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Allergy

26 March 2019

Tick bites more likely to cause red meat allergy than thought

When people develop an allergic immune response to alpha-gal, found in non-human mammal blood, it can lead to a red meat allergy.

Certain tick bites can cause a red meat allergy, and now scientists are shedding new light on the condition, known as alpha-gal syndrome.

Alpha-gal is a sugar found in most mammal blood, but not in humans.

Risk higher than anticipated

"Our original hypothesis was that humans developed the allergy after being exposed to alpha-gal through a tick that had fed on a deer, dog or other small mammal that has alpha-gal," said researcher Scott Commins.

When people develop an allergic immune response to alpha-gal, it can lead to a red meat allergy, explained Commins, who is an associate professor of medicine at the University of North Carolina School of Medicine in Chapel Hill.

"This new data suggests that ticks can induce this immune response without requiring the mammal blood meal, which likely means the risk of each bite potentially leading to the allergy is higher than we anticipated," he said in a university news release.

In this study, scientists did a series of laboratory experiments with human immune cells and saliva from four species of ticks: Lone Star, deer, Gulf Coast and American dog. Some had fed on blood containing alpha-gal; others had not.

No treatment for alpha-gal syndrome

As expected, saliva from Lone Star and deer ticks that had recently fed on blood containing alpha-gal caused an immune cell reaction. But saliva from ticks that had not recently fed on blood also triggered a reaction, the findings showed.

"These results suggest that more tick bites than we initially suspected could pose a risk for developing red meat allergy," Commins said.

However, no saliva from the Gulf Coast or the American dog ticks caused a reaction, according to the report.

The study was presented at an American Academy of Allergy, Asthma and Immunology meeting, in San Francisco. Research presented at meetings should be considered preliminary until published in a peer-reviewed journal.

There is no treatment for alpha-gal syndrome, other than avoiding foods and products that cause a reaction, the researchers noted.

Image credit: iStock

 

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Dr Morris is the Principal Allergist at the Cape Town and Johannesburg Allergy Clinics with postgraduate diplomas in Allergology, Dermatology, Paediatrics and Family Medicine dealing with both adult and childhood allergies.

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