Atopy and Asthma in Migrants: The Function of Parasites

Migration studies have shown that environmental factors in more developed and industrialized countries facilitate atopy and asthma in a time-dependent manner and are affected by age at immigration. Levels of immunoglobulin E are higher in immigrants than in the local population and gradually decrease to the levels of the general population. Parasitic infestation may function in the prevention and pathogenesis of atopic conditions in immigrants from developing countries. Helminths are associated with a reduced prevalence of clinically important atopic disorders, likely because of induction of a regulatory cell population mechanism. Improved understanding of the immunologic background of helminths and their protective function in humans has led to a growing interest in the possibility of reversal of allergies using parasites and the development of new therapies, such as immunomodulation for allergy using ova from parasites orally or intranasally. Strategies for primary prevention in high-risk atopic individuals and secondary prevention guidelines should be developed for populations in developing countries and for immigrants from developing countries to atopy-prevalent developed countries. Improved understanding of the function of parasitic infection in modulation of the immune response may lead to new therapeutic options for allergic conditions.