Charlotte Nicholas

Lifetime dog and cat exposure and dog‐ and cat‐specific sensitization at age 18 years

Background Prior research about whether keeping a dog or cat at home causes allergies to that pet has been limited to outcomes in early childhood.

How Accurately Do Young Adults Recall Childhood Pets? A Validation Study

Epidemiologic research shows that pets influence human health, demonstrating both protective and deleterious health risks; therefore, valid definitions of pet exposure would enhance research. The authors determined how well young adults aged 18 years report their early childhood pets. Subjects in an established birth cohort from Detroit, Michigan, born in 1987-1989 (n = 820) were asked a series of questions about pets in the home during their first 6 years of life. Pet recall was compared with annual prospectively collected parental report from 12-18 years prior. Exposure to cats was correctly reported on average 86.3% of the time (95% confidence interval: 85.0, 87.5) and dogs 79.2% (95% confidence interval: 77.7, 80.6) of the time (P < 0.01). Cats and dogs were more likely to be underreported than overreported, from as few as 1.8-fold to as many as 8.3-fold (P < 0.05). Reporting differed by sex of the respondent and current pet ownership. No differences were found in reporting by those who experienced allergy symptoms near dogs or cats. Findings suggest good reliability of young adult pet reporting for ages 0-6 years but that childhood pet exposure may need to be assessed separately depending on the participants sex and the outcome of interest.

Influence of cat characteristics on Fel d 1 levels in the home

BACKGROUND Previous studies investigating cat characteristics and cat allergen production focused on clinical experiments that quantified allergen from either the shaved skin or the fur of the animal; however, these studies did not address these experimental relationships in the home. OBJECTIVE To determine the relationships between cat characteristics and cat allergen isolated from household dust. METHODS Fel d 1 allergen levels in dust from homes participating in a population-based study of environmental effect on allergy development were analyzed using a standard monoclonal antibody-based assay. Cat characteristics were based on interviews conducted during home visits by study personnel. RESULTS Households with any cats had higher geometric mean Fel d 1 levels than households without cats (32.88 vs 0.43; P < .01), and cat allergen levels increased with increasing numbers of cats in the home (P < .01). Length of cat hair, cat sex, reproductive status, and time spent indoors were analyzed; the only characteristic associated with higher levels of Fel d 1 was whether the cat had been neutered or spayed. CONCLUSIONS Having cats in the home is significantly associated with increased Fel d 1 levels, and having more cats in the home is correlated with more cat allergen. Cat reproductive characteristics may be associated with measurable differences in cat allergen levels.

Are cats and dogs the major source of endotoxin in homes

UNLABELLED Previous studies have suggested that exposure to cats and dogs during early childhood reduces the risk of allergic disease, possibly by increasing home endotoxin exposure. This study asked the question of whether cats and dogs are the dominant influence on dust endotoxin concentrations in homes after considering other variables reportedly associated with endotoxin. The presence of cats or dogs in homes, household and home characteristics, and dust endotoxin concentrations from 5 locations were assessed in 966 urban and suburban homes. Whether considered together as pets or as cats and dogs separately, the presence of cats and dogs significantly contributed to living room and bedroom floor endotoxin concentrations, but not to bed endotoxin concentrations. However, the two variables consistently related to endotoxin in all home sites were the home occupant density (occupants/room) and cleanliness of the home. Our data suggest that reducing occupant density and improving home cleanliness would reduce home endotoxin concentrations more than removing pet cats or dogs from the home. PRACTICAL IMPLICATIONS Many studies have shown that early childhood exposure to indoor cats or dogs is associated with a reduced risk of later allergic disease and asthma. An important question is whether alteration in allergic risk associated with cat and dog exposure results from increased endotoxin exposure or from some other associated exposure. Our findings show that cats and dogs are not the dominant source of endotoxin in homes; rather, the density of human occupation and poor cleaning contribute more consistently to higher home endotoxin concentrations especially in the beds.

Dog allergen levels in homes with hypoallergenic compared with nonhypoallergenic dogs.

