Dust Mite Allergy
Dust mite allergy is an allergic reaction to tiny bugs that commonly live in house dust. Signs of dust mite allergy include sneezing and runny nose. Many people with dust mite allergy also experience signs of asthma, such as wheezing and difficulty in breathing.
Dust mites, close relatives of ticks and spiders, are too small to see without a microscope. Dust mites eat skin cells shed by people, and they thrive in warm, humid environments. In most homes, bedding, upholstered furniture and carpeting provide an ideal environment for dust mites.
Steps to reduce the number of dust mites in the home can often control dust mite allergy. Medications or other treatments may be necessary to relieve symptoms and manage asthma.
Dust mite allergy symptoms caused by inflammation of nasal passages including:
- Runny nose
- Itchy nose, red or watery eyes
- Nasal congestion
- Itchy nose, roof of mouth or throat
- Postnasal drip
- Facial pressure and pain
- Swollen, blue- colored skin under eyes
- In a child, frequent upward rubbing of the nose
If dust mite allergy contributes to asthma, patient may also experience:
- Difficulty in breathing
- Chest tightness or pain
- An audible whistling or wheezing sound when exhaling
- Trouble sleeping caused by shortness of breath
- Bouts of coughing or wheezing that are worsened by a respiratory virus such as a cold or the flu.
A dust mite allergy can range from mild to severe. A mild case of dust mite allergy may cause an occasional runny nose, watery eyes and sneezing. In severe cases, the condition may be ongoing (chronic), resulting in persistent sneezing, cough, congestion, facial pressure or severe asthma attack.
What causes the allergic reactions:
Allergies occur when immune system reacts to a foreign substance such as pollen, pet dander or dust mites.
The immune system produces proteins known as antibodies. Some of these antibodies protect the patient from unwanted invaders that could make the patient sick or cause an infection. When the patient has allergies, the patient’s immune system, makes antibodies that identify the particular allergen as something harmful, even though it is not. When the patient inhales the allergen or comes into contact with it, the patient’s immune system responds and produces an inflammatory response in the nasal passages or lungs. Prolonged or regular exposure to the allergen can cause the ongoing ( chronic ) inflammation associated with asthma.
The following factors increase the risk of developing a dust mite allergy:
Having a family history of allergies. A patient is more likely to develop a sensitivity to dust mites if allergens are more common in the family.
Exposure to dust mites. Being exposed to high levels of dust mites, especially early in life, increases the risk.
Being a child or a young adult. The patient is more likely to develop dust mite allergy during childhood or early adulthood.
Ongoing ( chronic ) inflammation of tissues in the nasal passages caused by dust mite allergy can obstruct the sinuses, the hollow cavities connected to the nasal passages. These obstructions may make the patient more likely to develop infections of the sinuses ( Sinusitis ).
People with asthma and dust mite allergy often have difficulty managing asthma symptoms. They may be at risk of asthma attacks that require immediate medical treatment or emergency care.
Allergy skin test:
In this test, tiny amounts of purified allergen extracts- including an extract for dust mites – are pricked onto the skin’s surface. This is usually carried out on the forearm, but it may be done on the upper back.
There will be signs of allergic reactions after 15 minutes. If the patient is allergic to dust mites, the patient will develop a red, itchy bump where the dust mite extract was pricked onto the skin. The most common side effects of these skin tests are itching and redness. These side effects usually go away within 30 minutes.
The first treatment for controlling dust mite allergy is avoiding dust mites as much as possible. When the patient minimizes the exposure to dust mites, the patient should expect fewer allergic reactions or the reactions should be less severe. However, it is impossible to completely eliminate dust mites from the environment. The patient may also need medications to control symptoms.
The doctor may direct the patient to take one of the following medications to improve nasal allergy symptoms:
Antihistamines reduce the production of an immune system chemical that is active in an allergic reaction. These drugs relieve itching, sneezing and runny nose. Over the counter antihistamine tablets, such as fexofenadine, loratadine, cetirizine and others, as well as antihistamine syrups for children, are available. Prescription antihistamines taken as a nasal spray are also available.
Corticosteroids delivered as a nasal spray can reduce inflammation and control symptoms of hay fever. These drugs include fluticasone propionate, mometasone fur orate, triamcinolone and others. Nasal corticosteroids provide a few dose of the drug and have a much lower risk of side effects compared with oral corticosteroids.
Decongestants can help shrink swollen tissues in the nasal passages make it easier to breathe through the nose. Some over- the- counter allergy tablets combine an antihistamine with a decongestant. Oral decongestants can increase blood pressure and should not be taken if the patient has severe high blood pressure, glaucoma or cardiovascular disease. In man with an enlarged prostate, the drug can worsen the condition. Over- the- counter decongestants taken as a nasal spray for more than three days in a row, it can actually make nasal congestion worse.
Cromolyn sodium prevents the release of an immune system chemical and may reduce symptoms. The patient may need to use this over- the – counter nasal spray several times a day, and it is most effective when used before signs and symptoms develop. Cromolyn sodium doesn’t have serious side effects.
Leukotriene modifiers block the action of certain immune system chemicals. The doctor may prescribe the prescription tablet, moteleukast. Possible side effects of monteleukast include upper respiratory infection, headache and fever. Less common side effects include behavior or mood changes, such as anxiousness or depression.
Dr. A.K.M. Aminul Hoque
Associate Prof. (Medicine)
Dhaka Medical College & Hospital,