Allergy

Allergy is a disorder of the immune system also known as atopy. Allergic reactions are acquired, predictable and rapid that occur to environmental substances known as allergens.Allergy consists of four forms of hypersensitivity.Type 1 or immediate hypersensitivity is characterized by excessive activation of certain white blood cells called mast cells and basophils, a type of antibody known as IgE, which causes an extreme inflammatory response. Common allergic reactions include eczema, hives, hay fever, asthma, food allergies, and reactions to the poison of stinging insects such as wasps and bees.

The human population mostly suffers with mild allergies like hay fever and results in symptoms such as allergic conjunctivitis, itchiness, and runny nose. Allergies can play a major role in conditions such as asthma.In some people, severe allergiesmay 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.




Signs and symptoms

common symptoms of allergies


Nose: Swelling of the nasal mucosa (allergic rhinitis).

Sinuses: Allergic sinusitis.

Eyes: Redness and itching of the conjunctiva (allergic conjunctivitis).

Airways: Sneezing, coughing, bronchoconstriction, wheezing and
dyspnea, sometimes outright attacks of asthma, in severe cases
the airway constricts due to swelling known as angioedema.

Ear: 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


Cause:

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. There have been recent increases in the incidence of allergic disorders, however, that cannot be explained by genetic factors alone. The four main environmental candidates are alterations in exposure to infectious diseases during early childhood, environmental pollution, allergen levels, and dietary changes.

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.

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.