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==Overview==
==Overview==
'''Allergy''' is a disorder of the [[immune system]] that is often called [[atopy]].  Allergic reactions occur to environmental substances known as [[allergen]]s; these reactions are [[Acquired disorder|acquired]], predictable and rapid.  Strictly, allergy is one of four forms of [[hypersensitivity]] and is called ''type I'' (or ''immediate'') hypersensitivity. It is characterized by excessive activation of certain [[white blood cell]]s called [[mast cell]]s and [[basophil granulocyte|basophils]] by a type of [[antibody]], known as [[IgE]], resulting in an extreme [[Inflammation|inflammatory]] response.  Common allergic reactions include [[eczema]], [[urticaria|hives]], [[hay fever]], [[asthma]], [[food allergy|food allergies]], and reactions to the [[venom]] of stinging insects such as wasps and bees.<ref>{{cite journal |author=Kay AB |title=Overview of 'allergy and allergic diseases: with a view to the future' |journal=Br. Med. Bull. |volume=56 |issue=4 |pages=843–64 |year=2000 |pmid=11359624 |doi=}}</ref>
''Allergy'' is a disorder of the [[immune system]] that is often called [[atopy]].  Allergic reactions occur to environmental substances known as [[allergen]]s; these reactions are [[Acquired disorder|acquired]], predictable and rapid.  Strictly, allergy is one of four forms of [[hypersensitivity]] and is called ''type I'' (or ''immediate'') hypersensitivity. It is characterized by excessive activation of certain [[white blood cell]]s called [[mast cell]]s and [[basophil granulocyte|basophils]] by a type of [[antibody]], known as [[IgE]], resulting in an extreme [[Inflammation|inflammatory]] response.  Common allergic reactions include [[eczema]], [[urticaria|hives]], [[hay fever]], [[asthma]], [[food allergy|food allergies]], and reactions to the [[venom]] of stinging insects such as wasps and bees.<ref>{{cite journal |author=Kay AB |title=Overview of 'allergy and allergic diseases: with a view to the future' |journal=Br. Med. Bull. |volume=56 |issue=4 |pages=843–64 |year=2000 |pmid=11359624 |doi=}}</ref>


Mild allergies like [[hay fever]], are highly prevalent in the human [[population]] and cause [[symptom]]s such as [[allergic conjunctivitis]], itchiness and [[rhinorrhea|runny nose]]. Similarly, conditions  such as [[asthma]] are common, in which allergy plays a major role. In some people, severe allergies to environmental or dietary allergens, or to [[medication]], occur that may result in life-threatening [[anaphylaxis|anaphylactic reactions]] and potentially death.
Mild allergies like [[hay fever]], are highly prevalent in the human [[population]] and cause [[symptom]]s such as [[allergic conjunctivitis]], itchiness and [[rhinorrhea|runny nose]]. Similarly, conditions  such as [[asthma]] are common, in which allergy plays a major role. In some people, severe allergies to environmental or dietary allergens, or to [[medication]], occur that may result in life-threatening [[anaphylaxis|anaphylactic reactions]] and potentially death.
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A variety of tests now exist to diagnose allergic conditions; these include testing the skin for responses to known allergens or analyzing the blood for the presence and levels of allergen-specific IgE. Treatments for allergies include allergen avoidance, use of [[antihistamine]]s, [[steroid]]s or other [[oral]] medications, [[immunotherapy]] to [[Desensitization (medicine)|desensitize]] the response to allergen, and [[targeted therapy]].
A variety of tests now exist to diagnose allergic conditions; these include testing the skin for responses to known allergens or analyzing the blood for the presence and levels of allergen-specific IgE. Treatments for allergies include allergen avoidance, use of [[antihistamine]]s, [[steroid]]s or other [[oral]] medications, [[immunotherapy]] to [[Desensitization (medicine)|desensitize]] the response to allergen, and [[targeted therapy]].


