What is Dust Mite Allergy?
Dust mite allergy, also known as house dust allergy, is a reaction to dust mite allergens found in common household dust. This allergy happens when you become sensitive to and inhale the droppings of dust mites. These droppings, once in the air, can trigger an allergic reaction. Over time, allergies caused by dust mites, such as allergic rhinitis and asthma, have been on the rise. Dust mites were first linked to allergies in the 1920s, but it wasn’t until 1967 that researchers identified the specific allergen responsible for this condition. In 1980, the first dust mite allergen was identified, followed by others in subsequent years.
Dust mites are one of the most common sources of indoor allergies and are linked to several allergic conditions, such as allergic rhinoconjunctivitis, allergic asthma, and atopic eczema. The best way to manage these allergies includes avoiding allergens as much as possible, using medication, and undergoing allergen immunotherapy, a treatment designed to increase tolerance to allergens. The most common medications include antihistamines, leukotriene receptor antagonists, and inhaled or nasal corticosteroids. These treatments are proven to be effective and safe, though unfortunately, they haven’t been able to alter the progression of dust mite-associated allergic diseases.
What Causes Dust Mite Allergy?
Dust mite allergies often start during childhood or teenage years, with most people showing symptoms before they turn 20. The biggest cause of this allergy is a digestive enzyme called peptidase 1, which is found in the gut of the dust mite. This enzyme is present in their poop and triggers the allergic reaction. There are different types of this allergen, depending on the type of dust mite.
The dust mites’ poop particles are microscopic and similar in size to pollen, which means they can be easily breathed in. In addition to their poop, the dust mites’ exoskeleton, or outer shell, can also cause allergic reactions. When the allergens are inhaled, they can sneak into our respiratory system by slipping through the tight gaps between the cells in our airway. This makes our cells more permeable, or porous, letting more dust mite allergens get to our immune cells.
But don’t worry, dust mites don’t live under our skin, and they’re not parasites. They’re tiny bugs, about 0.4 millimeters long, that are too small to see with the naked eye. They enjoy eating dead skin cells from humans and pets, and they love to live in warm and damp environments. Therefore, items that hold moisture, like bedding, linens, carpets, and furniture, provide the perfect home for dust mites.
There are several different types of dust mites, but the most common ones include Dermatophagoides pteronyssinus, Dermatophagoides farinae, and Euroglyphus maynei, which make up between 80 to 90 percent of the dust mites in most homes. Dermatophagoides pteronyssinus is the most common dust mite, especially in drier areas. In tropical areas, the storage mite or glycyphagid mite, specifically Blomia tropicalis, is a major cause of allergies. In rural homes, you might also find other types of mites like Gylcyphagus and Lepidoglyphus.
Risk Factors and Frequency for Dust Mite Allergy
Dust mite allergy is a common form of allergy that affects around 20 million people in the United States and is prevalent worldwide, due to the ubiquitous presence of house dust mites. In fact, about 84% of homes in the U.S. have been found to contain these mites. In industrialized countries like Germany, it’s estimated that 1 in every 4 people suffer this allergy. Adding together allergic rhinitis (a type of nose inflammation) and asthma, the count goes up to approximately 800 million sufferers globally, as per data from the World Health Organization.
A significant percentage of people with asthma are also affected by allergies. Among them, as much as 85% shows an allergic reaction to house dust mites. This is observed across America, Europe, southeast Asia, and Australia. Furthermore, anywhere between 5 and 30% of the general population exhibit sensitivity to house dust mites, as demonstrated by skin tests.
- Nearly all (97%) of those suffering from dust mite allergies have a reaction to an allergen named ‘Der p 1’.
- Another allergen, known as ‘Der p 11’, is typically linked to a skin condition called atopic dermatitis.
- About 70% of people with a dust mite allergy exhibit a reaction to yet another allergen known as ‘Der p 23’.
- As of now, scientists have identified 24 allergens associated with house dust mites.
