It's spring time, and dust mites just love spring! An occasionally squeamish Andrew Collins of ABC Pilbara interviewed dust mite expert Associate Professor Euan Tovey of the Woolcock Institute of Medical Research about these tiny creatures – what are they, why are we allergic to them, and what can we do about them?
Thank you to ABC Pilbara for letting us share the recording of this interview. For more insights on dust mites from Euan, read What are dust mites, why do they cause allergies and can we get rid of them?, ABC News 11 October 2021.
ABC's Andrew Collins: As a definition, dust mites: what are they?
Euan Tovey: They're what we refer to as arachnids. They're little things that are very closely related to tics, which are related to spiders. So they've got eight legs and not six. They're a very large group of arachnids. They're found all around the world and they live in your house.
They probably came from birds. They used to live on bird feathers, probably. And they've taken a liking to our skin – our dead skin, that is, not our live skin, fortunately.
There's lots of dead skin in house dust. It's probably the main component of house dust in many cases. When you put clothes in the washing machine, you know how the water all goes white? Well, a lot of that is just the skin off your body floating around in the washing machine. That's what dust mites feed on: the dead decaying skin.
Andrew: So, okay you talked about dead skin there. But is dust the common denominator with where you'll find dust mites? Does it have to be dust present in order to find the dust mite, or could it just be the dead skin and there they are?
Euan: Well they need the appropriate conditions of temperature and humidity. They're a bit fussy. Otherwise, they don't grow very much. So, usually on clothing which is in storage, or in the dust in your mattress or in the dust on the floors, you'll be able to find live dust mites.
The material, they produce – the poo amongst other things, but also their broken-down bodies – have got these proteins in them you become allergic to. They become distributed right around the house. So even if you collected dust off the top of your doorway or something, you may not find live mites in it, but you would still find the dust mite allergens.
So those proteins that you become allergic to get distributed right around the house.
Andrew: Okay. So you've talked about the weather conditions that are required, some of the physical things that I need to find the dust mites. So are they eating the dust? Is that's what they're attracted to in order to survive? Is that important to them?
Euan: Yeah. Probably. It may be that it's the fungi that grow on the dust, or some process of the dust breaking down. They don't eat live skin.
We used to grow them in culture, and found you can culture them on a whole range of things, not just skin, but good protein sources, they will grow on.
But for some unknown reason our skin is an appropriate food for them and they do very well. Whisker shavings mixed with a bit of yeast was one of the favourite things we used to raise dust mites on!
Andrew: Okay, not that anyone's particularly going to be doing a science experiment in their kitchen this afternoon, Professor. But you talked about the allergies, for example, that can be the mites themselves or the proteins. Is it just a matter of, if people do have allergies, just to keep clean spaces, and that is just the best tried and true method to avoiding these dust mites from entering your life?
Euan: More or less, yes. There's lots of allergens around, it's very difficult to get rid of it all in houses. That's one of the problems. When you move in your house, or you walk across the carpet, or you climb into bed, put on some clothes and all these things, you disturb that dust and you inhale these particles which contain the allergens.
The mites produce a lot of different proteins – we're calling them allergens because they're the things you become allergic to – probably about 38 to 40 of them. There are some more major ones. And it's those things that you develop a particular sort of immune response to.
Andrew: Are certain parts of the house worse than others? Parts that don't get cleaned as often?
Euan: Maybe, maybe not. They need some place they can hide, so things like carpets and bedding, clothing. All those places are good because they can burrow down between the fibres, and they can keep their humidity.
You don't find them on tiled surfaces or benchtops or anything like that. They need to be able to hide, to get out of the light, and they like to preserve their moisture so they like to be down stuck between some fibres.
Andrew: Thanks for coming on Professor. An enlightening and somewhat eerie conversation.
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