|Classification and external resources|
Hives are a common allergic symptom.
An allergy is a hypersensitivity disorder of the immune system. Symptoms include red eyes, itchiness, and runny nose, eczema, hives, or an asthma attack. Allergies can play a major role in conditions such as asthma. In some people, severe allergies to environmental or dietary allergens or to medication may result in life-threatening reactions called anaphylaxis. Food allergies, and reactions to the venom of stinging insects such as wasps and bees are more often associated with these severe reactions. Not all reactions or intolerances are forms of allergy.
Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid. Allergy is one of four forms of hypersensitivity and is formally called type I (or immediate) hypersensitivity. Allergic reactions are distinctive because of excessive activation of certain white blood cells called mast cells and basophils by a type of antibody called Immunoglobulin E (IgE). This reaction results in an inflammatory response which can range from uncomfortable to dangerous.
A variety of tests exist to diagnose allergic conditions. If done they should be ordered and interpreted in light of a person's history of exposure as many positive test results do not mean a clinically significant allergy. Tests include placing possible allergens on the skin and looking for a reaction such as swelling and blood tests to look for an allergen-specific IgE.
Treatments for allergies include avoiding known allergens, steroids that modify the immune system in general, and medications such as antihistamines and decongestants which reduce symptoms. Many of these medications are taken by mouth, although epinephrine, which is used to treat anaphylactic reactions, is injected. Immunotherapy uses injected allergens to desensitize the body's response. Mild allergies like hay fever are very common.
- 1 Signs and symptoms
- 2 Cause
- 3 Pathophysiology
- 4 Diagnosis
- 5 Management
- 6 Prevention
- 7 Epidemiology
- 8 History
- 9 Medical specialty
- 10 See also
- 11 References
- 12 External links
Signs and symptoms
|Nose||swelling of the nasal mucosa (allergic rhinitis) runny nose, sneezing|
|Eyes||redness and itching of the conjunctiva (allergic conjunctivitis, watery|
|Airways||Sneezing, coughing, bronchoconstriction, wheezing and dyspnea, sometimes outright attacks of asthma, in severe cases the airway constricts due to swelling known as laryngeal edema|
|Ears||feeling of fullness, possibly pain, and impaired hearing due to the lack of eustachian tube drainage.|
|Skin||rashes, such as eczema and hives (urticaria)|
|Gastrointestinal tract||abdominal pain, bloating, vomiting, diarrhea|
Many allergens such as dust or pollen are airborne particles. In these cases, symptoms arise in areas in contact with air, such as eyes, nose, and lungs. For instance, allergic rhinitis, also known as hay fever, causes irritation of the nose, sneezing, itching, and redness of the eyes. Inhaled allergens can also lead to asthmatic symptoms, caused by narrowing of the airways (bronchoconstriction) and increased production of mucus in the lungs, shortness of breath (dyspnea), coughing and wheezing.
Aside from these ambient allergens, allergic reactions can result from foods, insect stings, and reactions to medications like aspirin and antibiotics such as penicillin. Symptoms of food allergy include abdominal pain, bloating, vomiting, diarrhea, itchy skin, and swelling of the skin during hives. Food allergies rarely cause respiratory (asthmatic) reactions, or rhinitis. Insect stings, antibiotics, and certain medicines produce a systemic allergic response that is also called anaphylaxis; multiple organ systems can be affected, including the digestive system, the respiratory system, and the circulatory system. Depending on 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 EpiPen or Twinject auto-injector. The nature of anaphylaxis is such that the reaction can seem to be subsiding, but may recur throughout a prolonged period of time.
Substances that come into contact with the skin, such as latex, are also common causes of allergic reactions, known as contact dermatitis or eczema. Skin allergies frequently cause rashes, or swelling and inflammation within the skin, in what is known as a "wheal and flare" reaction characteristic of hives and angioedema.
Risk factors for allergy can be placed in two general categories, namely host and environmental factors. Host factors include heredity, sex, race, and age, with heredity being by far the most significant. However, there have been recent increases in the incidence of allergic disorders that cannot be explained by genetic factors alone. Four major environmental candidates are alterations in exposure to infectious diseases during early childhood, environmental pollution, allergen levels, and dietary changes.
A wide variety of foods can cause allergic reactions, but 90% of allergic responses to foods are caused by cow's milk, soy, eggs, wheat, peanuts, tree nuts, fish, and shellfish. Other food allergies, affecting less than 1 person per 10,000 population, may be considered "rare".
The most common food allergy in the US population is a sensitivity to crustacea. Although peanut allergies are notorious for their severity, peanut allergies are not the most common food allergy in adults or children. Severe or life-threatening reactions may be triggered by other allergens, and are more common when combined with asthma.
Rates of allergies differ between adults and children. Peanut allergies can sometimes be outgrown by children. Egg allergies affect one to two percent of children but are outgrown by about two-thirds of children by the age of 5. The sensitivity is usually to proteins in the white, rather than the yolk.
Milk-protein allergies are not Immunoglobulin E reactions, and are usually attributable to proctocolitis. They are most prevalent in children. Some people are unable to tolerate milk from goats or sheep as well as from cows, and many are also unable to tolerate dairy products such as cheese. Roughly 10% of children with a milk allergy will have a reaction to beef. Beef contains a small amount of protein that is present in cow's milk. Lactose intolerance, a common reaction to milk, is not a form of allergy at all, but rather due to the absence of an enzyme in the digestive tract.
Those with tree nut allergies may be allergic to one or to many tree nuts, including pecans, pistachios, pine nuts, and walnuts. Also seeds, including sesame seeds and poppy seeds, contain oils in which protein is present, which may elicit an allergic reaction.
Allergens can be transferred from one food to another through genetic engineering; however genetic modification can also remove allergens. Little research has been done on the natural variation of allergen concentrations in the unmodified crops.
Latex can trigger an IgE-mediated cutaneous, respiratory, and systemic reaction. The prevalence of latex allergy in the general population is believed to be less than one percent. In a hospital study, 1 in 800 surgical patients (0.125 percent) reported latex sensitivity, although the sensitivity among healthcare workers is higher, between seven and ten percent. Researchers attribute this higher level to the exposure of healthcare workers to areas with significant airborne latex allergens, such as operating rooms, intensive-care units, and dental suites. These latex-rich environments may sensitize healthcare workers who regularly inhale allergenic proteins.
The most prevalent response to latex is an allergic contact dermatitis, a delayed hypersensitive reaction appearing as dry, crusted lesions. This reaction usually lasts 48–96 hours. Sweating or rubbing the area under the glove aggravates the lesions, possibly leading to ulcerations. Anaphylactic reactions occur most often in sensitive patients, who have been exposed to a surgeon's latex gloves during abdominal surgery, but other mucosal exposures, such as dental procedures, can also produce systemic reactions.
Latex and banana sensitivity may cross-react. Furthermore, those with latex allergy may also have sensitivities to avocado, kiwifruit, and chestnut. These patients often have perioral itching and local urticaria. Only occasionally have these food-induced allergies induced systemic responses. Researchers suspect that the cross-reactivity of latex with banana, avocado, kiwifruit, and chestnut occurs because latex proteins are structurally homologous with some plant proteins.
