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House dust mites are invisible to the naked eye and are around 0.25 mm in length. They thrive off skin cells that have been shed and they thrive in places with 70% humidity. You will find house dust mites all over the world and they tend to lurk in clothing, soft furnishings, carpets and bedding.
Being allergic to house dust mites is common. In the developed world particularly, as many as one-third of people are affected by atopic diseases like hay fever, eczema and asthma. Of these people, half of adults who have asthma and around 80% of children who have asthma will also have a linked allergy.
What is a dust mite allergy?
Dust mites are a part of the spider family. They live among house dust and feed on human skin cells that we shed naturally. Though these bugs tend to thrive at 70% relative humidity and 21°C, they can survive in nearly all climates and at almost all altitudes. They’re more common in humid areas and less common within the Arctic Circle, for example.
An average dust mite will live between 65 and 100 days. Females will lay between 60 and 100 eggs over a period of five weeks. This makes them very difficult to get rid of.
No matter how clean a UK home is, there will be dust mites present. Our climate and homes are an ideal breeding ground. These bugs love bedrooms due to the soft furnishings within them and our activities there. Since we spend a lot of time in bed, we shed a lot of skin here. We also sweat a lot in bed, which gives them water. Lastly, we’re warm, making our beds an ideal breeding ground.
Someone with a dust mite allergy will have allergic reactions to the faeces of house dust mites, rather than the mites themselves.
The invisible dust mite droppings contain a protein, which is the allergen causing the reaction. Because the droppings are dry, they fragment quickly and float around in the air as fine particles. The particles then settle on our soft furnishings, upholstery and carpets. When people are around these items and have an allergy to dust mites, they’ll find their symptoms become worse.
This major allergen is called tropomyosin and it’s also responsible for reactions to shellfish and has been implicated in other conditions like ulcerative colitis.
Dust mites are very difficult to get rid of and each individual mite will produce around 20 allergy-causing droppings per day. Even once a mite has died, its droppings will still be present to cause symptoms.
No matter your income or lifestyle, you will have dust mites at home. The problem is worse than it used to be given how well-insulated our homes are: there are fewer drafts, reduced ventilation, and warmer environments thanks to cavity wall insulation and double glazing, for example.
This type of allergy is very common indeed. It is associated with eczema, perennial allergic rhinitis and asthma. It is triggered when a person breathes in the particles containing the protein allergen. The immune system will kick in and produce antibodies.
This response is overzealous as these proteins are harmless. However, for those with a house dust mite allergy, there will be associated symptoms like a runny nose and sneezing. This is the same for those with a pollen or animal allergy.
What are the types of dust mite allergies?
What causes a dust mite allergy?
Usually, a person will develop a dust mite allergy in childhood or adolescence. Most symptoms come out before the age of 20. Like seasonal allergies, dust mite allergies are an immune response to a substance (an allergen) that the body sees as harmful, even though it isn’t.
Even though you can have a clean house, you will still have dust mites. They are most prevalent in bedrooms as these have the ideal breeding ground with cushions, carpets and bedding etc. that all hold on to moisture, which means the bugs can flourish. People with a dust mite allergy might experience more symptoms in their bedrooms compared to other rooms of the house.
Allergies and allergic reactions are caused by a hypersensitive immune system. The development of an allergy is down to both environmental and genetic factors. The mechanism involved in an allergy developing involves IgE (immunoglobulin E antibodies). These are part of the immune system and in dust mite allergies, bind to the protein found in dust mite faeces and then to receptors that trigger the release of an inflammatory chemical called histamine.
What are the signs and symptoms of a dust mite allergy?
A dust mite allergy can come with a different range of symptoms that can be mild or severe.
- An itchy or runny nose.
- Postnasal drip.
- Itchy skin.
- Sinus pressure that causes facial pain.
- Red, watery or itchy eyes.
- A cough.
- A scratchy throat.
- Bluish, swollen skin under the eyes.
- Poor sleep.
If a person with a dust mite allergy has associated asthma, they might experience the following:
- Difficulty breathing.
- Tightness or chest pain.
- Coughing, wheezing, shortness of breath.
- Problems talking.
- Asthma attack (that can be severe and fatal).
How is a dust mite allergy diagnosed?
If you suspect a dust mite allergy, you’ll probably notice symptoms that are worse at home than outside the house.
They might also be worse at night when you’re in bed or when you’re cleaning. If this is something you suspect, you should go to see your doctor and ask to be referred to an allergist, which is a specialist in diagnosing and treating allergies.
Allergists can carry out tests to determine whether or not a dust mite allergy is present. One of the most common diagnostic tests is a skin-prick test. During a skin-prick test, the doctor will prick a patch of skin, usually on the forearm, and safely apply the allergen to the pricked area.
After fifteen minutes, the allergist will look at the area to see if a reaction has occurred. If the area looks normal, there is no allergic reaction; if there’s a red bump or itchiness, a dust mite allergy will be present.
