Bla g 1 Allergen Levels in Zagreb Area Household Dust
Cockroach allergy is a health problem in many parts of the world. In urban environments, indoor exposure to cockroach allergens involves a risk of asthma. The aim of this study was to measure the mass fraction of Bla g 1, a major allergen of the German cockroach (Blatella germanica) in 30 house samples, collected at random from Zagreb area households, Croatia. Dust samples were collected on cellulose filters by vacuuming living rooms floors. After extraction, Bla g 1 was detected using the commercial enzyme-linked immunosorbent assay (ELISA). Only four of the thirty households had detectable Bla g 1 levels, and only in one was its concentration higher than 2.0 U g-1, the threshold associated with sensitisation. The Bla g 1 ELISA proved highly sensitive, with the detection limit of 0.12 U g-1. The within- and between-assay imprecision was 8.9 % and 14.4 %, respectively, and accuracy 85 % to 120 %. Low Bla g 1 levels in the household dust support previously reported low prevalence of skin sensitisation to B. germanica among Zagreb residents. Further monitoring should reveal if there are differences in cockroach allergen exposure and sensitisation between households from other geographic areas in Croatia.
Determination of mite Allergens in House Dust Using the Enzyme Immunoassay
The aim of this study was to determine the level of two major mite allergens Dermatophagoides pteronyssinus (Der p 1) and Dermatophagoides farinae (Der f 1) in 30 urban homes in Zagreb, Croatia, using the enzyme immunoassay with two monoclonal antibodies which has been established as the reference method for indoor allergen analysis. Dust samples were taken by vacuuming a carpeted area and collected on cellulose filters. The ranges of Der p 1 and Der f 1 were (0.1-12.5) μg g-1 (median 0.32 μg g-1) and (0.1-31.2) μg g-1 (median 0.35 μg g-1), respectively. Der p 1 and Der f 1 (>2 μg g-1) associated with increased risk of sensitization to mite allergens were found in approximately 16% homes for each allergen. The sum of allergen (Der p 1 + Der f 1) exceeded the lower threshold in 27% of homes. Analytical evaluation of the ELISA assay showed satisfactory results for precision (intra-assay CV <6.9%, inter-assay CV<13.3%), accuracy (91% to 93%), and sensitivity (2 ng mL-1).
The ELISA assay for the measurement of dust mite allergens demonstrated very good analytical characteristics for routine laboratory use, and will provide the essential basis for our future studies of various indoor allergens.
Dust mites, cockroaches, and pets (cats, dogs) are common in homes worldwide, and many species are the source of potent allergens which cause allergic diseases. These diseases are influenced by genetic predisposition and environmental exposure. Generally, the levels of house dust mite (Der p 1 and Der f 1) and cockroach (Bla g 1, Bla g 2) allergens are used as markers of indoor exposure to arthropods.
This article reviews the findings of allergens Der p 1, Der f 1, and Bla g 1 in randomly selected urban households in Zagreb (Croatia) measured from 2006 to 2010 and compares them with exposure to arthropod allergens in other countries. In short, house dust mite allergen levels in Croatian homes are low, but exposure is common; Der p 1 was found in 73 % and Der f 1 in 83 % of the households. By contrast, exposure to cockroach allergen Bla g 1 was both low and uncommon (13 %). Exposure to multiple allergens associated with sensitisation and asthma was not frequent in urban homes in Croatia. However, further studies should include monitoring of both arthropod and pet allergens in high-risk populations in inland and coastal Croatia. They should also investigate a complex dose-response relationship between exposure and sensitisation/asthma development, especially in early childhood.
Pyroglyphid Mites as a Source of Work-Related Allergens
Pyroglyphid mites are primarily associated with allergen exposure at home; hence the name house dust mites. However, we have found numerous studies reporting pyroglyhid mite levels in public and occupational settings. This review presents the findings of house dust mite allergens (family Pyroglyphidae, species Dermatophagoides) as potential work-related risk factors and proposes occupations at risk of house dust mite-related diseases. Pyroglyphid mites or their allergens are found in various workplaces, but clinically relevant exposures have been observed in hotels, cinemas, schools, day-care centres, libraries, public transportation (buses, trains, taxies, and airplanes), fishing-boats, submarines, poultry farms, and churches. Here we propose a classification of occupational risk as low (occasional exposure to mite allergen levels up to 2 μg g-1), moderate (exposure between 2 μg g-1 and 10 μg g-1), and high (exposure >10 μg g-1). The classification of risk should include factors relevant for indoor mite population (climate, building characteristics, and cleaning schedule). To avoid development or aggravation of allergies associated with exposure to house dust mites at work, occupational physicians should assess exposure risk at work, propose proper protection, provide vocational guidance to persons at risk and conduct pre-employment and periodic examinations to diagnose new allergy cases. Protection at work should aim to control dust mite levels at work. Measures may include proper interior design and regular cleaning and building maintenance.