ENT and Allergy Magazine Volume I, Issue VIII - ENT & Allergy ...

13
Any patient with a history of possible tick exposure, who is
now experiencing unexplained allergic reactions, should seek
out consultation...
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. Dairy products do contain
a small amount of α-gal, and patients with this allergy will often
demonstrate IgE antibody for milk, but this is rarely of any
clinical significance. Gelatin, which is usually derived from
beef or pork, does contain α-gal, and there have been cases of
patients experiencing clinical symptoms after gelatin ingestion.
It is not yet known what predisposes some patients to develop
this allergy. The Lonestar Tick is an aggressive species, and
in indigenous areas, tick and chigger 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 tick or chigger bites that persist for weeks or
even longer. Due to the fact that α-gal is a mammalian blood
group carbohydrate, there is some suspicion that certain blood
types predispose a patient to develop the allergy, but thus far
this research has not shown any correlation between a specific
blood type and development of the allergy. In my own case
series, 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.
Due to the fact that there is a 3-6 hour delay in the onset of
symptoms, as well as the fact that meat has historically never
been considered a common allergen, patients often do not
make the connection between meat ingestion and development
of symptoms. Similarly, due to the regional distribution of the
Lonestar Tick, physicians who are not familiar with this allergy
may not consider this diagnosis in patients presenting with acute
attacks of hives or anaphylaxis.
Prick skin testing, the test of choice for diagnosing most IgEmediated
food allergies, is of little use in identifying patients
with allergy to α-gal. If the diagnosis is suspected, there are
both commercial and research labs that are capable of testing a
blood specimen for α-gal-specific IgE. Patients will also typically
have measurable IgE antibodies to mammalian meats, cat, dog,
and milk. As with most food allergy tests, false positive tests
for α-gal allergy do occasionally occur. A positive test is more
likely to correlate with true allergy to α-gal if the amount of IgE
that is specific for α-gal makes up 30% or more of the patient’s
total serum IgE.
Most of the α-gal cases reported in the medical literature came
from southeastern states, with the majority of cases occurring
in Virginia, Arkansas, Tennessee, North Carolina, Missouri, and
Oklahoma. 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 27
patients with this food allergy.
As I have previously discussed, allergy to α-gal tends to be
prevalent only in areas that are heavily populated by the Lonestar
Tick. However, 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
served by our offices. Any patient with a history of possible tick
exposure, who is now experiencing unexplained allergic reactions,
should seek out consultation with one of our experienced
allergists at ENT and Allergy Associates.
References:
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 Immunol. 2009;123:426–33.
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): 1286-93.
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