From the Guidelines
House dust mite exposure is a significant risk factor for developing persistent asthma, as evidenced by studies linking sensitization to common indoor allergens, including house dust mites, to the development and severity of asthma 1. The most common indoor allergens that should be avoided include house dust mites, animals, cockroaches, and fungi.
- Key points to consider:
- Mite bodies and mite feces are the principal source of many of these allergens.
- Many of the purified and characterized house dust mite allergens associated with mite fecal matter are enzymes that originate from the mite’s digestive system.
- Immunoassays have been developed that allow for the quantitation of these allergens in dust samples, and higher levels have been associated with the development of sensitization (IgE antibodies) and the development of asthma in susceptible children.
- Mite allergen levels above 2 μg/g settled dust are a risk factor for sensitization, as noted in the study published in the Journal of Allergy and Clinical Immunology 1. To reduce exposure, implement dust mite control measures including:
- Using allergen-proof mattress and pillow covers
- Washing bedding weekly in hot water (130°F/54°C)
- Reducing indoor humidity below 50%
- Removing carpeting if possible
- Regular vacuuming with a HEPA filter vacuum For those already sensitized, medications such as inhaled corticosteroids (like fluticasone, budesonide, or beclomethasone) may be needed to control inflammation, while antihistamines can help manage immediate allergic responses, as supported by the American Academy of Asthma, Allergy and Immunology's position statement 1. In severe cases, allergen immunotherapy (allergy shots) may be recommended to gradually desensitize the immune system to dust mite allergens. The relationship between dust mites and asthma is explained by the allergic cascade, where repeated exposure leads to IgE antibody production, mast cell activation, and inflammatory mediator release that causes airway constriction and mucus production characteristic of asthma, highlighting the importance of avoiding house dust mite exposure to prevent the development of persistent asthma 1.
From the Research
House Dust Mite Exposure and Asthma
- House dust mite exposure is considered a significant risk factor for developing persistent asthma, as evident from various studies 2, 3, 4.
- The relationship between house dust mite allergen exposure and the risk of acquiring sensitization to this allergen, as well as the risk of developing asthma, has been established, with a dose-response relation apparent at levels of exposure below 10 microg/g 3.
- Reducing exposure to house dust mite allergen has been suggested to lessen the risk of developing sensitization and asthma, with effective interventions including allergen-impermeable encasement of mattresses along with other strategies 3, 5.
Evidence from Studies
- A study published in 2018 discussed the evidence linking dust mites with respiratory disease and outlined studies that support the efficacy of home environmental interventions 2.
- Another study from 1998 found that there is a dose-response relation between the level of exposure to house dust mite allergen and the risk of acquiring sensitization to this allergen as well as the risk of developing asthma 3.
- A 2006 study assessed whether exposure to house dust mite allergens hampers a tapering off of inhaled corticosteroid dosage in HDM-sensitive asthma patients and found that high exposure to HDM allergens seems to coincide with the use of higher dose ICS treatment in asthma patients sensitised to HDM allergens 4.
- However, a 2008 systematic review found no effect of house dust mite control measures on asthma outcomes, despite including 54 trials with 3002 patients 6.
- A more recent review from 2020 suggested that physicians should adopt a pragmatic approach to mite allergen avoidance and advise sensitized patients to implement a multifaceted set of measures to achieve as great a reduction in exposure as possible 5.
Key Findings
- The evidence suggests that house dust mite exposure is a significant risk factor for developing persistent asthma 2, 3, 4.
- Reducing exposure to house dust mite allergen can be an effective strategy for preventing sensitization and minimizing the development and severity of respiratory disease 2, 3, 5.
- However, the effectiveness of house dust mite control measures may depend on various factors, including the level of exposure and the individual's sensitization status 3, 4, 5.