==Historical Perspective==
Allergy, as a concept, was first defined in the early 1900s. It has later developed into several different disease mechanisms related to disordered activation of immune system. The overall study of allergy, as a concept, drastically evolved in the 1960s with the discovery of [[immunoglobulin E]] (IgE) - [[Kimishige Ishizaka]].
==Pathophysiology==
The development of allergic response occurs in two phases: acute and late-phase reaction. The body's response varies largely on the type of phase and the advancement of chemical mediation.
==Causes==
Allergy causation can categorized as [[Host (biology)|host]] or environmental factors. Biological factors are strongly familial related. Environmental factors very largely on the type of living environment. Allergies are more common in industrialized countries than in countries that are more traditional or agricultural, and there is a higher rate of allergic disease in urban populations versus rural populations.
==Differentiating Allergy from other Diseases==
Allergic response must be differentiated from other similar diseases such as [[vasomotor rhinitis]]. Proper diagnosis ensures that the patient receives the most appropriate course of treatment.
==Diagnosis==
===History and Symptoms===
Allergy has the potential to influence various organ systems differently. Depending of the rate of severity, it can cause [[cutaneous]] reactions, bronchoconstriction, [[edema]], [[hypotension]], [[coma]] and even [[death]].
==Treatment==
==Treatment==
There have been enormous improvements in the medical treatments used to treat allergic conditions. With respect to anaphylaxis and hypersensitivity reactions to foods, drugs, and insects and in allergic skin diseases, advances have included the identification of food proteins to which IgE binding is associated with severe reactions and development of low-allergen foods, improvements in skin prick test predictions; evaluation of the [[atopy]] patch test; in wasp sting outcomes predictions and a rapidly disintegrating epinephrine tablet, and anti-IL-5 for eosinophilic diseases.<ref>{{cite journal |author=Sicherer SH, Leung DY |title=Advances in allergic skin disease, anaphylaxis, and hypersensitivity reactions to foods, drugs, and insects |journal=J. Allergy Clin. Immunol. |volume=119 |issue=6 |pages=1462-9 |year=2007 |pmid=17412401 |doi=10.1016/j.jaci.2007.02.013}}</ref>
===Medical Therapy===
 
Treatment for allergic response is primarily pharmacotherapeutic. Common methodologies include immunotherapy via desensitization or hyposensitization, enzyme potentiated desensitization.
Traditionally treatment and management of allergies involved simply avoiding the allergen in question or otherwise reducing exposure.  For instance, people with cat allergies were encouraged to avoid them. While avoidance may help to reduce symptoms and avoid life-threatening anaphylaxis, it is difficult to achieve for those with pollen or similar air-borne allergies.  Strict avoidance still has a role in management though, and is often used in managing food allergies.
===Secondary Prevention===
 
Once allergies have developed, treating the allergies and carefully avoiding those things that cause reactions can prevent allergies in the future.
==Medical specialty==
In the [[United States]] physicians who hold certification by the American Board of Allergy and Immunology (ABAI) have successfully completed an accredited educational program and an evaluation process, including a secure, proctored examination to demonstrate the knowledge, skills, and experience to the provision of patient care in allergy and immunology.<ref>{{cite web |url=http://www.abai.org/training.asp |title=ABAI: American Board of Allergy and Immunology |accessdate=2007-08-05 |format= |work=}}</ref> An '''allergist-immunologist''' is a physician specially trained to manage and treat asthma and the other allergic diseases. Becoming an allergist-immunologist requires completion of at least nine years of training. After completing medical school and graduating with a medical degree, a physician will then undergo three years of training in internal medicine (to become an internist) or pediatrics (to become a pediatrician). Once physicians have finished training in one of these specialties, they must pass the exam of either the American Board of Pediatrics (ABP) or the American Board of Internal Medicine (ABIM). Internists or pediatricians who wish to focus on the sub-specialty of allergy-immunology then complete at least an additional two years of study, called a fellowship, in an allergy-immunology training program. Allergist-immunologists who are listed as ABAI-certified have successfully passed the certifying examination of the American Board of Allergy and Immunology (ABAI), following their fellowship.<ref>{{cite web |url=http://www.aaaai.org/media/resources/allergist.asp |title=AAAAI - What is an Allergist? |accessdate=2007-08-05 |format= |work=}}</ref>
 