Signs and Symptoms of Dust Mite Allergy
A dust mite allergy can cause symptoms all year round, and these symptoms may be more prominent during the night and early morning. The mites that trigger this allergy are commonly found on pillows, bedcovers, mattresses, and blankets. Here are the common symptoms of dust mite allergy:
- Sneezing
- Runny nose
- Allergic reaction affecting the eyes
- Nasal congestion
- Itchiness in nose, mouth or throat
- Itchiness on the skin
- Chronic cough and postnasal drip
- Coughing that might get worse with a common cold
- Feeling tired and unwell
- Sleep disturbances caused by shortness of breath, coughing or wheezing
If the dust mite allergy triggers an asthma attack, these symptoms may appear:
- Shortness of breath
- Feeling tightness or discomfort in the chest
- Wheezing when breathing out
The following factors can increase a person’s chances of developing a dust mite allergy:
- Being a child or a teenager
- Having a family history of allergies
- Being regularly exposed to a high concentration of dust mites
In some cases, people with dust mite allergies can also develop an allergic reaction to certain foods such as shellfish or mollusks due to a process known as cross-reactivity.
Testing for Dust Mite Allergy
If you have symptoms that suggest a dust mite allergy, like sneezing or a runny nose, your doctor might recommend further tests to confirm the diagnosis. These tests take into account your current symptoms, past allergies, your home environment, and other relevant factors.
In-person tests include the skin prick test, which is usually the first one to be done. It’s quick, affordable, and highly sensitive to dust mite allergies, but it can sometimes give false positives. Also, it’s not suitable for people with skin conditions like dermatitis or those who are on antihistamines.
Atopic patch tests are another option, which help to detect allergic reactions. The basophil activation test (BAT) is a bit more complicated; it measures the markers on the surface of specific cells in your blood. It’s good because you can still do it even if you’re taking antihistamines, but results can vary somewhat.
Nasal provocation tests are also an option. These expose the inside of your nose to the dust mite allergen and monitor your body’s reaction to it. These tests help to identify and measure the effect of the allergen.
There are also tests that can be done in a lab. One of them is the enzyme-linked immunosorbent assay (ELISA), which can measure both total and specific levels of a type of antibody called IgE in your blood. However, it’s less useful when testing for multiple allergens. There’s also the radio allergen sorbent test (RAST), another in vitro (lab-based) test, but this one is used less frequently since ELISA became available.
Another technique is microarrays, which can detect many antigens on a single slide. While these tests are useful for profiling your allergen sensitivity, they are expensive and typically only available in large hospitals.
Dust mite allergies can eventually lead to asthma or make existing asthma worse. In these cases, your doctor might use tests like the peak expiratory flow rate test (measuring the speed of your breath) or spirometry (measuring the volume of your breath), to diagnose asthma.
Lastly, techniques like immunochemical assays can help to measure the amount of dust mite allergens in your house. These tests, however, require highly skilled lab staff and advanced equipment, and are thus less commonly used.
Treatment Options for Dust Mite Allergy
One of the most effective strategies to combat dust mite allergies is to avoid the allergens outright–essentially by keeping your environment as free from dust mites as possible.
Measures for a dust-mite-free bedroom could include:
* Use special, tightly-woven covers for mattresses and pillows to prevent dust mites from settling in.
* Wash your bedding each week in hot water (130 – 140°F), or freeze it overnight to kill any dust mites.
* Remove any carpets and curtains, which often gather dust mites.
* Install a high-efficiency particulate air (HEPA) filter, which can remove up to 99.7% of particles around 0.1 microns silent.
There are also measures you can take throughout your entire house:
* Keep the humidity level to 45 percent or less.
* Regularly vacuum clean your house to limit dust build-up. Major dust disturbances, such as moving furniture or drapes, can cause allergens to become airborne and increase exposure.
* Use cross ventilation in your house.
* Use chemicals specifically designed to kill dust mites. However, they might not last long and could potentially pose safety concerns.
Over-the-counter medications that can help control the symptoms of a dust mite allergy include:
* Antihistamines
* Nasal corticosteroids
* Leukotriene receptor blockers
* Cromolyn sodium (a substance that stabilizes mast cells and prevents them from releasing substances that promote inflammation)
* Decongestants
Non-drug approaches can also help manage dust mite allergy symptoms. These include:
* Saline nasal irigation and sprays
Another method to combat dust mite allergies is “allergen immunotherapy or desensitization.” In this approach, extracts from allergens that trigger the allergy are administered to the individual on a regular basis. This treatment helps the body tolerate these allergens effectively, reducing symptoms, and the need for symptom-relief medications. It can be beneficial for conditions like allergic rhinitis and asthma, and its effects can still be seen years after discontinuing the treatment.
There are various forms of allergen immunotherapy available:
Subcutaneous immunotherapy involves injecting the dust mite allergen extract in gradually increasing doses. This process triggers immune responses that increase tolerance to the allergens, reduce symptoms, and improve lung function.
