May's unseasonably warm weather and freak heatwave helped drive pollen levels sharply upwards, leaving many islanders suffering from the misery of itchy eyes, streaming noses and relentless sneezing. For most people, these symptoms improve once the pollen season subsides.
House dust mite allergy is one of the commonest causes of perennial allergic rhinitis, affecting people of all ages and often having a much greater impact on health and wellbeing than many realise.
House dust mites are microscopic creatures, related to spiders and ticks, which live in our homes all year round. They thrive in warm, humid environments and are particularly abundant in mattresses, pillows, carpets and upholstered furniture. Invisible to the naked eye, they are present in virtually every home. The allergy is not caused by the mites themselves biting or stinging us. Rather, it is the proteins found in their droppings and body fragments that trigger an allergic reaction in susceptible individuals. Because these allergens are present throughout the year, symptoms can become a constant feature of daily life rather than a seasonal inconvenience.
Typical symptoms include sneezing, a runny or blocked nose, itchy watery eyes and post-nasal drip. Some people also experience an irritating cough. Symptoms are often worse first thing in the morning, reflecting prolonged exposure overnight from bedding and mattresses where dust mites are particularly abundant.
More than just a nuisance
For many sufferers house dust mite allergy can have a substantial impact on quality of life. Persistent nasal congestion can disrupt sleep, leading to daytime tiredness, poor concentration and reduced productivity at work or school. Many patients describe feeling permanently ‘bunged up’, struggling to breathe freely through their nose and feeling exhausted by symptoms that never seem to go away.
There can also be a significant emotional impact. Constant symptoms can affect mood, enjoyment of activities and overall wellbeing. Unlike seasonal hay fever, where sufferers can usually see an end in sight, year-round allergy can feel relentless.
Importantly, house dust mite allergy is also closely linked with asthma and eczema. In many individuals, the same allergic inflammation affecting the nose is also present in the lungs and skin. For asthmatic patients, exposure to house dust mite allergens can trigger wheeze, chest tightness, cough and breathlessness, and may contribute to poor asthma control. Identifying and treating any underlying allergies can form an important part of improving asthma and eczema symptoms and reducing the risk of flare-ups – the nose, lungs and skin are intimately connected, and controlling inflammation in one often helps the others.
Getting the diagnosis right
Although symptoms may strongly suggest house dust mite allergy, testing is important to confirm the diagnosis. This can usually be achieved through either skin prick testing or special blood tests for antibodies to house dust mites. Testing helps identify exactly which allergens are responsible for symptoms and can distinguish house dust mite allergy from other airborne allergens such as grass pollen, tree pollen, mould spores or animal dander. Obtaining an accurate diagnosis is particularly important when symptoms are severe or when considering more advanced treatments such as immunotherapy.
Reducing exposure
Although it is impossible to eliminate house dust mites completely, reducing exposure can often improve symptoms significantly.
Practical measures include using allergen-proof mattress and pillow covers, washing bedding weekly at temperatures of 60C or above, reducing humidity levels within the home and minimising dust-trapping furnishings where possible. Regular vacuuming using a HEPA-filter vacuum cleaner and damp dusting of surfaces can also help reduce allergen levels.
While these measures are unlikely to cure the allergy, they can reduce the allergen burden and form an important part of overall management.
Medical treatments
Many patients achieve good symptom control using conventional allergy treatments.
Non-sedating antihistamines can reduce itching, sneezing and runny nose symptoms, while steroid nasal sprays are often highly effective at controlling the underlying inflammation responsible for nasal blockage and congestion. Most of these medications can be obtained over the counter although there are stronger versions on prescription from your GP if required.
For those with associated asthma, regular asthma reviews and optimisation of inhaler regimens is also important.
These medications can be very effective at controlling symptoms, but they do not change the underlying allergic tendency. When treatment is stopped, symptoms usually return.
A new era of allergy treatment
One of the most exciting developments in allergy medicine over the past decade has been the growing use of allergen immunotherapy. For decades, treatment focused on avoidance and symptom control, but we are now entering an era where, for selected patients, we can actually influence the underlying allergic response itself, addressing the root cause of the allergy.
The principle is surprisingly simple. By exposing the immune system to carefully controlled amounts of the allergen over a prolonged period, it is possible to gradually retrain the immune response. Over time, the immune system becomes less reactive and more tolerant of the allergen that previously triggered symptoms.
This approach has already become well established in pollen allergy. In my last column I discussed Grazax, an immunotherapy tablet used to treat grass pollen allergy. For house dust mite allergy, an important recent development is immunotherapy in the form of Acarizax.
Acarizax is a daily tablet that dissolves under the tongue and contains standardised house dust mite allergen. This treatment is not suitable for everybody and careful patient selection is essential.
Patients must first undergo allergy testing to confirm that house dust mite is genuinely responsible for their symptoms. It is most suitable for those whose symptoms are exclusively due to house dust mite allergy rather than a mixture of multiple aeroallergens. It is for those patients who have symptoms on the severe end of the spectrum, affecting quality of life despite sensible avoidance measures and appropriate use of standard medical treatment. Perhaps most importantly, immunotherapy requires commitment. Treatment is typically taken daily for several years and patients need to stick with the programme to obtain the maximum benefit.
For the right patient, however, the results can be extremely rewarding. Rather than simply controlling symptoms from day to day, immunotherapy offers the possibility of long-term improvement and a genuine reduction in allergic sensitivity.
Looking ahead
For those who experience ‘hay fever’ symptoms throughout the year, house dust mite allergy is an important possibility that should not be overlooked.
The good news is that effective diagnostic tests are available, along with a range of treatment options that can dramatically improve symptoms and quality of life.
I am pleased to say that Acarizax is now available in Guernsey. However, successful treatment begins with an accurate diagnosis. Establishing that house dust mite allergy is genuinely responsible for symptoms allows medication to be optimised and helps determine whether immunotherapy is likely to be appropriate.
Both allergy diagnostics and immunotherapy treatment are available through the allergy clinic at Healthcare Group. Make an appointment to see myself or my colleague Dr Chloe Savident if you would like further advice – details on the Healthcare Group website.
