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Biomedical subjects

P Fitzharris

Publications and source records attributed to P Fitzharris.

At least 37 records · Page 2Linked to original sources
PubMed1998

House dust mite allergen accumulation on sheepskins.

AIM: Sheepskins, which are often used as infant bedding in New Zealand, are known to harbour large quantities of house dust mites and their allergens. In this study we determined the rate of accumulation of the house dust mite allergen, Der p 1 on new sheepskins, and the effects of washing and dry cleaning on its removal. METHODS: New sheepskins were placed on living-room floors (n = 6) and mattresses (n = 6) in six domestic dwellings in Wellington. Sheepskin dust samples were collected by vacuuming before placement, and at two, four and six weeks, after which they were warm-washed. They were replaced for a further six weeks, then dry-cleaned. Dust samples were collected before and after washing and dry-cleaning, and from mattresses and living-room floors. Dust samples were analysed for Der p 1 by double monoclonal antibody ELISA. RESULTS: Der p 1 levels rapidly increased in sheepskins placed on living-room floors and mattresses to a geometric mean level (range) of 9.0 micrograms/g (1.1-102.2) and 29.4 micrograms/g (5.3-131.1) at six weeks, respectively. After warm-water washing and replacement for a further six weeks, these levels were higher at 75.5 micrograms/g (50.1-260.4) and 31.9 micrograms/g (11.1-75.2), respectively. Sheepskin Der p 1 accumulation correlated with mattress (r = 0.78), and living-room floor Der p 1 levels (r = 0.94). Warm water washing and dry-cleaning reduced sheepskins Der p 1 levels by a mean of 79.2% and 95.3%, respectively. CONCLUSIONS: Sheepskins rapidly accumulate house dust mite allergens from the domestic environment. Due to very high levels and rapid accumulation of Der p 1, sheepskins as infant bedding should be discouraged for infants at risk of sensitisation to house dust mites. If they are to be used then it is important that they are washed or dry-cleaned regularly.

Allergens↗
PubMed1998

Cat allergen levels in public places in New Zealand.

AIMS: Cat allergen (Fel d 1) is a known risk factor for asthma. Studies have demonstrated Fel d 1 in both public buildings and domestic dwellings where cats have never been. The aims of this study were to measure reservoir Fel d 1 levels in public buildings in New Zealand, to examine determinants of these levels and to compare them with previously measured domestic levels. METHODS: Dust was obtained in two centres (Wellington and Christchurch) from hotels, hospitals, rest homes, churches, primary schools, childcare centres, cinemas, bank head offices and aeroplanes; and from North Island ski lodges. Measurements of temperature and relative humidity were taken. Information was collected on building characteristics. Fel d 1 levels (microg/g of fine dust) for floors (n=203), beds (n=64) and seats (n=24) were expressed as geometric means (95% confidence intervals). RESULTS: Detectable Fel d 1 levels were found in 95% of floor samples, 91% of bed samples and 100% of seat samples. Fel d 1 levels [geometric mean (95% confidence intervals)] were significantly higher on cinema and domestic aircraft seats [36.8 (20.8-65.3) microg/g and 33.3 (28.0-39.7) microg/g respectively] than on floors [3.6 (2.5-5.1) microg/g and 2.4 (1.8-3.0) microg/g respectively]. Floor Fel d 1 levels in the public buildings sampled were lower than those of domestic dwellings without cats [0.9 (0.6-1.4) microg/g vs 1.7 (1.2-2.4)] microg/g in Wellington and [2.0 (1.6-2.6) microg/g vs 4.0 (2.7-6.0] microg/g in Christchurch. After controlling for potential confounders, floor Fel d 1 levels were higher with carpeted floors (p<0.001) and lower in banks and hospitals (p<0.001). CONCLUSION: Fel d 1 levels in public buildings are low in New Zealand public places except for cinema and domestic aircraft seats where all but one sample had Fel d 1 levels potentially high enough to precipitate asthma symptoms in sensitised individuals.

Air Pollution, Indoor↗
PubMed1998

Biologic pollution in infant bedding in New Zealand: high allergen exposure during a vulnerable period.

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 (microgram/g fine dust) and content (microgram/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 micrograms/g (13.8 to 24.1) and 3.51 micrograms/m2 (2.4 to 5.2). By 15 months, Der p 1 had risen significantly to 44.0 micrograms/g (35.0 to 55. 3) and 49.0 micrograms/m2 (36.0 to 66.8). Bedding that included a sheepskin was used by a third of the infants and contained higher concentrations (microgram/g) and content (microgram/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 micrograms/g (23.5 to 84.9) for houses with cats and 3.0 micrograms/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.

Allergens↗
PubMed1998

Classification of asthma severity: should the international guidelines be changed?

