention (CDC), emphasize that lone star ticks remain the most common source of AGS in the U.S.
Black-Legged Ticks Linked to Alpha-Gal Syndrome, Expanding Risk Beyond Lone Star TickThe discovery that black-legged ticks may also transmit alpha-gal syndrome does not come as a surprise to some researchers. Jennifer Platt, co-founder of Tick-Borne Conditions United, had long suspected that black-legged ticks, alongside other tick species, might be responsible for the rising number of patients who report meat allergies after contracting Lyme disease.
Dr. Salzer noted that the new reports are not necessarily the first instances of AGS linked to these ticks but are likely the earliest documented cases, underlining the importance of continued research.
Case Reports Highlight Tick-Borne Alpha-Gal Syndrome, Underlining Risks and Unknown Mechanisms
Two significant cases of AGS were reported in the CDC journal Emerging Infectious Diseases. In one case, a 45-year-old woman in Maine developed AGS after a black-legged tick bite, experiencing severe digestive issues after eating red meat. Blood tests confirmed an allergy to alpha-gal, which eventually resolved after 10 months.
Another case involved a wildlife biologist in Washington who developed AGS after being bitten by a western black-legged tick, leading to a severe allergic reaction. This case highlighted the potential risks of subsequent tick bites, which could exacerbate the condition by increasing the number of alpha-gal antibodies in the body.
The exact mechanism behind how tick bites trigger alpha-gal syndrome remains unclear, though it is believed that ticks may secrete alpha-gal antigens in their saliva, which causes an immune reaction in humans. These ticks do not transmit the antigens from animals but produce them independently.
More research is needed to understand why certain ticks, like the lone star tick, are more likely to cause AGS than others. Until then, prevention remains the best defense, with experts recommending the use of insect repellents and permethrin-treated clothing when venturing into areas with high tick populations.
