Genetic predisposition and increased environmental allergen exposure in cat allergy: The pandemic is a very good example.

Objective: Domestic cats are among the most common sources of indoor allergens. There was an increase in indoor allergen exposure, especially cats and house dust mites, as people spent more time at home during the COVID-19 pandemic lockdowns. In this study, our aim was to examine the frequency of cat sensitization and ownership after the COVID-19 pandemic and its relationship with other indoor and pollen allergen sensitizations.

Methods: The data of patients who applied to our clinic between 2018 and 2022, with a history of hypersensitivity reaction after contact with cats and diagnosed with cat allergy by positive skin test or specific immunoglobulin E (sIgE) level, were examined retrospectively. Skin test was performed in accordance with the manufacturer's instructions. sIgE levels against cat allergens were measured using The Phadia CAP System FEIA method.

Results: There has been an increase in the rate of cat ownership (P < 0.001) during the COVID-19 pandemic. The prevalence of cat allergy in 2020 and beyond (5.89%) was significantly higher than the pre-COVID period (4.53%; P < 0.001). The prevalence of concomitant df (dermatophagoides farinae) (1.53-1.58%), dp (dermatophagoides pterynossinus) (1.53-1.48%), and pollen (3.47-3.62%) hypersensitivity before COVID-19 did not differ significantly after COVID, but the prevalence of "penicillium" hypersensitivity before COVID (= 8/5825) was found to be significantly lower (0.14-1.28%).

Conclusion: During the pandemic period, both the increase in cat ownership and spending more time indoors seem to have led to an increase in cat allergy. No increase in indoor allergen sensitization other than penicillium accompanying cat allergy was detected.