Allergy is one of the most widespread diseases of the modern world. More than 25% of the population in industrialized countries suffers from allergies (Valenta; 2002). According to the Asthma and Allergic Foundation of America (2002), allergies are the sixth leading cause of chronic diseases in the U.S, and the annual cost of dealing with them is estimated at $18 Billion.
Every individual has his or her own immune system; the stronger the immune system, the healthier will be the person. Allergies, also known as hypersensitive reactions, occur when the immune system overreacts to substances that do not affect most people. These substances, also known as allergens, could be pollen, animal dander, chemicals, fungi, dust mites, or foods such as nuts, eggs, shellfish, fish, and milk.
Different people show different symptoms of allergies, which
can be mild (runny nose) to severe (anaphylaxis). Symptoms
generally depend upon the part of body contacted by the allergen,
e.g., pollens from the air enter the respiratory tract via the
nose and cause respiratory symptoms such as cough, itchy and runny
nose, nasal congestion, sneezing, and wheezing. Food allergy related
symptoms include vomiting, nausea, abdominal pain, and diarrhea.
Skin allergy symptoms are lesions, rashes, blisters, redness and
itchiness, and so on.
Go To The Immunology of Allergies
Special thanks to Deborah
Whitman for her invaluable help with this Discovery Guide
List of Visuals
- Grass showing anthers (the brown bits dangling from the top of the grass) which shed pollen
Dr. John Bailey (Dept of Botany, University of Leicester)
- The house dust mite, its feces and chitin are common allergens around the home
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