House Dust Allergies to Dust Mites, Cockroaches, Molds, Pollens, Pets

What Is a House Dust Allergy?

A dust allergy is where a person reacts to contact with dust, particularly with inhaling the dust. It may lead to sneezing, coughing, watery eyes and exacerbate symptoms of asthma such as wheezing and chest tightness. It is particularly prominent when i a dusty environment or when the dust is made airborne as is the case with sweeping, moving objects, emptying closets and so on.

The dust is not the cause of the allergy but instead serves as the trigger (allergen). It is actually the substances in the dust that are the triggering factors and may include house dust mite, coackroach particles, pollen, mold spores and pet hair/fur (dander). When inhaled, the allergen triggers the production of immunoglobulin E (IgE) antibodies in a sensitive person.

On subsequent dust exposures, these antibodies bind to mast cells in mucosa in eye conjunctiva, nose, throat, and bronchi, and triggers the release of histamine which results in inflammation. Histamine causes dilation of vessels in mucosa, and secretion of mucus from mucous glands, resulting in mucosal swelling and mucus secretion. Even a small amount of dust in thoroughly cleaned homes may be enough to cause allergy so dust allergies do not appear only in “dirty houses”.

Causes of House Dust Allergy

The main allergens (substances causing allergic reaction in sensitive people) found in the house dust are particles from the following organisms and substancs.

1. House Dust Mites

House dust mites (Picture 1), about half a millimeter sized organisms, can be found on carpets, under beds, on bed lining, mattresses and pillows, armchairs and sofas. Sensitive persons get allergy to body particles of mites usually after they are inhaled.

Dust mite under electron microscope
Picture 1. Dust mite, as seen under the microscope

2. Cockroaches

Cockroaches (check types of cockroaches with pictures), about 1-3 cm (0,5-1,2 inch) sized insects (Picture 2), live in hot humid climates all around the world; in houses they are mainly found in kitchens and bedrooms. Sensitive persons (those with asthma or other chronic allergy) may develop a skin rash (urticaria), itchy throat or, in severe cases, an asthmatic attack, when they come in contact or inhale cockroach feces or parts of their body. Prevention is in keeping the house dry and disposing any food remnants and garbage out from the house.

Cockroach

Picture 1. American cockroach (source: Wikipedia)

3. Indoor Mold Allergy

Spores are inactive forms of molds. They come into the house through windows, mainly from outdoor plants. They appear as microscopic particles in the house dust even if no molds can be found on the walls in the house. When spores land on the moist walls, carpets, or furniture or in wet places like bathrooms and basements, new molds may start to grow. In sensitive people they usually cause symptoms of rhinitis (sneezing, eye itching) after inhalation.

Molds may be irritating to some people because of their strong odor but this is not an allergy.

4. Indoor Animals (Pets)

Cats and dogs, or any other indoor warm blooded animal like guinea pigs or birds or even mice may shed allergens with skin particles and hair but also with saliva and urine. Pet owners may carry these allergens on their clothes and transfer them to environments outside of the home.

5. Pollens

Pollens from outdoor plants come into houses through open windows. Pollens from indoor plants may also cause allergy. This includes both tree and grass pollen as well as pollen from flowers and other plants.

Diagnosis of a Dust Allergy

Diagnosis of dust allergy can be done by certified allergist or immunologist. A blood test may reveal raised eosinophils (a sub-type of white blood cells) and IgE antibodies. These findings usually only tell that a person may have an allergy but to find an exact cause tests with injecting suspicious substances under the skin (skin prick test) or placing patches with an allergen onto the skin (skin patch test) and then evaluating eventual skin reaction is needed.

Treatment of Dust Allergies

Antihistamines are the main drug used to treat dust allergies. These drugs reduce histamine release thereby minimizing the inflammation that would arise with an allergy. Antihistamines largely have a symptomatic effect and does not target the root cause of the problem. House dust allergies can be extremely difficult to treat and desensitization therapy may prove useful.

Although dust allergies are usually not life-threatening, some people may experience anaphylactic reactions to unusual substances within dust. Anaphylaxis is a severe type of allergic reaction and can be life-threatening without prompt medical treatment. It may require the use of adrenalin (epinephrine) which is injected into a muscle. People who are at risk of anaphylaxis may need to carry personal injections (epi-pen) for self-administration.

Prevention of House Dust Allergies

The following measures can help to reduce exposure to the allergens or even avoid it altogether.

  1. Do not have pets, plush toys, dry flowers, heavy carpets, wool bedding, or upholstered furniture in the house.
  2. Clean floors , carpets, and mattresses by using a vacuum cleaner with HEPA filter thoroughly once a week rather than every day, since dust remains in the air for up to 2 hours after cleaning.
  3. Use a protective mask when cleaning, or do not participate in cleaning at all.
  4. Use mite-proof covers on mattresses and pillows.
  5. Avoid situations where dust is likely to float in the air.
  6. Do not have uncovered food in the house and dispose food waste from the house regularly. Food attracts mice and cockroaches.
  7. Keep the home dry (below 55% humidity) to prevent thriving of dust mites.
  8. Children with an allergy to dust mites should not sleep close to the floor.

Do Down and Feather Cause House Dust Allergy?

Feathers and down are used in a number of household items such as pillows and certain blankets. According to the EDFA (European Down and Feather Association), feather and down do not cause allergy, and do not attract house dust mites. However, skin particles that may accumulate on these objects can attract house dust mite and regular washing or sun exposure is therefore important to remove, destroy or repel the mites.

References:

  1. House dust allergy  (acaai.org)
About Jan Modric (249 Articles)
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