PROPHYLAXIS OF ALLERGIES IN INFANTS

There is no dispute that manifestations of atopy are occurring more of ten in the parts of the world in which prevalence rates have been comp ared. This applies not only to asthma but to other IgE-mediated disord ers, seasonal and perennial rhinitis, atopic dermatitis and immediate forms of food allergy. The reasons for this increase are largely a mat ter of conjecture, but the consequences in terms of effect on educatio n and work are real and the cost of provision of healthcare for this g roup of diseases massive. Any intervention that would prevent or dimin ish the expression of atopy would therefore be of substantial benefit to the individual and to society. It has long been realised that there is a substantial genetic influence in atopic disease. Some progress h as been made in pinpointing the locus or loci that may carry the gene or genes predisposing to atopy. However, only limited success can be r eported in identifying infants at high risk of developing atopy, who w ould be obvious candidates for any programme of prophylactic measures. It was hoped that a screening method might be found that would identi fy such infants at birth. The level of cord IgE has proven a disappoin ting tool in this respect, and family history is at present the best i ndication of risk. Substantial progress has been made in identifying e nvironmental factors that may play a sensitising role in vulnerable in fants. There is some evidence that sensitisation can take place transp lacentally, although it has been difficult to find specific evidence f or such sensitisation in newborns. Certainly the currently available m ethods rarely indicate the presence of specific IgE in cord blood. How ever, recent research raises the possibility of intrauterine sensitisa tion work which, if confirmed, will have substantial implications for prevention programmes. The infant is exposed to antigenic material tha t he/she ingests or inhales. The pattern of sensitisation to foods and to aeroallergens is described here. Emphasised is the considerable in fluence of external factors, particularly passive smoking and other fo rms of pollution, and factors such as season of birth may be relevant. Finally, the published evidence is reviewed on the benefit (if any) o f intervention during pregnancy or in the newborn period. The measures that can reasonably be advised for any family considered to be at hig h risk of producing infants with atopy are outlined. Potential problem s, and the need for close medical and dietetic support when using rest rictive or so-called hypoallergenic diets, are emphasised.