“You’ll find them in carpets, beds and on your clothes, but as far as we know they don’t live on the skin,” says Euan Tovey of the Woolcock Institute for Medical Research, who studies allergies from dust mites.
“When you wash your clothes, the reason the water turns cloudy is because your skin cells are floating!” says Professor Tovey. As they soften dead skin cells, the mites release enzymes into their gut where they break down human skin cells.
In the 1980s, Professor Tovey discovered that one of these enzymes is a powerful allergen that floats in the air from dust mite droppings. “This allergen from the mite’s dirt breaks down into smaller dust particles,” says Professor Tovey. “These particles are less than a millimeter in size, so that means they’re inhalable.”
Dust mites are tiny arachnids, closely related to ticks. They measure about a third of a millimeter in length.
Mites feed on dead skin cells, which are abundant throughout the home, since humans shed “about 1 teaspoon of skin cells per week.”
People can also be allergic to a number of other proteins in the mites, but this enzyme accounts for only about 60% of allergies. This is because a mite can produce a lot of dirt during its life, which is about 90 days.
Dust mite allergens can also remain for a long time in the room, depending on the humidity level. “In dry conditions, they can remain for years, while in wet conditions they break down in a few months.”
Are there more mites at certain times of the year?
The amount of allergens from mites varies according to the season.
“Growing conditions for mites are quite ideal in the spring because they like 25 degrees Celsius and fairly high humidity, around 75%,” says Professor Tovey.
The warmer and more humid the weather, the better, but our homes provide the perfect environment for them to thrive year-round, even in arid areas. “There are few wet places in the houses, such as the underlay of the carpet and the mattresses on the beds that have wet patches due to condensation of sweat and lint. So we’re not immune to dust mites,” says Professor Tovey.
But even though the number of dust mites in the home fluctuates, exposure to their allergens increases during the winter when the house is closed.
Why are some people affected by dust mites while others are not?
Dust mite allergens can cause allergies, eczema and asthma. But the big question is why some people become very allergic to dust mites and others don’t.
“It used to be thought that the more dust mite exposure someone had, the worse their allergy was, but that turned out not to be the case,” says Professor Tovey. “There’s a huge paradox about dust mite exposure.”
No one knows why some are more allergic than others, says Wayne Thomas, of the Telethon Kids Institute, who has studied dust mite allergens.
Professor Thomas says some studies show that respiratory infections can trigger allergic reactions. “It may be a matter of timing. “When you are exposed to a lot of dust mite allergens compared to the last time you had a respiratory infection could be important.”
Bacteria in the gut can also affect whether or not you develop allergies, he added.
Diagnosing dust mite allergies is difficult
“The standard test that doctors like to do with the allergy skin test is very sensitive,” says Professor Thomas. He estimates that about 75% of people who are positive for dust mites have very low levels of sensitivity, or react to different factors in the environment.
But for people who are sensitive to dust mites, the news is not good. “Our ability to deal with them has not improved in the last 30 years,” says Professor Thomas.
Although we have identified the main allergens, we don’t know much about exactly what they do to the human body and why different people are allergic to different dust mite allergens.
Are there more mites in some parts of the house compared to others?
We used to think that our main exposure to dust mite allergens happened in bed. But experiments by Professor Tovey have shown that we are exposed to them every time we move around the house.
Studies show that we kick up dust when we first lie in bed, which settles when we finally lie still. If you sleep restlessly, you will likely have more exposure to dust mites as well.
However, we are also exposed to them during the day. They come out of your clothes, when you sit on the sofa and when you walk on carpets and rugs.
And be careful if you plan to take clothes out of storage. It’s probably where the highest levels of allergens are than anywhere else in the home, says Professor Tovey. “If you wear clothes straight out of your closet that you’ve had for a while, if you’re a little allergic to dust mites, then you might definitely start sneezing.”
What is the best way to reduce dust mite allergens?
While you can never get rid of them completely, there are a few things you can do to reduce your exposure to them.
The simplest is washing!
“Dust mite allergens are incredibly soluble. If you use hot water, which is really hard to do, you can kill the mites, but they’ll come back from somewhere else.”
By keeping your home dry, you will also keep the levels of dust mites and their allergens down.
Regularly airing clothes and carpets in sunlight can also kill dust mites, but you won’t get rid of allergens if you don’t wash the items first.
Using a damp cloth to dust can help reduce allergens slightly.
Professor Tovey says vacuuming will also help reduce the allergen on surfaces, but “it’s not a panacea. There are still a lot of dust mites after you mop the floor pretty well. There are a lot of mites on the base of the carpet and the carpet.”
There is not enough evidence that any special mattress covers stop dust mites.
“You can spend a huge amount of money on better vacuums and mattress covers, but the best thing is just regular washing,” says Professor Tovey.
And forget about special sprays. “Once you kill some mites, some others are just going to replace them, so I’d say it’s a bit of a futile move,” he says.
Source: abc.net.au
The article What to do about dust mites: They are everywhere in the house and cause allergies was published on NewsIT .
