A “Cat Free” Zone in Schools?

Abstract

Source: Almqvist C, Larsson PH, Egmar AC, et al. School as a risk environment for children allergic to cats and a site for transfer of cat allergen to homes. J Allergy Clin Immunol. 1999;103(6):1012–1017.In areas where there is little dust mite antigen, cat and dog allergens are the most common indoor sensitizers.1 Sensitization to these pets is significantly related to the presence of asthma.2 Consequently, parents of sensitized asthmatics are encouraged to remove these animals from their homes if present and to avoid any contact with these animals in other settings. These other settings include schools, which are a major site for exposure.3 In this article Almqvist et al in Stockholm looked at the possible mechanisms by which cat allergen is disseminated. They demonstrated that in those classes with few (<10%) cat owners the level of airborne Fel d 1 (cat allergen) was significantly lower than in those classes with many (>25%) cat owners, 0.59 ng/m3 vs 2.94 ng/m3 (p<.01). These levels were intermediate between Fel d 1 levels in homes with or without a cat, 19.8 ng/m3 (p<.001) and 0.15 ng/m3 (p<.001). In classes with many cat owners the airborne Fel d 1 levels did not significantly vary with the site of the sampling (ie, in the breathing zone of, nearby, or across the room from the cat owner). The levels dropped off significantly away from the breathing zone of the cat owner in classes with few cat owners. The level of Fel d 1 on new T-shirts worn by cat owners one evening and to school the next day was 3030 (900–15620) ng. The level of Fel d 1 on a new unworn T-shirt was 0.3 (0.2–2.2) ng (p<.001); this increased to 146 (86–234) ng on a non-cat owner after one day in school with cat owners. Although the airborne levels of Fel d 1 in homes of non-cat owners did not differ whether the student was in a class with few or many cat owners, the mattress levels showed a significant difference, 0.38 μg/g dust vs 0.85 μg/g dust (p<.01).Whether the airborne levels of Fel d 1 reported in the above article are sufficient to sensitize or to elicit asthma symptoms is unknown,4 but low doses of allergen can make the lungs more hyper-reactive.5,6 If this is the case, then in the future might we want to place cat allergic asthmatics in school rooms with fewer cat owners? This would be a difficult suggestion in our society. We now have tobacco smoke free environments for our children. But how far are we willing to change the environment of the group to benefit the few? I doubt that we would, or could, segregate cat owners even if we found that their breath and clothes were a danger to others. For the time being, studies must now be conducted that answer the question of whether the airborne levels of Fel d 1 reported in this article sensitize and/or provoke allergic symptoms.We won’t pussy-foot around: not only is the idea of separating children in school by their allergen exposures potentially discriminatory, it is purr-ticularly impractical.