June 2, 2014
Health Insights Articles
Tick-borne illnesses are increasing on Eastern Long Island. From
Lyme disease to Rocky Mountain Spotted Fever, from erlichiosis to babesiosis,
just about every resident of the Hamptons can share a story about an ailment
they have experienced as the result of a tick bite. Now there is another
adverse reaction to tick bites that can be added to the list: meat allergy.
Erin McGintee, MD
In February 2009, researchers at the University of Virginia
identified this novel allergy to mammalian meat. Patients develop allergic
reactions 3-6 hours after ingestion of mammalian meat, such as beef, pork, or
lamb. Poultry, fish, and shellfish do not trigger allergic reactions in these
patients. The responsible allergen for this reaction has been identified as
galactose-α-1,3-galactose (nicknamed α-gal), which is a blood group
carbohydrate (sugar) present in all non-primate mammals.
The α-gal allergy differs from most other food allergies in
several important ways. First, the allergy develops in response to a
carbohydrate allergen, whereas the vast majority of other food allergies are in
response to a protein. Second, the reaction is delayed by 3-6 hours. Most food
allergies occur within minutes of food ingestion, and almost universally will
occur within 2 hours. Third, patients
who develop this allergy have previously been able to tolerate meat without
issue, while most other food allergies present early in life. These unexpected findings
raised a question for researchers: What is triggering the development of this
It is not yet known what predisposes some patients to
develop the α-gal allergy. The Lonestar tick is an aggressive species, and in
indigenous areas, tick bites are a frequent occurrence. It is clear that α-gal allergy is more likely
to develop in patients who have sustained multiple bites. In my experience,
α-gal allergy is more commonly seen in patients with jobs or hobbies that
increase their risk of tick exposure.
Patients with the allergy often spend time hiking or mountain biking,
hunting, landscaping, or gardening.
Additionally, patients who develop the allergy tend to experience local
reactions to Lonestar tick bites that persist for weeks or even longer.
Patients with α-gal allergy can present with symptoms
ranging from generalized hives, swelling, and itching, to anaphylaxis, which is
a multi-system allergic reaction that, in severe cases, can lead to death. Due to the fact that reactions to α-gal occur
3-6 hours after meat ingestion, the classic patient gives a history of
awakening in the middle of the night with severe itching, redness, and hives
over their entire body. Patients with more
severe episodes may also describe abdominal cramping, vomiting, diarrhea,
wheezing, shortness of breath, or even loss of consciousness.
The patients invariably give a history of ingesting
mammalian meat several hours prior to the reaction. Reactions do not necessarily occur each time
a patient ingests meat. Reactions are
more likely to occur when a large quantity of meat is consumed. Meats that are higher in fat are more likely
to trigger a reaction than leaner cuts. Gelatin, which is usually derived from
beef or pork, contains α-gal, and there have been cases of patients
experiencing clinical symptoms after gelatin ingestion.
There is some suspicion that certain blood types predispose
a patient to develop the allergy, but research has not shown any correlation
between a specific blood type and development of the allergy. In my own case studies, I have identified two
sets of first cousins with the allergy, and a father and daughter who both have
allergy to α-gal. This suggests that
there could be some sort of genetic predisposition for development of the allergy.
Most of the α-gal cases reported in the medical literature came
from southeastern states. However, the Lonestar tick has become ubiquitous on
the East End of Long Island, and so it serves to follow that cases of α-gal
allergy are on the rise. To date, I have
identified over 180 patients with this food allergy.
The Hamptons are unique in that, while they are clearly
becoming a hotspot for α-gal allergy, they are also a hotspot for tourists and
visitors from all over the New York Tri-State area. For this reason, I would
expect to see an increase in the incidence of α-gal allergy throughout the
entire region. Any patient with a history of possible tick exposure, who is now
experiencing unexplained allergic reactions, should seek out consultation with an
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Erin McGintee, MD
Commins SP, Satinover SM, Hosen J, et al. Delayed
anaphylaxis, angioedema, or urticaria after consumption of red meat in patients
with IgE antibodies specific for galactose-α-1,3-galactose. J Allergy Clin
Commins SP, James HR, Kelly LA, et al. The relevance of tick
bites to the production of IgE antibodies to the mammalian oligosaccharide
galactose-α-1,3-galactose. J Allergy Clin Immunol. 2011; 127(5):