Toxins interacting with proteins
Another non-food protein reaction, urushiol-induced contact dermatitis, originates after contact with poison ivy, eastern poison oak, western poison oak, or poison sumac. Urushiol, which is not itself a protein, acts as a hapten and chemically reacts with, binds to, and changes the shape of integral membrane proteins on exposed skin cells. The immune system does not recognize the affected cells as normal parts of the body, causing a T-cell-mediated immune response. Of these poisonous plants, sumac is the most virulent. The resulting dermatological response to the reaction between urushiol and membrane proteins includes redness, swelling, papules, vesicles, blisters, and streaking.
Estimates vary on the percentage of the population that will have an immune system response. Approximately 25 percent of the population will have a strong allergic response to urushiol. In general, approximately 80 percent to 90 percent of adults will develop a rash if they are exposed to .0050 milligrams (7.7×10−5 gr) of purified urushiol, but some people are so sensitive that it takes only a molecular trace on the skin to initiate an allergic reaction.
Allergic diseases are strongly familial: identical twins are likely to have the same allergic diseases about 70% of the time; the same allergy occurs about 40% of the time in non-identical twins. Allergic parents are more likely to have allergic children, and those children's allergies are likely to be more severe than those in children of non-allergic parents. Some allergies, however, are not consistent along genealogies; parents who are allergic to peanuts may have children who are allergic to ragweed. It seems that the likelihood of developing allergies is inherited and related to an irregularity in the immune system, but the specific allergen is not.
The risk of allergic sensitization and the development of allergies varies with age, with young children most at risk. Several studies have shown that IgE levels are highest in childhood and fall rapidly between the ages of 10 and 30 years. The peak prevalence of hay fever is highest in children and young adults and the incidence of asthma is highest in children under 10.
Overall, boys have a higher risk of developing allergies than girls, although for some diseases, namely asthma in young adults, females are more likely to be affected. These differences between the sexes tend to decrease in adulthood.
Ethnicity may play a role in some allergies; however, racial factors have been difficult to separate from environmental influences and changes due to migration. It has been suggested that different genetic loci are responsible for asthma, to be specific, in people of European, Hispanic, Asian, and African origins.
Allergic diseases are caused by inappropriate immunological responses to harmless antigens driven by a TH2-mediated immune response. Many bacteria and viruses elicit a TH1-mediated immune response, which down-regulates TH2 responses. The first proposed mechanism of action of the hygiene hypothesis was that insufficient stimulation of the TH1 arm of the immune system leads to an overactive TH2 arm, which in turn leads to allergic disease. In other words, individuals living in too sterile an environment are not exposed to enough pathogens to keep the immune system busy. Since our bodies evolved to deal with a certain level of such pathogens, when they are not exposed to this level, the immune system will attack harmless antigens and thus normally benign microbial objects — like pollen — will trigger an immune response.
The hygiene hypothesis was developed to explain the observation that hay fever and eczema, both allergic diseases, were less common in children from larger families, which were, it is presumed, exposed to more infectious agents through their siblings, than in children from families with only one child. The hygiene hypothesis has been extensively investigated by immunologists and epidemiologists and has become an important theoretical framework for the study of allergic disorders. It is used to explain the increase in allergic diseases that have been seen since industrialization, and the higher incidence of allergic diseases in more developed countries. The hygiene hypothesis has now expanded to include exposure to symbiotic bacteria and parasites as important modulators of immune system development, along with infectious agents.
Epidemiological data support the hygiene hypothesis. Studies have shown that various immunological and autoimmune diseases are much less common in the developing world than the industrialized world and that immigrants to the industrialized world from the developing world increasingly develop immunological disorders in relation to the length of time since arrival in the industrialized world. Longitudinal studies in the third world demonstrate an increase in immunological disorders as a country grows more affluent and, it is presumed, cleaner. The use of antibiotics in the first year of life has been linked to asthma and other allergic diseases. The use of antibacterial cleaning products has also been associated with higher incidence of asthma, as has birth by Caesarean section rather than vaginal birth.
Other environmental factors
International differences have been associated with the number of individuals within a population have allergy. Allergic diseases 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, although these differences are becoming less defined.
Exposure to allergens, especially in early life, is an important risk factor for allergy. Alterations in exposure to microorganisms is another plausible explanation, at present, for the increase in atopic allergy. Endotoxin exposure reduces release of inflammatory cytokines such as TNF-α, IFNγ, interleukin-10, and interleukin-12 from white blood cells (leukocytes) that circulate in the blood. Certain microbe-sensing proteins, known as Toll-like receptors, found on the surface of cells in the body are also thought to be involved in these processes.
Gutworms and similar parasites are present in untreated drinking water in developing countries, and were present in the water of developed countries until the routine chlorination and purification of drinking water supplies. Recent research has shown that some common parasites, such as intestinal worms (e.g., hookworms), secrete chemicals into the gut wall (and, hence, the bloodstream) that suppress the immune system and prevent the body from attacking the parasite. This gives rise to a new slant on the hygiene hypothesis theory — that co-evolution of man and parasites has led to an immune system that functions correctly only in the presence of the parasites. Without them, the immune system becomes unbalanced and oversensitive. In particular, research suggests that allergies may coincide with the delayed establishment of gut flora in infants. However, the research to support this theory is conflicting, with some studies performed in China and Ethiopia showing an increase in allergy in people infected with intestinal worms. Clinical trials have been initiated to test the effectiveness of certain worms in treating some allergies. It may be that the term 'parasite' could turn out to be inappropriate, and in fact a hitherto unsuspected symbiosis is at work. For more information on this topic, see Helminthic therapy.
In the early stages of allergy, a type I hypersensitivity reaction against an allergen encountered for the first time and presented by a professional Antigen-Presenting Cell causes a response in a type of immune cell called a TH2 lymphocyte, which belongs to a subset of T cells that produce a cytokine called interleukin-4 (IL-4). These TH2 cells interact with other lymphocytes called B cells, whose role is production of antibodies. Coupled with signals provided by IL-4, this interaction stimulates the B cell to begin production of a large amount of a particular type of antibody known as IgE. Secreted IgE circulates in the blood and binds to an IgE-specific receptor (a kind of Fc receptor called FcεRI) on the surface of other kinds of immune cells called mast cells and basophils, which are both involved in the acute inflammatory response. The IgE-coated cells, at this stage, are sensitized to the allergen.
If later exposure to the same allergen occurs, the allergen can bind to the IgE molecules held on the surface of the mast cells or basophils. Cross-linking of the IgE and Fc receptors occurs when more than one IgE-receptor complex interacts with the same allergenic molecule, and activates the sensitized cell. Activated mast cells and basophils undergo a process called degranulation, during which they release histamine and other inflammatory chemical mediators (cytokines, interleukins, leukotrienes, and prostaglandins) from their granules into the surrounding tissue causing several systemic effects, such as vasodilation, mucous secretion, nerve stimulation, and smooth muscle contraction. This results in rhinorrhea, itchiness, dyspnea, and anaphylaxis. Depending on the individual, allergen, and mode of introduction, the symptoms can be system-wide (classical anaphylaxis), or localized to particular body systems; asthma is localized to the respiratory system and eczema is localized to the dermis.
