Katten också! Exponering för pälsdjur och dess konsekvenser för pälsdjursallergiska barn

In Sweden about 40-50 % of the population has furred pets at home, primarily a cat or a dog, and about 1520% of the population is allergic to pets. Allergic symptoms may be provoked among pet allergic individuals by direct or indirect exposure to furred pets. For a number of children with allergic disease the quality of life may be impaired as a consequence of their disease. The overall aim of this thesis was to examine: 1) exposure to pet allergens in relation to keeping of furred pets and dispersion of allergens from such animals, 2) consequences of perceived allergy to furred pets in terms of keeping of such animals and 3) health-related quality of life (HRQOL) within families having a child considered by the parents to be allergic to pets.

Dust samples were collected from mattresses and textile-covered floors in 70 homes and analysed by ELISA for cat allergen (Fel d 1) and dog allergen (Can f 1). Fel d 1 was found in dust from all mattresses and textilecovered floors while Can f 1 was found in all but one. The highest levels of cat and dog allergen were found in homes with a cat or dog and were significantly higher compared to such concentrations in homes of former pet-owners or homes without cats or dogs ever.

In six furniture stores dust was collected from 17 factory-new mattresses, 15 used mattresses tried by customers and from another 5 factory-new mattresses vacuumed once a week the following 3 weeks. The mattress dust was analysed for content of Fel d 1 and Can f 1. The factory-new mattresses contained low levels of Fel d 1 and Can f 1, possibly due to contamination during the manufacturing. The used mattresses that had been displayed for 2-78 weeks contained high levels of Fel d 1 and Can f 1 and especially the allergen levels from cat correlated to the period of time that the mattresses had been displayed. The increase over time occurred rapidly and after 3 weeks reached concentrations similar to those that have been found in homes where furred pets previously had been kept.

In the BAMSE cohort 4,089 children have been followed since birth. The parents answered questions about heredity for allergic disease, keeping of pets and questions about symptoms after contact with furred pets up to 4 years of age. Dust samples were collected from the mother's bed and analysed for concentrations of Fel d 1 and Can f 1. Cats were less often kept in families with parental pet allergy (3%) than in families without (12%). Families with smoking mothers and those with low socioeconomic status kept cats and dogs more frequently. Concentrations of Fel d 1 were lower in homes if parental allergy to pets was reported, in particular if the mother had pet allergy.

Based on questionnaire data, 668 children from the BAMSE study, with or without reactions to pets, were identified at the age of 9. One hundred and thirty-one children were considered by their parents to be allergic to furred pets and a majority of these children (80%) had reactions to other allergens as well. A generic HRQOL questionnaire (CHQ-PF28) together with a disease-specific questionnaire was completed by the parents. The pet allergic children, particularly those with multiple reactions, scored significantly lower in 4 of 12 items in the CHQ-PF28 scales than the controls. The families of children with reactions to pets reported considerable restrictions in daily life and avoidance behaviors, in particular those with reactions to pollen and food as well.

This thesis highlights a conflict in the society. Many people enjoy having furred animals at home, but this results in a dispersion of furred pet allergens in public environments. However, pet allergic individuals may react to indirect exposure to pets with a subsequent worsening of the disease. Pet allergic families often avoid exposure to furred pets in order to reduce the risk of symptoms of the child or other family members, but with limited success. Avoidance in combination with a reduced general health results in an impairment of the child's quality of life.

List of scientific papers

I. Egmar AC, Emenius G, Almqvist C, Wickman M (1998). Cat and dog allergen in mattresses and textile covered floors of homes which do or do not have pets, either in the past or currently. Pediatr Allergy Immunol. 9(1): 31-5.
https://pubmed.ncbi.nlm.nih.gov/9560840

II. Egmar AC, Almqvist C, Emenius G, Lilja G, Wickman M (1998). Deposition of cat (Fel d 1), dog (Can f 1), and horse allergen over time in public environments--a model of dispersion. Allergy. 53(10): 957-61.
https://pubmed.ncbi.nlm.nih.gov/9821475

III. Almqvist C, Egmar AC, van Hage-Hamsten M, Berglind N, Pershagen G, Nordvall SL, Svartengren M, Hedlin G, Wickman M (2003). Heredity, pet ownership, and confounding control in a population-based birth cohort. J Allergy Clin Immunol. 111(4): 800-6.
https://pubmed.ncbi.nlm.nih.gov/12704361

IV. Egmar AC, Ostblom E, Lilja G, Nordstrom G, Wickman M, Gardulf A (2005). Health-related quality of life in children considered to be allergic to furred pets by their parents. [Manuscript]