Controlling indoor allergens.
PURPOSE OF REVIEW: Epidemiological surveys indicate that there has been a notable increase in the prevalence of asthma and other allergic diseases in children and adults. The purpose of this review is to report and comment on recent studies about the role of allergen in primary prevention and to seek new insights on the effects of allergen control in allergic patients. RECENT FINDINGS: This paper deals with allergen reduction in primary prevention, the effect of early exposure to pets on atopic diseases and the development of new occupational activity improving allergen control in allergic patients. SUMMARY: The role of allergen dose involved in the onset of atopy is controversial. Studies hypothesizing that a reduction of allergen dose might reduce atopy failed to confirm the data from the Isle of Wight study and found no effect on the frequency of immunoglobulin E sensitization. This effect might nonetheless occur later in life. Other studies indicate that high doses of allergen early in life have a protective effect against cat and dog sensitization. Only one retrospective study found that cat exposure was protective against cat sensitization. A German prospective study suggested, however, that it is more probable that cat allergen exposure is harmfully related to sensitization, by increasing IgE synthesis. The effect of high doses must be clarified by further prospective studies. Accordingly, we must be very careful when giving advice on primary prevention, particularly about the protective effect of cat and dog allergens. Secondary prevention may be dramatically improved with the help of a new occupational activity: the medical indoor environment counsellor.