Sublingual immunotherapy is an alternative to subcutaneous immunotherapy and is effective in treating mild to moderate atopic dermatitis in children allergic to dust mites.
Allergy specific immunotherapy, on the other hand, uses recombinant allergens instead of allergen extracts. In this promising therapy, modified, hypoallergenic derivatives of dust-mite allergens are used for better efficacy with fewer side effects.
For those with asthma triggered by dust mites, the treatment varies based on the severity. Short-acting beta-agonists provide short-term relief, while long-acting beta-agonists, anticholinergics, and low-dose inhaled corticosteroids offer long-term relief. Leukotriene antagonists and mast cell stabilizers can also be beneficial.
What else can Dust Mite Allergy be?
Besides dust mites, allergies caused by house dust can be triggered by other substances including:
- Mold: This fungus thrives in damp places like basements, kitchens, gardens, and bathrooms. When mold spores become airborne and are breathed in, they can cause allergy symptoms.
- Cockroaches: The allergens from cockroaches can come from their saliva, droppings, and shed skin. In fact, about 68% of US homes have detectable levels of cockroach allergens, and this number is even higher in urban areas.
- Pollen: Pollen from flowers, grass, weeds, and trees can mix with house dust and trigger allergies.
- Pets: Pet allergens can come from fur, feathers, hair, dander (dead skin flakes), saliva, or droppings.
Allergies to dust mites might be mistaken for non-allergic conditions that also affect the nose. These conditions can include:
- Vasomotor rhinitis: This causes chronic sneezing and can be set off by weather changes, certain foods or medications, emotions, chronic health problems, or certain smells.
- Rhinitis medicamentosa: This condition can occur from overusing nasal decongestant sprays or in cocaine users.
- Atrophic or senile rhinitis: This happens when the inner lining of the nose gets thinner and harder with age or after multiple nose surgeries. This can make it more vulnerable to injuries and infections.
- Non-allergic rhinitis with eosinophilia syndrome (NARES)
- Infectious rhinitis: This is a nose infection that can be caused by bacteria or viruses.
- Chemical rhinitis
- Hormonally induced rhinitis
What to expect with Dust Mite Allergy
If you reduce or avoid exposure to dust mite allergens, you’ll likely experience fewer allergic reactions. Despite this, house dust mite allergies can significantly impact the quality of life in the long term. This is due to several factors:
- More absences from school or work
- Difficulty concentrating, which can lead to less effective work performance
- Ideal performance in tasks like driving and mental functions can decline, especially after long work hours
- For families with asthmatic members, treating allergic symptoms can put a considerable financial strain
- It may strain personal relationships
- There can be a reduction in daily productivity
- It can limit participation in fun activities and sports
When taking cost into account over the long term, immunotherapy (a treatment to train the immune system to desensitize it to allergens) has been shown to be more cost-effective compared to merely treating the symptoms.
Possible Complications When Diagnosed with Dust Mite Allergy
If someone is sensitized, or made sensitive, to dust mite allergens and continuously exposed to them, they might experience a range of health complications such as:
- Sinusitis: This is a condition where the lining of the sinuses become inflamed due to the body’s immune response to the dust mite allergens. This inflammation can block the sinuses and make a person more susceptible to infection.
- Development of Asthma: Dust mite allergens have been strongly linked to the development of asthma, more so than other common household allergens.
- Acute Asthmatic Attacks: These can result from exposure to dust mite allergens.
- Atopic Dermatitis: Dust mites are not just allergens, but irritants as well. Therefore, those who have atopic dermatitis, a type of skin inflammation, can experience aggravated symptoms regardless of whether they are sensitive to dust mite allergens.
At the same time, chronic inflammation can damage the lining of the respiratory tract and make it overly sensitive. This makes it more reactive to irritants such as cigarette smoke, environmental pollution, and dry heated indoor air, as compared to those who are not sensitized.
Preventing Dust Mite Allergy
Teaching patients, their families, and the public about dust mite allergies is crucial for the best results. People often underestimate the seriousness of these allergies, which can prevent them from seeking medical treatment. While the annual medical costs from dust mites can be high, the loss of work productivity can be even costlier, mainly due to asthma symptoms caused by the allergy.
Dust mite allergies often result in more visits to the doctor. Educational materials like handouts, internet resources, and media can increase awareness about where dust mites may be found and how to avoid them. It’s also extremely important to educate people on how to properly use nasal sprays and sublingual immunotherapy (a kind of allergy treatment) to manage their allergies.