BACKGROUND: International guidelines recommend that, in addition to symptoms and medication requirements, measurements of forced expiratory volume in one second (FEV1) and peak expiratory flow (PEF) are necessary for the objective assessment of asthma severity. The guidelines suggest that parity exists between measurements of FEV1 and PEF when expressed as percentage of predicted normal values, and that asthma severity can be classified as mild, moderate or severe on the basis of FEV and PEF measurements of > 80%, 60-80% and < 60% of predicted values, respectively. OBJECTIVE: To determine the relationship between measurements of FEV1 and PEF when expressed as percentage predicted values. METHODS: A total of 1198 paired measurements of FEV1 and PEF were obtained from the medical records of a random sample of 25 adult asthmatic patients attending a hospital-based chest clinic. Measurements of lung function were expressed as a percentage of predicted normal values, using the European Respiratory Society prediction equations for PEF and FEV1. For the individual paired measurements, the mean differences between PEF and FEV percentage predicted were calculated. Measurements of lung function were used to determine asthma severity with <60%, 60-80%, and >80% predicted FEV1 and PEF values representing severe, moderate and mild asthma, respectively. The proportion of paired measurements in which differences in classification resulted from the use of FEV1 or PEF percentage predicted values was then calculated. RESULTS: In asthma of differing severity, there was considerable variability between measurements of FEV1 and PEF when expressed as percentage predicted values; calculation of the FEV1% predicted resulted in lower values than those of the PEF percentage predicted, with a mean difference of -17.2% (95% CI -16.3%, -18.1%). There was agreement in classification of asthma severity in only 49.9% (598/1198) of paired measurements. Different prediction equations, while variably altering the degree of misclassification, did not correct the basic differences in the assessment of asthma severity dependent on the use of FEV or PEF. CONCLUSION: FEV1 and PEF values, expressed as percentage predicted, are not equivalent. Pending further evaluation, the authors suggest that published asthma guidelines should avoid the assumption of parity between these two measurements.

Adolescent↗
PubMed1998

A pilot study of the effect of mechanical ventilation and heat exchange on house-dust mites and Der p 1 in New Zealand homes.

We have examined the effect of reducing relative humidity (RH), with inbuilt mechanical ventilation and heat-exchange (MVHE) units, on house-dust-mite (HDM) counts and allergen levels, in a pilot study of 10 Wellington dwellings. Recent international prevalence studies in adults and children have confirmed a high prevalence of asthma in New Zealand. Sensitivity to HDM is common among the general population, and HDM is the major allergen associated with asthma. Recent studies of allergen levels have confirmed high concentrations of Der p 1 in the domestic environment. While humidity was significantly reduced in those dwellings fitted with ventilation units, no systematic effect on mites or Der p 1 was observed during the study period. When the reductions in humidity were examined in the context of the time spent below the critical equilibrium humidity (CEH), the intervention led to RH values below the CEH for only 39% of the total of 24-h periods for which measurements were made. Reducing RH by means of MVHE in New Zealand domestic dwellings does not lower humidity sufficiently, or long enough, to have any measurable effect on HDM populations.

Allergens↗
PubMed1997

The effect of frequent vacuum cleaning on the house dust mite allergen, Der p 1 in carpets: a pilot study.

AIM: To determine the effect of frequent vacuum cleaning of carpets on Der p 1, the major group one allergen of the house dust mite Dermatophagoides pteronyssinus. METHODS: Nine rooms and three hallways in the resident medical officers quarters at Wellington Hospital were regularly vacuum cleaned (daily, except weekends) over a five week period. Dust samples were collected before and at weekly intervals for Der p 1 measurement by a double monoclonal antibody ELISA technique. RESULTS: Der p 1 concentrations progressively declined from an initial geometric mean level (95% CI) of 4.47 micrograms/g fine dust (0.11-21.73) to 1.83 micrograms/g (0.29-9.57) after five weeks, a mean reduction of 48.0% (31.7-65.5). Similarly when expressed per unit area Der p 1 levels declined from 6.35 micrograms/m2 (1.15-35.16) to 1.66 micrograms/m2 (0.33-9.04), a mean reduction of 68.5% (58.6-78.3). CONCLUSIONS: Frequent vacuum cleaning over a short time significantly reduces house dust mite allergen levels in carpets. Larger long term trials are warranted to determine if greater reductions are possible that would be beneficial to house dust mite sensitive individuals.

Animals↗
PubMed1997

House dust mite allergen levels in public places in New Zealand.

