How to Treat House Dust Mite Allergy (SLIT) in Singapore: De-sensitisation!

Did you know that the house dust mite is the Number one cause of nasal and skin allergies in Singapore? House dust mite (HDM) allergy can trigger off flare-ups of allergic rhinitis and eczema skin issues. It can also trigger an asthma attack. You can’t get rid of house dust mite problems just by cleaning vigorously away. The three species of house dust mites live happily in our warm and humid climate in Singapore. So don’t go too crazy with the house-cleaning just yet!

WHAT ARE THE THREE TYPES OF HOUSE DUST MITE WHICH CAUSE ALLERGIES IN SINGAPORE?

The three types of house dust mites, Blomia Tropicalis, D. Farinae and D. Pterronysinus, are endemic to Singapore. They produce droppings to irritate your skin and airways to cause allergic rhinitis and sensitive skin issues. Blomia is a tropical species, D. Farinae is the American house dust mite and D. Pterronysinus is the European counterpart. But you can find all three in vast abundance in Singapore, with each dust mite laying up to 80 eggs daily!

In a typical 10-week lifespan of each house dust mite, they will produce up to 2000 tiny faecal pellets. Each pellet measures 10-40 micrometers in length. Guess what the house dust mites love feeding on? The millions of microscopic skin flakes which human beings shed from their bodies everyday! Do you see why those house dust mites aren’t easy to get rid of? Lovely warm weather with rich food sources everywhere, so why would they ever leave?

The house dust mite is microscopic so you cannot see them with your naked eye. You can’t get rid of them completely so you can only control their levels.

WHY IS IT IMPORTANT TO TREAT HOUSE DUST MITE ALLERGIES?

House dust mite allergies cause allergic rhinitis (nasal allergy of the upper airways), allergic dermatitis (eczema) and allergic asthma (narrowing of the lower airways). It is important to control any upper airway allergy or allergic rhinitis. A persistent overproduction of mucus from the nose will flow as a postnasal drip to irritate the lower airways. So allergic rhinitis is a well-recognised risk factor for triggering an asthma attack, leading to a sudden wheeze, chest tightness and difficulty breathing. This arises due to severe muscle spasm of the hypersensitive lower airways, in response to the mucus postnasal drip.

WHAT SIMPLE ANTI-HOUSE DUST MITE MEASURES CAN I CARRY OUT AT HOME?

So how do we manage house dust mite allergies? For mild nasal and skin allergy caused by house dust mites, washing the bedlinen and pillowcases in hot water is helpful. Drying them in sunlight also helps to reduce the house dust mite burden. Don’t forget to clean your aircon vents and ceiling fans too.

Removing carpets and soft plush toys, especially in the bedroom where you or your child sleep at night. Air purifiers may help but you don’t need to buy expensive ones! You might not notice a huge difference especially if your house dust mite allergies are severe.

Buying a good anti-dust mite pillow protector may help protect you when you sleep. This may help to minimise the amount of dust mite material which you are breathing in at night.

We have to be sensible about cleaning to get rid of house dust mites!

WHAT IS THE STANDARD TREATMENT FOR HOUSE DUST MITE ALLERGIES?

Severe house dust mite allergies affect your nose to cause a persistent blocked nose, runny nose and backdrip. But you may also suffer blocked ears, itchy nose with sneezing and recurrent nosebleeds:

1. Daily douching of your nose with a gentle alkaline saline rinse
2. Nasal steroid sprays eg Nasonex or Avamys (please take note that the body’s absorption of nasal steroids is very low)
3. Antihistamines e.g. Telfast and Clarityn.
4. Montelukast (Singulair) may help patients with both nasal allergies and asthma.

The above medications are all targeted towards symptom relief, just like taking Panadol for knee pain. It doesn’t offer a longer term solution!

WHAT DO I NEED TO KNOW ABOUT SUBLINGUAL IMMUNOTHERAPY FOR HOUSE DUST MITE?

SUBLINGUAL IMMUNOTHERAPY, known as SLIT or Desensitisation Treatment for House Dust Mite is a game-changer! Previously, desensitisation therapy was given in the form of multiple skin injections. It was painful, troublesome and involved needles. Now, it is a sublingual spray administered under your tongue daily. It is absorbed into the blood supply found underneath your tongue. SLIT is safe, highly effective and easy to use at home.

But you need to keep using this daily for at least three years. Sublingual immunotherapy is strongly evidence-based. Multiple studies show up to 80% success rate at improving your allergy symptoms. The risk of recurrence is higher if you don’t complete your 3 years. This is not medication. It does not contain steroids nor possess immunosuppressant side effects. It is also not a vaccine!

What Types of Sublingual Immunotherapy for House Dust Mite are there?

In Singapore, we have the sublingual spray form called OralTek, or the sublingual tablet form called Acarizax. OralTek is usually what we prescribe for the younger children as it is licensed for age 5 and above, while Acarizax is licensed here for above age 12, although the age cutoff may vary from country to country. These desensitisation therapies can only be prescribed by a doctor and both are readily available at our ENT clinics in Singapore.

A newer version of Oraltek is called SLIM, a more efficient form of the house dust mite molecular protein. So this is what we now offer patients who prefer the sublingual spray version.

You should have an allergy test first. This is either a skin prick test or an allergy blood test, to determine what you might be allergic to before embarking on desensitisation therapy. See your friendly ENT specialist in Singapore for more information!

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