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Allergy

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An allergy is an exaggerated immune response by the body. It occurs when the immune system mistakenly identifies a harmless substance as a dangerous threat. These substances are known as allergens.

The Allergy Pathway
The Allergy Pathway

This biological mistake can lead to various allergic diseases. These include hay fever, allergic conjunctivitis, and allergic asthma. Other conditions include atopic dermatitis, food allergies, and anaphylaxis. Symptoms vary depending on the part of the body affected. They can include red eyes, itchy rashes, sneezing, or coughing. Some people experience shortness of breath or swelling.

The biological mechanism of an allergy is a specific chain of events. It begins when immunoglobulin E antibodies, or IgE, bind to an allergen. These IgE antibodies then attach to receptors on specific cells called mast cells or basophils.

Allergy degranulation processes 01
Allergy degranulation processes 01

Once this binding occurs, it triggers the cells to release inflammatory chemicals. One of the most important chemicals released is histamine. This chemical release causes the physical symptoms of an allergy. For example, when an allergen enters the skin, mast cells activate. This increases the permeability of blood vessels, leading to fluid leakage and swelling.

Allergy skin testing
Allergy skin testing

Allergic reactions can affect many different organ systems. If allergens are airborne, such as pollen or dust, they often affect the nose, eyes, and lungs. Allergic rhinitis, or hay fever, irritates the nose and causes sneezing. Inhaled allergens can also cause the lungs to produce more mucus. This can lead to wheezing or shortness of breath.

Tissues Affected In Allergic Inflammation
Tissues Affected In Allergic Inflammation

Food allergies often affect the gastrointestinal tract. This can cause abdominal pain, bloating, vomiting, or diarrhea. Some allergies, like insect stings or certain medications, can cause a systemic response. This is called anaphylaxis. Anaphylaxis can affect the digestive, respiratory, and circulatory systems simultaneously. It can cause low blood pressure, swelling, or even coma.

There are many different types of allergens that people encounter. Common airborne allergens include pollen and house dust mites.

House dust mites (5247996458)
House dust mites (5247996458)

Dust mite allergies are often triggered by the droppings of these mites. Certain foods are also major triggers for allergic reactions. About 90% of food allergies are caused by cow's milk, soy, eggs, wheat, peanuts, tree nuts, fish, and shellfish.

Insect stings are another frequent source of allergies. Additionally, some people react to materials like latex.

Latex mask eg
Latex mask eg

Even common medications, such as penicillin or aspirin, can cause reactions.

Scientists have been studying these responses for over a century. The term "allergy" was first used by Clemens von Pirquet in 1906. Since then, researchers have identified various risk factors. These include host factors like heredity, sex, race, and age. Heredity is considered the most significant factor. However, there is a recent increase in allergic disorders that cannot be explained by genetics alone. Environmental factors also play a role. These include changes in dietary habits, environmental pollution, and levels of allergens. Changes in exposure to infectious diseases during early childhood are also considered candidates.

Allergies are very common in the modern world. In developed nations, about 20% of people suffer from allergic rhinitis. Atopic dermatitis affects about 20% of people at some point in their lives. Food allergies affect 10% of adults and 8% of children.

Peanut Snack (26238488870)
Peanut Snack (26238488870)

The rates of asthma vary by country, ranging from 1% to 18%. Anaphylaxis is less common, occurring in between 0.05% and 2% of the population. These numbers show how widespread these conditions are globally. Understanding these statistics helps researchers track how allergy rates appear to be increasing.

Doctors use several methods to diagnose and treat allergies. A person's medical history is often the first step in diagnosis. Doctors may also use skin or blood tests to confirm a specific allergy.

Allergy skin testing
Allergy skin testing

One primary treatment is avoiding known allergens. Medications like antihistamines and steroids are also used to manage symptoms. For severe cases of anaphylaxis, injectable adrenaline, also called epinephrine, is recommended. Some people use allergen immunotherapy. This involves gradually exposing the person to larger amounts of an allergen. This can be useful for hay fever or insect bite reactions.

Anti-Allergy Immunotherapy
Anti-Allergy Immunotherapy
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🖼️ Images & Media (22)
File:Allergy test on arm.jpg
Allergy test on arm.jpg
File:House dust mites (5247996458).jpg
House dust mites (5247996458).jpg
File:Summer Palace restaurant menu back pages displaying vegetarian options, rice dishes, set dinners and desserts with allergy information.jpg
Summer Palace restaurant menu back pages...
File:Latex mask eg.jpg
Latex mask eg.jpg
File:530424647922ef532def2o.jpg
530424647922ef532def2o.jpg
File:Mauch Twins.jpg
Mauch Twins.jpg
File:Klimt hygeia.jpg
Klimt hygeia.jpg
File:Hookworm LifeCycle.gif
Hookworm LifeCycle.gif
File:The Allergy Pathway.jpg
The Allergy Pathway.jpg
File:Tissues Affected In Allergic Inflammation.jpg
Tissues Affected In Allergic Inflammation.jpg
File:Allergy degranulation processes 01.svg
Allergy degranulation processes 01.svg
File:Allergy testing machine.jpg
Allergy testing machine.jpg

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