After the chemical mediators of the acute response subside, late-phase responses can often occur. This is due to the migration of other leukocytes such as neutrophils, lymphocytes, eosinophils and macrophages to the initial site. The reaction is usually seen 2–24 hours after the original reaction. Cytokines from mast cells may play a role in the persistence of long-term effects. Late-phase responses seen in asthma are slightly different from those seen in other allergic responses, although they are still caused by release of mediators from eosinophils and are still dependent on activity of TH2 cells.
Allergic contact dermatitis
Although allergic contact dermatitis is termed an "allergic" reaction (which usually refers to type I hypersensitivity), its pathophysiology actually involves a reaction that more correctly corresponds to a type IV hypersensitivity reaction. In type IV hypersensitivity, there is activation of certain types of T cells (CD8+) that destroy target cells on contact, as well as activated macrophages that produce hydrolytic enzymes.
Effective management of allergic diseases relies on the ability to make an accurate diagnosis. Allergy testing can help confirm or rule out allergies. Correct diagnosis, counseling, and avoidance advice based on valid allergy test results reduces the incidence of symptoms and need for medications, and improves quality of life. To assess the presence of allergen-specific IgE antibodies, two different methods can be used: a skin prick test, or an allergy blood test. Both methods are recommended, and they have similar diagnostic value.
Skin prick tests and blood tests are equally cost-effective, and health economic evidence shows that both tests were cost-effective compared with no test. Also, early and more accurate diagnoses save cost due to reduced consultations, referrals to secondary care, misdiagnosis, and emergency admissions.
Allergy undergoes dynamic changes over time. Regular allergy testing of relevant allergens provides information on if and how patient management can be changed, in order to improve health and quality of life. Annual testing is often the practice for determining whether allergy to milk, egg, soy, and wheat have been outgrown, and the testing interval is extended to 2–3 years for allergy to peanut, tree nuts, fish, and crustacean shellfish. Results of follow-up testing can guide decision-making regarding whether and when it is safe to introduce or re-introduce allergenic food into the diet.
Skin prick testing
Skin testing is also known as "puncture testing" and "prick testing" due to the series of tiny punctures or pricks made into the patient's skin. Small amounts of suspected allergens and/or their extracts (e.g., pollen, grass, mite proteins, peanut extract) 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). A small plastic or metal device is used to puncture or prick the skin. Sometimes, the allergens are injected "intradermally" into the patient's skin, with a needle and syringe. 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 a full-blown hive (called "wheal and flare") in more sensitive patients similar to a mosquito bite. Interpretation of the results of the skin prick test is normally done by allergists on a scale of severity, with +/- meaning borderline reactivity, and 4+ being a large reaction. Increasingly, allergists are measuring and recording the diameter of the wheal and flare reaction. Interpretation by well-trained allergists is often guided by relevant literature. Some patients may believe they have determined their own allergic sensitivity from observation, but a skin test has been shown to be much better than patient observation to detect allergy.
If a serious life-threatening anaphylactic reaction has brought a patient in for evaluation, some allergists will prefer an initial blood test prior to performing the skin prick test. Skin tests may not be an option if the patient has widespread skin disease, or has taken antihistamines in the last several days.
Patch testing is a method used to determine if a specific substance causes allergic inflammation of the skin. It tests for delayed reactions. It is used to help ascertain the cause of skin contact allergy, or contact dermatitis. Adhesive patches, usually treated with a number of common allergic chemicals or skin sensitizers, are applied to the back. The skin is then examined for possible local reactions at least twice, usually at 48 hours after application of the patch, and again two or three days later.
An allergy blood test is quick and simple, and can be ordered by a licensed health care provider (e.g., an allergy specialist), GP, or PED. Unlike skin-prick testing, a blood test can be performed irrespective of age, skin condition, medication, symptom, disease activity, and pregnancy. Adults and children of any age can take an allergy blood test. For babies and very young children, a single needle stick for allergy blood testing is often more gentle than several skin tests.
An allergy blood test is available through most laboratories. A sample of the patient’s blood is sent to a laboratory for analysis, and the results are sent back a few days later. Multiple allergens can be detected with a single blood sample. Allergy blood tests are very safe, since the person is not exposed to any allergens during the testing procedure.
The test measures the concentration of specific IgE antibodies in the blood. Quantitative IgE test results increase the possibility of ranking how different substances may affect symptoms. A general rule of thumb is that the higher the IgE antibody value, the greater the likelihood of symptoms. Allergens found at low levels that today do not result in symptoms can nevertheless help predict future symptom development. The quantitative allergy blood result can help determine what a patient is allergic to, help predict and follow the disease development, estimate the risk of a severe reaction, and explain cross-reactivity.
A low total IgE level is not adequate to rule out sensitization to commonly inhaled allergens. Statistical methods, such as ROC curves, predictive value calculations, and likelihood ratios have been used to examine the relationship of various testing methods to each other. These methods have shown that patients with a high total IgE have a high probability of allergic sensitization, but further investigation with allergy tests for specific IgE antibodies for a carefully chosen of allergens is often warranted.
Challenge testing: Challenge testing is when small amounts of a suspected allergen are introduced to the body orally, through inhalation, or via other routes. Except for testing food and medication allergies, challenges are rarely performed. When this type of testing is chosen, it must be closely supervised by an allergist.
Elimination/Challenge tests: This testing method is used most often with foods or medicines. A patient with a suspected allergen is instructed to modify his diet to totally avoid that allergen for a set time. If the patient experiences significant improvement, he may then be “challenged” by reintroducing the allergen, to see if symptoms are reproduced.
Unreliable tests: There are other types of allergy testing methods that the that are unreliable, including applied kinesiology (allergy testing through muscle relaxation), cytotoxicity testing, urine autoinjection, skin titration (Rinkel method), and provocative and neutralization (subcutaneous) testing or sublingual provocation.
Before a diagnosis of allergic disease can be confirmed, other possible causes of the presenting symptoms should be considered. Vasomotor rhinitis, for example, is one of many maladies that shares symptoms with allergic rhinitis, underscoring the need for professional differential diagnosis. Once a diagnosis of asthma, rhinitis, anaphylaxis, or other allergic disease has been made, there are several methods for discovering the causative agent of that allergy.
In recent times, there have been enormous improvements in the medical practices 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.
Traditional treatment and management of allergies consisted simply of avoiding the allergen in question or otherwise reducing exposure. For instance, people with cat allergies were encouraged to avoid them. However, while avoidance of allergens may reduce symptoms and avoid life-threatening anaphylaxis, it is difficult to achieve for those with pollen or similar air-borne allergies. Nonetheless, strict avoidance of allergens is still considered a useful treatment method, and is often used in managing food allergies.
New technology approaches to decreasing IgE overproduction, and regulating histamine release in allergic individuals have demonstrated statistically significant reduction on Total Nasal Symptom Scores.
