Prevalence of allergic diseases has increased several folds in western world over the last two decades, and similar trend is being observed recently in India. There have been several postulations to explain increasing occurrence of allergic diseases. "Allergic march" refers to sequence of events that starts during fetal life as a result of sensitization to foods and may manifest as eczema, gastrointestinal symptoms, asthma, or hay fever, or combinations of any of these symptoms. A link between genetics and immunology is hypothesized that results in such allergic diseases. Recurrent and Persistent Wheezing in Young Children Acute Asthma: Advances in Management Long-Term Management of Asthma Immunotherapy in Children Summary Other Books in this Series