Asher MI, Montefort S, Bjorksten B, Lai CK, Strachan DP, Weiland SK, et al. Worldwide time trends in the prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and eczema in childhood: ISAAC Phases One and Three repeat multicountry cross-sectional surveys. Lancet. 2006;368(9537):733–43.PubMedCrossRef
Robertson CF, Heycock E, Bishop J, Nolan T, Olinsky A, Phelan PD. Prevalence of asthma in Melbourne schoolchildren: changes over 26 years. BMJ. 1991;302(6785):1116–8.PubMedCrossRef
Robertson CF, Roberts MF, Kappers JH. Asthma prevalence in Melbourne schoolchildren: have we reached the peak? Med J Aust. 2004;180(6):273–6.PubMed
Devenny A, Wassall H, Ninan T, Omran M, Khan SD, Russell G. Respiratory symptoms and atopy in children in Aberdeen: questionnaire studies of a defined school population repeated over 35 years. BMJ. 2004;329(7464):489–90.PubMedCrossRef
Osborne NJ, Koplin JJ, Martin PE, Gurrin LC, Lowe AJ, Matheson MC, et al. Prevalence of challenge-proven IgE-mediated food allergy using population-based sampling and predetermined challenge criteria in infants. J Allergy Clin Immunol. 2011;127(3):668-76 e1-2.
Yemaneberhan H, Bekele Z, Venn A, Lewis S, Parry E, Britton J. Prevalence of wheeze and asthma and relation to atopy in urban and rural Ethiopia. Lancet. 1997;350(9071):85–90.PubMedCrossRef
Carrer P, Maroni M, Alcini D, Cavallo D. Allergens in indoor air: environmental assessment and health effects. Sci Total Environ. 2001;270(1–3):33–42.PubMedCrossRef
Qureshi AI, Memon MZ, Vazquez G, Suri MF. Cat ownership and the Risk of Fatal Cardiovascular Diseases. Results from the Second National Health and Nutrition Examination Study Mortality Follow-up Study. J Vasc Interv Neurol. 2009;2(1):132–5.PubMed
Serpell J. Beneficial effects of pet ownership on some aspects of human health and behaviour. J R Soc Med. 1991;84(12):717–20.PubMed
Flohr C, Yeo L. Atopic dermatitis and the hygiene hypothesis revisited. Curr Probl Dermatol. 2012;41:1–34.CrossRef
Kjellman B, Petterson R. The problem of furred pets in in childhood atopic disease. Allergy. 1983;38:65–73.PubMedCrossRef
Svanes C, Heinrich J, Jarvis D, Chinn S, Omenaas E, Gulsvik A, et al. Pet-keeping in childhood and adult asthma and hay fever: European community respiratory health survey. J Allergy Clin Immunol. 2003;112(2):289–300.PubMedCrossRef
Platts-Mills TA. Allergens and asthma. Allergy Proc. 1990;11(6):269–71.PubMedCrossRef
Strachan DP. Hay fever, hygine and household size. BMJ. 1989;299:1259–60.PubMedCrossRef
Hesselmar B, Aberg N, Aberg B, Eriksson B, Bjorksten B. Does early exposure to cat or dog protect against later allergy development? Clin Exp Allergy. 1999;29(5):611–7.PubMedCrossRef
Popp W, Rauscher H, Sertl K, Wanke T, Zwick H. Risk factors for sensitization to furred pets. Allergy. 1990;45(1):75–9.PubMedCrossRef
Dharmage S, Bailey M, Raven J, Mitakakis T, Cheng A, Guest D, et al. Current indoor allergen levels of fungi and cats, but not house dust mites, influence allergy and asthma in adults with high dust mite exposure. Am J Respir Crit Care Med. 2001;164(1):65–71.PubMed
Custovic A, Hallam CL, Simpson BM, Craven M, Simpson A, Woodcock A. Decreased prevalence of sensitization to cats with high exposure to cat allergen. J Allergy Clin Immunol. 2001;108(4):537–9.PubMedCrossRef
Custovic A, Simpson BM, Simpson A, Hallam CL, Marolia H, Walsh D, et al. Current mite, cat, and dog allergen exposure, pet ownership, and sensitization to inhalant allergens in adults. J Allergy Clin Immunol. 2003;111(2):402–7.PubMedCrossRef
Chen CM, Gehring U, Wickman M, Hoek G, Giovannangelo M, Nordling E, et al. Domestic cat allergen and allergic sensitisation in young children. Int J Hyg Environ Health. 2008;211(3–4):337–44.PubMedCrossRef
Thien FCK, Leung RCK, Czarny D, Walters EH. Indoor allergens and Ig E mediated respiratory illness. Immunol Allergy Clin N Am. 1994;14(3):567–90.
