Inhalant Allergy
Posted by admin on June 2nd, 2009
Microscopic inhaled airborne allergens are responsible for most respiratory allergy (Table 2). In temperate climates, seasonal allergic rhinitis is induced by tree pollens in the early spring, grass pollens in the late spring and early summer, and ragweed in the late summer and early fall. Because of geographic differences in the US, clinicians must become familiar with the pollination patterns in their individual regions.
Hay fever is an inappropriate term for allergic rhinitis because these patients neither are allergic to hay nor have fever. Flowering vegetation, such as roses and fruit blossoms, rarely cause allergy because these pollens are too heavy to become airborne; their germination is facilitated by bees and other insects. Fungi (mold) spores may be important outdoor aeroallergens in humid climates throughout the year, but their numbers decrease once there is significant frost in temperate climates. Fungi can be important indoor perennial allergens in damp environments. In perennial allergic rhinitis, house dust, animals, and molds all may be significant indoor inhalant allergens. The principal allergens in house dust are the cuticles and feces of the microscopic house dust mite Dermatophagoides.
Animal allergens, such as epidermal danders, salivary proteins, urinary proteins, feces, and feathers, especially from pets such as cats, dogs, and birds are important because about 50% of households in the US have indoor animal pets. Food allergens are of lesser importance in the etiology of allergic rhinitis but cannot be ignored, especially in young children. Patients can be sensitive to one or multiple allergens. Certain individuals react to miniscule amounts of inhaled allergens, while others tolerate a large allergen dose before developing symptoms.
In addition to allergens, viral infections, aerosolized cosmetics, cigarette smoke, industrial fumes, and changes in temperature, humidity, and barometric pressure contribute to exacerbation of both upper and lower respiratory tract symptoms in the allergic child.
Psychologic and social stresses also can enhance symptoms. The importance of these additional contributory factors varies greatly from patient to patient but should not be ignored when evaluating any individual.
Symptoms of nasal allergy consist of frequent sneezing, nasal pruritus, watery rhinorrhea, and often, nasal obstruction. Patients also may complain of red, itchy eyes as well as itchy throat and ears. If there is nasal obstruction, the patient will be a mouth breather and snoring can be a bedtime symptom; smell and taste also may be lost. Increased symptoms frequently are noted with increased exposure to the responsible allergen, such as after cutting grass or sleeping on a feather pillow.
When an allergic reaction develops, clear nasal secretions will be evident, and the nasal mucous membranes will become edematous without much erythema. The mucosa appear boggy and blue-gray. With continued exposure to the allergen, the turbinates will appear swollen and can obstruct the nasal airway. Conjunctival edema, itch, tearing, and hyperemia are frequent findings in patients who have associated allergic conjunctivitis. Patients who have allergic rhinitis, particularly children who have significant nasal obstruction and venous congestion, also may demonstrate edema and darkening of the tissues beneath the eyes. These so-called “shiners” are not pathognomonic for allergic rhinitis because they also can be seen in patients who have chronic rhinitis and/or sinusitis. Thick, purulent secretions indicate the presence of infection, including the possibility of sinusitis.
Tags: allergic diseases, Allergies, allergies symptoms, allergy