Sensitization of Children in the Stockholm Area to House Dust Mites

Abstract

Atopic sensitization of children in the Stockholm area to house dust mites (HDM) was investigated in a case-control study. Sixty children with and 60 without positive skin prick tests for HDM were matched for age and sex. HDM-sensitized children had previously more often lived in other areas known to be mite infested than the control children. Sensitization to mites was related to dampness in the homes, but no significant relationship was found to the type of residence, frequent visits to a summer house in the archipelago or parental smoking. Dust samples from mattresses of the children with the strongest positive reactions to mites in skin prick tests and the respective controls were subjected to an enzyme immunoassay, to measure the content of the major allergens of the Dermatophagoides (D.) species D. pterinyssinus, D. farinae and D. microceras. Mattress dust samples from the beds of HDM-sensitized children contained significantly higher HDM antigen concentrations than those from the beds of controls. Private houses contained significantly more HDM antigens than flats and 10 of 11 homes in which a dampness problem was recognized contained mite antigens. It is postulated that mite infestation is increasing in the area, energy-saving measures creating improved conditions for HDM survival.

House dust mite allergen levels in two cities in Canada: effects of season, humidity, city and home characteristics

“…The levels of mite allergens in the homes of patients with asthma are relatively low in these two cities for all seasons in the year, particularly in Winnipeg, compared with those reported in other parts of the world such as in the UK [3,15], USA [5] and the coastal areas in Australia [16]. Similar low levels have been reported previously in homes in Denmark and in Sweden where climatic conditions are similar to those in Canada [17][18][19]. This study was carried out on patients with asthma of moderate severity and some of them had been told about dust avoidance measures before they were recruited into the study.…”

“…In the winter months in Vancouver, the mean relative humidity was only 54% despite the high outdoor humidity (mean level of 86 7 ± 5-9%). The prolonged use of central heating in the homes in both cities may be responsible for the low indoor relative humidity, more so in Winnipeg than in Vancouver, as reported in the Scandinavian homes [17][18][19].…”

Environmental risk factors for allergy and socioeconomic status in a birth cohort (BAMSE)

“…Environmental tobacco smoke (ETS) is of importance for wheezy bronchitis (8,9) and is a well‐known trigger of asthma in children (10). As regards allergen exposure, there is a clear relationship between exposure and sensitization to house dust mites (11). The risk to become sensitized to furred pets among wheezing children in Stockholm, also seems to increase with the degree of exposure and allergy to fur‐coated pets; cats in particular, are of the greatest importance for childhood asthma in Scandinavia (12).…”

Is the increase in asthma prevalence linked to increase in allergen load?

“…Green et al measured the number of mites in a small sample of household dusl from homes in two Australian towns (one with a humid, coastal climate, and one with a drier, inland climate) on two occasions, 10 years apart, and found a large change (16). House-dust mite infestation has also been shown to have increased in Stockholm (17)(18)(19). It is known that in climates in which house-dust mites exist, dust-mite allergen exposure is the most important risk factor for the development of asthma, and the literature linking mites causally to the disease has been reviewed (20).…”