(Image credit: Ladislav Kubes via Getty Images)
Previously, scientists believed that a rare and potentially life-threatening meat allergy was transmitted exclusively by one species of tick found in the United States, the lone star tick (Amblyomma americanum). But new evidence about the allergy, known as alpha-gal syndrome, suggests that the more common black-legged tick (Ixodes) may also carry the disease.
According to the Mayo Clinic, while lone star ticks are found primarily in the southern and eastern United States, black-legged ticks (Ixodes scapularis), also known as deer ticks, are found in the eastern United States and the Midwest, and the western black-legged tick (Ixodes pacificus) inhabits the West Coast.
The new case data suggests that people across a wide swath of the U.S. may be at risk for developing tick-borne alpha-gal syndrome. However, “evidence continues to support that in the U.S., most patients with alpha-gal syndrome develop allergies after being bitten by a lone star tick,” Dr. Joanna Salzer, a veterinarian and epidemiologist at the CDC who co-authored two case reports, told Live Science in an email.
Given that alpha-gal syndrome has been linked to multiple tick species outside the United States, scientists have long suspected that deer ticks in the United States may also carry the allergy.
“For us, it was never just a lone tick,” Jennifer Platt, co-founder of the nonprofit Tick-Borne Conditions United and an adjunct professor at the University of North Carolina at Chapel Hill, wrote in a blog post. “Because thousands of Lyme patients tell us they can’t tolerate red meat, we’ve long suspected black-legged ticks and other tick species in the U.S.,” she said.
“While our publications are among the first to link black-legged ticks in the United States to alpha-gal syndrome, bites from these species in the United States that result in the syndrome almost certainly occurred before these publications,” Salzer added.
In alpha-gal syndrome, the immune system overreacts to a sugar known as galactose-α-1,3-galactose, or “alpha-gal” for short. Affected individuals may have severe allergic reactions not only to red meat, but also to certain medications, personal care products, and medical procedures that contain ingredients from mammalian tissues that contain this sugar.
The first case, described in the April 4 issue of the CDC's journal Emerging Infectious Diseases, involves a Maine woman who developed alpha-gal syndrome after a confirmed bite from a deer tick (I. scapularis).
A 45-year-old woman initially experienced inflammation and itching at the bite site, followed by abdominal pain and malaise nine days later after eating rabbit. Over the next two weeks, she continued to experience digestive problems after eating red meat. Severe bouts of diarrhea and vomiting within hours of eating beef prompted her to seek medical attention 20 days after the tick bite. Blood tests showed extremely high levels of alpha-gal-specific immunoglobulin E (IgE), confirming alpha-gal syndrome. Her allergy resolved within 10 months.
The second case of alpha-gal syndrome, described in the same issue of the journal, involved a 61-year-old wildlife biologist from Washington. After a confirmed bite from a western black-legged tick (I. pacificus), she developed a rash and swollen lips, and 29 days later, she had a severe allergic reaction after eating red meat, requiring emergency treatment with epinephrine (EpiPen). After being diagnosed with alpha-gal syndrome, she avoided meat and experienced no further reactions. Several years later, she was bitten by two more I. pacificus ticks, which resulted in elevated IgE antibodies to alpha-gal.
To date, the reasons why tick bites can cause alpha-gal syndrome are not well understood. “We only
Sourse: www.livescience.com