Several antagonistic drugs are used to block the action of allergic mediators, or to prevent activation of cells and degranulation processes. These include antihistamines, glucocorticoids, epinephrine (adrenaline), theophylline and cromolyn sodium. Anti-leukotrienes, such as montelukast (Singulair) or zafirlukast (Accolate), are FDA approved for treatment of allergic diseases. Anti-cholinergics, decongestants, mast cell stabilizers, and other compounds thought to impair eosinophil chemotaxis, are also commonly used. These drugs help to alleviate the symptoms of allergy, and are imperative in the recovery of acute anaphylaxis, but play little role in chronic treatment of allergic disorders.
Desensitization or hyposensitization is a treatment in which the person is gradually vaccinated with progressively larger doses of the allergen in question. This can either reduce the severity or eliminate hypersensitivity altogether. It relies on the progressive skewing of IgG antibody production, to block excessive IgE production seen in atopys. In a sense, the person builds up immunity to increasing amounts of the allergen in question. Studies have demonstrated the long-term efficacy and the preventive effect of immunotherapy in reducing the development of new allergy. Meta-analyses have also confirmed efficacy of the treatment in allergic rhinitis in children and in asthma. A review by the Mayo Clinic in Rochester confirmed the safety and efficacy of allergen immunotherapy for allergic rhinitis and conjunctivitis, allergic forms of asthma, and stinging insect based on numerous well-designed scientific studies. In addition, national and international guidelines confirm the clinical efficacy of injection immunotherapy in rhinitis and asthma, as well as the safety, provided that recommendations are followed.
A second form of immunotherapy involves the intravenous injection of monoclonal anti-IgE antibodies. These bind to free and B-cell associated IgE; signalling their destruction. They do not bind to IgE already bound to the Fc receptor on basophils and mast cells, as this would stimulate the allergic inflammatory response. The first agent of this class is omalizumab. While this form of immunotherapy is very effective in treating several types of atopy, it should not be used in treating the majority of people with food allergies.
A third type, sublingual immunotherapy, is an orally administered therapy that takes advantage of oral immune tolerance to non-pathogenic antigens such as foods and resident bacteria. This therapy currently accounts for 40 percent of allergy treatment in Europe. In the United States, sublingual immunotherapy is gaining support among traditional allergists and is endorsed by doctors treating allergy.
Allergy shot treatment is the closest thing to a ‘cure’ for allergic symptoms. This therapy requires a long-term commitment.
An experimental treatment, enzyme potentiated desensitization (EPD), has been tried for decades but is not generally accepted as effective. EPD uses dilutions of allergen and an enzyme, beta-glucuronidase, to which T-regulatory lymphocytes are supposed to respond by favouring desensitization, or down-regulation, rather than sensitization. EPD has also been tried for the treatment of autoimmune diseases but is not approved by the U.S. Food and Drug Administration or of proven effectiveness.
Systematic literature searches conducted by the Mayo Clinic through 2006, involving hundreds of articles studying multiple conditions, including asthma and upper respiratory tract infection, showed no effectiveness of homeopathic treatments and no difference compared with placebo. The authors concluded that, based on rigorous clinical trials of all types of homeopathy for childhood and adolescence ailments, there is no convincing evidence that supports the use of homeopathic treatments.
The consumption of various foods during pregnancy has been linked to eczema; these include celery, citrus fruit, raw pepper, margarine, and vegetable oil. A high intake of antioxidants, zinc, and selenium during pregnancy may help prevent allergies. This is linked to a reduced risk for childhood-onset asthma, wheezing, and eczema. Further research needs to be conducted. Probiotic supplements taken during pregnancy or infancy may help to prevent atopic dermatitis. After birth, an early introduction of solid food and high diversity before week 17 could increase a child's risk for allergies. Studies suggest that introduction of solid food and avoidance of highly allergenic food such as peanuts during the first year does not help in allergy prevention.
Many diseases related to inflammation such as type 1 diabetes, rheumatoid arthritis, and allergic diseases — hay fever and asthma — have increased in the Western world over the past 2–3 decades. Rapid increases in allergic asthma and other atopic disorders in industrialized nations, it is estimated, began in the 1960s and 1970s, with further increases occurring during the 1980s and 1990s, although some suggest that a steady rise in sensitization has been occurring since the 1920s. The incidence of atopy in developing countries has, in general, remained much lower.
|Allergy type||United States||United Kingdom|
|Allergic rhinitis||35.9 million (about 11% of the population)||3.3 million (about 5.5% of the population)|
|Asthma||10 million have allergic asthma (about 3% of the population). The prevalence of asthma increased 75% from 1980 to 1994. Asthma prevalence is 39% higher in African Americans than in Europeans.||5.7 million (about 9.4%). In six and seven year olds asthma increased from 18.4% to 20.9% over five years, during the same time the rate decreased from 31% to 24.7% in 13- to 14-year-olds.|
|Atopic eczema||About 9% of the population. Between 1960 and 1990 prevalence has increased from 3% to 10% in children.||5.8 million (about 1% severe).|
|Anaphylaxis||At least 40 deaths per year due to insect venom. About 400 deaths due to penicillin anaphylaxis. About 220 cases of anaphylaxis and 3 deaths per year are due to latex allergy. An estimated 150 people die annually from anaphylaxis due to food allergy.||Between 1999 and 2006, 48 deaths occurred in people ranging from five months to 85 years old.|
|Insect venom||Around 15% of adults have mild, localized allergic reactions. Systemic reactions occur in 3% of adults and less than 1% of children.||Unknown|
|Drug allergies||Anaphylactic reactions to penicillin cause 400 deaths per year.||Unknown|
|Food allergies||About 6% of US children under age 3 and 3.5–4% of the overall US population. Peanut and/or tree nut (e.g. walnut) allergy affects about three million Americans, or 1.1% of the population.||5–7% of infants and 1–2% of adults. A 117.3% increase in peanut allergies was observed from 2001 to 2005, an estimated 25,700 people in England are affected.|
|Multiple allergies (Asthma, eczema and allergic rhinitis together)||Unknown||2.3 million (about 3.7%), prevalence has increased by 48.9% between 2001 and 2005.|
Although genetic factors fundamentally govern susceptibility to atopic disease, increases in atopy have occurred within too short a time frame to be explained by a genetic change in the population, thus pointing to environmental or lifestyle changes. Several hypotheses have been identified to explain this increased prevalence; increased exposure to perennial allergens due to housing changes and increasing time spent indoors, and changes in cleanliness or hygiene that have resulted in the decreased activation of a common immune control mechanism, coupled with dietary changes, obesity and decline in physical exercise. The hygiene hypothesis maintains that high living standards and hygienic conditions exposes children to fewer infections. It is thought that reduced bacterial and viral infections early in life direct the maturing immune system away from TH1 type responses, leading to unrestrained TH2 responses that allow for an increase in allergy.
Changes in rates and types of infection alone however, have been unable to explain the observed increase in allergic disease, and recent evidence has focused attention on the importance of the gastrointestinal microbial environment. Evidence has shown that exposure to food and fecal-oral pathogens, such as hepatitis A, Toxoplasma gondii, and Helicobacter pylori (which also tend to be more prevalent in developing countries), can reduce the overall risk of atopy by more than 60%, and an increased prevalence of parasitic infections has been associated with a decreased prevalence of asthma. It is speculated that these infections exert their effect by critically altering TH1/TH2 regulation. Important elements of newer hygiene hypotheses also include exposure to endotoxins, exposure to pets and growing up on a farm.
