House dust mites are microscopic bugs that live on dead skin cells regularly shed by humans and animal pets. Dust mites are harmless to most people and they don’t carry diseases, but they can cause allergic reactions in asthmatics and others who are allergic to their presence.
The house dust mite (Dermatophagoides pteronyssinus) is 0.2mm to 0.3mm long – so tiny it can comfortably perch on the sharp end of a pin.
Mites are unable to regulate their own body temperature, so they need to live somewhere warm. They also dislike sunlight and prefer dark places. Their body is about 75 per cent water, so they rely on high levels of humidity to survive. Therefore, the ideal conditions that help them to survive and flourish are warm, dark and damp environments.
In winter, our heated homes, combined with the elevated atmospheric humidity and reduced ventilation, create the ideal breeding ground for this mite. Similarly, our warm humid Maltese summers provide excellent conditions for them to thrive.
Not surprisingly, the favourite nesting site for dust mites is our bedroom because it is invariably the darkest, warmest and most humid room in the house. Moreover, bedrooms are filled with skin cells and body scales, commonly called dander, that is continually shed from our skin. This is also often concentrated in lounging areas, mattresses, frequently used furniture and carpeted areas.
A typical mattress can contain tens of thousands of invisible dust mites. Each single mite produces an average of 20 waste droppings per day, each containing a protein to which some people are allergic. This combination of faeces and shed skin is what causes allergic reactions in humans and even pets.
Some people have a genetic disposition that makes them allergic to dust mites, but like many allergies it can also develop over time.
Depending on the person and exposure, reactions can range from watery eyes, sneezing, itching, to asthmatic attacks, headaches, fatigue and even depression.
A dust mite’s dropping is so tiny and lightweight that in an unventilated bedroom it will hang suspended in the air for up to 20 minutes and is easily breathed in while we sleep.
Droppings that have settled onto the bed come into contact with our delicate human skin and, just like a corrosive acid, penetrate our body cells and continue working their way into our body. They are so invasive that the enzymes of dust mites can be found in the amniotic fluid that surrounds unborn children.
The microscopic carcasses of dead dust mites and their droppings, which are so easy to breathe in, add to the problem.
Although the dust mite has a short lifespan of 10 to 12 weeks, a female house dust mite can lay about 40 to 80 eggs during its lifetime and those eggs can reproduce within four weeks. They multiply so rapidly that their cumulative effect on our health and that of our pets can be significant.
It’s worth bearing in mind that the skin is often the first outward sign of an allergy. In fact, scientific studies have shown that reducing mite allergens has benefitted sufferers of atopic dermatitis (eczema).
The same applies to dogs. Up to 30 per cent of pet dogs are found to suffer from atopic dermatitis, which is a canine skin condition similar to eczema. The cause of this dermatitis is sometimes found to be a reaction to dust mite allergens.
Conducting standard allergy testing through your doctor is necessary to establish whether an allergy to mites exists, and testing is usually performed accurately and reliably by means of skin or blood tests conducted at a special laboratory.
If it is found that you are positive for dust mite allergens, you can take steps to discourage an infestation of dust mites in your home.
Under normal living conditions, it is impossible to keep a house totally dust mite free at all times. However, there are professional pest control companies that can definitely help.
Professional pest management will focus on making the environment in your house inhospitable to dust mites. Your pest controller will take the time to discuss your needs and understand your living arrangements so as to find the best solution to your problem.
Mario Borg is a pest management consultant.
What you can do
• Keep the level of humidity inside your home at below 50 per cent, particularly in the bedroom.
• Avoid wall-to-wall carpeting at all costs. Vacuum the carpets at least twice a week, preferably when your children are away from home, and always aerate the room while vacuuming. Non-washable carpets should be steam-cleaned at the highest temperature possible.
• Wash all bed linen every week at 60 degrees Celsius. Mites cannot survive heat, so place in a hot tumble dryer for at least 10 minutes.
• Once a week, thoroughly vacuum mattresses (for at least 20 minutes), bedframes and soft furnishings with vacuums specially designed for use with dust mite allergies. If your house is damp, replace your mattress every two years.
• Don’t let your children sleep with soft toys, as this significantly increases their sensitivity to dust mite allergens. Regularly wash at 60 degrees if possible, or place in a plastic bag and freeze.
• Don’t let pets sleep with you or in your room.
• Use micro-porous mattress covers and bed linen that has been designed to impede mites.
• Ventilate your house carefully. Direct sunlight kills dust mites, so air your bed and hang your bed linen out in the sun as often as you can.
• Do not dry-dust furniture as this merely stirs up the dust, which settles onto your skin. Instead, dust with a damp cloth or use furniture polish directly onto surfaces to reduce airborne particles.
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