What are dust mites, why do they cause allergies and can we get rid of them?
When the weather warms up, it’s time to open the windows and put away your winter woolens for another year.
If you’re very enthusiastic, you may even decide to do a deep clean in an attempt to wage war on one of life’s boring realities: dust mites.
These microscopic insects can cause allergic reactions such as sneezing, wheezing, and itching.
Why some people are affected and others are not remains a mystery, and there are many myths about how to control them.
So, before you embark on your spring dusting mission, let’s get to work with the bugs themselves.
What are dust mites?
Mites are tiny arachnids, closely related to ticks.
Only about a third of a millimeter long, these white spider-like bugs are everywhere.
“You’ll find them in carpets and beds and in your clothes, but as far as we know, they don’t live on your skin,” says Euan Tovey of the Woolcock Institute of Medical Research, who has studied dust mite allergies.
Instead, they feast on dead skin cells, which is a healthy dose of house dust.
“When you wash your clothes, the reason the water gets cloudy is because your skin cells are floating around,” says Professor Tovey.
By munching on dead skin cells, the mites release enzymes in their gut that break down the cells.
In the 1980s, Professor Tovey discovered that one of these enzymes is a strong allergen that floats in the air on the mite’s poop.
“This poop allergen spreads over smaller dust particles,” says Professor Tovey.
“[These particles] go down to less than a millimeter, so that means they are inhalable. “
People can also be allergic to a number of other proteins in the mite body, but the enzyme accounts for about 60% of allergies.
This is because a mite can produce a lot of poop over its lifespan of up to 90 days.
Dust mite allergens can also hang around for a long time, depending on the humidity level.
“In dry conditions it will hang around for years, in wet conditions it will decompose in months.”
Are some times of the year worse than others?
The amount of dust mite allergens fluctuates throughout the year, depending on the season.
“The growing conditions for mites are rather ideal in the spring because they like 25 degrees Celsius and a fairly high humidity of around 75 percent,” says Professor Tovey.
The hotter and more humid the better, but our homes give them the perfect environment to thrive all year round, even in arid areas.
“There are small damp places in the houses, like the bottom layer of the carpet is quite damp, and the beds have damp spots from the condensation… so you will have mites all the way to Broken Hill”, explains the professor. Tovey.
But even though the number of dust mites is exploding at this time of year, exposure to the allergen is greatest in the winter when your home is closed.
Why are some people affected by dust mites and others not?
Dust mite allergens can cause conditions such as hay fever, eczema, and asthma.
But the big question is why some people get allergic to dust mites and others don’t.
We thought the more a person was exposed to dust mites, the worse their allergy got, but that turned out not to be the case, says Professor Tovey.
“There is a huge paradox about exposure to dust mites,” he says.
No one knows why some people are more allergic than others, says Wayne Thomas of the Telethon Kids Institute, who has studied dust mite allergens.
Professor Thomas says that some studies indicate that respiratory infections can trigger allergic reactions.
“It may be a question of timing; whenever you are exposed to a large number of dust mite allergens compared to the last time you had a [respiratory] the infection could be significant. ”
Bacteria in your gut can also influence whether or not you become allergic, he added.
The diagnosis of dust mite allergies is tricky.
“The standard test that doctors like to do with the skin test is way too sensitive,” says Professor Thomas.
He estimates that about 75 percent of people who test positive for dust mites have very low sensitivity levels or respond to different environmental factors.
But for those susceptible to dust mites, the news is not good.
“Our ability to treat it has not improved much over the past 30 years,” says Professor Thomas.
Even though we have identified the main allergens, we still don’t understand much about what they do in the human body and why different people are allergic to different dust mite allergens.
“If we want to do better treatment for therapy or [develop a vaccine], we have to use the allergens that we think cause all allergic reactions, ”he says.
Are some parts of the house worse than others?
We used to think that we were mainly exposed to dust mite allergen in bed, but Professor Tovey’s experiments have shown that we are exposed every time we move.
Studies show you stir up dust when you first go to bed, but it usually sets in until you turn around.
“If you’re a restless sleeper you’re probably more exposed,” he says.
But you are also exposed during the day.
“It comes off your clothes, it comes off when you sit on the sofa and when you walk on the carpet.”
And beware if you plan to take clothes out of storage.
“They probably have the highest levels of allergens I have ever seen,” says Professor Tovey.
“If you put them on or shake them, if you’re a little allergic to dust mites, you can definitely develop sniffles and sneezes.”
What’s the best way to reduce dust mite allergens?
While you can never get rid of it completely, there are things you can do to reduce your exposure.
The easiest way is to wash yourself.
“The dust mite allergen is incredibly soluble, it dissolves like the snap of your fingers,” says Professor Tovey.
“If you use very hot water, which is very difficult to do, you can kill the mites, but they will come back anyway. ”
Keeping your home dry will also keep dust mite and allergen levels low.
Airing out clothes and rugs in the sun can also kill dust mites, but you won’t get rid of the allergen if you don’t wash the items first.
Using a damp cloth for dusting may help reduce the allergen slightly.
Professor Tovey says vacuuming will also help reduce allergens a bit on surfaces, but “it’s not great.”
“There’s still a lot of stuff after you’ve vacuumed a floor pretty carefully, there’s still a lot of material in the base of the carpet,” he says.
There is little evidence to recommend special mattress covers because they do not stop dust mites in other areas.
“You can spend a lot of money on better vacuums and mattress covers, but you can achieve a lot of that just by washing them regularly,” says Professor Tovey.
And forget about the special sprays.
“Once you kill a few mites, others will just replace them, so I would say it’s a bit of a futile exercise,” he says.
“Even if they kill dust mites or destroy allergens a bit, do they really make people better?
“I am very confident that there is no decent data showing this.”