House Dust Mites - Can We Do Anything About Them?

For more than a decade, attempts to reduce exposure to house dust mites (HDM) have been made through patient education and research. Sensitization to HDM and exposure has been linked to asthma symptoms; moreover, HDM are a known trigger of asthma. Hence the reason for the past doctrine that espoused a variety of physical and chemical measures to reduce exposure to HDM, involving:

  • mattress and pillow covers
  • ventilation
  • freezing
  • washing
  • air-filtration
  • air purifiers, including ionizers
  • vacuuming
  • acaricides

Health care professionals and asthma educators promoted a variety of these methods to reduce exposure to HDM and in so doing hoped to reduce the burden of asthma for patients.

The recent Asthma Management Guidelines published by the British Thoracic Society noted a Cochrane review of a number of HDM trials wherein:

  • 10 trials were of acaricides
  • 26 trials of physical measures such as mattress covers
  • 37 trials of heating, ventilation, freezing and air purifiers
  • 8 trials that combined both physical and chemical approaches

The Cochrane review demonstrated no benefit for a single or multiple approach in any of the standard measurable outcomes such as peak flows, symptoms scores, medication usage, etc. The British Guidelines clearly state,“Physical and chemical methods of reducing house dust mite levels in the home are ineffective and should not be recommended by health care processionals.”

Can anything be done to reduce exposure to HDM? A review by Eifan and colleagues found that there was beneficial evidence ofHDM subcutaneous (SCT) immunotherapy for both children and adults. Trebuchon and colleagues found that sublingual(SLIT) immunotherapy for HDM was effective for children and adolescents. This study of 736 pediatric patients, 95.5% with allergic rhinitis and 59.5% with both rhinitis and asthma, and all sensitized to HDM, found SLIT was effective in 83.8% of the patients, with both symptoms and medication reduced after treatment.

A cautionary note was sounded by Calderon and colleagues who reviewed 44 studies that looked for evidence of the efficacy of SLIT and SCT with respect to HDM. They warned that currently there is no consensus on dosage or duration of treatment for either of these procedures and that further research is essential before proceeding either with SCT or SLIT for HDM.

References

British Guidelines on the Management of Asthma 2014. www.brit-thoracic.org.uk Accessed September 2015

Eifan AO, Calderon MA, Durham SR. Allergen immunotherapy for house dust mite: clinical efficacy and immunological mechanisms in allergic rhinitis and asthma. Expert Opin Biol Ther. 2013 Nov;13(11):1543-56. doi: 10.1517/14712598.2013.844226. Abstract.

Trebuchon F, Lhéritier-Barrand M, et al. Characteristics and management of sublingual allergen immunotherapy in children with allergic rhinitis and asthma induced by house dust mite allergens. Clin Transl Allergy. 2014 Apr 29;4:15. doi: 10.1186/2045-7022-4-15.

Calderon MA, Casale TB, Nelson HS, Demoly P. An evidence-based analysis of house dust mite allergen immunotherapy: a call for more rigorous clinical studies. J Allergy Clin Immunol. 2013 Dec;132(6):1322-36. doi: 10.1016/j.jaci.2013.09.004.