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What are allergic diseases of the respiratory system?
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These diseases are caused by hypersensitivity to certain environmental substances that we come to contact with via the respiratory system, air, i.e. via inhalation Allergic rhinitis and asthma are a common disorder manifested in the upper (nose, sinuses) or lower respiratory tract (bronchi, lungs) and very often in both respiratory tracts. The effect of the environmental allergen to the mucous membrane of the respiratory system in hypersensitive individuals triggers a complex chain of events causing very typical symptoms. Depending on the allergens causing disorders, allergic rhinitis and asthma can be seasonal (pollens) or perennial (dust mites, pets and molds).
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What is hay fever (seasonal allergic rhinitis)?
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Seasonal allergic rhinitis is allergic diseases of the upper respiratory tract, nose and paranasal sinuses that appears seasonally at the time when the air is filled with particles of pollen. In Croatia seasonal allergic rhinitis is caused by tree, grass and weed pollen. It can appear in combination with other allergic diseases (asthma, atopic dermatitis), or contribute to emergence of other non-allergic diseases (sinusitis, otitis media). Hay fever usually includes allergic rhinitis and allergic conjunctivitis. In case of the latter, allergic reaction is manifested in the conjunctiva of the eye.
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What causes hay fever?
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Hay fever is caused by allergenic pollen from trees, grass and weeds. Symptoms are triggered by a corresponding concentration of pollen in the air. The higher the concentration, the stronger the symptoms which further means that they become more severe towards the peak of the blooming season. Pollen concentration is higher in the morning, in sunny and windy weather. In these conditions, dry and light pollen can be carried by wind over a greater distance. On the other hand, at the beginning and at the end of the blooming season and in humid and rainy weather, concentration of pollen in the air is much lower. Pollen from decorative flowers and flowers pollinated by insects causes difficulties very rarely due to its low concentration. Plants pollinated by wind (trees, grass, weeds) produce huge amounts of pollen.
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When is the period of hay fever?
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Blooming season accompanied by a high concentration of pollen in the air depends on the climate and vegetation of a specific region as well as on the microclimatic conditions. The following rules apply to the continental part of Croatia: blooming season for trees begins in the early spring, usually in February (hazel) and culminates in April and May (birch). Grass blooms from May to July and weeds from August to October. Blooming period for trees and weeds is shorter and more intensive whereas for grass it is longer and accompanied by a lower concentration of pollen in the air. In the coastal region, blooming starts earlier. In the Mediterranean region, disorders are caused by cypress pollen, olive pollen and pellitory weed pollen. Interestingly enough, sensitization is more frequent in case of birch, grass and Ambrosia pollen and children born during or immediately after the blooming season of a given plant are more prone to allergies.
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How to identify hay fever?
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Typical symptoms of conjunctivitis are itching, burning sensation and lacrimation. Nasal symptoms include itching of the tip of the nose, nasal obstruction, sneezing, sniffling, watery discharge and decreased smell or complete loss of smell. In some patients, certain symptoms prevail whereas others are less visible. In children, allergic rhinitis is usually accompanied by otitis. Symptoms of accompanying diseases (otitis, sinusitis or asthma) can conceal symptoms of allergic rhinitis.
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Do I have a cold or an allergy?
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Symptoms of cold and hay fever are similar and thus sometimes difficult to differ. Cold is identified via general symptoms, fever, cough and epidemiological data. Allergic rhinitis is accompanied by repeated appearance of symptoms in a given time period or following the contact with the same external factors. Allergic symptoms last usually longer and decrease upon consumption of corresponding drugs whereas cold symptoms cease spontaneously.
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What is perennial allergic rhinitis?
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In case of perennial allergic rhinitis, difficulties do not occur seasonably but in any time of the year. Sometimes they can be present throughout the year with different intensity. This disease is caused by allergens that remain in our environment throughout the year. In Croatia the perennial allergic rhinitis is most frequently caused by dust mites, allergens from pets' fur or molds. Among animal allergens, cat and dog allergens are more frequent than hamster and guinea-pig ones. In some patient perennial allergic rhinitis can be accompanied by seasonal relapses. Such patients are sensitive to perennial and seasonal allergens alike.
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What are the causes of perennial allergic rhinitis?
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The most frequent causes of perennial allergic rhinitis are dust mite allergens and less frequently allergens from the fur of pets or mold. It should be noted that the concentration of dust mite allergens is not directly connected to the amount of dust. Dust in humid (80% humidity), warm (25oC) and not aired premises has a higher concentration of mites. Dust mites usually live in mattresses, carpets and upholstered furniture. Dust mite allergy is the most important singular risk factor for appearance of other allergic diseases.
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What are the symptoms of the disease?
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Symptoms of perennial allergic rhinitis correspond to those of the seasonal one: itching, nasal obstruction, sneezing, sniffling, watery discharge and decreased smell or complete loss of smell. However, these symptoms are more severe and last longer whereas nasal obstruction is specially severe. Expert literature usually identifies three types of the disease: a) the one dominated by sneezing; b) the one dominated by itching; and c) the one dominated by swelling and darker pigmentation of lower eyelids. The disease is often accompanied by nasal polyposis and chronic sinusitis that can sometimes lead to incorrect clinical decision.
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How to prevent the disease
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The first step in treating allergic diseases of the respiratory system is to avoid allergens which the patient is sensitive to. This sometimes represents a hard and strenuous task, but sometimes the complete success of the therapy depends on it. Indeed, it is believed that insufficient elimination of allergens from the surrounding is the most frequent cause of an unsuccessful therapy. The only useful measure for avoiding seasonal allergens (pollens) is to stay indoor and avoid physical activities in the open during a high concentration of pollen in the air. Early morning jogging and recreation activities must be avoided especially in the area with abundant vegetation. Rooms must be aired briefly. In patients sensitive to perennial allergens, it is important to decrease the concentration of dust mites in home by eliminating upholstered furniture, carpets and curtains.
