Respiratory allergy is a major health problem worldwide, often manifested in the shape of allergic rhinitis (hay fever). As examples, at least 10% of the world population suffers from pollen allergy and 5-30% is allergic to house dust mites, and the numbers are growing each year. On a global basis, the cost of medication, care and absenteeism is astronomical.
International guidelines define allergic rhinitis as a ‘symptomatic disorder of the nose induced by an IgE-mediated inflammation after allergen exposure of the membranes lining the nose’.
Allergic rhinitis may be either seasonal or perennial: seasonal allergic rhinitis is commonly known as ‘hay fever’. Grass and tree pollens (and some fungi) trigger seasonal allergic rhinitis, whereas allergens such as house-dust mites or animal dander may result in perennial allergic rhinitis.