The effect of infectious agents on the prevalence of allergies

The role of infectious agents in allergy development is ambivalent. On one hand, there are reports of an association between a previous infection (especially a viral respiratory tract infection) and developing hypersensitivity to inhaled allergens, which in turn may increase the risk of developing allergic reactions. On the other hand, there are reports emphasizing a protective effect of a number of infectious agents against allergy development. The aim the study was to find possible associations between a past infectious or parasitic disease and an allergic condition. The study population was a group of 18,648 subjects. The study, which was a part of the project: ‘Implementation of a System for the Prevention and Early Detection of Allergic Diseases in Poland’, was conducted in 9 selected regions of Poland and used the ECRHS and ISAAC questionnaires adapted for Europe. The following statistical tools were used: Pearson's chi-squared test, Fisher's exact test, and logistic regression. This research was an attempt to clear association between a history of measles or viral hepatitis and the likelihood of developing asthma, especially in males (χ2 = 5.29; p<0.05). Past parasitic disease showed a clear association with a suspected allergic rhinitis in various groups of patients (differing both in terms of sex and age). A history of some forms of either infectious or parasitic diseases has a measurable effect on the risk of developing allergies.