Allergy knows no boundaries and affects differently people of all age groups, infants, children, teenagers, adults and the elderly.
Allergy, defined by the World Health Organization (WHO) as ‘immunologically mediated hypersensitivity,’ has been on the rise for a long time and it is estimated that over 20% of the world’s population suffers from IgE-mediated allergic diseases.
People with allergy react abnormally to normally harmless things. Contact with these makes their body react aggressively, producing in many cases so-called immunoglobulin (IgE) antibodies, and activating immune cells, such as eosinophils or mast cells. This usually happens after repeated exposure. The initial process, by which an individual becomes sensitive, is called “allergic sensitisation”. The offending substances are called “allergens”.
The allergy symptoms are a consequence of the release of damaging substances from the activated cells. People who are predisposed to produce IgE antibodies and have allergy symptoms are called “atopic.”
The type of allergic reaction depends on the individual’s immunological makeup and the organ affected by allergy, i.e., the “target organ”). So, allergic people may have allergic rhinitis and asthma (target organ: upper and lower airways), conjunctivitis (target organ: the eye), eczema, urticaria and angioedema (target organ: the skin), and food allergy (target organ: all the above, plus in some cases the gastrointestinal tract). Even if allergic symptoms appear in these target organs, allergy is a systemic disease in which the whole defence system of the body is involved, although symptoms may appear in only one target organ. A person may have just one allergy or several and this may vary at any time during life. If the whole body suddenly responds to the allergen, there will be an acute, generalized allergic reaction, which is called “anaphylactic” reaction. Anaphylactic reactions may result in the drop of blood pressure, in which case we have an anaphylactic shock, which can be very severe and may even be fatal.