Dog introduction alters the home dust microbiota.

Research has largely reported that dog exposure is associated with reduced allergic disease risk. Responsible mechanism(s) are not understood. The goal was to investigate whether introducing a dog into the home changes the home dust microbiota. Families without dogs or cats planning to adopt a dog and those who were not were recruited. Dust samples were collected from the homes at recruitment and 12 months later. Microbiota composition and taxa (V4 region of the 16S rRNA gene) were compared between homes that did and did not adopt a dog. A total of 91 dust samples from 54 families (27 each, dog and no dog; 17 dog and 20 no dog homes with paired samples) were analyzed. A significant dog effect was seen across time in both unweighted UniFrac and Canberra metrics (both P = .008), indicating dog introduction may result in rapid establishment of rarer and phylogenetically related taxa. A significant dog-time interaction was seen in both weighted UniFrac (P < .001) and Bray-Curtis (P = .002) metrics, suggesting that while there may not initially be large relative abundance shifts following dog introduction, differences can be seen within a year. Therefore, dog introduction into the home has both immediate effects and effects that emerge over time.

Prenatal antimicrobial use and early-childhood body mass index.

BACKGROUND/OBJECTIVES: Growing evidence suggests that antibiotic use is associated with childhood body mass index (BMI), potentially via mechanisms mediated by gut microbiome alterations. Less is known on the potential role of prenatal antimicrobial use in offspring obesity risk. We examined whether prenatal antibiotic or antifungal use was associated with BMI at the age of 2 years in 527 birth cohort participants. METHODS/SUBJECTS: Antimicrobial use was obtained from the prenatal medical record. Height and weight were measured at the age of 2 years. Overweight/obesity was defined as a BMI ⩾85th percentile. RESULTS: A total of 303 (57.5%) women used antibiotics and 101 (19.2%) used antifungals during pregnancy. Prenatal antifungal use was not associated with child BMI at the age of 2 years. In the fully adjusted model, prenatal antibiotic use was associated with a 0.20±0.10 (P=0.046) higher mean BMI Z-score at the age of 2 years. Associations between prenatal antibiotic use and childhood BMI varied by trimester of exposure, with first or second-trimester exposure more strongly associated with larger BMI at the age of 2 years for both BMI Z-score (interaction P=0.032) and overweight/obesity (interaction P=0.098) after covariate adjustment. CONCLUSIONS: Prenatal antibiotic, but not antifungal, use is associated with larger BMI at the age of 2 years; associations were stronger for antibiotic exposures in earlier trimesters. Future studies examining whether these associations are due to alterations in the maternal and/or infant microbiome are necessary. Children who are overweight at the age of 2 years are at higher risk for being overweight as they age; prenatal antibiotic use is a potentially modifiable exposure that could reduce childhood obesity.

Subgroup differences in the associations between dog exposure during the first year of life and early life allergic outcomes.

BACKGROUND: The effect of dog exposure on the risk of children developing allergic disease remains controversial. Many analyses have not considered that associations may vary within population subgroups. OBJECTIVE: To examine whether associations between living with a dog in the first year of life and allergic outcomes vary within subgroups selected a priori (race, gender and delivery mode). METHODS: Black (n = 496) and White (n = 196) children enrolled in the WHEALS birth cohort study had a clinical examination at age 2 years to assess eczema and allergen-specific IgE (sIgE) and perform skin prick testing (SPT). Whether the child lived with an indoor dog in the first year of life was assessed through interview, as was doctor diagnosis of asthma at ages 3-6 years. RESULTS: Living with a dog was associated with decreased odds of having ≥ 1 positive SPT (OR = 0.56, 95% CI: 0.34, 0.91) and having eczema (OR = 0.34, 95% CI: 0.20, 0.60). The association with SPT was stronger in those children born via caesarean section (c-section) vs. vaginally (OR = 0.29, 95% CI: 0.12, 0.74 vs. OR = 0.76, 95% CI: 0.43, 1.37, respectively, interaction P = 0.087) and in those who were firstborn vs. not (OR = 0.27, 95% CI: 0.11, 0.67 vs. OR = 0.82, 95% CI: 0.45, 1.47, respectively, interaction P = 0.044). The association with eczema was stronger in children born vaginally compared with those born via caesarean section (OR = 0.17, 95% CI: 0.06, 0.43 vs. OR = 0.65, 95% CI: 0.31, 1.35, respectively, interaction P = 0.025) and was stronger in Black vs. White children (OR = 0.30, 95% CI: 0.15, 0.61 vs. OR = 0.78, 95% CI: 0.29, 2.11, respectively, interaction P = 0.12). Dog keeping was not significantly inversely associated with having ≥ 1 elevated sIgE and only approached statistical significance with asthma. CONCLUSIONS AND CLINICAL RELEVANCE: Results likely vary between studies due to variability of specific exposure-outcome associations in subgroups defined by other factors as well as the relative distributions of those subgroups. Important allergic disorder associations will be missed without subgroup analyses.

