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Melanie Cole (Host): In most homes, dust mites are everywhere, often found in linens, bedding, carpeting, and other fabric materials. Dust mites are a big problem for people who have indoor winter allergies. My guest today is Dr. Kenneth Johns. He’s an allergy and immunology physician for Allina Health Clinics. Welcome to the show, Dr. Johns. What are dust mites?

Dr. Kenneth Johns (Guest): Well, dust mites are these microscopic little creatures probably most closely related to spiders. You’ve seen pictures of them on TV. They’re really too small to be seen. They look horrifying up close. They look like a humpback spider, basically. They live in everyone’s home, especially in the bedroom, and their pieces, their bodies, their detritus is extremely allergenic. They’re thought to be the most important indoor allergen and probably the most common year-round allergy.

Melanie: So, why are people allergic to dust mites? And, really, they sound like scary little things.

Dr. Johns: Well, again, they look scary but they’re too small to do you any harm other than being an important allergen. It’s really not clear why some substances, they’re usually proteins, become allergens and some don’t. There are many people that are studying the structure of the protein that we’re allergic to in dust mites and in pet dander and in pollen to find some sort of common thread. I’m just going to say there are some proteins that we become allergic to.

Melanie: So, the, how would you even know if you have a dust mite allergy as opposed to. . . If everybody or many people have these dust mites, first question, Dr. Jones, is how do you know if you have them in your house? Is there a way to detect them?

Dr. Johns: Well, there is. We can test someone to see if they’re allergic to dust mite or not. You’re exactly right. Dust mites are in everyone’s home but only 10 to 20 percent of us are allergic to them. And, that really is important because much to what we talk about to reduce dust mite exposure or to avoid dust mites is very expensive and very time extensive. So, I really only want to recommend that to people that I know are allergic to dust mites, otherwise it doesn’t make sense. Certainly, the treatments in terms of medication as in allergy shots, I really only want to use those when they’re appropriate, if the person is allergic or not.

Melanie: Well, how would we know if we are allergic. I mean because certain allergies, fall season allergies, come and go, you kind of get those red flags and triggers, but something that’s in your home could be a little bit more subversive in the way that it conducts your allergy.

Dr. Johns: I like subversive. So, dust mite is usually year-round allergy symptoms. It may peak a bit in the fall when our heating/cooling systems stirring up the heavier particles but, ultimately, it comes down to we need to test you to see if you’re allergic to dust mite and we have different ways to do allergy testing to see if you have that specific allergy. And, again, it’s important to have a yes or no on that because so much of what we do for dust mite allergy is expensive and time intensive and somewhat disruptive.

Melanie: So, then, what are those tests?

Dr. Johns: Well, we do a skin test and then we have a similar test that’s done through a blood test. So, allergy skin tests are done by a variety of methods. It’s a very safe test and very small amounts of dust mite extract, and you don’t want to know how they make dust mite extract, but very small amounts are introduced underneath the skin and cause a reaction similar to a mosquito bite that tells us the person is allergic. The blood test is basically a blood draw and it does a similar thing. It measures specific IgE antibodies against dust mite. And, again, they’re equally accurate. People seem to have strong feelings about which type of test they would prefer but they’re equally accurate.

Melanie: So, then, if you have detected that somebody does have this allergy to dust mites, what can they do about it at their home level? What is the first line of defense that you would like them to do? Do they change their bedding? Do they prefer dry environments or humid? What should they do?

Dr. Johns: So, there certainly has been a lot of revisionism in the last 20 years or so about what you can do to affect dust mite. The focus has been on a couple of things which are easy for me to talk about but very difficult and expensive and disruptive to do. So, unfortunately, things like air cleaners and air filters and doing a lot of cleaning and what have you really hasn’t been shown to be very effective. It certainly doesn’t seem to make patients feel better. So, the focus has been on flooring in the bedroom. So, any kind of carpeting on the flooring is ideal for dust mites to grow in. So, we’re always better off without carpeting on the bedroom floor. Secondly, concrete floors like a basement bedroom or a concrete floor in a split level, again, is ideal for dust mites to grow on. They need that humidity. They like those damp conditions as you alluded to. Dust mites don’t grow very well on low humidity, so high humidity like a constantly damp floor is ideal to grow dust mites. The allergist’s nightmare of course is carpeting on a concrete floor. So, the most important thing that someone can do is to not have those carpeting and not have concrete floors in the bedroom. A third issue that’s frequently talked about is encasements. So, dust mites actively grow within mattresses and pillows and it’s difficult to remove them. But, in encasement where the entire pillow or entire mattress is encased in a dust mite proof cover can be very helpful to provide that barrier. You know, pillows can be washed or dry cleaned or replaced from time to time, but with a mattress, really, it boils down to that encasement.

Melanie: Then, what about medication intervention, antihistamines or nasal corticosteroids? Are there certain things that you recommend for people that do have an allergy to dust mites if they can’t go about, as you say, the expensive process of totally getting rid of these things?

Dr. Johns: Well, we can help somewhat with medication. It is one of the allergies that can sort of overwhelm a good medication. So, we focus on, these days, on topical steroids. The nose sprays work beautifully for perennial year-round allergens like dust mite. They are safe. They are very effective. We really coach patients to be patient with the topical steroid nose sprays because they do take a while to work. It’s more like weeks or months rather than the American way which is immediate turn overnight. But, they work very nicely. If there’s a lot of itching involved, we might add some antihistamine. But, I would say our topical steroid nose sprays are really our most effective medication here.

Melanie: And so, could you give us some cleaning advice? Is there any cleaning advice as far as you mentioned the carpets and the concrete floors? Do vacuum cleaners or the vacuum cleaners with filters, do any of these things make a difference?

Dr. Johns: No, I think there’s some wishful thinking there but we think that if you do a lot of cleaning and a lot of vacuuming, you’d basically stir up these heavy particles and might even cause things to be worse. So, it isn’t a matter or more cleaning or more dusting or more vacuuming.

Melanie: I don’t know if that’s great news, Dr. Jones, but in the last few minutes, can you please just wrap this up for us and tell the listeners what you want them to know about these difficult to control or manage little dust mites and why people with allergies really need to be concerned about them. What do you want them to know?

Dr. Johns: Well, again, I would emphasize that it’s a very common and a very important year-round allergen. We’re all exposed to them. Again, we do have effective medication treatment. We do have some avoidance or abatement measures that can be very helpful but some might be difficult to accomplish. We do have allergy shots or immunotherapy that’s very effective for dust mite as well, sort of as a last resort. So, we do have good treatment but, again, I’m going to emphasize, I really want to know whether a person is allergic to dust mite or not so here’s an area where the testing is really important.

Melanie: Thank you so much for being with us. It’s really great information. You're listening to The WellCAST with Allina Health. For more information, you can go to www.allinahealth.org. That's www.allinahealth.org. This is Melanie Cole. Thanks so much for listening.