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Background: Numerous aeroallergens have been associated with the development of asthma, including Alternaria, house-dust mite, and pet dander. Tucson, Arizona, is located in the Sonoran Desert, which has the highest diversity of vegetation of any desert in the world. Given the unique pollen profile in this region, we sought to identify the most common aeroallergens associated with rhinitis and asthma diagnosis in the local adult population., Objective: To identify the prevalence of aeroallergen sensitivity in the Tucson adult population and to identify which aeroallergens are associated with a diagnosis of asthma., Methods: We conducted a retrospective electronic chart review of 226 consecutive adult patients who underwent aeroallergen skin-prick testing for rhinitis at The University of Arizona Adult Allergy and Immunology Clinic over the course of 1 year. All the subjects were tested to a standard panel of tree, grass, weed, mold, house-dust mite, animal dander, cockroach, and feather extracts. Asthma was diagnosed by using the Expert Panel Report 3 guidelines., Results: Skin testing results were most commonly positive to mesquite (54%), Bermuda (48%), palo verde (47%), olive tree (43%), and chenopodium (43%). Compared with the subjects without asthma, those subjects with asthma were more often sensitized to molds (odds ratio [OR] 2.25 [95% confidence interval {CI}, 1.22-4.14]; p = 0.005), including Alternaria alternata (OR 2.58 [95% CI, 1.23-5.39]; p = 0.011), and cat hair and/or pelt (OR 2.13 [95% CI, 1.24-3.69]; p = 0.006)., Conclusion: Regional pollens contributed significantly to allergic disease in this unique climate. Sensitization to Alternaria and other nonregional aeroallergens were related to asthma, which supported the current practice of testing and treating patients for allergy to both locally significant and ubiquitous aeroallergens.

Skin tests are used in addition to a directed history and physical exam to exclude or confirm IgE-mediated diseases such as allergic rhinitis, asthma, and anaphylaxis to aeroallergens, foods, insect venoms, and certain drugs. There are two types of skin testing used in clinical practice. These include percutaneous testing (prick or puncture) and intracutaneous testing (intradermal). Prick testing involves introducing a needle into the upper layers of the skin through a drop of allergen extract and gently lifting the epidermis up. Other devices are available for prick testing. Intracutaneous (intradermal) testing involves injecting a small amount of allergen (0.01-0.02 mL) into the dermis. The release of preformed histamine from mast cells causes increased vascular permeability via smooth muscle contraction and development of a wheal; inflammatory mediators initiate a neural reflex causing vasodilatation, leading to erythema (the flare). Prick testing methods are the initial technique for detecting the presence of IgE. They may correlate better with clinical sensitivity and are more specific but less sensitive than intradermal testing. Sites of skin testing include the back and the volar aspect of the arm. Although the back is more reactive, the difference is minimal. By skin testing on the arm, the patient can witness the emergence and often sense the pruritus of the skin test reaction. Because more patients are sensitized (have IgE antibodies and positive skin test reactions) than have current symptoms, the diagnosis of allergy can be made only by correlating skin testing results with the presence of clinical symptoms.

Urticaria, also known as hives, may affect up to 20% of the population at some time in their lives. Urticaria is characterized by extreme pruritus and described as erythematous, raised, circumscribed lesions with central pallor that blanch with pressure. The pathogenesis of urticaria involves mast cell activation, with subsequent release of histamine and other vasoactive mediators, leading to increased vascular permeability of postcapillary venules and development of edema, erythema, and pruritus. Urticaria is closely associated with angioedema in 40% of individuals; ∼10% of patients experience angioedema without urticaria. Urticarial lesions often are generalized with multiple lesions in no specific distribution; angioedema tends to be localized, commonly affecting the face (periorbital and perioral regions), tongue, uvula, soft palate or larynx, extremities, and genitalia. Urticaria is subdivided into acute and chronic urticaria based on duration of symptoms. Acute urticaria lasts <6 weeks and an identifiable cause may be discovered such as food products, medications (aspirin, nonsteroidal anti-inflammatory drugs, and antibiotics), or insect stings. Urticaria lasting >6 weeks is designated as chronic urticaria, and an etiology is seldom identified and thus considered idiopathic. Chronic urticaria may have an autoimmune basis. There is a well-documented association between autoimmune hypothyroidism (Hashimoto's disease) and urticaria and angioedema with higher incidence of antithyroid (antithyroglobulin and antiperoxidase) antibodies in these usually euthyroid patients. Furthermore, studies have revealed a circulating IgG antibody directed against the IgE receptor (F(Cε)RIα) or IgE in 40-60% of patients with chronic urticaria. Histamine 1-receptor antagonists (antihistamines) are initial therapy.

The goals of treatment are prevention of fatalities, hospitalizations, and emergency department visits, along with achieving good long-term control of asthma, with reduction of symptoms, maintenance of normal activity level, prevention of exacerbations, and accelerated loss of pulmonary function (forced expiratory volume in 1 second [FEV(1)]) as well as avoiding harm from therapies. Treatment often is initiated based on severity of symptoms, physical examination findings, and, for some patients, the FEV(1) or peak expiratory flow rates. Comorbidities such as gastroesophageal reflux disease and laryngopharyngeal reflux, rhinitis or rhinosinusitis, sleep apnea, recurrent infections, smoking, and substance abuse should be addressed. Two treatment modalities are indicated only for individuals with allergic asthma: allergen-specific immunotherapy, commonly known as allergy shots, and omalizumab. Allergen immunotherapy is effective in decreasing symptoms and medication use in selected patients with mild-to-moderate allergic asthma. In addition, patients receiving allergen immunotherapy for allergic rhinitis may have a decreased risk of developing asthma. Omalizumab, a recombinant humanized monoclonal anti-IgE antibody indicated for persistent moderate-to-severe allergic asthma, has been shown to improve asthma-related quality of life, decrease clinically significant exacerbation rates, number of courses of oral corticosteroids, and reduce the severity of exacerbations. It is administered every 2-4 weeks subcutaneously, and improvement should be ascertained after 4-6 months.