Maternal group B Streptococcus and the infant gut microbiota.

Early patterns of gut colonization may predispose children to adult disease. Exposures in utero and during delivery are associated with the infant gut microbiome. Although ~35% of women carry group B strep (GBS; Streptococcus agalactiae) during pregnancy, it is unknown if GBS presence influences the infant gut microbiome. As part of a population-based, general risk birth cohort, stool specimens were collected from infant's diapers at research visits conducted at ~1 and 6 months of age. Using the Illumina MiSeq (San Diego, CA) platform, the V4 region of the bacterial 16S rRNA gene was sequenced. Infant gut bacterial community compositional differences by maternal GBS status were evaluated using permutational multivariate analysis of variance. Individual operational taxonomic units (OTUs) were tested using a zero-inflated negative binomial model. Data on maternal GBS and infant gut microbiota from either 1 (n=112) or 6-month-old stool (n=150) specimens was available on 262 maternal-child pairs. Eighty women (30.5%) were GBS+, of who 58 (72.5%) were given intrapartum antibiotics. After adjusting for maternal race, prenatal antifungal use and intrapartum antibiotics, maternal GBS status was statistically significantly associated with gut bacterial composition in the 6 month visit specimen (Canberra R 2=0.008, P=0.008; Unweighted UniFrac R 2=0.010, P=0.011). Individual OTU tests revealed that infants of GBS+ mothers were significantly enriched for specific members of the Clostridiaceae, Ruminococcoceae, and Enterococcaceae in the 6 month specimens compared with infants of GBS- mothers. Whether these taxonomic differences in infant gut microbiota at 6 months lead to differential predisposition for adult disease requires additional study.

Combined effects of prenatal medication use and delivery type are associated with eczema at age 2 years.

BACKGROUND: Separately, prenatal antibiotics and Caesarian delivery have been found to be associated with increased risk of allergic diseases. It is not clear whether these factors may modify the effect of each other. OBJECTIVE: To assess whether the associations between delivery types and eczema, sensitization and total IgE at age 2 years were modified by maternal use of prenatal medications. METHODS: Prenatal charts of women enrolled in the WHEALS birth cohort were reviewed for delivery mode and medications prescribed and administered throughout their entire pregnancy, including systemic antibiotics and vaginally applied antifungal medications. The associations between the delivery mode and select medications and, eczema, sensitization (≥ 1 of 10 allergen-specific IgE ≥ 0.35 IU/mL) and total IgE at age 2 years were assessed. RESULTS: There was a lower risk of eczema among vaginally vs. c-section born children (relative risk adjusted for race = aRR = 0.77, 95% CI 0.56, 1.05). Although not statistically significantly different, this association was stronger among the subset of children born vaginally to a mother who did not use systemic antibiotics or vaginal antifungal medications (aRR = 0.69, 95% CI 0.44, 1.08) compared to those born vaginally to mothers who used systemic antibiotics or vaginal antifungals (aRR = 0.81, 95% CI 0.57, 1.14). A protective association between vaginal birth and sensitization (aRR = 0.86, 95% CI 0.72, 1.03) was similar for those children born vaginally to a mother who did not (aRR = 0.87, 95% CI 0.69, 1.10) and who did (RR = 0.85, 95% CI 0.70, 1.04) use systemic antibiotics or vaginal antifungal medications. There were no associations with total IgE. CONCLUSIONS: Children born vaginally had lower risk of eczema and sensitization compared with those born via c-section; however, the protective association with eczema may be slightly weakened when mothers took systemic antibiotics or vaginally applied medications during pregnancy.

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.

Racial disparities in allergic outcomes in African Americans emerge as early as age 2 years.

