Is primary prevention of asthma possible?

The increased prevalence of asthma over the past quarter century has become a major public health problem for the industrialized world. Asthma is a di sease process which has a strong heritable component which is impacted by m ultiple environmental factors. Given the rapid increase in asthma prevalenc e, it is difficult to ascribe the change to a genetic alteration. Therefore , the focus for understanding the changing prevalence of asthma must be on environmental factors. This article reviews factors which may contribute, i n whole or in part, to the development of the disease process. In questioni ng whether ii is possible to prevent development of a disease (primary prev ention), it is critical to understand these factors. The environment may ev en have an impact on the fetus during intrauterine life. There does appear to be a "window of opportunity" in early life where a variety of factors, i ncluding food and inhalant allergen exposure, exposure to pollutants, and i nfection with both viral and bacterial agents, may be important in initiati ng the development of asthma and allergy. Potential approaches to primary p revention of asthma and allergy must consider each of these important facto rs. Given that asthma is a multifactorial disease with both complex genetic and environmental components, it is unlikely that any single intervention will significantly decrease the prevalence of asthma. (C) 2000 Wiley-Liss, Inc.