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Allergies

Introduction/Overview
Types
Causes & Risk Factors
Signs & Symptoms
Medical Tests & Diagnosis Methods/Tools
Treatment Options
Prevention Methods

Introduction/Overview

Allergies and other type of immune hypersensitivities are an important but undesirable side effect of our immune system. These problems occur in people who have a specific allergic tendency. Over 50 million fellow Americans or one in 6 suffer from allergies. Fortunately, very few people experience life threatening allergic conditions. In most allergy sufferers, problems appear to be trivial such as runny nose, sneezing, itchy eyes, sinus problem, rash and skin complaints but these otherwise minor problems can make the allergy sufferers lives quite miserable.

Our immune system, essential for defending our bodies against foreign organisms, produces antibodies and activated white cells to attack invaders like viruses and bacteria. Occasionally, this immune response results in an inappropriate or exaggerated reaction called hypersensitivity.

Hypersensitivity is classified into four types; Types I, II, III and IV. Types I to Type III hypersensitivities are antibody-mediated while Type IV is a cell mediated hypersensitivity. Type II & III are Immunoglobulin G (IgG) mediated while Type I sensitivity is Immunoglobulin E mediated. The term ‘Allergy’ is confined to IgE mediated reactions or Type I hypersensitivity [Levinson, 2004] .

Immunoglobulin E (IgE) is our body’s host defense system against certain parasites such as worms. In developed countries, where parasitic infection is uncommon, most people have no or very low level of IgE. An allergic reaction or allergy occurs when our body’s immune system mistakenly considers a harmless substance, called ‘allergen’ as dangerous and starts producing IgE to trigger an allergic reaction [Levinson, 2004].

Types of Allergies

Allergic Rhinitis: This type of allergy causes swelling of nasal mucosa with respiratory discomforts like sneezing and runny nose by inhaling allergens such as pollen, molds, dust, dander and other allergens.

Allergic Conjunctivitis: The allergic reaction affects the eyes, redness and itching are the signs of this allergy.

Bronchoconstriction: Wheezing and shortness of breath caused by narrowing of bronchial cavities. Asthma is a serious type of bronchoconstriction. This type of allergy is also caused dust, pollen, mites, and other allergens.

Ear Allergies: The allergens affect ear passages causing pain and impairing hearing.

Skin Allergies: Itchy rashes, blisters, hives, and contact dermatitis caused by touching certain substances such a poison ivy or food items are manifestation of this type of allergy. In allergies where swelling occurs as a result of hives, swelling can cause breathing and swallowing difficulties.

Food Allergies: Certain kind of foods, such as fish egg, nuts and milk can cause intestinal upsets due to allergic reactions.

Time Delayed Allergies: An allergic response appearing hours or days after application or absorption of an allergen; including contact dermatitis and bacterial allergy [Allergies, 2006]

Anaphylaxis: This is the most severe systemic allergic reaction causing bronchoconstriction, swelling of body tissues, vomiting, cramps, skin reactions and drop in blood pressure, coma and even death [Guyton & Hall, 2006].

Allergy can also be classified on the basis of its effect and allergen as:

• Respiratory Allergies
• Skin Allergies
• Food Allergies
• Asthma
• Drug Allergies
• Sting Allergies

Causes & Risk Factors

Problems with normal immune responses are believed to be the result of both genetic and environmental factors. Children of allergic parents are more likely to have similar allergies though the allergens may differ. [Allergies, 2006] Genetic research is leading scientists to believe that skin and tissue specific genes may be responsible for causing allergy symptoms [NIH, 2000]. Stress and anxiety are acknowledged a common cause of allergic reaction. [Lenzoff, 1997] subjected patients suspected of multiple chemical sensitivities concluded that in some sufferers allergy symptoms might be triggered by their perception of an environmental insult.

Increasing use of chemicals has resulted in introduction of new toxins into the atmosphere. The increase in number of allergy cases during the last decades is often attributed to atmospheric pollution [Bornehag et al, 2004]. Better identification of problem as allergy and not other minor condition such as cold is perhaps also responsible for increased numbers.

Allergy or Cold
A number of symptoms of common cold are also the symptoms of allergy. It is not unusual to mistake one for the other. The major difference between the cold and flu are [Allergy, 2006b]:

1. Both cold and allergy show the common symptoms of allergy but the cold is also accompanied by fever and pain.
2. Allergy begins immediately after exposure to the allergen while cold takes a day or more to develop to full strength.
3. Cold is a self terminating diseases and the symptoms disappear in 3 to 7 days while allergies continue till the person remains exposed to the allergen

Allergens
The body’s immune system has the capability to attack a foreign organism. If it identifies a substance such as pollen as foreign, even mistakenly, the defense mechanism comes into action and IgE is produced to fight off that particular substance. Thus, there will be separate IgE for pollen and for dust allergies. There are many allergens as any person could be allergic to a common substance, which is not an allergen to others, but the common allergens include pollen and fungus from weeds, grasses. Trees and outdoor mold, dog and cat dander, dust particles, noxious vapors and smog, foods such as fish, eggs, nuts and insect bites.

Signs & Symptoms
In addition to the usual sneezing, runny nose, rashes allergy and red or itchy eyes symptoms include atopic dermatitis, contact dermatitis, headache, earache, hives, coughing, sinusitis, and other discussed above.

Medical Tests & Diagnosis Methods/Tools

The diagnostic tests for Allergy include:

1. Skin Prick Test (SPT)
2. Total IgE Test
3. Range of Specific IgE Test
4. Phadiatop Assay
5. Specific IgE Pediatric Food Mix fx5

Skin Prick Test:
Skin prick test is a common and simple method of diagnosing allergy. In this test small amount of suspected allergens are injected either intra-dermally or into the scratching made in the patient’s skin. Patient allergic to any of the allergen shows a visible inflammation after half an hour.

