Distribution and Abundance of House Dust Mites, Dermatophagoides spp., in Different Climatic Zones of Southern California
ABSTRACT The distribution and abundance of house dust mites, Dermatophagoides spp., were studied in August, October, and December, 1975 in 4 different climatic zones in southern California. During these months, a total of 15 houses were sampled in each climatic zone. Ninety-three percent of the coastal houses were infested with mites, where D. pteronyssinus (Trouessart) dominated (78%) over D. farinae Hughes. Sixty percent of the Riverside (inland valley) houses sampled were infested, where D. farinae was dominant (67%). A 3rd species, D. evansi Fain, Hughes and Johnson, commonly occurring in birds' nests, was found once in a coastal and Riverside house. Densities of both D. pteronyssinus and D. farinae were considerably higher in coastal than in Riverside houses. Live mites were not found in the lightly mite infested houses sampled in the desert (54% positive) and mountains (27% positive). Relative humidity, which varied in houses located in different climatic zones of southern California, was noted to be the principal limiting factor influencing the distribution and abundance of D. pteronyssinus and D. farinae in these zones. Temperatures did not appear to be an important factor influencing distribution and abundance of these mites in the study zones.
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ABSTRACT: The most important allergy-causing mites found in homes worldwide are the house dust mites Dermatophagoides farinae, D. pteronyssinus, Euroglyphus maynei, and the storage mite Blomia tropicalis. Most homes contain multiple species. The most prevalent mite species and allergen in homes differ geographically, between homes within a geographical region, and among areas within a home. Therefore, it is important to know which mite species are present in a geographical area when performing diagnostic testing and prescribing immunotherapy. The key factor that influences mite survival and prevalence is relative humidity. Mites are present in homes in humid geographical areas and are rare or absent in drier climates unless humidity is artificially raised. Generally speaking, dust mite allergen levels are low in public buildings and transportation compared to levels in homes.Current Allergy and Asthma Reports 10/2002; 2(5):401-11. · 2.75 Impact Factor
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ABSTRACT: A survey of dust samples from dwellings, hospitals and some public utilities (libraries, institutes) in several Upper Silesian towns was undertaken to determine the prevalence, number and species of mites. Total seasonal dynamics of dust mite species of the family Pyroglyphidae in dust from beds, floors/carpets and upholstery furniture in dwellings was analysed. Over a 4-years period, 402 dust samples were studied: 238 samples from dwellings, 122 samples from hospitals, 14 from libraries and 28 from institutes. Mites were present in 51.3%, 50.0%, 21.3% and 17.9% of dust samples from dwellings, libraries, hospitals and institutes, respectively. Generally, they were found in 160 samples (39.8%) out of 402 examined. The majority of mites (96.0%) were found in samples from the dwellings, especially in dust from upholstery furniture, couches, sofas and beds. More than 30 mite species were found of which the most abundant and common were pyroglyphids, especially Dermatophagoides pteronyssinus and D. farinae. The pyroglyphid mites constituted 89.2%, 78.9% and 57.5% of a total count of mites collected from dwellings, libraries and hospitals, respectively, and were not found in institutes. D. pteronyssinus was the dominant, especially in libraries and hospitals, however, in dwellings D. farinae was more abundant per 1 gram of dust as the former species. Another pyroglyphid mite, Euroglyphus maynei, occurred in very small numbers. The highest mite densities per gram of dust were noted in dwellings and libraries. A mean number of mites per 1 gram of dust from dwellings was 73.7 +/- 182.9 (range 1.0 - 1560.0), whereas mean values of indoor relative humidity and temperature were 64.5% RH and 22.7 degrees C, respectively. The low mean indoor relative humidity of ambient air, resulted in the relatively low mite frequency (only about 51.3% of samples were positive for mites) and density detected in the dwellings.Annals of agricultural and environmental medicine: AAEM 02/1998; 5(1):73-85. · 3.06 Impact Factor