Allergy Testing and Immunotherapy
The Bottom Line
Allergy problems are extremely prevalent in the United States. The American Academy of Otolaryngic Allergy (AAOA) estimates that allergies significantly affect about 50 million Americans, and allergies represent some of the most common types of chronic illness in the US. Allergy issues can range from seasonal allergies, such as allergic reactions to certain types of pollen, to environmental allergies like problems with pet dander and dust mites. Allergic responses to insect stings, like bee venom, can also be severe and even life-threatening.
Types of Allergies
There are several common types of allergies, classified according to the kind of allergen or substance that triggers the allergy. These allergy types include:
Seasonal allergies – This type of allergy is triggered by exposure to pollen. As the name implies, seasonal allergies are usually limited to one or two seasons of the year. For example, ragweed pollen is a frequent cause of seasonal fall allergies, and pollen from trees is often the source of spring and seasonal summer allergies. Seasonal allergies are usually minimized in the winter due to low pollen counts.
Mold allergies – Many species of mold can trigger allergies. These species include Penicillium, Aspergillus, and Alternaria. While it is possible to suffer mold allergies from outdoor exposure, most mold allergy cases occur from indoor exposure due to a higher concentration of mold spores.
Insect allergies – Insect stings can be painful and annoying for anyone, but around 5 – 7.5% of the population suffers from allergic reactions to bee, wasp, yellow jacket, and other insect stings. The severity of reactions ranges from intense swelling and discomfort near the site of the sting to difficulty breathing, which may lead to death without immediate treatment.
Food allergies – Allergies to certain foods have increased in recent decades. The most common foods that cause allergic reactions include cow’s milk, shellfish, tree nuts, peanuts, and eggs.
Latex allergies – Latex is a type of rubber frequently used in healthcare. Latex allergies are most common in healthcare workers who experience frequent exposure to latex gloves and other latex products.
Environmental allergies – This is a broad group of allergies that can include mold allergies as well as allergies to animal dander, dust mites, and other irritants.
Allergy symptoms vary according to the type of allergy. A runny nose, watery and red eyes, sneezing, coughing, and congestion are the hallmarks of seasonal, mold, and environmental allergies. If allowed to continue, these symptoms may worsen into a case of sinusitis or bronchitis.
An allergic reaction to certain foods usually manifests as stomach upset, diarrhea, and nausea and vomiting. In addition to these gastrointestinal symptoms, food allergies can cause hives, itching of the mouth and skin, and facial and throat swelling. A latex allergy also causes a localized reaction of hives and itching along with swelling and sometimes a runny nose.
An allergic reaction to an insect sting will cause swelling at the site of the sting and may also cause swelling in other parts of the body. Insect allergies may also result in hives, flushing, redness of the skin, and anaphylaxis.
In certain individuals, food, insect, and latex allergies can lead to a condition called anaphylaxis. Anaphylaxis is potentially life-threatening and constitutes an extreme medical emergency. Characteristics of anaphylaxis include swelling of the throat and face, skin reactions like hives and flushing, difficulty breathing, fainting and dizziness, low blood pressure, and a rapid pulse. Anaphylaxis requires an immediate injection of epinephrine, also called adrenaline, and professional medical attention.
What Causes Allergies?
An inappropriate immune response is the source of allergy symptoms. Specifically, a foreign substance like wasp venom or pollen triggers the immune system. The immune system identifies this foreign substance as an invasive microorganism like bacteria or a virus. In turn, the immune system produces antibodies and other factors that cause inflammation.
In reality, allergens do not pose a major threat to the body. It is the immune system’s overblown response to allergens that causes allergy symptoms from a mildly runny nose to deadly anaphylaxis.
Allergies can strike anyone. However, there are a few risk factors that can make an individual more likely to experience allergies.
Family history – A family history of allergies or related conditions such as hives, asthma, and eczema may increase the likelihood of allergy problems.
Age – Children are more likely to experience allergies than adults. Sometimes children will “grow out” of childhood allergies as they mature.
