Introduction.

The increasing prevalence of allergic diseases throughout the world has been established by the publication of more than 10 national and multinational epidemiologic studies during the past 10 years. (1) The prevalence for allergic rhinitis ranges from 3 to 40% of the population, depending on the geographic area and the age of the patients. Allergic rhinitis and asthma, as common respiratory diseases, affect school performance, work productivity, and the social life of patients, and the cost to society is substantial. For instance, total direct medical costs of allergic rhinitis are estimated to be $3.4 billion per year in the United States alone. (2) This cost is divided equally between prescription medications and outpatient visits.

A better understanding of immunoglobulin E-mediated, mast cell-dependent allergic inflammation has resulted in the development of new therapies for allergic respiratory disease. (3) The newest of these are antileukotriene drugs and anti-immunoglobulin E monoclonal antibodies. Many more are in the pipeline. How T-cell subpopulations facilitate the genetic propensity to develop allergic diseases and their role in control of the inflammatory response is rapidly being elucidated. Meanwhile, the roles of allergens, pollution, and childhood infections in allergic sensitization are under careful study. (4) Our new understanding of the basic mechanisms of allergic inflammation, present throughout the upper and lower airways in both symptomatic and some asymptomatic allergic individuals, may ultimately lead to technologies that prevent allergic disease altogether.

Since the translation of science to the bedside now occurs at lightning speed, we thought it useful to provide an update on allergic diseases focused on our new understanding of their pathophysiology. Thus, the first article in our symposium focuses on basic mechanisms of allergic disease. As you read the articles on allergic rhinosinusitis, asthma, and atopic dermatitis, you will see how recent scientific discoveries have focused treatment on control of allergic inflammation. Because insect allergy and drug allergy are such common allergic problems, we have also included updates on these topics. Our group hopes you find these articles interesting and useful in the care of your patients.

Acknowledgment

My colleagues and I thank Dawn Chism, who provided editorial assistance in the preparation of this series of CME articles.

References

1. Bachert C, van Cauwenberge P, Khaltaev N, et al; World Health Organization. Allergic rhinitis and its impact on asthma: Executive summary of the workshop report 7-10 December 1999, Geneva, Switzerland. Allergy 2002;57:841-855.

2. Law AW, Reed SD, Sundy JS, et al. Direct costs of allergic rhinitis in the United States: Estimates from the 1996 Medical Expenditure Panel Survey. J Allergy Clin Immunol 2003;111:296-300.

3. Larche M, Robinson DS, Kay AB. The role of T lymphocytes in the pathogenesis of asthma. J Allergy Clin Immunol 2003;111:450-464.

4. Liu AH, Murphy JR. Hygiene hypothesis: Fact or fiction? J Allergy Clin Immunol 2003;111:471-478.

Richard D. deShazo, MD