OBJECTIVETo investigate the short and long term efficacy of a commercial air ionizer in killing Dermatophagoides pteronyssinus (D. pteronyssinus) and Dermatophagoides farinae (D. farinae) mites.

METHODSThe effect of a commercial ionizer on D. pteronyssinus and D. farinae was evaluated in the laboratory, using a specially designed test. Mortality was assessed after 6, 16 and 24 hours for direct exposure and after 24, 36, 48, 60 and 72 hours for exposure in simulated mattress. New batches of mites were used for each exposure time.

RESULTSLT50 for direct exposure of ionizer was 10 hours for D. pteronyssinus and 18 hours for D. farinae. The LT50 for exposure in simulated mattress was 132 hours or 5.5 days for D. pteronyssinus and 72 hours or 3 days for D. farinae. LT95 for direct exposure of ionizer was 36 hours for D. pteronyssinus and D. farinae. Meanwhile, the LT95 for exposure in simulated mattress was 956 hours or 39.8 days for D. pteronyssinus and 403 hours or 16.8 days for D. farinae.

CONCLUSIONSThis study demonstrates the increasing mite mortalities with increasing exposure time of a commercial ionizer and suggests that negative ions produced by an ionizer kill dust mites and can be used to reduce natural mite populations on exposed surfaces such as floors, clothes, curtains, etc. However, there is reduced efficacy on mites inside stuffed materials as in mattresses and furniture.

Air Ionization ; Animals ; Dermatophagoides farinae ; drug effects ; Dermatophagoides pteronyssinus ; drug effects ; Pest Control ; methods

This experiment was undertaken to screen the acaricidal effects of herb essential oils (pennyroyal, ylang ylang, citronella, lemon grass, tea tree, and rosemary) at different doses (0.1, 0.05, 0.025, 0.0125, and 0.00625 microliter/cm2) and exposure times (5, 10, 20, 20, 30 and 60 min) on house dust mites Dermatophgoides farinae and D. pteronyssinus. The most effective acaricidal components of pennyroyal (Mentha pulegium) were analyzed using a gas chromatography-mass spectrometer (GC-MS). Of these essential oils, the most effective was pennyroyal, which is composed essentially of pulegone (> 99%), at a dose of 0.025 microliter/cm2, which at an exposure time of 5 min killed more than 98% of house dust mites. In the pennyroyal fumigation test, the closed method was more effective than the open method and maximum acaricidal effect was 100% at 0.025 microliter/cm2, 60 min. The results show that herb essential oils, in particular, pennyroyal was proved to have potent acaricidal activity
Time Factors ; Plant Oils/chemistry/*pharmacology ; Oils, Volatile/chemistry/*pharmacology ; Mentha pulegium/*chemistry ; Insecticides/pharmacology ; Dose-Response Relationship, Drug ; Dermatophagoides pteronyssinus/*drug effects ; Dermatophagoides farinae/*drug effects ; Animals

AIMTo establish an antigen-specific asthmatic model of guinea pig induced by protein antigen extracted from Dermatophagoides farinae (Der f), and study the desensitization of dust mite drops (DMD, extracted from Der f) in a dose progressive manner and long-term sublingual administration.

METHODSTo sensitize the guinea pigs, the protein antigen emulsified in aluminium hydroxide gel was subcutaneously and intraperitoneally injected. To observe early-phase reaction of asthma, lung resistance (R(L)) and lung dynamic compliance (Cdyn) in the sensitized guinea pigs were determined by intravenously injecting antigen. To observe late-phase reaction of asthma, the sensitized guinea pigs were challenged with aerosolized antigen for 7 days. Subsequently, methacholine (Mch) in a cumulative dose-manner induced-airway hyperreactivity (AHR), inflammatory cells numbers in bronchoalveolar lavage fluid (BALF) and pathological changes of lung tissue were measured in the model. From the first day of sensitization, the guinea pigs in treatment group sublingually received DMD in a dose progressive manner. The model group sublingually received equivalent saline. The normal control group did not receive any treatment.

RESULTSThe guinea pigs in model group showed a significant increase in R(L) and decrease in Cdyn, and developed a marked AHR to Mch. The number of total leukocytes and eosinophils increased significantly in BALF. Serious infiltration of eosinophils was observed in pathological section of lung tissue. Compared with model group, DMD treatment group exhibited a significant amelioration for early-phase and late-phase reaction of asthma.

CONCLUSIONDMD in a dose progressive manner and long-term sublingual administration displays a significant desensitization on Der f antigen-specific asthmatic reaction. The results provided experimental evidence for clinical therapy.

Administration, Sublingual ; Airway Resistance ; drug effects ; Allergens ; immunology ; Animals ; Antigens, Dermatophagoides ; administration & dosage ; isolation & purification ; therapeutic use ; Asthma ; immunology ; physiopathology ; therapy ; Bronchoalveolar Lavage Fluid ; cytology ; Dermatophagoides farinae ; immunology ; Desensitization, Immunologic ; methods ; Eosinophils ; drug effects ; pathology ; Female ; Guinea Pigs ; Leukocyte Count ; Lung Compliance ; drug effects ; Male