Frequent exposure – Repeated and prolonged exposure to certain allergens can cause allergies to develop. For example, healthcare workers who often wear latex gloves may develop a latex allergy. Similarly, beekeepers have a higher rate of bee sting allergies than the general population.
Once allergies surface, avoidance of allergens is among the most effective measures to prevent allergy symptoms. For instance, being careful concerning a diet is important for those with food allergies. Likewise, wearing good quality filter masks when doing yard work and taking measures to limit exposure to outside air may help significantly with seasonal allergies.
Lifestyle changes are sometimes necessary to control allergies. Those with allergies to cat dander may need to consider a different choice of pet, for example. Also, latex allergy triggers can be avoided by switching to a different material, like nitrile protective gloves.
Of course, avoidance is not always possible. Those with severe allergies need to be prepared. Individuals who suffer from severe allergic reactions should always carry an epinephrine delivery device (brand names include EpiPen and Adrenaclick) and a medical identification alert. They should also ensure that those close to them are aware of their allergy and the symptoms of anaphylaxis. Fortunately, there are also desensitization immunotherapy treatments available for some types of allergies, discussed in the section below.
In the case of mild seasonal or environmental allergies, over-the-counter medications are often sufficient to control symptoms. Effective medications include antihistamines for nasal symptoms and cortisone creams for skin problems. Symptoms of moderate severity may require prescription medications such as corticosteroids.
When allergy symptoms are severe or interfere with daily life and avoidance of triggers is not feasible, allergy testing and immunotherapy can be quite beneficial. Doctors perform allergy testing to identify the specific allergens causing the symptoms. A patient may only know that they develop allergy symptoms during the spring. They may not realize that oak tree pollen is the offending substance. Allergy testing pinpoints the problem while eliminating other potential causes.
Allergy testing can be done in several ways. The modified quantitative testing (MQT) protocol is an allergy diagnostic that is dependable, minimally invasive, and proven safe. This protocol is a combination of skin prick testing and intradermal testing (IDT) that is quite comfortable and causes no pain. Ear, nose, and throat (ENT) specialists use MQT to identify moderate to severe allergies. MQT can be performed safely in-office and does not require a hospital visit.
Blood testing for allergies, called RAST, may be an option for individuals who have severe skin conditions, take medications that interfere with MQT testing, or are otherwise not good candidates for the MQT protocol. RAST testing involves a simple blood draw. The blood sample is analyzed in a laboratory, and the results are provided to the ENT physician.
Immunotherapy, commonly called allergy shots, can often be done when more conservative measures like allergen avoidance and medications have failed. Immunotherapy involves injecting minute amounts of an allergen to desensitize the immune system to that allergen.
Only certain types of allergies respond to immunotherapy. Unfortunately, food allergies and latex allergies cannot currently be controlled through immunotherapy. However, insect, environmental, and seasonal allergies often show good responses to immunotherapy treatments. For instance, about 85% of people experience excellent results from immunotherapy for hayfever (allergic rhinitis).
In immunotherapy, the ENT creates a customized vial for each patient. The vial contains a mixture of allergens to which testing has demonstrated the patient has a sensitivity. The patient receives an injection each week, gradually advancing the dose at a safe rate. Over time, this treatment will cause the immune system to create antibodies to the offending allergens. Ultimately, immunotherapy will result in immunity to the offending allergen, and the patient will have no symptoms when they are around the allergen.
Typically, in our practice, we perform a four-month trial of immunotherapy, and if there is a significant reduction in symptoms, we will continue with the full course of immunotherapy. The course consists of injections weekly for the first year, twice monthly for the second year, and monthly for the last year. Over-the-counter and prescription allergy medications only help to mask the symptoms of allergies. Immunotherapy is the only method of actually eliminating symptoms by acclimating the body to allergens and stimulating antibody production.
Immunotherapy through desensitization injections can allow allergy sufferers to experience a greatly improved quality of life. Often, they are able to enjoy the outdoors again and are no longer limited by their symptoms. In the case of insect allergies, immunotherapy can even be potentially lifesaving.