Leung TF, Wong YS, Chan IH, Yung E, Sy HY, Lam CW, et al. Domestic exposure to aeroallergens in Hong Kong families with asthmatic children. Pediatr Pulmonol. 2011;46(7):632–9.PubMedCrossRef
Luczynska CM, Li Y, Chapman MD. Airborne concentrations and particle size distribution of allergen derived from domestic cats (Felis domesticus). Measurments using a cascade impactor, liquid impinger and two site monoclonal antibody assay for Fel d 1. Am Rev Respir Dis. 1990;141:361.PubMed
Bateman BJ, Dean TP. The cheshire cat's grin- is cat allergy here to stay? Clin Exp Allergy. 1999;29:725–8.PubMedCrossRef
Swanson MC, Campbell AR, Klauck MJ, Reed CE. Correlations between levels of mite and cat allergens in settled and airborne dust. J Allergy Clin Immunol. 1989;83(4):776–83.PubMedCrossRef
Platts-Mills TA, Woodfolk JA. Allergens and their role in the allergic immune response. Immunol Rev. 2011;242(1):51–68.PubMedCrossRef
Platts-Mills T, Vaughan J, Squillace S, Woodfolk J, Sporik R. Sensitisation, asthma, and a modified Th2 response in children exposed to cat allergen: a population-based cross-sectional study. Lancet. 2001;357(9258):752–6.PubMedCrossRef
Hanski I, von Hertzen L, Fyhrquist N, Koskinen K, Torppa K, Laatikainen T, et al. Environmental biodiversity, human microbiota, and allergy are interrelated. Proc Natl Acad Sci USA. 2012;109(21):8334–9.PubMedCrossRef
Lau S, Illi S, Platts-Mills TA, Riposo D, Nickel R, Gruber C, et al. Longitudinal study on the relationship between cat allergen and endotoxin exposure, sensitization, cat-specific IgG and development of asthma in childhood–report of the German Multicentre Allergy Study (MAS 90). Allergy. 2005;60(6):766–73.PubMedCrossRef
Fujimura KE, Johnson CC, Ownby DR, Cox MJ, Brodie EL, Havstad SL, et al. Man's best friend? The effect of pet ownership on house dust microbial communities. J Allergy Clin Immunol. 2011;126(2):410-2, 2 e1-3.
Atkinson W, Harris J, Mills P, Moffat S, White C, Lynch O, et al. Domestic aeroallergen exposures among infants in an English town. Eur Respir J. 1999;13(3):583–9.PubMedCrossRef
Chew GL, Burge HA, Dockery DW, Muilenberg ML, Weiss ST, Gold DR. Limitations of a home characteristics questionnaire as a predictor of indoor allergen levels. Am J Respir Crit Care Med. 1998;157(5):1536–41.PubMed
Raunio P, Pasanen AL, Reiman M, Virtanen T. Cat, dog, and house-dust-mite allergen levels of house dust in Finnish apartments. Allergy. 1998;53(2):195–9.PubMedCrossRef
Patchett K, Lewis S, Crane J, Fitzharris P. Cat allergen (Fel d 1) levels on school children's clothing and in primary school classrooms in Wellington, New Zealand. J Allergy Clin Immunol. 1997;100(6 Pt 1):755–9.PubMedCrossRef
Munir AKM, Einarson R, Schou C, Dreborg SKG. Allergens in school dust: the amount of major cat (Fel d 1) and dog ( Can f 1) allergens in dust from Swedish schools is high enough to to probably cause perennial symptoms in most children with asthma who are sensitized to cat and dog. J Allergy Clin Immunol. 1993;91:1067–74.PubMedCrossRef
Custovic A, Fletcher A, Pickering CAC, Francis HC, Green R, Smith A, et al. Domestic allergens in public places III—house dust mite, cat, dog and cockroach allergens in British Hospitals. Clin Exp Allergy. 1998;28(1):53–9.PubMedCrossRef
Wood R, Chapman M, Adkinson N, Eggleston P. The effect of cat removal on Fel d 1 content in house hold dust samples. J Allergy Clin Immunol. 1989;83:730–4.PubMedCrossRef
Svanes C, Zock JP, Anto J, Dharmage S, Norback D, Wjst M, et al. Do asthma and allergy influence subsequent pet keeping? An analysis of childhood and adulthood. J Allergy Clin Immunol. 2006;118(3):691–8.PubMedCrossRef
Svanes C, Dharmage S, Sunyer J, Zock JP, Norback D, Wjst M, et al. Long-term reliability in reporting of childhood pets by adults interviewed twice, 9 years apart. Results from the European Community Respiratory Health Survey I and II. Indoor Air. 2008;18(2):84–92.PubMedCrossRef
Nicholas C, Wegienka G, Havstad S, Ownby D, Johnson CC, Zoratti E. How accurately do young adults recall childhood pets? A validation study. Am J Epidemiol. 2009;170(3):388–92.PubMedCrossRef
Rhodes HL, Thomas P, Sporik R, Holgate ST, Cogswell JJ. A birth cohort study of subjects at risk of atopy: twenty-two-year follow-up of wheeze and atopic status. Am J Respir Crit Care Med. 2002;165(2):176–80.PubMed
