In the UK, house dust mite (HDM) is found in all homes. Allergy to HDM is quite common. In the general population, 1 in 20 young children, rising to 1 in 5 adults will test positive when tested for HDM allergy, though not all will have symptoms. 1 in 3 children with eczema and asthma will test positive to HDM.
HDM allergy commonly causes hay fever-like symptoms all year round, such as sneezing, coughing, itchy watery, red eyes or runny nose and can be a trigger for asthma and eczema.
These tiny creatures are distant relatives of spiders! They thrive in warm (26°C) damp conditions and feed on shed skin scales. They are found in all UK homes, no matter how clean. The protein that leads to the allergy is present in HDM faeces. Faecal pellets are about the same size as pollen grains and it is therefore not surprising that mite allergy and pollen allergy cause similar symptoms – pollen allergy being a seasonal problem, while mite allergy can be a problem all year. HDM allergy is not associated with severe / life threatening allergic reactions, though its link to asthma can be important.
Four out of 5 patients with allergy to HDM are also allergic to other allergens in the air such as pollens and animal danders.
Skin prick tests, or a blood test if skin prick tests cannot be done because you are taking regular antihistamines, show if you have allergy antibiotics to the house dust mite. Persistent symptoms combined with a positive test result make the diagnosis in most cases.
Your bed (mattress and pillowcase) is the perfect breeding ground, particularly when you are in it! They can also be found all around the home (furniture, carpets, curtains, clothes, fluffy toys). If the temperature rises (or falls) these insects might become inactive or die.
There is little evidence that any measures lead to an improvement in allergy symptoms and it is not possible to remove these creatures and their faeces from the home. But if you are found to be allergic to HDM you should avoid damp and dusty places
The following are suggested as ways of reducing the number of HDM at home.
- House dust mite proof covers on the pillow cases and mattresses prevent the mites/their faeces reaching your bedding so they cannot build up, but will be washed away each week.
- Do not sleep on the lower bunk bed.
- Dust surfaces weekly with a damp cloth and vacuum weekly using a vacuum cleaner that has a high-efficiency particulate air (HEPA) filter.
- Remove or reduce clutter, soft toys, carpets, draperies and upholstery in the bedroom.
- Lower room temperatures and reduce humidity by opening windows
The person with HDM allergy should not be in the room when cleaning is done, as high levels of dust occur during cleaning.
Firstly, we recommend you try to reduce exposure to HDM, if possible, taking the measures you can without wasting money.
Secondly, either a long acting non-sedating antihistamine or a nasal steroid spray can be used. Some patients get more benefit from taking both together. These may need to be used regularly for a long time.
If nasal symptoms persist, your doctor may recommend additional treatment with montelukast. If asthma is troublesome, asthma treatments might need to be revised.
Antihistamines and nasal steroids do not cure the allergy. They just treat the symptoms.
Desensitisation (immunotherapy) is sometimes performed for HDM allergy by specialist children’s centres if you still have troublesome symptoms despite taking antihistamines and nasal spray regularly. It can reduce symptoms but does not usually lead to a complete cure. The treatment program is 3 years long and therefore may not be suitable for all patients.
Most children with HDM allergy will not outgrow the problem. However, symptoms often become more manageable with time, lifestyle changes and use of medication.