Food Allergy

As a child I had battled allergies, specifically food allergies, that childhood experience was itchy, painful and terrible. All through my childhood, I did not understand the disease and failed to manage it properly. I grow up with a belief it was my fault and deserved the discomfort. My ignorance, indignity and shame had been a useful tool my parents utilized to keep me in check and controlled. There is no permanent physical damage, but emotional and psychological scars, manifested with self-esteem, confidence and autonomy issues. Learning from that mistake I would like to share tidbits about allergy with initial focus on food allergy.

Allergy

Allergy is the most common form of immunologic disease. It is defined as an altered and/or exaggerated immune reaction to foreign substances or physical agents, also known as antigen (allergen), causing tissue inflammation, that leads to organ dysfunction.  Colloquially, it implies that an individual become over reactive to an antigen which would not normally produce an adverse response.

Classification 

Allergy or allergic diseases can be classified according to (1) immune system mechanism, (2) affected organs, and (3) the nature and source of allergen, example route of exposure.  The last classification makes the diagnosis or identification and management of allergy more convenient. The 4 routes of exposure are inhalants (pollens), injectants (bee sting), contactants (nickel in jewelries), and ingestants (food and medicine).

Food Allergy

The rise in prevalence of allergic disease has continued in the industrialized world for more than 5 decades. Allergic conditions are the most common health issues that affect children. In addition, children have food allergies more than adults.

Pathological Mechanism

Immune system induced inflammation involves two major pathways,  the reaction of the (1) antigen with T cells and (2)  with B cell products, which is also known as antibodies. Of the five classes of antibodies, only three: IgG, IgM and IgE, are known to be involved in hypersensitivity reactions. For most food allergy involves IgE antibodies, as it occupies receptors sites of mast cells, then within minutes after exposure to the allergen, vascular activity and inflammatory mediators are activated causing vasodilation (skin rashes, , itchy nose and eyes, nausea, vomiting), visceral smooth muscle contraction (cramp, bloating, diarrhea), and mucus secretary gland stimulation (sneezing wheezing, coughing). Other mediators have late-phase inflammatory response that appears several hours later.   

Food allergens cause two clinical sub-groups of IgE-mediated allergy: atopy and anaphylaxis. Atopy denotes a group of disease, namely, allergic rhinitis, allergic asthma, atopic dermatitis and allergic gastroenterophy. This happen in certain persons with an inherited tendency to develop IgE antibodies to multiple common environmental allergens. The reaction maybe localized to the target organ, but more than one of diseases may occur simultaneously. While anaphylaxis, a fatal condition that warrant medical emergency, is characterized by hypotension or shock, bronchospasm, gastrointestinal and uterine  muscle contraction, urticaria (hives) and angioedema. The most common allergens that trigger this deadly disease are drugs, insect venom and foods.

Diagnosis

Almost all of the symptoms of allergy can occur in the absence of an immunological mechanism. For example, Inhalation of dusts and fumes trigger an non-allergic asthma attack. Therefore, a thorough history is essential, including the symptoms and survey of possible allergens. Aside from physical examination during a period of being expose to allergen, there are allergy tests that reveal an immune response to a particular allergen. There is IgE antibody test, in which IgE antibodies are detected by skin tests or in vitro methods. Another is provocation tests, in which under a controlled conditions, a double-blind placebo-controlled oral challenge is conducted, but this test is not recommended on patients with history of anaphylaxis.

Management

Allergic disease management requires both symptomatic therapy and allergen-specific treatment. The three basic principles of allergic management are avoidance therapy, drug therapy and immunotherapy. And when it comes to health issues always seek professional help, see the proper health care specialist, for allergic diseases please see an allergist or immunologist.

This will be an introduction on future articles on allergy. Is there a health issue you want to talk about? Please share your thoughts, feel free to post your inquiry, violent reaction, suggestion, and/or correction, as it will help create better content. And do not forget to follow this blog for more interesting information and ideas. Thank you!

As always please take care, keep it simple, be real and enjoy!

References

1. Centers for Disease Control and Prevention (CDC). National Center for Health Statistics. (n.d.) FastStats: Allergies and Hay Fever.  Retrieved from https://www.cdc.gov/nchs/fastats/allergies.htm

2. Guyton, A.C. & Hall, J.E. (2006). Textbook of Medical Physiology, 11^th Edition. Philadelphia, Pennsylvania, USA: Elsevier Saunders.

3. American College of Allergy, Asthma, and Immunology. (n.d.). Allergy Facts. [Blog Post]. Retrieved from https://acaai.org/news/facts-statistics/allergies