Background Despite the public interest in hypoallergenic dogs, few scientific, including epidemiological studies have attempted to evaluate claims of hypoallergenicity. This study was designed to determine whether dog breeds reported as hypoallergenic correspond to lower dog allergen in the home versus nonhypoallergenic dogs. Methods A web search was conducted to identify breeds cited as hypoallergenic. Four separate classification schemes using combinations of purebred and mixed breed dogs were used to compare the levels of Canis familiaris 1 in dust samples collected from homes with hypoallergenic versus nonhypoallergenic dogs from an established birth cohort. Results No classification scheme showed that the level of dog allergen in homes with hypoallergenic dogs differed from other homes. Conclusion Dog-allergic individuals should have access to scientifically valid information on the level of allergen shedding of different breeds of dogs.

Transforming growth factor beta (TGFβ1) in breast milk and indicators of infant atopy in a birth cohort.

The infant guts ability to suppress immunologic reactions to food proteins could be influenced by levels of TGFβ in breast milk. We hypothesized that lower levels of TGFβ1 in the breast milk (BM) of mothers in the WHEALS birth cohort are associated with atopy at infant age 2–3 yrs.

Relationships between total and allergen-specific serum IgE concentrations and lung function in young adults.

BACKGROUND Prior studies have shown relationships between serum immunoglobulin E (IgE) and asthma. OBJECTIVE To investigate relationships between total and allergen-specific IgE concentrations and lung function in young adults. METHODS Measurements of total IgE, allergen-specific IgE to 6 common allergens, and spirometry (forced expiratory volume in one second [FEV(1)], forced vital capacity [FVC], FEV(1)/FVC, and percent change in FEV(1) after bronchodilation) were used to calculate correlations between the logarithmically transformed IgE values and measures of lung function among participants in a birth cohort not selected for risk of allergic disease stratified by current asthma, prior asthma, or no asthma. RESULTS The 428 participants were 51.6% female, 93% white, and 18.4 (standard deviation = 0.6) years old. Forty-eight (11.2%) had current asthma, 55 (12.9%) had a history of asthma, and 325 (75.9%) never had asthma. For males with current asthma, correlations between total IgE and FEV(1)% and FVC% were -0.51 (P = .06) and -0.70 (P = .005), respectively. For females with current asthma, the only significant correlation was between total IgE and the FEV(1)/FVC ratio (-0.55, P = .001). After excluding smokers and individuals without detectable allergen-specific IgE, the negative correlations for both males and females remained statistically significant. The correlations among males or females with prior asthma or no history of asthma were minimal and not statistically significant. The sum of the allergen-specific IgEs showed the same pattern of relationships to lung function as did total IgE. CONCLUSION Our results show significant negative correlations that vary by gender between both total and allergen-specific IgE and measurements of lung function in young adults with current asthma.

Using a physician panel to estimate food allergy prevalence in a longitudinal birth cohort

The incidence of immunoglobulin E-mediated food allergy (IgE-FA) has increased in the US and Europe, likely due to a complex interplay between biologic, genetic and environmental factors.1-4 The estimated prevalence (95% Confidence Interval) of allergy to milk, egg, and peanut among US 0-2 year olds is 2.0% (1.6-2.4), 1.0% (0.7, 1.3), and 1.4% (1.1-1.8), respectively.5 Determining the prevalence of IgE-FA status for epidemiologic studies is challenging.6 Self-report may result in overestimates due to the inability of respondents to distinguish food intolerance from IgE-FA.7, 8 The double-blind placebo controlled food challenge (DBPCFC), while a gold standard for diagnosis of IgE-FA, is seldom feasible for large, epidemiologic studies. It is costly in terms of materials and staff and there is risk to the patient.9-11 The use of predictive decision points for specific IgE (sp-IgE) and skin prick tests (SPT) that predict clinical reactivity with > 95% certainty also have limitations and do not incorporate patient symptoms.12, 13 Even using sp-IgE as an outcome in research is problematic, since only 40% of persons who are sensitized to food allergens will respond to a DBPCFC.14 The challenge for advancing epidemiologic investigations in IgE-FA is to combine physician expertise with clinical assessments, medical history and self-report of symptoms. We describe the process of establishing a physician panel to systematically review data from infants enrolled in a birth cohort. Physicians then classified them according to the presence of IgE-FA.