Exposure to animals, allergies and parental education

Background:

Studies have yielded different results regarding the associations between animal exposure and atopy. Whether or not these associations are homogeneous across social strata has not yet been investigated. To estimate the association between current animal exposure (cat and dog) and allergic sensitization and manifestations of atopic diseases in 5 to 7 year old school beginners, stratified by parental educational level.

Methods:

30794 six year old children participated in cross-sectional studies between 1991 and 2000 in Germany. Allergic sensitizations to common areoallergens as measured by skin prick and Radio Allergo Sorbent Test and symptoms and diagnoses of atopic diseases (asthma, atopic dermatitis, hay fever) were the dependent variables. Exposure to dog and cat were the independent variables. Logistic regression was used to adjust for confounding. Analyses were stratified for parental educational level (stratum I, II, III corresponding to <10 years, 10 years and >10 years of schooling).

Results:

Prevalences of hay fever, eczema, specific sensitization to pollen and house dust mite and contact to cat or dog were significantly different between educational strata. Globally significant associations between cat contact and sensitization to cat (RAST OR 1.92, 95% CI 1.18-3.11) and hay fever (OR 0.61, 95% CI 0.45-0.82) remained significant after stratification only in the highest educational stratum (OR 3.68, 95% CI 1.90-7.12 and OR 0.55, 95% CI 0.36-0.85). Globally significant associations of contact to dog with sensitization to pollen (OR 0.71, 95% CI 0.56-0.89), wheezing (OR 1.31, 95% CI 1.11-1.55), nose problems (OR 0.72, 95% CI 0.56-0.93) and eczema (OR 0.84, 95% CI 0.77-0.92) remained significant in educational stratum II. Globally significant associations of dog contact with sneezing attacks (OR=0.84, 95% CI 0.71-1.00) and eczema (OR=0.82, 95% CI 0.75-0.91) remained significant in educational stratum III, and in stratum I and II respectively.

Conclusion:

In 5 to 7 year old German children, differences across social strata concerning allergic sensitizations, hay fever and eczema may possibly be explained by animal exposure differences. Associations between animal contact and allergic sensitization and manifestations of atopic diseases are not homogeneous across social strata.