Perennial Allergic Rhinitis

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What is Perennial Allergic Rhinitis?

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Allergic rhinitis is an allergic disease which affects many people worldwide. Rhinitis means 'inflammation of the nose', whilst the term allergic describes 'a normal but exaggerated response to a substance'. It may be perennial, which means symptoms are present throughout the year, or seasonal, with symptoms peaking during the months of spring and summer when pollen levels are at their highest.

Perennial rhinitis is characterised primarily by nasal symptoms including watering or congestion of the nose and sneezing. It occurs due to an exaggerated response to an environmental trigger which results in inflammation of the lining of the nose. It is similar to hayfever, however, the substances which cause the allergic reaction are present all year round.

Common causes include the faecal matter of the house dust-mite, animal proteins from domestic pets, and industrial dusts and fumes.

Who gets Perennial Allergic Rhinitis?

The prevalence of perennial allergic rhinitis varies worldwide. Many people do not seek treatment and the exact figures for perennial rhinitis are often under-reported, although it is universally acknowledged that it is an extremely common condition.

The 2004-05 National Health Survey stated that 3.2 million Australians (approximately 16.1% of the population) self-reported experiencing symptoms of hay-fever and perennial rhinitis. The prevalence was found to be highest amongst those aged 25-34 and was slightly higher among females (1.7 million) than males (1.5 million).

Number of people with allergic rhinitis (by age)

Age	0-14	15-24	25-34	35-44	45-54	55-64	65-74	>74	Male	Female	Total
thousand	303.4	521.8	618.6	601.7	528.6	315.1	158.2	118.3	1463.5	1702.2	3165.7

Percentage of the population with allergic rhinitis (by state)

State	NSW	Vic	Qld	SA	WA	Tas	ACT	Aust
%	13.8	18.2	14.1	20.9	18.8	14.7	21.6	16.1

Predisposing Factors

Atopy

Atopy describes a syndrome of over-active immune responses, in which individuals are more likely to develop allergy-related diseases including allergic rhinitis, asthma, and eczema. These individuals have higher levels of IgE antibody in their blood which is responsible for the inflammatory response seen in allergies.

Predisposing factors to atopy include:

Genetics - atopy is inherited as an autosomal dominant condition.
Maternal and neonatal factors - such as smoking in pregnancy and early childhood, low birth weight, birth during the pollen season (though this is still being debated), early introduction of formula and food.

There is much research underway into other factors which may predispose to atopy in childhood, including early exposure to allergens in the environment, and maternal and early childhood diet. Exposure to allergens is the second component of allergic rhinitis.

Perennial allergic rhinitis is caused by house-dust mite faeces, domestic pets (saliva or skin proteins), industrial dust, vapours and fumes. In those with perennial rhinitis, cigarette smoke, washing powders, detergents, strong perfume, and traffic fumes may exacerbate the condition.

Progression

Some people are predisposed to have an exaggerated response to a substance that is usually tolerated by the body. When these substances promote an allergic reaction they are known as allergens. In susceptible individuals, allergens initiate an immune response which is controlled by immune cells in the body (such as mast cells). The allergen binds to a protein called IgE on the surface of mast cells, causing them to release potent inflammatory agents such as histamine.

In the case of allergic rhinitis, the early response to allergens results in a runny nose, itching, and sneezing. The late response is similar, however the nose is usually more congested.

Perennial allergic rhinitis results in symptoms all year round, as the allergens causing the disease (dust-mite, pets) are always present in the environment.

Nasal polyps occur in some people with perennial rhinitis; they are smooth, round, soft structures attached to the lining of the nose. They can cause obstruction of the nose, and loss of smell. Occasionally they need to be surgically removed due to extreme discomfort.

Over time, people with perennial rhinitis may experience a reduced sense of smell, headaches, and recurrent infections. Other potential complications include infections of the middle ear and sinuses.

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