The concept of "allergy" was originally introduced in 1906 by the Viennese pediatrician Clemens von Pirquet, after he noted that some of his patients were hypersensitive to normally innocuous entities such as dust, pollen, or certain foods. Pirquet called this phenomenon "allergy" from the Ancient Greek words ἄλλος allos meaning "other" and ἔργον ergon meaning "work".
All forms of hypersensitivity used to be classified as allergies, and all were thought to be caused by an improper activation of the immune system. Later, it became clear that several different disease mechanisms were implicated, with the common link to a disordered activation of the immune system. In 1963, a new classification scheme was designed by Philip Gell and Robin Coombs that described four types of hypersensitivity reactions, known as Type I to Type IV hypersensitivity. With this new classification, the word "allergy" was restricted to type I hypersensitivities (also called immediate hypersensitivity), which are characterized as rapidly developing reactions.
A major breakthrough in understanding the mechanisms of allergy was the discovery of the antibody class labeled immunoglobulin E (IgE) – Kimishige Ishizaka and co-workers were the first to isolate and describe IgE in the 1960s.
Radiometric assays include the radioallergosorbent test (RAST test) method, which uses IgE-binding (anti-IgE) antibodies labeled with radioactive isotopes for quantifying the levels of IgE antibody in the blood. Other newer methods use colorimetric or fluorescence-labeled technology in the place of radioactive isotopes.
The RAST methodology was invented and marketed in 1974 by Pharmacia Diagnostics AB, Uppsala, Sweden, and the acronym RAST is actually a brand name. In 1989, Pharmacia Diagnostics AB replaced it with a superior test named the ImmunoCAP Specific IgE blood test, which uses the newer fluorescence-labeled technology.
American College of Allergy Asthma and Immunology (ACAAI) and the American Academy of Allergy Asthma and Immunology (AAAAI) issued the Joint Task Force Report “Pearls and pitfalls of allergy diagnostic testing” in 2008, and is firm in its statement that the term RAST is now obsolete:
The term RAST became a colloquialism for all varieties of (in vitro allergy) tests. This is unfortunate because it is well recognized that there are well-performing tests and some that do not perform so well, yet they are all called RASTs, making it difficult to distinguish which is which. For these reasons, it is now recommended that use of RAST as a generic descriptor of these tests be abandoned.
The new version, the ImmunoCAP Specific IgE blood test, is the only specific IgE assay to receive FDA approval to quantitatively report to its detection limit of 0.1kU/l.
An allergist is a physician specially trained to manage and treat allergies, asthma and the other allergic diseases. In the United States physicians holding certification by the American Board of Allergy and Immunology (ABAI) have successfully completed an accredited educational program and evaluation process, including a proctored examination to demonstrate knowledge, skills, and experience in patient care in allergy and immunology. 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 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), the American Osteopathic Board of Pediatrics (AOBP), the American Board of Internal Medicine (ABIM), or the American Osteopathic Board of Internal Medicine (AOBIM). Internists or pediatricians wishing 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 listed as ABAI-certified have successfully passed the certifying examination of the ABAI following their fellowship.
In the United Kingdom, allergy is a subspecialty of general medicine or pediatrics. After obtaining postgraduate exams (MRCP or MRCPCH), a doctor works for several years as a specialist registrar before qualifying for the General Medical Council specialist register. Allergy services may also be delivered by immunologists. A 2003 Royal College of Physicians report presented a case for improvement of what were felt to be inadequate allergy services in the UK. In 2006, the House of Lords convened a subcommittee. It concluded likewise in 2007 that allergy services were insufficient to deal with what the Lords referred to as an "allergy epidemic" and its social cost; it made several recommendations.
- "allergy" at Dorland's Medical Dictionary
- Kay AB (2000). "Overview of 'allergy and allergic diseases: with a view to the future'". Br. Med. Bull. 56 (4): 843–64. doi:10.1258/0007142001903481. PMID 11359624.
- Bahna SL (Dec 2002). "Cow's milk allergy versus cow milk intolerance.". Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology 89 (6 Suppl 1): 56–60. doi:10.1016/S1081-1206(10)62124-2. PMID 12487206.
- Cox L, Williams B, Sicherer S, Oppenheimer J, Sher L, Hamilton R, Golden D (December 2008). "Pearls and pitfalls of allergy diagnostic testing: report from the American College of Allergy, Asthma and Immunology/American Academy of Allergy, Asthma and Immunology Specific IgE Test Task Force". Annals of Allergy, Asthma & Immunology 101 (6): 580–92. doi:10.1016/S1081-1206(10)60220-7. PMID 19119701.
- Bope, Edward T.; Rakel, Robert E. (2005). Conn's Current Therapy 2005. Philadelphia, PA: W.B. Saunders Company. p. 880. ISBN 0-7216-3864-3.
- Holgate ST (1998). "Asthma and allergy—disorders of civilization?". QJM 91 (3): 171–84. doi:10.1093/qjmed/91.3.171. PMID 9604069.
- Rusznak C, Davies RJ (1998). "ABC of allergies. Diagnosing allergy". BMJ 316 (7132): 686–9. doi:10.1136/bmj.316.7132.686. PMC 1112683. PMID 9522798.
- Golden DB (2007). "Insect sting anaphylaxis". Immunol Allergy Clin North Am 27 (2): 261–72, vii. doi:10.1016/j.iac.2007.03.008. PMC 1961691. PMID 17493502.
- Schafer JA, Mateo N, Parlier GL, Rotschafer JC (2007). "Penicillin allergy skin testing: what do we do now?". Pharmacotherapy 27 (4): 542–5. doi:10.1592/phco.27.4.542. PMID 17381381.
- Tang AW (2003). "A practical guide to anaphylaxis". Am Fam Physician 68 (7): 1325–32. PMID 14567487.
- Brehler R, Kütting B (2001). "Natural rubber latex allergy: a problem of interdisciplinary concern in medicine". Arch. Intern. Med. 161 (8): 1057–64. doi:10.1001/archinte.161.8.1057. PMID 11322839.
- Muller BA (2004). "Urticaria and angioedema: a practical approach". Am Fam Physician 69 (5): 1123–8. PMID 15023012.
- Grammatikos AP (2008). "The genetic and environmental basis of atopic diseases". Annals of Medicine 40 (7): 482–95. doi:10.1080/07853890802082096. PMID 18608118.
- Janeway, Charles; Paul Travers; Mark Walport; Mark Shlomchik (2001). Immunobiology; Fifth Edition. New York and London: Garland Science. pp. e–book. ISBN 978-0-8153-4101-7.
- "Asthma and Allergy Foundation of America". Retrieved 23 December 2012.
- Maleki, Soheilia J; Burks, A. Wesley; Helm, Ricki M. (2006). Food Allergy. Blackwell Publishing. pp. 39–41. ISBN 1-55581-375-5.
- Järvinen KM, Beyer K, Vila L, Bardina L, Mishoe M, Sampson HA (July 2007). "Specificity of IgE antibodies to sequential epitopes of hen's egg ovomucoid as a marker for persistence of egg allergy". J. Allergy 62 (7): 758–65. doi:10.1111/j.1398-9995.2007.01332.x. PMID 17573723.
