Epidemiology of atopic dermatitis

Over a decade ago, AD was thought to be a complex interaction of genetic susceptibility and environmental influences which, however, need not be the same in different parts of the world. Although many aspects of the epidemiology of AD have been clarified in the intervening period, there might be undetected factors associated with the lower occurrence of atopy in larger and less priviliged households. If the hygiene hypothesis is correct and some infections at critical times are protective factors, controlled longitudinal studies with sufficient participants and of sufficient duration are needed to provide those appropriate comparisons that are the essence of epidemiologic research in the nature of AD.