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Washington: Waking up at
midnight with breathing difficulties and in a state of shock could
be due to a severe allergic reaction (delayed anaphylaxis) to red
meat, warn researchers.
Delayed anaphylaxis, triggered by a tick bite, is a new syndrome
identified initially in the southeastern US. Patients may wake up
with hives (urticaria or red rashes that spring up all over the
skin) or anaphylaxis usually three to six hours after having eaten
red meat for dinner. Until recently, the link between red meat and
anaphylaxis had remained elusive.
Significantly, anaphylaxis is the also the first food-induced
severe allergic reaction due to a carbohydrate rather than a
protein. It is also the first time anaphylaxis has been noted to
be delayed rather than occurring immediately after exposure, the
Journal of General Internal Medicine reported.
Susan Wolve and Diane Sun, from Virginia Commonwealth University,
US, and colleagues identified the allergic reaction as being
caused by antibodies to a carbohydrate (alpha-gal), produced in a
patient's blood in response to a tick bite, specifically the Lone
Star tick.
This carbohydrate substance is also present in meat. When an
individual who has been bitten by a tick eats the meat, his or her
immune system activates the release of histamine in response to
the presence of alpha-gal, which can cause hives and anaphylaxis,
according to a university statement.
Histamine is a compound in mammalian tissues that causes
dilatation of capillaries, contraction of smooth muscle, and
stimulation of gastric acid secretion, that is released during
allergic reactions.
The authors concluded: "Where ticks are endemic, clinicians should
be aware of this new syndrome when presented with a case of
anaphylaxis. Current guidance is to counsel patients to avoid all
mammalian meat - beef, pork, lamb and venison."
Respiratory symptoms occur in about 70 percent of reactions, and
are especially common in people who also have asthma or another
chronic respiratory disease. Extremely low blood pressure, causing
light headedness, dizziness, blurred vision, or loss of
consciousness (passing out) occurs in about 30 percent of
reactions.
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