In the United Kingdom, allergy is a subspecialty of [[general medicine]] or [[pediatrics]]. After obtaining postgraduate exams ([[Membership of the Royal College of Physicians|MRCP]] or MRCPCH respectively) a doctor works as several years as a [[specialist registrar]] before qualifying for the [[General Medical Council]] specialist register. Allergy services may also be delivered by [[immunologist]]s. A 2003 [[Royal College of Physicians]] report presented a case for improvement of what were felt to be inadequate allergy services in the UK.<ref>Royal College of Physicians (2003). ''Allergy: the unmet need''. London, UK: Royal College of Physicians. ISBN 1-86016-183-9. {{PDFlink|[http://www.rcplondon.ac.uk/pubs/contents/81e384d6-0328-4653-9cc2-2aa7baa3c56a.pdf PDF version]|1.03&nbsp;[[Mebibyte|MiB]]<!-- application/pdf, 1089174 bytes -->}}</ref> In 2006, the House of Lords convened a subcommittee that reported in 2007. It concluded likewise that allergy services were insufficient to deal with what the Lords referred to as an "allergy epidemic" and its social cost; it made several other recommendations.<ref>{{cite book |author=House of Lords - Science and Technology Committee |title=Allergy - HL 166-I, 6th Report of Session 2006-07 - Volume 1: Report |year=2007 |publisher=TSO (The Stationery Office) |location=London, UK |isbn=0104011491|url= http://www.publications.parliament.uk/pa/ld200607/ldselect/ldsctech/166/16602.htm}}</ref>
 
==References==
==References==
{{reflist|2}}
{{reflist|2}}
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Latest revision as of 20:21, 29 July 2020

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Allergy is a disorder of the immune system that is often called atopy. Allergic reactions occur to environmental substances known as allergens; these reactions are acquired, predictable and rapid. Strictly, allergy is one of four forms of hypersensitivity and is called type I (or immediate) hypersensitivity. It is characterized by excessive activation of certain white blood cells called mast cells and basophils by a type of antibody, known as IgE, resulting in an extreme inflammatory response. Common allergic reactions include eczema, hives, hay fever, asthma, food allergies, and reactions to the venom of stinging insects such as wasps and bees.[1]

Mild allergies like hay fever, are highly prevalent in the human population and cause symptoms such as allergic conjunctivitis, itchiness and runny nose. Similarly, conditions such as asthma are common, in which allergy plays a major role. In some people, severe allergies to environmental or dietary allergens, or to medication, occur that may result in life-threatening anaphylactic reactions and potentially death.

A variety of tests now exist to diagnose allergic conditions; these include testing the skin for responses to known allergens or analyzing the blood for the presence and levels of allergen-specific IgE. Treatments for allergies include allergen avoidance, use of antihistamines, steroids or other oral medications, immunotherapy to desensitize the response to allergen, and targeted therapy.

Historical Perspective

Allergy, as a concept, was first defined in the early 1900s. It has later developed into several different disease mechanisms related to disordered activation of immune system. The overall study of allergy, as a concept, drastically evolved in the 1960s with the discovery of immunoglobulin E (IgE) - Kimishige Ishizaka.

Pathophysiology

The development of allergic response occurs in two phases: acute and late-phase reaction. The body's response varies largely on the type of phase and the advancement of chemical mediation.

Causes

Allergy causation can categorized as host or environmental factors. Biological factors are strongly familial related. Environmental factors very largely on the type of living environment. Allergies are more common in industrialized countries than in countries that are more traditional or agricultural, and there is a higher rate of allergic disease in urban populations versus rural populations.

Differentiating Allergy from other Diseases

Allergic response must be differentiated from other similar diseases such as vasomotor rhinitis. Proper diagnosis ensures that the patient receives the most appropriate course of treatment.

Diagnosis

History and Symptoms

Allergy has the potential to influence various organ systems differently. Depending of the rate of severity, it can cause cutaneous reactions, bronchoconstriction, edema, hypotension, coma and even death.

Treatment

Medical Therapy

Treatment for allergic response is primarily pharmacotherapeutic. Common methodologies include immunotherapy via desensitization or hyposensitization, enzyme potentiated desensitization.

Secondary Prevention

Once allergies have developed, treating the allergies and carefully avoiding those things that cause reactions can prevent allergies in the future.

References

  1. Kay AB (2000). "Overview of 'allergy and allergic diseases: with a view to the future'". Br. Med. Bull. 56 (4): 843–64. PMID 11359624.

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