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What is a pollen calendar and how is it used?
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Pollen calendar contains information about blooming seasons for certain plants in a given region. Pollen calendars are different for regions with different weather conditions. Getting to know the pollen calendar helps in foretelling the time of appearance of allergy rhinitis and asthma symptoms which enables timely introduction of a corresponding treatment method. In case of these two diseases it is important to start with the treatment one to two weeks before the anticipated blooming season. In case of a major deviation from the usual weather conditions (unusually warm or cold weather), one can expect certain shifts in the pollen calendar, i.e. early or late blooming season.
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What is allergy traffic light?
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Allergy traffic light is a method for informing about the daily quantity of pollen particles in the air in a given region usually stated in newspapers or in some other public information media (www.plivazdravlje.hr). The colors on the allergy traffic light are defined by the measured quantity of pollen particles per cubic meter of atmospheric air. The green color denotes a concentration of pollen that can cause allergic symptoms in very few sensitive persons. The yellow color denotes a concentration causing symptoms in majority of allergic persons whereas the red color denotes a very high concentration of pollen that shall cause allergic symptoms in all sensitive persons and that might cause very severe symptoms in hypersensitive persons. Simultaneous estimation of the concentration of pollen in the air and climactic elements (temperature, humidity, wind condition) can offer very useful prognostic data enabling allergy patients to plan daily activities and corresponding preventive measures.
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What drugs might help mitigate hay fever symptoms?
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Treatment of hay fever includes various drugs in the form of tablets, drops, nasal sprays and injections: decongestants, antihistamines, corticosteroids, cromolyns, anticholinergics and antileukotrien drugs. It should be mentioned that the medications from the stated groups are not available in Croatia, but the present selection offers a possibility of successful treatment.
Decongestants ("nose drops") are drugs directly affecting blood vessels in the nasal mucous membrane thus decreasing obstruction and unpleasant abundant nasal water discharge. In patients with allergic rhinitis, drugs (naphazoline, oxymetazoline, tetrahydrozoline) are often overdosed or unnecessarily taken which can cause serious side-effects. It is recommended to take for a very short period decongestants to unblock the nose in order to apply intranasal antihistamines and corticosteroids that effectively decrease the stated symptoms.
Antihistamines are most frequently proscribed drugs for hay fever allergy symptoms. They are usually proscribed in tablets (loratadine, fexofenadine, cetirizine, diphenhidramine) and less frequently locally in the form of nasal spray or eye drops (levokacastin, azelastin). Modern antihistamines are reliable drugs that successfully mitigate the majority of allergy symptoms, especially if taken before appearance of symptoms.
Corticosteroids are anti-inflammatory drugs that most effectively mitigate allergy symptoms. They are proscribed when application of antihistamines has not completely eliminated the symptoms, i.e. in serious cases of disease, and are taken either independently or in combination with antihistamines. By rule, they are proscribed in the form of a nasal spray (beclomethasone, fluticasone, mometasone i budesonid), and only exceptionally in cases of serious forms of the disease, in the form of tablets.
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What is hyposensitization?
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Hyposensitization (desensitization) or immunotherapy is a type of treatment of allergic diseases based on the use of allergenic vaccines. This means that production and tolerance of the allergen the patient is sensitive to is incited by application of a small and gradually increasing concentration of that specific allergen. In patients that have successfully undergone immunotherapy, the next contact with a specific allergen shall not provoke symptoms of the disease or if it does, these shall be much weaker than beforehand. Vaccines can be given in the form of subcutaneous injections or solutions taken under the tongue. Immunotherapy is recommended in younger patients with perennial, long-lasting or serious seasonal allergic rhinitis, especially when avoiding the allergens is not possible or has not proved to be sufficiently successful and when drugs have not been completely effective.
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When is immunotherapy effective?
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Immunotherapy should be used only for carefully selected patients (see the previous question). It should be based on the high-quality standardized allergy vaccines and the treatment, lasting no more than 3 to 4 years, should be carried out and monitored by an experienced doctor. In such conditions immunotherapy can be a very effective method of treatment. Immunotherapy is especially effective in patients with the allergy caused by insect venom. It should be noted that immunotherapy can cause side-effects that can sometimes be very severe. Thus, it is important that an experienced doctor keeps monitoring the patient 30 to 45 minutes following the received allergy vaccine.
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What is asthma?
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Asthma is a disease characterized by coughing attacks and obstructed or audible respiration ("wheezing", "whistling") that cease spontaneously or after application of the corresponding drugs. The patients usually feels well between the attacks. Asthma is caused by the chronic airways inflammation, development and intensity of which is unsteady. Contraction of airways muscles and increased mucus secretion occur in the stage of active inflammation obstructing the passage of the air and causing the stated symptoms. The disease is most frequently allergy-based and the attacks are triggered by various allergens. Due to the hypersensitivity of airways in asthmatic patients, attacks can also be triggered by non-allergenic factors: physical straining, inhalation of cold or dry air, virus infections, strong emotions and air pollution (cigarette smoke).
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Are asthma and allergic rhinitis interconnected?
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They are very frequently interconnected. It is believed that approx. 40% of patients with allergic rhinitis suffer from asthma, and as high as 90% of asthmatic patients suffer from allergic rhinitis. Allergic rhinitis precedes asthma for several years and is thus regarded as a direct risk factor for development of asthma. It seems that in patients with active allergic rhinitis, asthma develops more seriously and that for a successful treatment of asthma it is important to treat allergic rhinitis simultaneously.
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