Role of current and childhood exposure to cat and atopic sensitization

Background: Clinical and population studies have shown that exposure and se nsitization to allergens derived from furred pets, particularly cats, repre sent an important risk factor of allergic respiratory disease and also a si gnificant risk factor for asthma, Objective: In the framework of the multicenter European Community Respirato ry Health Survey an analysis of the association of current and childhood ex posure to cat with atopic sensitization to cat was conducted. Methods: This study included cross-sectional data from 35 centers represent ing 16 countries. Altogether, 18,097 subjects were included, of whom 13,509 (75%) provided a blood sample for the measurement of specific IgE, Exposur e data and data for potential confounders were extracted from an interviewe r-led questionnaire. Results: The prevalence of sensitization to cat (serum specific IgE >0.35 k U/L) was 9%.Among those who did not report allergic symptoms in the presenc e of pets or house dust, those who owned cats were significantly more likel y to be sensitized to eats than were those who did not (odds ratio [95% con fidence interval] 1.57 [1.20-2.06], Childhood exposure to pets including ca ts was associated with lower sensitization to cats in adulthood, particular ly among those with a positive family history of atopy (odds ratio [95% con fidence interval] 0.68 [0.51-0.93], Positive correlations were found betwee n the community prevalence of cat and the prevalences of sensitization to c at, respiratory symptoms, physician-diagnosed asthma, and current asthma me dication. Conclusions: Current cat ownership represents a significant risk for sensit ization to cat if cats are allowed indoors. Our results support the hypothe sis that childhood exposure to pets, including cats, might modulate immunol ogic mechanisms and reduce sensitization to eat in adulthood. The significa nt correlation found between the community prevalence of cat ownership and community prevalence of specific sensitization to cat represents the first documentation of such a relationship.