Researchers Link Sudden Meat Allergies to Tick Bites

Life for Linda Quinn, 61, and her husband was idyllic except in one respect. After leaving the Washington, DC, suburbs and settling in rural Farmville, Virginia, she started experiencing frightening episodes doctors assumed were linked to one or more allergies they couldn't identify. Quinn eventually became part of a group of patients studied to determine the link between tick bites and sudden meat allergies, according to AARP.

After Quinn moved to rural Virginia, she discovered she was a magnet for the ticks that ignored her husband. At one point, she suspected an allergy to hay or mold in their barn.

Doctors repeatedly treated her on an emergency basis with epinephrine and Benadryl, then sent her home once her symptoms retreated. She was advised to carry an EpiPen all the time. She finally learned what was causing her sudden difficulty breathing, dizziness and low blood pressure after a referral to the allergy clinic at the University of Virginia.

The Virginia Study

Thomas Platts-Mills, M.D., heads the University of Virginia (UVA) allergy clinic in Charlottesville. His initial tests showed Quinn had a very rare allergy to beef, pork and lamb. Platts-Mills then determined his patient ate meat every day and had also developed reactions to recent tick bites.

Quinn agreed to become a patient in a UVA study of the possible trigger between a reaction to a tick bite and sudden meat allergies. Results thus far suggest that seed tick bites can create major health risks for people with specific blood types. The term seed ticks includes the larval form of ticks as opposed to adults. Researchers believe all types of ticks can cause the problem.

The initial study included 24 adults. Researchers subsequently followed 100 other individuals. The results appeared in 2009. They suggested that in affected patients, individuals previously bitten by seed ticks developed anaphylactic shock three to six hours after they ate beef, pork or lamb.

Initial itching turned into hives, followed by intestinal irritation and life-threatening symptoms such as a wild heartbeat, a quick drop in blood pressure, airway constriction and losing consciousness.

The researchers were able to identify one cause as the sugar known as alpha-gal in the blood of all the patients they studied. The delayed allergic response was triggered by an IgE antibody that binds to alpha-gal. This contradicted the belief that such sugars never cause allergic reactions.

The team also discovered that 80 percent of their initial subjects reported having been bitten by ticks either weeks or months prior to allergy symptoms. Considering all the patients they followed, the group swelled to 90 percent. They concluded there was a link between tick bites and alpha-gal. Their results also suggested that patients with Type B or AB blood were somehow protected from this chain of events.

The UVA study revealed several other surprises. The skin prick test favored by allergists was ineffective in identifying red meat allergy. Subjects only started to experience symptoms as adults. This contradicts the belief that food allergies seldom appear after childhood. While blood samples from cold climates almost never had alpha-gal antibodies, those from Virginia, North Carolina and other Southern states were full of them. Researchers concluded that the warmer areas don't have hard freezes that kill ticks.

The Australia Project

A second study was reported at approximately the same time. Medical News Today indicates that clinical immunologists in Sydney, Australia studied a group of 25 patients. Twenty-four of their subjects had a history of an allergic reaction to red meat and had recently experienced tick bites. Doctors classified 17 of them as suffering from severe bite reactions.

All of the 17 subjects lived in the area of Sydney's northern beaches. This section had been infected by several species of ticks.

Prognosis

The most practical step individuals can take is to avoid exposure to ticks. Patients must avoid meat as well as anything cooked with it. One of Quinn's worst episodes occurred after eating steak fries at dinner. The culprit: cooking them in oil previously used to fry beef.

Sources:

http://www.aarp.org/health/conditions-treatments/info-09-2010/mystery_allergy_strikes_adults.html

http://www.healthsystem.virginia.edu/internet/news/archives09/anaphylaxis.cfm

http://www.medicalnewstoday.com/articles/148583.php