BACKGROUND: Racial disparities in allergic disease outcomes have been reported with African Americans suffering disproportionately compared to White individuals. OBJECTIVE: To examine whether or not racial disparities are present as early as age 2 years in a racially diverse birth cohort in the Detroit metropolitan area. METHODS: All children who were participants in a birth cohort study in the Detroit metropolitan area were invited for a standardized physician exam with skin prick testing and parental interview at age 2 years. Physicians made inquiries regarding wheezing and allergy symptoms and inspected for and graded any atopic dermatitis (AD). Skin testing was performed for Alternaria, cat, cockroach, dog, Dermatophagoides farinae (Der F), Short Ragweed, Timothy grass, egg, milk and peanut. Specific IgE was measured for these same allergens and total IgE was determined. RESULTS: African American children (n = 466) were more likely than White children (n = 223) to have experienced any of the outcomes examined: at least 1 positive skin prick test from the panel of 10 allergens (21.7% vs. 11.0%, P = 0.001); at least one specific IgE ≥ 0.35 IU/mL (out of a panel of 10 allergens) (54.0% vs. 42.9%, P = 0.02); had AD (27.0% vs. 13.5%, Chi-square P < 0.001); and to ever have wheezed (44.9% vs. 36.0%, P = 0.03). African American children also tended to have higher total IgE (geometric means 23.4 IU/mL (95%CI 20.8, 27.6) vs. 16.7 IU/mL (95%CI 13.6, 20.6 IU/mL), Wilcoxon Rank Sum P = 0.004). With the exception of wheezing, the associations did not vary after adjusting for common social economic status variables (e.g. household income), environmental variables (endotoxin; dog, cat and cockroach allergen in house dust) or variables that differed between the racial groups (e.g. breastfeeding). After adjustment, the wheeze difference was ameliorated. CONCLUSIONS: With disparities emerging as early as age 2 years, investigations into sources of the disparities should include the prenatal period and early life.

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. OBJECTIVE: Evaluate the association between lifetime dog and cat exposure and allergic sensitization to the specific animal at 18 years of age. METHODS: Participants enrolled in the Detroit Childhood Allergy Study birth cohort during 1987-1989 were contacted at the age 18 years. Sensitization to dog or cat was defined as animal-specific IgE ≥ 0.35 kU/L. Annual interview data from childhood and follow-up interviews at age 18 years were used to determine lifetime indoor dog and cat exposure (indoor was defined when the animal spent >50% of their time inside the house). Exposure was considered in various ways: first year, age groups and cumulative lifetime. Analyses were conducted separately for dogs and cats. RESULTS: Among males, those with an indoor dog during the first year of life had half the risk [relative risk (RR)=0.50, 95% confidence interval (CI) 0.27, 0.92] of being sensitized to dogs at age 18 compared with those who did not have an indoor dog in the first year. This was also true for males and females born via c-section (RR=0.33, 95% CI 0.07, 0.97). Overall, teens with an indoor cat in the first year of life had a decreased risk (RR=0.52, 95% CI 0.31, 0.90) of being sensitized to cats. Neither cumulative exposure nor exposure at any other particular age was associated with either outcome. CONCLUSIONS AND CLINICAL RELEVANCE: The first year of life is the critical period during childhood when indoor exposure to dogs or cats influences sensitization to these animals.

Prenatal exposure to household pets influences fetal immunoglobulin E production.

BACKGROUND: Early life pet exposure may protect against allergic sensitization during childhood. Few studies have evaluated the effect of prenatal pet exposure on potential neonatal markers of allergic risk. OBJECTIVE: The aim of this study was to investigate whether maternal exposure to pets affects cord blood IgE levels in a population-based, general risk, ethnically mixed birth cohort. METHODS: Pet keeping during pregnancy was ascertained from women residing in a defined area of Wayne County Michigan and recruited from five staff model obstetric clinics. Maternal venous blood was analysed for total and allergen-specific IgE along with cord blood total IgE from 1049 infants. RESULTS: Compared with infants from households with no cats or dogs kept indoors during pregnancy, infants whose homes had either cats or dogs had significantly reduced mean cord IgE levels [0.34 IU/mL (95% CI 0.30-0.38) vs. 0.24 IU/mL (0.20-0.27), P=0.025]. Similar effects were apparent in cat-only households [0.21 IU/mL (0.16-0.27), P=0.020] and dog-only households [0.24 IU/mL (0.19-0.29), P=0.045]. There was no effect on results when excluding mothers who reported avoiding pets due to allergy-related concerns. CONCLUSION: Mothers with either cats or dogs in their home during pregnancy deliver children with lower cord blood IgE levels compared with mothers who do not live with these pets, supporting the hypothesis that pet exposure influences immune development in a manner that is protective for atopy and is operant even before birth.