BACKGROUND: House dust mite allergens are a risk factor for asthma in New Zealand, and levels in domestic dwellings have been found to be high compared with levels in most other countries. Studies in other countries have demonstrated lower levels of Dermatophagoides pteronyssinus allergens in public places compared with levels in domestic dwellings. OBJECTIVES: The purpose of this study was to measure reservoir Der p 1 levels in public places in New Zealand and to examine determinants of these levels. METHODS: Reservoir dust was obtained in the two centers (Christchurch and Wellington) from hotels, hospitals, rest homes, churches, primary schools, childcare centers, cinemas, bank head offices, and airplanes; samples were also obtained from ski lodges. Single measurements of temperature and relative humidity were taken with thermohygrometers and an average humidity over 2 weeks was estimated with use of waxed wooden sticks. Information was collected on building construction, type of heating, and frequency of cleaning. Der p 1 levels (micrograms per gram of fine dust) for floor (n = 202), bed (n = 65), and seat (n = 24) samples in public places were expressed as geometric means (95% confidence intervals). RESULTS: Der p 1 levels in public places were significantly lower than domestic levels in both Wellington and Christchurch. Both floor and bed levels were higher in hotels than in other public places. After controlling for potential confounders, floor Der p 1 levels were higher with carpeted floors (p < 0.0001) and lower with recent cleaning (p = 0.02) and bed Der p 1 levels were higher with timber wall construction (p = 0.03). Other building, heating, or cleaning characteristics did not show significant association with allergen levels. CONCLUSION: Der p 1 levels were much lower in public places than in domestic dwellings with floor levels primarily affected by floor covering.

Allergens↗
PubMed1997

Cat allergen (Fel d 1) levels on school children's clothing and in primary school classrooms in Wellington, New Zealand.

BACKGROUND: New Zealand has a high prevalence of the major allergic diseases including asthma, rhinitis, and eczema, and cat ownership is common, with more than 50% of homes containing a cat. OBJECTIVE: The study was designed to examine the levels of cat allergen (Fel d 1) in the primary school environment, both on floors and on children's clothing. METHODS: We collected and analyzed dust samples from 11 school classrooms and from 202 children's garments using vacuum sampling and two-site monoclonal antibody ELISA, respectively. Environmental variables were identified by questionnaire. RESULTS: The geometric mean level of Fel d 1 in classrooms was 2.61 micro/gm (95% confidence interval, 1.28 to 3.84); however, seven classrooms had a floor sample with Fel d 1 greater than 8 microg/m2. Carpeted floor levels at 2.21 microg/gm (1.28 to 3.84) were considerably higher than those on uncarpeted floors, at 0.33 microg/gm (0.1 to 1.14). Floor levels and pupil cat ownership rates were positively correlated (r2 = 0.93, p = 0.0003). Children from homes with cats carried allergen on their clothes (mean Fel d 1, 6.10 microg per garment compared with non-cat owners (0.72 microg per garment). Wool and polyester garments contained more Fel d 1 than cotton clothing. Girls' clothing had significantly higher levels of allergen than did that of boys, even after controlling for cat status and fabric differences. CONCLUSIONS: Carpeting should be discouraged in environments such as schools and child care centers, where children spend considerable time. Transport of Fel d 1 on clothing from the domestic to the school environment is a major source of classroom cat allergen.

Adult↗
PubMed1997

Is infant immunization a risk factor for childhood asthma or allergy?

The Christchurch Health and Development Study comprises 1,265 children born in 1977. The 23 children who received no diphtheria/pertussis/tetanus (DPT) and polio immunizations had no recorded asthma episodes or consultations for asthma or other allergic illness before age 10 years; in the immunized children, 23.1% had asthma episodes, 22.5% asthma consultations, and 30.0% consultations for other allergic illness. Similar differences were observed at ages 5 and 16 years. These findings do not appear to be due to differential use of health services (although this possibility cannot be excluded) or con-founding by ethnicity, socioeconomic status, parental atopy, or parental smoking.

Adolescent↗
PubMed1997

Determinants of house dust mite allergen in homes in Wellington, New Zealand.

OBJECTIVES: To measure levels of the major Dermatophagoidespteronyssinus allergen (Der p 1) in homes in Wellington, New Zealand, and to examine factors which affect these levels. METHODS: As part of a study of risk factors for asthma among 474 8-10-year-old children, standard procedures were used to collect reservoir dust and to measure Der p 1 levels on the living room floor and child's bedroom floor and bedding. Der p 1 levels were analysed both as geometric mean microg/g of fine dust and as microg/m2. Questionnaires collected information about factors which might influence these levels, and an average relative humidity in the bed and on the bedroom floor was also measured. RESULTS: Similar geometric mean levels of Der p 1 were found at each floor site - 25.5 microg/g (95% CI: 22.8-28.5) in the living room and 26.4 microg/g (95% CI: 23.7-29.3) on the child's bedroom floor. The geometric mean level of Der p 1 in the child's bed was 46.6 microg/g (95% CI: 42.3-51.3). After controlling for possible confounders, geometric mean living room and bedroom floor Der p 1 levels were significantly higher in households with older carpet than households with no carpets or newer carpets, and higher in the autumn. Households with three or more children had higher levels of Der p 1 than households with fewer children. Bedding levels were significantly higher in beds with kapok or inner sprung mattresses, or wool underlays and at relative humidities above the mean (51%). CONCLUSION: The very high levels of house dust mite allergen (Der p 1) found in Wellington are likely to be due to a variety of life-style and climatic factors. However, the type and age of floor covering appears to be the single most important factor.

Allergens↗