Wednesday, 3 September 2014
In individuals with a sensitized immune system, the allergen triggers the production of antibodyimmunoglobulin E (IgE). In turn, this IgE sticks to mast cells and basophils containing histamine.
When allergic rhinitis is caused by pollens (regardless of plant), it is called pollinosis. When it is caused specifically by grass pollens, it is called hay fever. An allergic reaction to pollens from plans and grasses can produce cold or flu-like symptoms, but it does not cause a fever. Consequently, the hay fever does not actually spike a fever.
Allergens stimulate IgE bound to mast cells, thus causing the body to react and release inflammatory mediators such as histamine and other chemicals. When this occurs, allergic individuals typically experience sneezing, itchy nose, itchy and watery eyes, swelling and inflammation of the nasal passages, as well as an increased mucus production.
While particulate matter in polluted air or chemicals such as detergents and chlorine are normally tolerated, individuals with allergic rhinitis can feel greatly aggravated symptoms. On the other hand, allergies are quite common.
Roughly one in three people have some sort of active allergy at any given time, while at least three in four people experience an allergic reaction at least once in their lives. Some individuals may be more prone to allergies than others, depending on heredity and environmental exposures. In Western countries, roughly 10 to 25 percent of people suffer from allergic rhinitis on an annual basis.
Types of Allergic Rhinitis/ Hay Fever
Allergic rhinitis may be either seasonal, i.e. particularly during pollen seasons, or perennial, persisting throughout the year. Seasonal allergic rhinitis typically develops after age 6, while perennial allergic rhinitis commonly affects younger children.
Another classification for allergic rhinitis breaks it down into four categories: Mild-Intermittent, Moderate-Severe Intermittent, Mild-Persistent, and Moderate-Severe Persistent.
When symptoms occur less than four days per week or less than four consecutive weeks, allergic rhinitis is considered intermittent. When the symptoms occur for more than four days per week and more than four consecutive weeks, it is considered persistent. Mild symptoms include normal sleep, no negative effect in daily activities, no impairment of work or school. These mild symptoms can be somewhat annoying at times, but are typically not very troublesome. Severe symptoms, meanwhile, cause sleep disturbance, have a negative effect on daily activities and impair school or work.
Signs and Symptoms of Allergic Rhinitis
The main characteristic symptoms of allergic rhinitis, including hay fever, include excess nasal secretion (rhinorrhea), itching, nasal congestion and obstruction. Physical signs include conjunctival swelling, erythema, swollen eyelids, lower eyelid venous stasis (also known as “allergic shiners,” these appear as rings under the eyes), swollen nasal turbinates, middle ear effusion.
While not all allergic individuals show behavioral signs, these might be present. Such signs may include wiping or rubbing the nose to relieve the irritation, itching or flow of mucus. This move is typically done with the palm of the hand in an upward motion and is known as the “allergic salute” or “nasal salute.” This, in turn, may cause a crease running across the nose, which is known as the “transverse nasal crease.” In time, this can result in permanent physical deformity, so it is advisable to refrain from this “allergic salute.”
Some allergic individuals may also experience some cross-reactivity. Someone allergic to birch pollen, for instance, may also experience an allergic reaction to the peel of apples or potatoes. Feeling an itchy throat after eating an apple or sneezing when peeling apples or potatoes is a clear sign of such cross-reactivity. There are a number of similarities in the proteins of the pollen and the food, and there are many cross-reacting substances that may prompt such allergic reactions. There are even some disorders associated with allergies, including eczema, asthma and depression.
Testing for Hay Fever & Other Allergies
Allergy testing can reveal the specific allergens to which an individual is sensitive. The most common method of allergy testing is skin testing, which may include intradermal, scratch, patch or other tests. The test can be harmful if done improperly, therefore it should only be conducted by a professional physician. If the physician determines that the patient cannot undergo such skin testing, the RAST blood test may be helpful in finding specific allergen sensitivity. Differential leukocyte count can show peripheral eosinophilia.
Allergy testing are not always 100 percent accurate. In some cases, such testing can show allergies even if they aren’t causing any actual symptoms, but in other cases it might miss allergies that do cause symptoms. The intradermal allergy test is more sensitive than the skin prick test. On the other hand, it is more often positive in people who do not have symptoms to that specific allergen. Truth be told, allergy tests can prove to be wrong in many occasions.
Even if an individual tests negative for allergies after skin-prick, intradermal and blood tests, they may still suffer from allergic rhinitis from a local allergy in the nose. This particular instance is called local allergic rhinitis, and requires specialized testing to diagnose it.
Pollen Allergies & Hay Fever
As previously mentioned, allergic rhinitis caused by the pollens of specific seasonal plants is commonly referred to as hay fever, due to its high prevalence during haying season. It is possible, however, to suffer for hay fever all throughout the year. The pollen triggering hay fever may vary from individual to individual, from region to region.
Overall, the predominant cause of hay fever consists of the tiny pollens of wind-pollinated plants, which are hardly visible to the naked eye. Pollens of insect-pollinated plans are too large to remain airborne, therefore posing no risk.
Plants Causing Hay Fever
There are many plans that may trigger hay fever reactions, but the most common ones include:
Trees: pine, birch, alder, cedar, hazel, hornbeam, horse chestnut, willow, poplar, plane (Platanus), linden/lime, and olive. Birch is the greatest allergenic tree pollen in northern regions, with roughly 15 – 20 percent of individuals with hay fever sensitive to birch pollen grains. Olive pollen, meanwhile, takes the top spot in Mediterranean regions. In Japan, hay fever is predominantly triggered by sugi and hinoki tree pollen. Trees that do not cause allergies include ash, red maple, yellow poplar, dogwood, magnolia, fir, double-flowered cherry, spruce, and flowering plum.
Grasses, especially ryegrass and timothy – roughly 90 percent of individuals suffering from hay fever are allergic to grass pollen.
Weeds, such as ragweed, plantain, netle/parietaria, Fat hen, mugwort, and sorrel/dock.
Hay Fever Treatment
Rhinitis treatment aims to prevent or at least reduce the symptoms caused by the inflammation of affected tissues. Avoiding the allergen can be very effective, but that’s not always possible or desirable (what if I want to roll around in grass?) If medications are required for managing hay fever symptoms, the preferred treatment involves intranasal corticosteroids. Mite proof covers, air filters, or avoiding certain foods during childhood have no evidence to support their effectiveness in reducing hay fever symptoms.
Intranasal corticosteroids are typically sued to manage symptoms such as sneezing, rhinorrhea, itching and nasal congestion. This treatment options provides great results for perennial rhinitis sufferers. Steroid nasal sprays, meanwhile, are an effective and safe treatment option, and may prove effective even without oral antihistamines. They do, however, take several days to become effective, and require continual use for several weeks. Their therapeutic effect increases as time passes. Systemic steroids such as prednisone can reduce nasal inflammation, but have a short-lasting effect. Prolonged steroid therapy also adds the risk of side effects.
Second line treatments include antihistamines, decongestants, leukotriene receptor antagonists, cromolyn, and non-pharmacologic therapies such as nasal irrigation. Antihistamines can be taken orally to handle symptoms such as rhinorrhea, sneezing, itching and conjunctivitis. For best results, allergic individuals should take the medication before exposure, especially for seasonal allergic rhinitis. Ophthalmic antihistamines are used for conjunctivitis, while intranasal solutions are used for sneezing, rhinorrhea and nasal pruritus.
