Desensitization, allergy Health Dictionary

A term generally used to describe an adverse reaction by the body to any substance ingested by the affected individual. Strictly, allergy refers to any reactions incited by an abnormal immunological response to an ALLERGEN, and susceptibility has a strong genetic component. Most allergic disorders are linked to ATOPY, the predisposition to generate the allergic antibody immunoglobulin E (IgE) to common environmental agents (see ANTIBODIES; IMMUNOGLOBULINS). Because IgE is able to sensitise MAST CELLS (which play a part in in?ammatory and allergic reactions) anywhere in the body, atopic individuals often have disease in more than one organ. Since the allergic disorder HAY FEVER was ?rst described in 1819, allergy has moved from being a rare condition to one a?icting almost one in two people in the developed world, with substances such as grass and tree pollen, house-dust mite, bee and wasp venom, egg and milk proteins, peanuts, antibiotics, and other airborne environmental pollutants among the triggering factors. Increasing prevalence of allergic reactions has been noticeable during the past two decades, especially in young people with western lifestyles.

A severe or life-threatening reaction is often termed ANAPHYLAXIS. Many immune mechanisms also contribute to allergic disorders; however, adverse reactions to drugs, diagnostic materials and other substances often do not involve recognised immunological mechanisms and the term ‘hypersensitivity’ is preferable. (See also IMMUNITY.)

Adverse reactions may manifest themselves as URTICARIA, wheezing or di?culty in breathing owing to spasm of the BRONCHIOLES, swollen joints, nausea, vomiting and headaches. Severe allergic reactions may cause a person to go into SHOCK. Although symptoms of an allergic reaction can usually be controlled, treatment of the underlying conditon is more problematic: hence, the best current approach is for susceptible individuals to ?nd out what it is they are allergic to and avoid those agents. For some people, such as those sensitive to insect venom, IMMUNOTHERAPY or desensitisation is often e?ective. If avoidance measures are unsuccessful and desensitisation ine?ective, the in?ammatory reactions can be controlled with CORTICOSTEROIDS, while the troublesome symptoms can be treated with ANTIHISTAMINE DRUGS and SYMPATHOMIMETICS. All three types of drugs may be needed to treat severe allergic reactions.

One interesting hypothesis is that reduced exposure to infective agents, such as bacteria, in infancy may provoke the development of allergy in later life.

Predicted developments in tackling allergic disorders, according to Professor Stephen Holgate writing in the British Medical Journal (22 January 2000) include:

Identi?cation of the principal environmental factors underlying the increase in incidence, to enable preventive measures to be planned.

Safe and e?ective immunotherapy to prevent and reverse allergic disease.

Treatments that target the protein reactions activated by antigens.

Identi?cation of how IgE is produced in the body, and thus of possible ways to inhibit this process.

Identi?cation of genes affecting people’s susceptibility to allergic disease.... allergy

A technique, used in behaviour therapy for treating phobias, in which the patient is gradually exposed to the cause of the fear.... desensitization

An estimated 8 per cent of infants suffer from cow’s milk intolerance.

Symptoms. Irritable bowel, respiratory troubles (asthma), skin disorders (eczema) and behavioural problems. Symptoms disappear when dairy products are discontinued but re-appear when they re-enter the diet.

Treatment and prevention. Garlic, for reduction of symptoms. A switch from cow’s to goat’s milk proves effective. Cases are on record of goat’s milk checking irritable bowel and the spread of eczema. ... cow’s milk allergy (cma)

An inappropriate or exaggerated reaction of the immune system to a food. Sensitivity to cow’s milk protein is a fairly common food allergy in young children. Other foods most commonly implicated in food allergy are nuts, wheat, fish, shellfish, and eggs. Food allergy is more common in people who suffer from other forms of allergy or hypersensitivity, such as asthma, allergic rhinitis, and eczema.Immediate reactions, occurring within an hour or sometimes minutes of eating the trigger food, include lip swelling, tingling in the mouth or throat, vomiting, abdominal distension, abnormally loud bowel sounds, and diarrhoea. Some serious allergies can cause anaphylactic shock, requiring immediate self-injection with adrenaline (epinephrine). The only effective treatment for food allergy is avoidance of the offending food. (See also food intolerance.)... food allergy

Irritation of the skin following contact with a specific substance that provokes an inappropriate or exaggerated reaction from the immune system. There are 2 main types of allergic skin reaction. In contact allergic dermatitis, red, itchy patches develop a few hours to 2 days after contact with the allergen. In contact urticaria, red, raised areas appear a few minutes after skin contact. In some cases, skin tests are needed, to identify the allergen, for contact with it to be minimized. (See also atopic eczema.)... skin allergy

(EMDR) a type of psychotherapy used for the treatment of significant anxiety or distress caused by traumatic events or in the context of *post-traumatic stress disorder. The aim is to separate the emotional from the actual memory of the event in order to reduce the anxiety related to the memory.... eye movement desensitization and reprocessing therapy