In 1906, the word "allergy" was coined by the Viennese pediatrician Clemens von Pirquet in 1906.
Historically, all forms of hypersensitivity were classified as allergies, and all thought to be caused by an improper activation of the antibody class called Immunoglobulin E - Teruka and Kimishige Ishizaka were among the first to isolate and describe IgE in the 1960s.
Later, it became clear that several different disease mechanisms were implicated, with the common link between these varying hypersensitivities being a disordered activation of the immune system in one way or another. A new classification scheme was designed by P. Gell and R. Coombs to reflect what were then rebaptized hypersensitivity reactions.
The word "allergy" was then restricted to type I hypersensitivities, which are caused by the classical IgE mechanism.
Type I hypersensitivity is characterised by excessive activation of mast cells and basophils by IgE, resulting in a systemic inflammatory response that can result in symptoms as benign as a runny nose, to life-threatening anaphylactic shock and death.
Knowing any allergies that a patient may have is important in a clinical setting. Full allergy history is taken down when obtaining a medical history of a patient. This ensures that no contradictory treatments are prescribed to the danger of the patient.
Signs and symptoms
Allergy is a local or systemic inflammatory response to allergens. Local symptoms are:
Nose: swelling of the nasal mucosa (allergic rhinitis)
Eyes: redness and itching of the conjunctiva (allergic conjunctivitis)
Airways: bronchoconstriction, wheezing and dyspnoea, sometimes outright attacks of asthma, in severe cases the airway constricts due to swelling known as anaphylaxis.
Ears: feeling of fullness, possibly pain, and impaired hearing due to the lack of eustachian tube drainage.
Skin: various rashes, such as eczema, hives (urticaria) and contact dermatitis.
Head: while not as common, headaches are seen in some with environmental or chemical allergies.
Systemic allergic response is also called anaphylaxis; multiple systems can be affected including the digestive system, the respiratory system, and the circulatory system. Depending of the rate of severity, it can cause cutaneous reactions, bronchoconstriction, edema, hypotension, coma and even death.
This type of reaction can be triggered suddenly or the onset can be delayed.
The severity of this type of allergic response often requires injections of epinephrine, sometimes through a device known as the Epi-Pen auto-injector. The nature of anaphylaxis is such that the reaction can seemingly be subsiding, but may recur throughout a prolonged period of time.
Diagnosis Information
There are several methods for the diagnosis and assessment of allergies.
Skin testing
For assessing the presence of specific IgE antibodies, allergy skin testing, when possible, is the preferred method in comparison with various in vitro tests.
The typical method of diagnosis and monitoring of Type I Hypersensitivity is skin testing, also known as "scratch testing" and "prick testing" due to the series of pricks and/or scratches made into the patient's skin.
Small amounts of suspected allergens and/or their extracts (pollen, grass, mite proteins, peanut extract, etc.) are introduced to sites on the skin marked with pen or dye (the ink/dye should be carefully selected, lest it cause an allergic response itself). The allergens are either injected intradermally or into small scratchings made into the patient's skin, often with a small plastic device. Common areas for testing include the inside forearm and the back. If the patient is allergic to the substance, then a visible inflammatory reaction will usually occur within 30 minutes.
This response will range from slight reddening of the skin to full-blown hives in extremely sensitive patients.
Considerations with skin test
The skin prick test is the most preferred means of testing because of its simplicity, economic implications and its accuracy relative to the other tests available.
Interpretation of the results of the skin prick test is normally done by allergists on a scale of severity, with +/- meaning borderline allergies, and 4+ being of critical severity.
Theoretical concerns include how to choose patients, interpret results, and maintain safety. If a serious life threatening anaphylactic reaction has brought a pateint in for evaluation, some allergists will prefer a blood test to the skin prick. Skin tests may not be an option if the patient has widespread skin disease or has not avoided antihistamines for several days.
Some people may display a small delayed-type hypersensitivity (DTH) reaction which can occur up 6 hours after application of the allergen and last up to 72 hours but is often easily treated with anti-inflammatory creams.
Blood Testing Information
This kind of testing is also known as a "total IgE count". In order to qualify type I hypersensitivity, this method measures the amount of serum IgE contained within the patient's serum. This can be determined through the use of radiometric and colormetric immunoassays.
Milk Protein Allergy
Lactose Intolerence
Peanut Allergy
Your Baby and Food Allergies
Latex Allergy
My House Is Killing Me! : The Home Guide for Families With Allergies and Asthma
The Parent's Guide to Food Allergies : Clear and Complete Advice from the Experts on Raising Your Food-Allergic Child
Editorial Reviews
Amazon.com....
Few things are scarier than witnessing a child having an allergic reaction, whether it manifests itself as wheezing or life-threatening anaphylaxis. Parents will do anything to avoid having their child suffer such a reaction again, but treading the line between being prepared and being paranoid can be tricky. The Parent's Guide to Food Allergies was written by a team of people who shared their expertise from the medical lab and the kitchen; two M.D.s and one Ph.D. collaborated with author Marianne Barber, the mother of a food-allergic son, who writes with a personal slant so often absent from medical guides. Barber understands the daily coping skills that are needed when living with an allergic child, from banning particular foods entirely to reading ingredient labels.
Especially common allergens like peanuts, wheat, and eggs merit separate chapters, while other foods are treated more generally. Each of the food-specific chapters includes a list of ways that the ingredients can "hide" in processed foods. Once you learn that milk also goes by hydrolysate, and that one of wheat's many aliases is seitan, you'll realize the importance of careful reading. The chapter titled "Hidden Allergens" expands on this theme, and while Barber does an excellent job of detailing the possible hiding places, she says, "careful labeling is well and good, but it doesn't eliminate the need for a judgment call on your part." There's also a chapter on anaphylaxis, in which the realities of living with Epi-pens and liquid antihistamines are faced in a kind, straightforward manner. A special recipe section includes enjoyable treats for the whole family that are baked with wheat-free flour, milk-free margarine, and applesauce instead of eggs. (The spice cake with fresh fruit is a delicious treat.)
At once gentle and authoritative, Barber's book is an excellent guide through the maze of childhood allergies. --Jill Lightner
The Parent's Guide to Food Allergies : Clear and Complete Advice from the Experts on Raising Your Food-Allergic Child
Paralumun New Age Village