Number of epidemiological jobs shows the increase of the prevalency of allergic diseases at the child: eczema, asthma and cold of hays so doubled in Scotland between 1964 and 1969 (Aberdeen), the reproductibilit of the tools of valuation moving aside any slantwise methodological idea, for example linked in better (re) knowledge pathologies.

Australia, Ireland, the United Kingdom and New Zealand are the countries where this prevalency is currently the most important, while China, Indonesia, Greece and Russia seem spared (study ISAAC). The German longitudinal inquiry FARMHOUSE IN PROVENCE (Multicenter allergy study) follows since 1990 a cohort of 7609 children: the biological sequential monitoring shows the preponderance of sensitisations in relation to the proteins of the cow's milk and of The egg until the age of two years, allergens then supplanted by the soya and the wheat. In six years, 20 % of this population is sensitised in the pollens of grasses. Finally, the sensitisation in domestic allergens, which also augments until the age of six years, appears, for a misunderstood, more important reason in the North of the country.

A link between presence of domestic allergens and level of subsequent sensitisation was shown: the precocious and massive exhibition to the dust mites of the dust of home is an obvious risk factor. The other factor prognosticates am genetic, the existence of family antecedents atopie increasing the risk of sensitisation for the same level of initial exhibition. However, character polyg nique these affections returns impossible, at the moment, any efficient genetic advice.

Finally, the exhibition in the annoying of environment, and first in the tobacco, increases the risk of sensitisation in domestic allergens and in food allergens: this risk was augmented, objectified in populations at risk (tabagique mother) by the urinary proportion of the nicotine persists until the age of the walk.