Martinez FD, Wright AL, Taussig LM, Holberg CJ, Halonen M, Morgan WJ. Asthma and wheezing in the first six years of life. The Group Health Medical Associates. N Engl J Med. 1995;332(3):133–8.PubMedCrossRef
Chen CM, Rzehak P, Zutavern A, Fahlbusch B, Bischof W, Herbarth O, et al. Longitudinal study on cat allergen exposure and the development of allergy in young children. J Allergy Clin Immunol. 2007;119(5):1148–55.PubMedCrossRef
Ahlbom A, Backman A, Bakke J, Foucard T, Halken S, Kjellman N. Pets indoors—a risk factor for or protection against sensitization/allergy. Indoor Air. 1998;8:219–35.CrossRef
Pearce N, Douwes J, Beasley R. Is allergen exposure the major primary cause of asthma? Thorax. 2000;55(5):424–31.PubMedCrossRef
Apelberg BJ, Aoki Y, Jaakkola JJ. Systematic review: exposure to pets and risk of asthma and asthma-like symptoms. J Allergy Clin Immunol. 2001;107(3):455–60.PubMedCrossRef
Langan SM, Flohr C, Williams HC. The role of furry pets in eczema: a systematic review. Arch Dermatol. 2007;143(12):1570–7.PubMedCrossRef
Flohr C, Yeo L. Atopic dermatitis and the hygiene hypothesis revisited. Curr Probl Dermatol. 2011;41:1–34.PubMedCrossRef
Takkouche B, Gonzalez-Barcala FJ, Etminan M, Fitzgerald M. Exposure to furry pets and the risk of asthma and allergic rhinitis: a meta-analysis. Allergy. 2008;63(7):857–64.PubMedCrossRef
Chen CM, Tischer C, Schnappinger M, Heinrich J. The role of cats and dogs in asthma and allergy–a systematic review. Int J Hyg Environ Health. 2010;213(1):1–31.PubMedCrossRef
Lodge CJ, Allen KJ, Lowe AJ, Hill DJ, Hosking CS, Abramson MJ, et al. Perinatal cat and dog exposure and the risk of asthma and allergy in the urban environment: a systematic review of longitudinal studies. Clin Dev Immunol. 2012;2012:176484.PubMedCrossRef
Herr M, Just J, Nikasinovic L, Foucault C, Le Marec AM, Giordanella JP, et al. Influence of host and environmental factors on wheezing severity in infants: findings from the PARIS birth cohort. Clin Exp Allergy. 2012;42(2):275–83.PubMedCrossRef
• Lampi J, Canoy D, Jarvis D, Hartikainen AL, Keski-Nisula L, Jarvelin MR, et al. Farming environment and prevalence of atopy at age 31: prospective birth cohort study in Finland. Clin Exp Allergy. 2011;41(7):987-93. This is a birth cohort study that showed that cat exposure before the age of 7 protects one from having atopic sensitization, allergic rhinitis, and allergic conjunctivitis at the age of 31 years, suggesting that any protective effect related to early life cat exposure can last into adulthood.
Pekkanen J, Lampi J, Genuneit J, Hartikainen AL, Jarvelin MR. Analyzing atopic and non-atopic asthma. Eur J Epidemiol. 2012.
• Roduit C, Wohlgensinger J, Frei R, Bitter S, Bieli C, Loeliger S, et al. Prenatal animal contact and gene expression of innate immunity receptors at birth are associated with atopic dermatitis. J Allergy Clin Immunol. 2011;127(1):179-85, 85 e1. This birth cohort study, conducted in five European countries, showed that cat exposure during pregnancy protects against atopic dermatitis in the first 2 years of life and that at least part of the protective effect of cat exposure may be mediated by innate immunity.
• Wegienka G, Johnson CC, Havstad S, Ownby DR, Nicholas C, Zoratti EM. Lifetime dog and cat exposure and dog- and cat-specific sensitization at age 18 years. Clin Exp Allergy. 2011;41(7):979-86. This birth cohort study demonstrated that the tolerance effect related to early cat exposure is still present at the age of 18 years. More importantly, they show convincingly that exposure to cats in the first year of life is critical.
• Olivieri M, Zock JP, Accordini S, Heinrich J, Jarvis D, Kunzli N, et al. Risk factors for new-onset cat sensitization among adults: a population-based international cohort study. J Allergy Clin Immunol. 2012;129(2):420-5. This is a longitudinal study of an adult cohort that was assembled as part of the European Community Respiratory Health Survey in 28 countries. Cat exposure before the age of 18 protected these participants against developing new cat sensitization. More important, they showed that cat acquisition during this follow-up increased cat sensitization, raising the complexity of the issues when advising parents about early life cat exposure.