- Sicherer 63
- Maleki, Burks & Helm 2006, pp. 41
- Sicherer 64
- Gottfried Schmalz, Dorthe Arenholt Bindslev (2008). Biocompatibility of Dental Materials. Springer. Retrieved March 5, 2014.
- Thomas P. Habif (2009). Clinical Dermatology. Elsevier Health Sciences. Retrieved March 6, 2014.
- Edward T. Bope, Rick D. Kellerman (2013). Conn's Current Therapy 2014: Expert Consult. Elsevier Health Sciences. Retrieved March 6, 2014.
- Herman, Eliot (2003). "Genetically modified soybeans and food allergies". Journal of Experimental Botany 54 (356): 1317–1319. doi:10.1093/jxb/erg164.
- Panda R, Ariyarathna H, Amnuaycheewa P, Tetteh A, Pramod SN, Taylor SL, Ballmer-Weber BK, Goodman RE (Feb 2013). "Challenges in testing genetically modified crops for potential increases in endogenous allergen expression for safety". Allergy 68 (2): 142–51. doi:10.1111/all.12076. PMID 23205714.
- Sussman GL, Beezhold DH (1995). "Allergy to Latex Rubber". Annals of Internal Medicine 122 (1): 43–46. doi:10.7326/0003-4819-122-1-199501010-00007. PMID 7985895.
- Fernández de Corres L, Moneo I, Muñoz D, Bernaola G, Fernández E, Audicana M, Urrutia I (January 1993). "Sensitization from chestnuts and bananas in patients with urticaria and anaphylaxis from contact with latex". Ann Allergy 70 (1): 35–9. PMID 7678724.
- C. Michael Hogan. Western poison-oak: Toxicodendron diversilobum. GlobalTwitcher, ed. Nicklas Stromberg. 2008. Retrieved 30 April 2010.
- Keeler, Harriet L. (1900). Our Native Trees and How to Identify Them. New York: Charles Scriber's Sons. pp. 94–96; Frankel, Edward, Ph.D. Poison Ivy, Poison Oak, Poison Sumac and Their Relatives; Pistachios, Mangoes and Cashews. The Boxwood Press. Pacific Grove, Calif. 1991. ISBN 978-0-940168-18-3.
- DermAtlas -1892628434
- Armstrong W.P., Epstein W.L. (1995). Herbalgram (American Botanical Council) 34: 36–42. cited in http://waynesword.palomar.edu/ww0802.htm
- Galli SJ (2000). "Allergy". Curr. Biol. 10 (3): R93–5. doi:10.1016/S0960-9822(00)00322-5. PMID 10679332.
- De Swert LF (1999). "Risk factors for allergy". Eur. J. Pediatr. 158 (2): 89–94. doi:10.1007/s004310051024. PMID 10048601.
- Croner S (1992). "Prediction and detection of allergy development: influence of genetic and environmental factors". J. Pediatr. 121 (5 Pt 2): S58–63. doi:10.1016/S0022-3476(05)81408-8. PMID 1447635.
- Jarvis D, Burney P (1997). "Epidemiology of atopy and atopic disease". In Kay AB. Allergy and allergic diseases 2. London: Blackwell Science. pp. 1208–24.
- Anderson HR, Pottier AC, Strachan DP (1992). "Asthma from birth to age 23: incidence and relation to prior and concurrent atopic disease". Thorax 47 (7): 537–42. doi:10.1136/thx.47.7.537. PMC 463865. PMID 1412098.
- Barnes KC, Grant AV, Hansel NN, Gao P, Dunston GM (2007). "African Americans with asthma: genetic insights". Proc Am Thorac Soc 4 (1): 58–68. doi:10.1513/pats.200607-146JG. PMC 2647616. PMID 17202293. Archived from the original on 2010-11-16.
- Folkerts G, Walzl G, Openshaw PJ (March 2000). "Do common childhood infections 'teach' the immune system not to be allergic?". Immunol. Today 21 (3): 118–20. doi:10.1016/S0167-5699(00)01582-6. PMID 10777250.
- "The Hygiene Hypothesis". Edward Willett. 2013-01-30. Retrieved 2013-05-30.
- Gibson PG, Henry RL, Shah S, Powell H, Wang H (September 2003). "Migration to a western country increases asthma symptoms but not eosinophilic airway inflammation". Pediatr. Pulmonol. 36 (3): 209–15. doi:10.1002/ppul.10323. PMID 12910582.. Retrieved 2008-07-06.
- Addo-Yobo EO, Woodcock A, Allotey A, Baffoe-Bonnie B, Strachan D, Custovic A (February 2007). "Exercise-induced bronchospasm and atopy in Ghana: two surveys ten years apart". PLoS Med. 4 (2): e70. doi:10.1371/journal.pmed.0040070. PMC 1808098. PMID 17326711. Archived from the original on 2010-11-16.
- Marra F, Lynd L, Coombes M, et al. (2006). "Does antibiotic exposure during infancy lead to development of asthma?: a systematic review and metaanalysis". Chest 129 (3): 610–8. doi:10.1378/chest.129.3.610. PMID 16537858.
- Thavagnanam S, Fleming J, Bromley A, Shields MD, Cardwell, CR (2007). "A meta-analysis of the association between Caesarean section and childhood asthma". Clin. And Exper. Allergy 38 (4): 629–33. doi:10.1111/j.1365-2222.2007.02780.x. PMID 18352976.
- Zock JP, Plana E, Jarvis D, et al. (2007). "The use of household cleaning sprays and adult asthma: an international longitudinal study". Am J Respir Crit Care Med 176 (8): 735–41. doi:10.1164/rccm.200612-1793OC. PMC 2020829. PMID 17585104.
- Cooper PJ (2004). "Intestinal worms and human allergy". Parasite Immunol. 26 (11–12): 455–67. doi:10.1111/j.0141-9838.2004.00728.x. PMID 15771681.
- Braun-Fahrländer C, Riedler J, Herz U, et al. (2002). "Environmental exposure to endotoxin and its relation to asthma in school-age children". N. Engl. J. Med. 347 (12): 869–77. doi:10.1056/NEJMoa020057. PMID 12239255.
- Garn H, Renz H (2007). "Epidemiological and immunological evidence for the hygiene hypothesis". Immunobiology 212 (6): 441–52. doi:10.1016/j.imbio.2007.03.006. PMID 17544829.
- Macpherson CN, Gottstein B, Geerts S (2000). "Parasitic food-borne and water-borne zoonoses". Rev. – Off. Int. Epizoot. 19 (1): 240–58. PMID 11189719.
- Carvalho EM, Bastos LS, Araújo MI (2006). "Worms and allergy". Parasite Immunol. 28 (10): 525–34. doi:10.1111/j.1365-3024.2006.00894.x. PMID 16965288.
- Yazdanbakhsh M, Kremsner PG, van Ree R (2002). "Allergy, parasites, and the hygiene hypothesis". Science 296 (5567): 490–4. doi:10.1126/science.296.5567.490. PMID 11964470.
