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Abstract
Allergic rhinitis is defined as a symptomatic disorder of the mucous membranes of the nose caused by immunoglobulin-E-mediated (IgE-mediated) inflammation after the membranes of the nose have been exposed to allergens. There are two distinct phases:
The acute-phase response: Following exposure to an allergen, histamine and other inflammatory mediators are released from mast cells in the nasal mucosa. These act on cells, nerve endings, and blood vessels to produce the acute symptoms of allergic rhinitis. Inflammatory cells then migrate to the nasal mucosa, in a process known as priming, resulting in sneezing, nasal congestion and/or secretion (Van Cauwenburge et al, 2000)
The late-phase response: Symptoms usually peak about 6-12 hours after the initial exposure to allergens, and tend to manifest as nasal obstruction, although running nose and sneezing may still be present (ARIA, 2001).
Prevalence:-
There is a high prevalence of allergic disease allover the world.
The true prevalence and incidence of allergic rhinitis is difficult to assess accurately, with surveys of the general population invariably showing a much higher prevalence than surveys confined to general practice: Many people self diagnose and treat themselves, as there is a product in each drug class available ’over the counter’.
It is possible that people who have mild symptoms may not perceive their symptoms to be serious enough to seek a consultation (Ross and Fleming, 2004).
A recent telephone survey of adults has estimated that the lifetime prevalence of allergic rhinitis is at least 20%, but probably over 30% (Bauchau and Durham, 2004).
The incidence of the type and severity of allergic rhinitis is related to age
Children of school age and adolescents are most commonly affected by seasonal allergic rhinitis.
Adults are more likely than children or adolescents to suffer from persistent allergic rhinitis.
Classification:-
A new international classification of allergic rhinitis has been proposed (ARIA, 2001). Previously, allergic rhinitis was described as seasonal, perennial, or occupational.
The new classification is based on the frequency and duration of symptoms (intermittent or persistent), and the severity of symptoms and effect on quality of life (mild or moderate-severe). See Table 1 for the definitions of each classification.