A rare red meat allergy, usually linked to a bite from the lone star tick, may also be caused by other tick species found in different parts of the U.S., a new report shows.
“Alpha-gal syndrome is relatively rare, but those who have it can have a full-on anaphylactic shock,” Douglas Norris, a professor of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health, said in a report from NBC News.
The U.S. Centers for Disease Control and Prevention (CDC) estimates nearly 450,000 people in the U.S. have this condition.
Most cases are linked to the lone star tick, which is common in the Southeast and lower Midwest.
But new case reports from Maine and Washington state found two women who developed alpha-gal syndrome after being bitten by ticks in places where lone star ticks aren't common.
This suggests that other types of ticks, like the black-legged tick (also called deer tick) that transmits the bacteria that causes Lyme disease, and the western black-legged tick, may also cause the condition.
“We do believe the lone star tick is still responsible for most of the cases of alpha-gal syndrome in the U.S.,” Dr. Johanna Salzer, a veterinary medical officer and epidemiologist with the CDC’s Division of Vector-Borne Diseases, told NBC News.
In the Washington case, a 61-year-old woman went into anaphylactic shock after eating beef tacos, nearly a month after being bitten by a tick.
Meanwhile, a 45-year-old woman in Maine experienced stomach issues after eating red meat, nine days after removing a deer tick from her arm. Both tested positive for alpha-gal antibodies.
“It’s unique because it’s a delayed reaction, roughly two to eight hours, so you can have a hard time knowing the trigger,” Salzer said, noting that with other IgE allergies, like peanuts or shellfish, the reaction is almost immediate.
Symptoms may include hives, stomach pain, vomiting and swelling of the tongue or throat.
Alpha-gal syndrome was first identified in 2009. It’s caused by an immune response to a sugar found in most nonprimate animals like cows, horses and deer.
“Tick populations in general, and particularly with lone star ticks, are exploding all over the United States,” said Matthew Aliota, an associate professor of veterinary and biomedical sciences at the University of Minnesota. “Lone star ticks are moving into bigger geographic areas, and that range is continuing to expand with climate change.”
Experts say the best way to protect against alpha-gal syndrome is to prevent tick bites: People should use bug spray containing DEET, wear long clothing, and check their body for ticks after being outdoors in tall grass or wooded areas, NBC News reported.
“The most important thing is preventing the tick bite altogether,” Salzer concluded.