title: Dust mite infestation in cooking flour: experimental observations and practical recommendations.
abstract: BACKGROUND
  The first documented case of oral mite anaphylaxis has recently been reported in Thailand, with mites possibly originating from cooking flour.
  
  
  OBJECTIVE
  Our study was designed to assess the effects of cooking flours enhancement and storage conditions on mite proliferation and to provide practical recommendations to prevent mite anaphylaxis.
  
  
  METHODS
  In a factorial experiment, six commercial brands of cooking flours were selected and either inoculated or set free of mites and stored in one of the four containers chosen for the study: original package, plastic bag, plastic box and glass bottle. The resulting experimental units where then stored at either room temperature or in a refrigerator (+4C). In order to determine levels of Der f 1 allergen, 0.1 gram of flour was sampled from each experimental unit and tested by ELISA. Sampling was carried out immediately after inoculation and subsequently at week 2, 4, 6, 8, 10, 12, 16 and 20.
  
  
  RESULTS
  Levels of Der f 1 allergen in the inoculated samples increased significantly in all conditions 6 weeks after inoculation (p <0.001) and reached the highest levels at week 8. While experimental units left at room temperature showed higher levels of mite growth (p <0.001), no statistical differences were found among types of containers. The highest amount of Der f 1 was observed for Gogi, followed by Gold Label, tempura flour, corn flour, wheat flour and tapioca starch, respectively (p <0.01).
  
  
  CONCLUSIONS
  In the context of our experiment, mites preferably grew in cooking flours containing high amounts of wheat at room temperature, particularly after 8 week of storage. According to our results, we thus advise to keep household cooking flour refrigerated and while the type of container does not matter, storage should not exceed 20 weeks.
authors.affiliation: Division of Allergy and Immunology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Sasikarn
authors.initials: S
authors.lastname: Suesirisawad
authors.forename: Nat
authors.initials: N
authors.lastname: Malainual
authors.forename: Anchalee
authors.initials: A
authors.lastname: Tungtrongchitr
authors.forename: Pantipa
authors.initials: P
authors.lastname: Chatchatee
authors.forename: Narissara
authors.initials: N
authors.lastname: Suratannon
authors.forename: Jarungchit
authors.initials: J
authors.lastname: Ngamphaiboon
mesh_terms: D000818:Animals; D039741:Antigens, Dermatophagoides / Q000378:metabolism; D060829:Arthropod Proteins / Q000378:metabolism; D003296:Cooking; D003546:Cysteine Endopeptidases / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005433:Flour / Q000469:parasitology*; D016266:Food Parasitology; D061353:Food Storage; D006801:Humans; D039981:Pyroglyphidae / Q000254:growth & development* / Q000378:metabolism; D013696:Temperature; D013997:Time Factors; D015854:Up-Regulation
chemical_list: D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; D003546:Cysteine Endopeptidases; C451159:Dermatophagoides farinae antigen f 1