- Emanuelsson C, Spangfort MD (2007). "Allergens as eukaryotic proteins lacking bacterial homologues". Mol. Immunol. 44 (12): 3256–60. doi:10.1016/j.molimm.2007.01.019. PMID 17382394.
- Falcone FH, Pritchard DI (2005). "Parasite role reversal: worms on trial". Trends Parasitol. 21 (4): 157–60. doi:10.1016/j.pt.2005.02.002. PMID 15780835.
- Grimbaldeston MA, Metz M, Yu M, Tsai M, Galli SJ (2006). "Effector and potential immunoregulatory roles of mast cells in IgE-associated acquired immune responses". Current Opinion in Immunology 18 (6): 751–60. doi:10.1016/j.coi.2006.09.011. PMID 17011762.
- Holt PG, Sly PD (2007). "Th2 cytokines in the asthma late-phase response". Lancet 370 (9596): 1396–8. doi:10.1016/S0140-6736(07)61587-6. PMID 17950849.
- Martín A, Gallino N, Gagliardi J, Ortiz S, Lascano AR, Diller A, Daraio MC, Kahn A, Mariani AL, Serra HM (2002). "Early inflammatory markers in elicitation of allergic contact dermatitis". BMC Dermatology 2: 9. doi:10.1186/1471-5945-2-9. PMC 122084. PMID 12167174.
- Portnoy, JM, et al.. Evidence-based Allergy Diagnostic Tests, Current Allergy and Asthma Reports 2006, 6:455–461
- NICE Diagnosis and assessment of food allergy in children and young people in primary care and community settings, 2011
- Boyce J et al.. Guidelines for the Diagnosis and Management of Food Allergy in the United States: Report of NIAID-Sponsored Expert Panel. J Allergy Clin Immunol 2010; 126: S1–S58
- Cox, L. Overview of Serological-Specific IgE Antibody Testing in Children. Pediatric Allergy and Immunology. 2011.
- Food Allergy in children and young people. Costing report. Implementing NICE guidance, 2011. http://guidance.nice.org.uk/CG116/CostingReport/pdf/English
- NIH Guidelines for the Diagnosis and Management of Food Allergy in the United States. Report of the NIAID- Sponsored Expert Panel, 2010, NIH Publication no. 11-7700.
- Verstege A, Mehl A, Rolinck-Werninghaus C, et al. (2005). "The predictive value of the skin prick test weal size for the outcome of oral food challenges". Clin. Exp. Allergy 35 (9): 1220–6. doi:10.1111/j.1365-2222.2005.2324.x. PMID 16164451.
- Li JT, Andrist D, Bamlet WR, Wolter TD (2000). "Accuracy of patient prediction of allergy skin test results". Ann. Allergy Asthma Immunol. 85 (5): 382–4. doi:10.1016/S1081-1206(10)62550-1. PMID 11101180.
- Yunginger J et al.. "Quantitative IgE antibody assays in allergic disease". J Allergy Clin Immunol 2000; 105: 1077–84.
- Sampson H et al.. "Utility of food-specific IgE concentrations in predicting symptomatic food allergy". J Allergy Clin Immunol 2001; 107: 891–6.
- Kerkhof M, Dubois AE, Postma DS, Schouten JP, de Monchy JG (2003). "Role and interpretation of total serum IgE measurements in the diagnosis of allergic airway disease in adults". Allergy 58 (9): 905–11. doi:10.1034/j.1398-9995.2003.00230.x. PMID 12911420.
- "Allergy Diagnosis". Archived from the original on 2010-11-16.The Online Allergist. Retrieved 2010-10-25.
- Allergic and Environmental Asthma at eMedicine – Includes discussion of differentials
- Wheeler PW, Wheeler SF (2005). "Vasomotor rhinitis". American Family Physician 72 (6): 1057–62. PMID 16190503.[dead link]
- Sicherer SH, Leung DY (2007). "Advances in allergic skin disease, anaphylaxis, and hypersensitivity reactions to foods, drugs, and insects". The Journal of Allergy and Clinical Immunology 119 (6): 1462–9. doi:10.1016/j.jaci.2007.02.013. PMID 17412401.
- Funada U, Wada M, Kawata T, Tanaka N, Tadokoro T, Maekawa A (2000). "Effect of cobalamin on the allergic response in mice". Biosci. Biotechnol. Biochem. 64 (10): 2053–8. doi:10.1271/bbb.64.2053. PMID 11129575.
- Straley, DR (January–February 2013). "Office IgE-mediated environmental allergy evaluation and treatment". Osteopathic Family Physician 5 (1): 9–16. doi:10.1016/j.osfp.2012.08.003.
- Ross RN, Nelson HS, Finegold I (2000). "Effectiveness of specific immunotherapy in the treatment of allergic rhinitis: an analysis of randomized, prospective, single- or double-blind, placebo-controlled studies". Clinical therapeutics 22 (3): 342–50. doi:10.1016/S0149-2918(00)80038-7. PMID 10963288.
- Penagos, M; Compalati, E; Tarantini, F; Baena-Cagnani, R; Huerta, J; Passalacqua, G; Canonica, GW (August 2006). "Efficacy of sublingual immunotherapy in the treatment of allergic rhinitis in pediatric patients 3 to 18 years of age: a meta-analysis of randomized, placebo-controlled, double-blind trials". Annals of Allergy, Asthma & Immunology 97 (2): 141–8. doi:10.1016/S1081-1206(10)60004-X. PMID 16937742.
- Abramson MJ, Puy RM, Weiner JM (April 1995). "Is allergen immunotherapy effective in asthma? A meta-analysis of randomized controlled trials". American Journal of Respiratory and Critical care Medicine 151 (4): 969–74. doi:10.1164/ajrccm/151.4.969. PMID 7697274.
- Rank MA, Li JT (September 2007). "Allergen immunotherapy". Mayo Clin. Proc. 82 (9): 1119–23. doi:10.4065/82.9.1119. PMID 17803880.
- Passalacqua G, Durham SR (2007). "Allergic rhinitis and its impact on asthma update: allergen immunotherapy". The Journal of Allergy and Clinical Immunology 119 (4): 881–91. doi:10.1016/j.jaci.2007.01.045. PMID 17418661.
- Canonica GW, Bousquet J, Casale T, Lockey RF, Baena-Cagnani CE, Pawankar R, Potter PC, Bousquet PJ, Cox LS, Durham SR, Nelson HS, Passalacqua G, Ryan DP, Brozek JL, Compalati E, Dahl R, Delgado L, van Wijk RG, Gower RG, Ledford DK, Filho NR, Valovirta EJ, Yusuf OM, Zuberbier T, Akhanda W, Almarales RC, Ansotegui I, Bonifazi F, Ceuppens J, Chivato T, Dimova D, Dumitrascu D, Fontana L, Katelaris CH, Kaulsay R, Kuna P, Larenas-Linnemann D, Manoussakis M, Nekam K, Nunes C, O'Hehir R, Olaguibel JM, Onder NB, Park JW, Priftanji A, Puy R, Sarmiento L, Scadding G, Schmid-Grendelmeier P, Seberova E, Sepiashvili R, Solé D, Togias A, Tomino C, Toskala E, Van Beever H, Vieths S (December 2009). "Sub-lingual immunotherapy: World Allergy Organization Position Paper 2009". Allergy. 64 Suppl 91: 1–59. doi:10.1111/j.1398-9995.2009.02309.x. PMID 20041860.
