In dust mite allergies, it isn’t the dust that causes the symptoms. Instead, the allergy is triggered by substances that are mainly found in the dust mites’ feces (“poop”). The tiny particles of feces are attached to the dust and spread in that way.
No home is completely free of dust mites. They are found in beds, carpets, rugs, upholstered furniture and curtains. Because of this, people who have a dust mite allergy have allergy symptoms such as sneezing and a runny nose all year round. If someone has an allergic reaction that affects their upper respiratory tract (upper airways – i.e. nose, sinuses and throat), it is called “allergic rhinitis."
People who have a dust mite allergy sneeze a lot, and have a runny or stuffy nose. If their symptoms are more severe, they might also feel weak and tired. Their eyes might water and itch, and they might have swollen eyelids. Asthma-like symptoms such as coughing, wheezing and shortness of breath may occur too.
Dust mite allergies usually cause milder symptoms than hay fever (a pollen allergy) does. But they occur all year round, whereas hay fever is seasonal. The symptoms are typically worse at night and in the morning because dust mites tend to live in mattresses, pillows and bedding.
Causes and risk factors
Allergy symptoms arise when your body overreacts to particular substances that are usually harmless. These substances (allergens) trigger a chain reaction in the immune system. First, the body makes antibodies to fight the allergen, and the antibodies bind to specific cells. If these cells come into contact with the allergen again, they are then able to “respond” by releasing chemical substances such as histamine. These substances then set off an allergic reaction, causing symptoms such as sneezing or itchy eyes.
It’s almost impossible to avoid contact with dust. If dust is stirred up – for instance, by a draft of wind or when shaking up bedding – it floats through the air and is breathed in, together with the allergens on it.
Allergies are quite common nowadays. This may be partly due to higher standards of hygiene and the fact that some infections have become less common in childhood. As a result, our immune systems are often not as “well trained” as they might have been in the past.
Prevalence and outlook
Allergic rhinitis affects about 1 out of 4 people in industrialized countries like Germany. It usually first arises before the age of 20.
Dust mite allergies typically first develop in childhood or puberty, and never go away again. If people have allergic rhinitis for many years, the allergy might “move down” into the lower airways (lungs) too, causing asthma.
Sometimes people become allergic to certain foods too after a while (a phenomenon known as cross-reactivity). This is less likely to happen with dust mite allergies than it is with other allergies, like hay fever. But people who have dust mite allergies may become allergic to foods like shellfish and mollusks such as mussels, crabs, lobsters, shrimps or snails.
Severe symptoms may increase the likelihood of developing other medical conditions such as sinusitis (inflammation of the sinuses). Allergic rhinitis makes mucous membranes overly sensitive in a lot of people too. As a result, their nose may react more strongly to irritants like dry air in heated rooms and cigarette smoke.
If you see a doctor, he or she will first ask you about your symptoms, circumstances in life, and medical history. The doctor can then do an allergy test (a skin prick test) to find out whether you are allergic to particular substances. This involves placing small drops of various allergens on the skin of your forearm, leaving enough space between them, and then gently pricking the surface of your skin where the allergens are, so the substances go into the skin. If the skin becomes red and swollen (like a big mosquito bite) where it was pricked, it’s a sign that you’re allergic to that substance.
You might also need a blood test or something known as a nasal provocation test. This is where the membranes lining the nose are exposed to extracts of the potential allergen using a nasal spray or drops. If the lining of your nose becomes swollen, you sneeze and your nose starts running, you are likely to be allergic to that substance.
The most effective way to prevent allergy symptoms is to avoid the substances that trigger the allergy. Although dust mites can’t be completely avoided, contact with them can be reduced. Particularly in the bedroom, it may be helpful to combine a number of different approaches: wiping the bedroom floor with a damp cloth, using mite-proof mattress covers, removing “dust traps” such as upholstered furniture and curtains, and regularly washing your bedding at temperatures above 60°C (140°F).
Dust mites survive longer in warm and humid conditions. So it can be a good idea to keep the bedroom temperature constant between about 18 and 20°C (about 64 to 68°F), and regularly open the windows to let fresh air in. Air humidifiers and plants can make it easier for dust mites to thrive, so it’s best to keep them out of bedrooms.
Dust mite sprays containing acaricides (pesticides against mites and ticks) could also help reduce the symptoms. They can be sprayed onto mattress covers, for instance. Special dust mite air filters are available too, but it isn’t clear how effective they are.
Various medications are available for the treatment of allergy symptoms:
- Steroids (corticosteroids)
- Chromones (mast cell stabilizers)
- Leukotriene receptor antagonists
- Decongestant nasal drops and sprays
There are also non-drug alternatives such as saline (salt water) nasal sprays and nasal washes (nasal irrigation).
Allergen-specific immunotherapy (also known as desensitization) can reduce your sensitivity to allergens over the long term. Like with vaccines, this treatment approach involves exposing people to small amounts of the allergen. Here it is done at regular intervals by either injecting the allergen into your skin or placing it under your tongue. Allergen-specific immunotherapy takes about three years to complete.
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Hermelingmeier KE, Weber RK, Hellmich M, Heubach CP, Mösges R. Nasal irrigation as an adjunctive treatment in allergic rhinitis: a systematic review and meta-analysis. Am J Rhinol Allergy 26(5): e119-125.
Sheikh A, Hurwitz B, Nurmatov U, van Schayck CP. House dust mite avoidance measures for perennial allergic rhinitis. Cochrane Database Syst Rev 2010; (7): CD001563.
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