Skin Prick Test (SPT) only responds to allergens used in the test. In cases where patient is allergic to any other allergen, this test will not show. Some patients with delayed type hypersensitivity may be adversely affected by the test.

Total IgE Test:
Patient serum IgE test is another method used for determining Type I hypersensitivity. The test provides useful indication for allergy. This test however is not considered conclusive. The test measures total IgE value and is said to be only to report existence of allergy 60% of the time [Labspec, 2006]. The extent of symptoms and type of allergy has an effect on the result. Severe skin allergy shows a higher IgE value than rhinitis or conjunctivitis. [Labspec, 2006] also point out that Standard IgE values appear to vary with ethnicity of the patient.

Range of Specific IgE Test:
Some diagnostic suppliers are manufacturing specific IgE test for allergens. Specific tests for over 400 allergens are available. Some of these specific tests have been approved for routine tests, other are awaiting approval. [Labspec, 2006]

Phadiatop Assay:
Instead of testing total IgE or specific test for a single allergen, this test tests serum for a wide range of inhalant allergens. The test is said to be 95% reliable and can be used to exclude allergens included in Phadiatop assay.

Specific IgE Pediatric Food Mix fx5
His test is similar to Phadiatop Assay, but instead of inhalant allergens, ingestant allergens are tested. This test is still in approval stages for general laboratory use.

Treatment Options

Many people with mild allergies avoid seeking medical help, but it is important to know that allergies if left untreated can develop into serious health problems like infections in sinuses, throat and ears, chronic respiratory problems, skin problems such as eczema.

The most common treatment options for allergies include:

1. Avoid allergen environment and/or food
2. Over the counter medication (histamines)
3. Prescription drugs & nasal drops,
4. Allergy shots
5. Allergy Drops
6. Immunotherapy
7. Alternate Therapies

Once a person knows the substance that causes allergy, the best treatment is to avoid that substance. However avoiding allergen is not always possible as it is not possible to breathe. Food allergens can be easily avoided [When Should I Get Medical Treatment for Allergy, 2006] .

In a very large number of cases of mild allergy over the counter medication is all one needs to relieve the symptoms. It is important to consult a doctor for over the counter medicine too, as some of these medicines if used excessively can cause serious side effects. Most of the histamines cause drowsiness.

Antihistamines and decongestants relieve the symptoms of most allergy sufferers. Again, a physician’s advice should be sought. Many new antihistamines relieve the symptoms of allergy without causing drowsiness. In sinus congestion, nasal sprays available on prescription provide quick relief from symptoms of allergy.

Allergy shots prevent the allergen from being recognized as a foreign body. This treatment is becoming very popular. Sublingual drops also known as sublingual Immunotherapy (SLIT) is an alternate to allergy shots and has the same principle of desensitization. Oral application of SLIT is also considered convenient by the patients.

Those interested in alternative medicine often recommend several alternate therapies. Dietary supplements are said to increase health of immune system and prevent allergies. The other alternative medicines are beyond the scope of this paper. [Allergies, 2006a] provides several references to alternative treatment websites.

Anaphylaxis must be considered a medical emergency and immediate medical help must be sought as it can cause low blood pressure, hyper-constriction, coma and even death.

Prevention Methods

The best prevention is to avoid the allergen responsible for causing the allergy. Cross the counter medicine approved by a patients physician may also be used before coming into contact with allergens. In view of the number of sufferers, various equipments such as vacuum cleaners, humidifiers, beddings and air purifiers are available in the market to control domestic allergens. A physician may be able to advice about prevention methods about other specific allergies.

Bibliography

1. Allergies, (2006a), Alternative Allergy Treatment Options, [Online], retrieved from Internet on 10 January 2007, http://allergies.about.com/od/alternatives/Alternative_Allergy_Treatment_Options.htm

2. Allergies, (2006b), [Online], retrieved from Internet on 10 January 2007, http://www.med-help.net/Allergies.html

3. Allergy, (2006), What is Allergy, [Online], retrieved from Internet on 10 January 2007, http://www.setel.com/~allergy/Products/allergy

4. Bornehag C, Sundell J, Weschler C, Sigsgaard T, Lundgren B, Hasselgren M, Hägerhed-Engman L (2004). "The association between asthma and allergic symptoms in children and phthalates in house dust: a nested case-control study.” Environ Health Perspective 112 (14): 1393-7.

5. Guyton, AC, and Hall, JE, (2006), Textbook of Medical Physiology-11th Edition, Published by Elsevier, Pa., ISBN 13-81-8147-920-3

6. LabSpec, Allergy Diagnostic Tests, (2006) [Online], retrieved from Internet on 10 January 2007, http://www.labspec.co.za/diag.htm

7. Levinson, W., (2004), Medical Microbiology & Immunology, 8th Edition, McGraw Hill Companies, ISBN 0-07-143199-3

8. Leznoff. A., (1999), Provocative challenges in patients with multiple chemical sensitivity, J Allergy Clin Immunol 1997 Apr; 99 (4):438-42

9. NIH- National Institute of Health/ National Institute of Allergy and Infectious Diseases (NIAID), (2000), International Team Accelerates Investigation of Immune-Related Genes, [Online], retrieved from Internet on 10 January 2007, http://www3.niaid.nih.gov/news/newsreleases/2000/ihwg.htm

10. When Should I Get Medical Treatment for Allergies?, (2006) [Online], retrieved from Internet on 10 January 2007, http://health.howstuffworks.com/allergy-treatments-ga1.htm