- Terr AI (2004). "Unproven and controversial forms of immunotherapy". Clinical allergy and immunology 18: 703–10. PMID 15042943.
- Altunç U, Pittler MH, Ernst E (2007). "Homeopathy for childhood and adolescence ailments: systematic review of randomized clinical trials". Mayo Clin. Proc. 82 (1): 69–75. doi:10.4065/82.1.69. PMID 17285788.
- Sausenthaler S; Heinrich J; Koletzko S. Early diet and the risk of allergy: what can we learn from the perspective birth cohort studies GINIplus and LISAplus?. AJCN [Online] 2011, 94, 2012S-7S.
- Patelarou E; Giourgouli G; Brokalaki H; et al.. Association between biomarker-quantified antioxidant status during pregnancy and infancy and allergic disease during early childhood: A systematic review. Nutrition Reviews [Online]. 2011, 69, 27–641.
- Pelucchi, C; Chatenoud, L; Turati, F; Galeone, C; Moja, L; Bach, JF; La Vecchia, C (May 2012). "Probiotics supplementation during pregnancy or infancy for the prevention of atopic dermatitis: a meta-analysis". Epidemiology (Cambridge, Mass.) 23 (3): 402–14. doi:10.1097/EDE.0b013e31824d5da2. PMID 22441545.
- Platts-Mills TA, Erwin E, Heymann P, Woodfolk J (2005). "Is the hygiene hypothesis still a viable explanation for the increased prevalence of asthma?". Allergy. 60 Suppl 79: 25–31. doi:10.1111/j.1398-9995.2005.00854.x. PMID 15842230.
- Bloomfield SF, Stanwell-Smith R, Crevel RW, Pickup J (2006). "Too clean, or not too clean: the hygiene hypothesis and home hygiene". Clin. Exp. Allergy 36 (4): 402–25. doi:10.1111/j.1365-2222.2006.02463.x. PMC 1448690. PMID 16630145.
- Isolauri E, Huurre A, Salminen S, Impivaara O (2004). "The allergy epidemic extends beyond the past few decades". Clin. Exp. Allergy 34 (7): 1007–10. doi:10.1111/j.1365-2222.2004.01999.x. PMID 15248842.
- "Chapter 4: The Extent and Burden of Allergy in the United Kingdom". House of Lords – Science and Technology – Sixth Report. 2007-07-24. Archived from the original on 2010-11-16. Retrieved 2007-12-03.
- "AAAAI – rhinitis, sinusitis, hay fever, stuffy nose, watery eyes, sinus infection". Archived from the original on 2010-11-16. Retrieved 2007-12-03.
- Based on an estimated population of 303 million in 2007 U.S. POPClock. U.S. Census Bureau.
- Based on an estimated population of 60.6 million UK population grows to 60.6 million
- "AAAAI – asthma, allergy, allergies, prevention of allergies and asthma, treatment for allergies and asthma". Archived from the original on 2010-11-16. Retrieved 2007-12-03.
- "AAAAI – skin condition, itchy skin, bumps, red irritated skin, allergic reaction, treating skin condition". Archived from the original on 2010-11-16. Retrieved 2007-12-03.
- "AAAAI – anaphylaxis, cause of anaphylaxis, prevention, allergist, anaphylaxis statistics". Archived from the original on 2010-11-16. Retrieved 2007-12-03.
- "AAAAI – food allergy, food reactions, anaphylaxis, food allergy prevention". Archived from the original on 2010-11-16. Retrieved 2007-12-03.
- "AAAAI – stinging insect, allergic reaction to bug bite, treatment for insect bite". Archived from the original on 2010-11-16. Retrieved 2007-12-03.
- Simpson CR, Newton J, Hippisley-Cox J, Sheikh A (2008). "Incidence and prevalence of multiple allergic disorders recorded in a national primary care database". Journal of the Royal Society of Medicine 101 (11): 558–563. doi:10.1258/jrsm.2008.080196. PMC 2586863. PMID 19029357.
- Strachan DP (1989). "Hay fever, hygiene, and household size". BMJ 299 (6710): 1259–60. doi:10.1136/bmj.299.6710.1259. PMC 1838109. PMID 2513902.
- Renz H, Blümer N, Virna S, Sel S, Garn H (2006). "The immunological basis of the hygiene hypothesis". Chem Immunol Allergy. Chemical Immunology and Allergy 91: 30–48. doi:10.1159/000090228. ISBN 3-8055-8000-2. PMID 16354947.
- Matricardi PM, Rosmini F, Riondino S, et al. (2000). "Exposure to foodborne and orofecal microbes versus airborne viruses in relation to atopy and allergic asthma: epidemiological study". BMJ 320 (7232): 412–7. doi:10.1136/bmj.320.7232.412. PMC 27285. PMID 10669445.
- Masters S, Barrett-Connor E (1985). "Parasites and asthma—redictive or protective?". Epidemiol Rev 7: 49–58. PMID 4054238.
- Sheikh A, Strachan DP (2004). "The hygiene theory: fact or fiction?". Current Opinion in Otolaryngology & Head and Neck Surgery 12 (3): 232–6. doi:10.1097/01.moo.0000122311.13359.30. PMID 15167035.
- Clemens Peter Pirquet von Cesenatico at Who Named It?
- Von Pirquet C (1906). "Allergie". Munch Med Wochenschr 53 (5): 388–90. PMID 20273584.
- Gell PGH, Coombs RRA. (1963). Clinical Aspects of Immunology. London: Blackwell.
- Ishizaka K, Ishizaka T, Hornbrook MM (1966). "Physico-chemical properties of human reaginic antibody. IV. Presence of a unique immunoglobulin as a carrier of reaginic activity". Journal of Immunology 97 (1): 75–85. PMID 4162440.
- Ten RM, Klein JS, Frigas E (1995). "Allergy skin testing". Mayo Clin. Proc. 70 (8): 783–4. doi:10.4065/70.8.783. PMID 7630219.[dead link]
- Cox, et al.. Pearls and pitfalls of allergy diagnostic testing. Annals of Allergy, Asthma & Immunology. 2008. 101(6): 580–592
- "ABAI: American Board of Allergy and Immunology". Archived from the original on 2010-11-16. Retrieved 2007-08-05.
- "AAAAI – What is an Allergist?". Archived from the original on 2010-11-16. Retrieved 2007-08-05.
- Royal College of Physicians (2003). Allergy: the unmet need. London, UK: Royal College of Physicians. ISBN 978-1-86016-183-4. PDF version (1.03 MB)
- House of Lords – Science and Technology Committee (2007). Allergy – HL 166-I, 6th Report of Session 2006–07 – Volume 1: Report. London, UK: TSO (The Stationery Office). ISBN 978-0-10-401149-2.
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- Allergies in children at Allergy UK
- American Academy of Allergy, Asthma & Immunology
- European Academy of Allergy & Clinical Immunology