19.2.1 Do Dust Mite Environmental Control Measures Work?

House dust mites (HDM), most commonly Dermatophagoides farinae in the United States and Dermatophagoides pteronyssinus in Europe, are common perennial allergens. EC measures for HDM may include physical methods and chemical treatments. Physical modalities include heating, freezing, barrier methods, air filtration and ventilation, vacuuming, and others. The efficacy of these physical techniques has been studied for the treatment of HDM-allergic rhinitis (AR). Findings across studies are varied. Most commonly, HDM antigen levels are decreased in the environment in which the physical techniques are used. However, improvement in respiratory symptoms has not been reliably confirmed. Studies investigating clinical improvement with HDM-impermeable bedding or high efficiency particulate air (HEPA) filtration generally failed to show clinical benefit.

Acaricides are chemical treatments to decrease HDM concentration. The use of acaricides has been shown to improve symptoms in allergic patients with HDM sensitization. No serious adverse effects were reported from these interventions.

In 2010, a Cochrane review evaluated EC measures for HDM-AR, including impermeable covers, HEPA filters, acaricides, or combination treatments. The authors of this systematic review noted significant methodological limitations in the studies that examined EC measures for HDM control in the perennial AR patients. Nonetheless, of all interventions, they noted that acaricides appeared to be the most promising and HDM impermeable bedding alone was unlikely to provide benefit. Overall, EC measures to treat AR with HDM sensitivity are considered an option.

19.2.2 Little Johnny Has a Cat Allergy. He Has to Get Rid of Fluffy the Cat. Right?

Pet removal is commonly advocated in the treatment strategy for AR patients with pet sensitivity. However, high-quality outcome studies are generally lacking for this intervention. In addition, compliance rates for pet removal are low.

Several studies have assessed EC for pet-sensitive allergic patients and their results are mixed. For multimodality EC measures, significant improvements in clinical symptoms and nasal airflow have been demonstrated. However, single-modality EC interventions generally do not result in improved symptoms, even if antigen levels are reduced. Studies of single-modality interventions have included HEPA filtration and pet washing. Furthermore, washing pets (cat and dog) must be performed twice a week in order to keep antigen levels low, and with removal of pets it may take several months to reduce antigen levels. Of note, current asthma treatment guidelines recommend removal of pets from a sensitized patient’s home, as asthma may be secondarily prevented when sensitized patients avoid pets. Current aggregate evidence for pet avoidance and EC measures is level B, with an option to incorporate this treatment for the AR patient with pet sensitivity.