Epstein TG, Bernstein DI, Levin L, Khurana Hershey GK, Ryan PH, Reponen T, et al. Opposing effects of cat and dog ownership and allergic sensitization on eczema in an atopic birth cohort. J Pediatr. 2011;158(2):265-71 e1-5.
Wood RA, Bloomberg GR, Kattan M, Conroy K, Sandel MT, Dresen A, et al. Relationships among environmental exposures, cord blood cytokine responses, allergy, and wheeze at 1 year of age in an inner-city birth cohort (Urban Environment and Childhood Asthma study). J Allergy Clin Immunol. 2011;127(4):913-9 e1-6.
• Gaffin JM, Spergel JM, Boguniewicz M, Eichenfield LF, Paller AS, Fowler JF, Jr., et al. Effect of cat and daycare exposures on the risk of asthma in children with atopic dermatitis. Allergy and asthma proceedings : the official journal of regional and state allergy societies. 2012;33(3):282-8. This is a follow-up of a cohort of children with atopic dermatitis who participated in a double-blind eczema treatment trial and were then followed up The findings are interesting since this is the only high-risk longitudinal study that has shown that early life cat exposure is protective against any allergic disease in early childhood.
Ege MJ, Mayer M, Normand A-C, Genuneit J, Cookson WOCM, Braun-Fahrländer C, et al. Exposure to environmental microorganisms and childhood asthma. N Engl J Med. 2011;364(8):701–9.PubMedCrossRef
Bisgaard H, Simpson A, Palmer CNA, Bnnelykke K, McLean I, Mukhopadhyay S, et al. Gene-environment interaction in the onset of eczema in infancy: Filaggrin loss-of-function mutations enhanced by neonatal cat exposure. PLoS Med. 2008;5(6):e131.PubMedCrossRef
Bianca AD, Wandalsen G, Mallol J, Sole D. Risk Factors for Wheezing Disorders in Infants in the First Year of Life Living in Sao Paulo, Brazil. Journal of tropical pediatrics. 2012.
Cai GH, Hashim JH, Hashim Z, Ali F, Bloom E, Larsson L, et al. Fungal DNA, allergens, mycotoxins and associations with asthmatic symptoms among pupils in schools from Johor Bahru, Malaysia. Pediatr Allergy Immunol. 2011;22(3):290–7.PubMedCrossRef
Dhabadi BB, Athavale A, Meundi A, Rekha R, Suruliraman M, Shreeranga A, et al. Prevalence of asthma and associated factors among schoolchildren in rural South India. Int J Tuberc Lung Dis. 2012;16(1):120–5.
Penaranda A, Aristizabal G, Garcia E, Vasquez C, Rodriguez-Martinez CE, Satizabal CL. Allergic rhinitis and associated factors in schoolchildren from Bogota, Colombia. Rhinology. 2012;50(2):122–8.PubMed
Williams AH, Smith JT, Hudgens EE, Rhoney S, Ozkaynak H, Hamilton RG, et al. Allergens in household dust and serological indicators of atopy and sensitization in Detroit children with history-based evidence of asthma. J Asthma. 2011;48(7):674–84.PubMedCrossRef
Shirai T, Yasueda H, Saito A, Taniguchi M, Akiyama K, Tsuchiya T, et al. Effect of exposure and sensitization to indoor allergens on asthma control level. Allergol Int. 2012;61(1):51–6.
Abbing-Karahagopian V, van der Gugten AC, van der Ent CK, Uiterwaal C, de Jongh M, Oldenwening M, et al. Effect of endotoxin and allergens on neonatal lung function and infancy respiratory symptoms and eczema. Pediatr Allergy Immunol. 2012.
Olmedo O, Goldstein IF, Acosta L, Divjan A, Rundle AG, Chew GL, et al. Neighborhood differences in exposure and sensitization to cockroach, mouse, dust mite, cat, and dog allergens in New York City. J Allergy Clin Immunol. 2011;128(2):284-92 e7.
Lin S, Jones R, Munsie JP, Nayak SG, Fitzgerald EF, Hwang SA. Childhood asthma and indoor allergen exposure and sensitization in Buffalo, New York. Int J Hyg Environ Health. 2012;215(3):297–305.PubMedCrossRef
Brozek JL, Bousquet J, Baena-Cagnani CE, Bonini S, Canonica GW, Casale TB, Global Allergy and Asthma European Network; Grading of Recommendations Assessment, Development and Evaluation Working Group, et al. Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines: 2010 revision. J Allergy Clin Immunol. 2010;26(3):466–76.CrossRef