[Environmental pollution and childhood morbidity]. / Znecistené ovzdusí a nemocnost detí.

BACKGROUND: A study of morbidity of children aged 0 to 3 years was organized in two districts in the Czech Republic. Comparisons were drawn between children living in district Teplice, known for its high air pollution, and those living in Practice, the district with consistently lower particulate and SO2 exposures. METHODS AND RESULTS: 452 children of the follow up study were born between May 1994 and December 1996. Childhood morbidity during the first three years of life was obtained from their pediatric records. Diagnoses were coded using the International Classification of Diseases--the 10th edition, and categorized into broad groups. Children born in Teplice experienced a significantly higher rate of otitis media (and otalgia), gastrointestinal infections, upper respiratory infections, and pneumonia, but they did not differ in the risk of bronchitis or that of viral infections such as varicella. These findings remained valid after the multiple linear regression models were calculated and adjusted for education, maternal age, maternal smoking, and other smokers in the household, breastfeeding, and attendance at the day care. CONCLUSIONS: Air pollution may alter early childhood susceptibility to infection, but other differences between the districts have to be considered: systematic diagnostic differences for several health outcomes between pediatricians in Teplice and Practice, differences in health-care seeking approach of parents, and some hitherto unidentified factors.

Childhood morbidity and air pollution in the Teplice program.

BACKGROUND: A study of morbidity of children aged 0 to 3 years was conducted in two districts in the Czech Republic. Comparisons were made between children living in Teplice district, known for its high air pollution, and children living in Practice, a district with consistently lower particulate and SO2 exposures. METHODS AND RESULTS: The children were selected for the follow up based on deliveries from May 1994 to December 1966. Childhood morbidity during the first three years of life of 452 children was extracted from their pediatric records. Diagnoses were coded using the International Classification of Diseases--10th edition, and categorized into broad groupings. Children born in Teplice experienced a significantly higher rate of otitis media and otalgia, gastrointestinal infections, upper respiratory infections, and pneumonia, but did not differ in their risk for bronchitis or for viral infections such as varicella. These findings remained after multiple linear regression models adjusted for education, maternal age, maternal smoking, and other smokers in the household, breastfeeding, and attendance at day care. CONCLUSIONS: Air pollution may alter early childhood susceptibility to infection, but other differences between the districts must be considered: systematic diagnostic differences for several health outcomes comparing pediatricians in Teplice vs. Practice, differences in health-care seeking behavior by the parents, and inadequate control for confounding.

[Parameters of cellular immunity in maternal and umbilical cord blood in relation to air pollution. Preliminary results of a pregnancy outcomes study]. / Parametry bunecné imunity v materské a pupecníkové krvi ve vztahu k znecistení ovzdusí. Predbezné výsledky projektu výsledky tehotenství.

BACKGROUND: The study is a part of the project Pregnancy Outcome (Teplice Program) examining effects of polluted environment on the quality of reproduction in Teplice (high polluted) and Prachatice (control) districts. Selected parameters of cell mediated and humoral immunity in maternal and umbilical samples after delivery were assayed. METHODS AND RESULTS: Lymphocytes in 768 samples of maternal venous blood and 739 samples of umbilical blood collected in May 1994-October 1997 were phenotyped using flow cytometry. Medical and personal questionnaires were used to obtain data on clinical risk factors during pregnancy, health and life style of mothers, the course and prolongation of labour and newborn's status. The percentages of T and NK lymphocytes in both umbilical and maternal blood were associated with a number of variables, including the course of labour. After adjustment for the other predictors, the percentage of NK lymphocytes was found significantly higher in Teplice than in Prachatice samples--in both maternal and umbilical blood. CONCLUSIONS: A part of the observed difference between distribution of NK and T lymphocytes can be attributed to living in the polluted district. To see effects of polluted environment, the association of seasonal difference in levels of major pollutants with seasonal changes in lymphocyte phenotype will be analyzed.