Biologic pollution in infant bedding in New Zealand: High allergen exposure during a vulnerable period,☆☆,,★★

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Abstract

Background: High exposure to house dust mite and cat allergens in early life predisposes to allergic sensitization and to the development and persistence of asthma. Prevalence and severity of asthma are high in New Zealand. Objective: The objective of this study was to determine the concentrations of Der p 1 and Fel d 1 in infant bedding in Wellington, New Zealand. Methods: Infants were visited at home at a mean age of 11 weeks and again at 15 months. The concentration (μg/g fine dust) and content (μg/m2 ) of Der p 1 (154 infants) and Fel d 1 (75 infants) were measured in dust samples taken from each infant’s bed. Results: At 11 weeks, geometric mean (95% confidence intervals) Der p 1 levels were 18.3 μg/g (13.8 to 24.1) and 3.51 μg/m2 (2.4 to 5.2). By 15 months, Der p 1 had risen significantly to 44.0 μg/g (35.0 to 55.3) and 49.0 μg/m2 (36.0 to 66.8). Bedding that included a sheepskin was used by a third of the infants and contained higher concentrations (μg/g) and content (μg/m2 ) of Der p 1 than beds without sheepskins. Cat ownership was the major determinant of Fel d 1 levels, with 48% of infants living with cats. At the first visit, the mean concentration of Fel d 1 in bedding was 44.6 μg/g (23.5 to 84.9) for houses with cats and 3.0 μg/g (2.1 to 4.3) for those without cats, remaining essentially unchanged at the second visit. When expressed as micrograms per square meter, there was a significant increase between visits, from 8.1 (3.9 to 16.6) to 39.6 (19.9 to 78.5) in the cat-inclusive households. Conclusions: Extremely high levels of house dust mite allergen have been found in these infants’ environments, which, together with the high levels of cat allergen in almost half who kept cats, are likely to be a major determinant of asthma prevalence and severity in New Zealand. (J Allergy Clin Immunol 1998;102:765-70.)

Section snippets

Infant study group

Over a 12-month period from November 1993 to November 1994, all Wellington-based mothers of healthy infants born at Wellington Women’s Hospital were approached on the postnatal ward during a 3-week period each 3 months, thereby ensuring that sampling took place during each season.

Mothers and infants were visited in their homes, and dust samples were obtained from the bedding, bedroom, and living room floors of 154 infants at age 5 and 16 weeks (mean 11 weeks) and again at age 12 to 19 months

RESULTS

All infants (49% female) lived with their birth mother. Ninety-two (59.7%) of the infants were the firstborn children in the family, 34 (22.1%) had 1 sibling, and 28 (18.2%) had 2 or more siblings. At the first visit (mean age 11 weeks), 78 (50.6%) slept in a cot (crib); 70 (45.5%) in a bassinet, cradle, or basket; and 2 (1.3%) in the parental bed. At the second visit, 129 (84.3%) were in a cot, 13 (8.5%) in their own bed, and 10 (6.5%) in the parental bed. The majority of beds included an

DISCUSSION

The reservoir concentrations of Der p 1 in bedding identified in this study are approximately 10-fold higher than those previously reported for infant mattresses from the Netherlands.27 Given the increased risks of sensitization and the development of asthma associated with levels considerably lower than those found in our study, it is perhaps not surprising that asthma in New Zealand is common, severe, and dominated by allergy to HDM. The great majority (96%) of the study infants were exposed

Acknowledgements

We acknowledge the research assistance provided by Rachel Kent, Tania Slater, Louise Stone, and Sarah Tohill and thank the parents and infants who participated in this study.

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    From the Wellington Asthma Research Group, Department of Medicine, Wellington School of Medicine.

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    Supported in part by the Asthma and Respiratory Foundation of New Zealand, the Wellington Medical Research Foundation, and the Marjorie Barclay Trust. J.C. is supported by a Professorial Research Fellowship from the Health Research Council of New Zealand, who also support the Wellington Asthma Research Group with a Programme Grant. The allergen laboratory was established with a grant from the Electricity Corporation of New Zealand.

    Reprint requests: Penny Fitzharris, MD, Department of Medicine, Wellington School of Medicine, PO Box 7343, Wellington South, New Zealand.

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