While control of house dust mites has been proposed for reducing allergies related to these microscopic pests, the use of bags to encase bedding is unlikely to have a significant impact, a study shows.

In the study reported in the journal Allergy, bedding encasings did not improve quality of life in a mixed population of dust mite-sensitive patients.

The belief that environmental control is an integral part of the management of individuals sensitive to house dust mites has been largely based on early observations that children with Asthma and allergy to dust mites recover at house dust mite-free high altitudes, the authors of the study note. Moreover, in one study, a long-term stay in a hospital led to a fall in lung hyperreactivity in asthmatic individuals allergic to house dust mites.

“It may be possible, however, that the beneficial effects of an allergen-free environment cannot be obtained by house dust mite reducing measures in our daily environment, Dr. I. Terreehorst, from Erasmus Medical Centre in Rotterdam, the Netherlands, and colleagues contend.

For their study, they randomized 224 adult patients with house dust mite allergy to use impermeable or permeable encasings for pillows, mattresses, and duvets. The patients had various combinations of rhinitis, asthma, and atopic dermatitis.

According to the team, subjects who used impermeable encasings experienced a quality of life no different from their peers using permeable encasings.

“The application of encasings does not have a beneficial effect on Asthma, rhinitis, or atopic dermatitis in subjects allergic to house dust mite,” the researchers conclude.

SOURCE: Allergy July 2005.