Sometimes an allergist will use a blood test instead of a skin-prick test. However, these aren’t always as accurate because the blood test will only screen for antibodies rather than a reaction to an allergen.
How is a dust mite allergy treated?
The best treatment for dust mite allergies is avoiding the allergen. This is a common practice for all allergies. However, it is very difficult to avoid dust mites completely since they’re present in the environment.
If symptoms persist despite avoidance, you can use over-the-counter medicines or prescription medicines issued by a doctor.
Here are some medicines that can help relieve dust mite allergy symptoms:
- Antihistamines – Antihistamines prevent the body’s histamines from causing an allergic response. As such, this medicine will relieve itching, runny nose and sneezing.
- Nasal corticosteroids – These reduce inflammation caused by the immune response and have fewer unpleasant side effects compared to oral medicine.
- Decongestants – Decongestants will make the nasal passage tissues smaller, which will make breathing easier.
- Medicines that combine decongestants and antihistamines.
As well as these medicines, there are other treatments available.
- Immunotherapy treatments – These can be in tablet form or injection and work in a similar way to cancer treatment chemotherapy drugs.
- Cromolyn sodium – This is a nasal spray that treats allergic rhinitis.
- Leukotriene modifiers – Also called leukotriene antagonists. These medicines manage allergic rhinitis symptoms and work by blocking leukotrienes, which are inflammatory chemicals released by the immune system when a person comes into contact with an allergen.
How to manage a dust mite allergy
Coping with a dust mite allergy is all about managing it. Removing dust mites from the home and keeping on top of them as much as possible can help to improve a person’s symptoms.
It isn’t possible to predict how beneficial avoidance measures will be but they’re always worth doing. It’s important to try all avoidance practices in order to see the biggest improvement. If you only do one thing, you won’t see so much of an improvement in your symptoms.
The most significant exposure to dust mites occurs in bed and so it’s important to make a bedroom as allergen-free as possible. This means regularly washing and changing the bedding and cushion covers and vacuuming the carpets. If the allergy is severe, it would be better to avoid having carpets and curtains and opt for blinds and hard flooring instead.
Dust mite load is also high in living rooms and any areas where there are soft furnishings and carpets.
Here are some more ways to manage dust mite allergies:
- Use covers that are made for allergy sufferers on mattresses, pillows and duvets. These need to be breathable and should cover the whole item.
- Always buy items that are hypoallergenic.
- Wash blankets, sheets and bedding at least once a week at above 60°C to kill the mites. If you wash at lower temperatures, you will wash the allergen away but it won’t kill the mites and so the problem will come back quicker.
- Avoid sleeping in a lower bunk bed as allergens can fall from above too.
- Avoid having carpets in bedrooms and use vacuum cleaners that have a high-filtration system that uses an S-class or HEPA filter.
- Seal floors with vapour barriers before covering them with linoleum or vinyl which are easy to clean.
- Look for allergy-friendly flooring (Allergy UK has details on these).
- Use steam cleaners at a high temperature to kill any mites.
- Do all dusting with a wet cloth and don’t forget areas like the tops of pelmets, cupboards and doors. This should be done at least once a week.
- If you use curtains, wash them often.
- Reduce soft furnishing like cushions.
- Vacuum upholstered furniture twice a week or more.
- Wash stuffed toys often at 60°C. If a toy cannot be washed at that temperature, you can place it in a plastic bag and put it in the freezer for 12 hours before washing it at its recommended temperature.
- Reduce the humidity of your home and increase ventilation. Instal trickle vents or open windows and use extractor fans in your kitchen and bathrooms.
- If possible, use a dehumidifier to manage the humidity in your home. It should be more than 30% but less than 50%.
- Use allergen barrier creams around your nostrils to block or trap allergens.
If you’re finding allergens harder to manage at work, there are some things you can do to improve things. Firstly, remember that ventilation is important so turn on the air conditioning or open windows and trickle vents.
Having clean air is crucial. If you’re finding ventilation to be a problem, use an air purifier to reduce the number of allergens in the air. You can also ask for a review of furnishings, flooring and vacuum cleaners too.
Other important points
Cigarette smoke will worsen allergic conditions. This is because it will aggravate the membranes in the nose, trachea and lungs. Don’t allow anyone to smoke in your home or around you. If you have children, they’re more likely to develop an allergy if they are exposed to smoke and allergens early.
Symptom relief will take time and keeping allergen-free as far as possible is the best way to reduce symptoms.
The outlook for those allergic to dust mites
Anyone who is allergic to dust mites will experience symptoms when they’re exposed to the allergen. Frequent exposure to the allergen will also increase a person’s risk of developing asthma, particularly in children.
Though it does take a lot of effort to control dust mite allergies, it can be done. Ensure you follow best practice at all times and take appropriate preventative medications to help avoid symptoms.