Spring, when grass grows and warblers fly and flourish, is people’s favorite. However, in the face of colorful flowers and plants, some people are very upset. They will be allergic to pollen, develop rashes and even have difficulty breathing.
But some allergies are less [hateful], for example-if allergies can reduce weight?
What allergy is so magical?
Over the past 20 years, Australian Dr. Nunen has treated nearly 50 patients with red meat allergy.
All patients showed severe allergic reactions such as urticaria, angioedema, respiratory distress and even shock after eating red meat. These patients could eat red meat before this onset and never had allergic reactions.
The main cause of allergy is ticks, a common small insect in forest areas. Ticks are arthropods (not insects) of the family Ixodes of Arachnida, which can suck the blood of mammals.
Each of us has learned in medical textbooks that ticks are the source of infection for many diseases, but textbooks do not say that allergies can be transmitted…
There are many kinds of ticks causing red meat allergy. In the United States, they are mainly American flower ticks (also known as Lone star ticks) and Ixodes paniculata, and in Europe, Ixodes pectinum. In 2010-2011, two similar cases have been reported in China, both occurring in rural areas of Beijing, and the ticks causing red meat allergy are mainly Haemaphysalis longicornis.
What is the magic of this allergy?
There are three reasons why red meat allergy caused by tick bites is called magical allergy:
(1) The allergen structure is not protein but carbohydrate (-galactose), which is also the only known carbohydrate structure that can induce allergic reaction, while the allergen of common food allergy is mostly protein;
(2) Although the pathogenesis is similar to IgE-mediated type I hypersensitivity, it shows delay and usually occurs 3 ~ 6 hours after eating.
(3) This kind of allergy only occurs after eating red meat, and the allergic reaction is more serious, with acute onset and severe symptoms, often involving multiple systems; Since it often occurs 3-6 hours after eating, if you eat red meat for dinner, it will happen at midnight, which can cause fatal anaphylactic shock in serious cases.
Why is red meat allergy?
Red meat mainly refers to meat that is red before cooking, such as pork, beef, mutton, rabbit, etc. The color of red meat mainly comes from myoglobin in mammalian meat.
-Galactose is mainly found in red meat, including the viscera of such animals and their products. It is not found in poultry and fish. This is also why tick bite allergies only occur after eating red meat.
The mechanism of red meat allergy caused by tick bites is not completely clear. Current studies have found that, Ticks repeatedly absorb the blood of the host for a long time during the growth process, so that the gastrointestinal tract and saliva of ticks contain-galactose. By injecting-galactose after biting the human body, the human body can be induced to produce a large number of-galactose IgE antibodies and bind to high affinity IgE receptors on mast cells and basophils.
When the patient ingests red meat for 3-6 hours, some sugars in the meat begin to be released after digestion of fat particles. The body contacts-galactose again, activating IgE receptor complexes on mast cells and basophils, causing allergies similar to type I allergy.
Besides ticks, be careful of what?
Several similar allergic reactions are equally rare and interesting, and deserve more attention in clinical practice.
Pork-cat syndrome
There is a disease called [pork-cat syndrome], in which patients develop allergic reactions after eating pork, similar to red meat allergy caused by tick bites, but with slightly different principles.
The disease is mainly due to cross-reaction between pork and cat epithelial allergens, and cross-sensitization of beef, pork, pet dandruff and milk allergens.
There is an IgE antibody in the serum of some patients allergic to cat hair, which can bind to the epitope of sugar on cat epithelial IgA, and this sugar is-galactose.
These patients generally have a history of cat hair contact, but the degree of allergic reaction symptoms is not related to the titer of serum-galactose IgE antibody, and there is no history of delayed reaction and tick bite, and there is no reaction when eating mutton and other mammalian meat.
Cetuximab allergy
Since 2005, there have been many cases of severe allergic reactions in tumor patients in the United States after the first injection of cetuximab (human-mouse chimeric monoclonal antibody of epidermal growth factor receptor). Studies have found that mouse-derived carbohydrate-galactose IgE antibody modified by cetuximab segment exists in patients’ bodies in advance.
Epidemiological investigation found that the above cases are also concentrated in the southwestern United States where ticks are born and tick-borne spotted fever occurs. Therefore, it is inferred that this allergic reaction is similar to red meat allergy caused by tick bites.
Milk allergies may also be allergic to red meat
A milk allergy associated with-galactose is also similar to red meat allergy caused by tick bites.
This kind of milk allergy patients will have allergic reactions after eating fresh milk, However, there was no reaction after eating boiled milk. The patient’s whey protein, lactoglobulin and casein specific IgE tests were negative, while the-galactose IgE test was positive. Studies have confirmed that beef and milk allergens have cross reactions, so patients with this milk allergy may suffer from red meat allergy at the same time.
In a word
Like other food allergies, red meat allergy cannot be cured at present and can only be prevented. The most important thing is to avoid eating red meat and viscera. If there is an acute allergy, first aid measures such as epinephrine and antihistamines should be given.
Ticks are mostly distributed and evils are found in forest areas and mountainous areas. Don’t stroll in undeveloped mountain areas and forest areas if you have nothing to do. If you really want to go in the wild, you should take protective measures and bring appropriate protective clothing and insect repellent to avoid bites. When returning home, you should thoroughly check your skin and clothes to remove attached ticks. If pets are kept, parasitic ticks should be regularly checked and killed.