Influence of storage conditions on the infestation of Tyrophagus putrescentiae and prevalence of mite hypersensitivity in Taiwan

Sensitization to mites is a considerable factor in the development of allergic diseases. Because of its abundance, Tyrophagus putrescentiae (Tp) is the predominant storage mite found in home storage rooms, kitchens, and bakeries. Patients allergic to mites might exhibit a severely hypersensitive reaction upon ingesting Tp-contaminated food. The objective of this study was to investigate the rates of Tp contamination in commercial storage products from various areas, storage conditions, and environments in Taiwan. A specific antibody against Tyr p 3, the allergen on Tp, could be used as an indicator to monitor the contamination condition in storage foods. The microscopic mite examination, allergen detection by ELISA and cultured mite chemotaxis were used to evaluate the prevalence of T. putrescentiae contamination. Moreover, the IgE responses of patients allergic to mites were examined. We found that pet food and mushrooms were commonly contaminated with Tp, and this was validated through Tyr p 3 concentration and chemotaxis experiments. Tp contamination rates decreased significantly when samples were sealed and stored at a low temperature (< 4 degrees C), low relative humidity (RH < 60%), or for longer periods at a low temperature. The results of the clinical study indicated that the mites that elicited major positive IgE responses in allergic subjects were Dermatophagoides pteronyssinus and D. farinae. Thus, people who are sensitized to D. pteronyssinus or D. farinae might be at risk of a second anaphylactic reaction due to cross-reactivity upon ingestion of Tp-contaminated food. Accordingly, Tp contamination can be prevented by keeping food packages sealed and stored at a low temperature. This prevents the severe allergic reaction caused by the inadvertent ingestion of contaminated food-borne Tp.