Respiratory Allergies - Can it be avoided?

Our exposure to allergy is absolute. There are very few places on earth that have relatively low allergens (think the Alps and Arctic!). To develop allergy, we must be genetically predisposed and must have sufficient exposure to allergens. To date, there have been many candidate genes identified for different allergies. However, inheriting these genes alone is insufficient to trigger allergies. One needs sufficient exposure time to allergens to develop allergies.

So, can a newborn be born with allergies? It's interesting to note that amniocentesis (Amniotic fluid) studies recently have shown the presence of allergic chemokines (chemicals that mediate allergies). We are not sure how and why this happens but epidemiological studies seems to suggest a connection between allergic and smoking mothers and the birth of an allergic child (atopy).

Another interesting finding is the association between the amount or level of allergen exposure and the development of allergy. Any allergist or doctor will tell you to get rid of your pet cat if you or your family members suffer from asthma. It's interesting to note more allergic and asthmatic children are born to mothers with low or partial exposure to furry animals (like cats). In household with many cats or furry animals, the incidence of birth of an asthmatic child is lower that that of household without pets. So, experts are re-thinking on the total avoidance advice for asthma at least-maybe what they need is lots more feline friends at home!

There have been a few systematic reviews on the efficacy of allergy avoidance. One review in particular focused on all allergy avoidance studies done in the past 10 years. The conclusion-allergen avoidance does not help in reducing allergic disease.

Don't despair, all's not lost, as there are a few individual clinical trials on asthmatic and rhinitis patients that support definitive allergen avoidance measures to alleviate or improve symptoms.

By far the most common allergen to trigger respiratory allergies (allergic rhinitis , asthma, atopic cough) is the House Dust Mite (HDM). Lets be clear- it's not the dust mite one can be allergic to, rather to its droppings (poo) that are a fraction of a micron in size (a few thousandth of a millimeter). There are so minute that it takes an electron microscope to view them. HDMs live a very contended life within our mattress, pillows, duvets and indeed, in any fabric. Soft toys are another common habitat of HDM. HDM feed on our dead skin that we shed daily. A warm humid climate (as in the tropics) are a fertile ground for its propagation. Millions of HDM live and thrive in a single mattress; the HDM droppings are minute enough to pass through normal weavings of the matress and bedsheets to float freely in the air. It's not easy to dust or clean mattresses, however if you are an asthmatic with frequent symptoms, it's advisable to get anti dust mite bed and pillow covers. There are basically 2 types of these covers- acaricide (an anti-mite chemical) infused and non chemical based covers. My personal opinion is biased toward the non chemical covers as there has not been any extensive studies on the long term effects of acaricide on an asthmatic child as presumebly they would inhale these chemicals on daily basis.

There are a couple of studies on the efficacy of different vacuum cleaners on HDM population. Generally speaking , water based vacuum with HEPA filters seem to be superior in its deep vacuuming of mattresses. If you are cat allergic, its best not to allow your pet indoors as studies show they tend to sneak into your room when your back is turned. Allow me to correct another misinformation - cat allergens are found in the cat saliva and not in their fur. When a cat licks its fur as they normally do, the saliva deposited in the fur dries over time and releases very minute sized allergens in to the air. This is why a cat sensitive individual sneeze just on entering a house with cats ; even when the cats are not there. Cat allergens tend to stay for years even after the cat is gone.

Although frequent vacuuming reduces allergy symptoms, the sheer effort of daily vacuuming is only done by the most committed parent. Mopping with mild soap and water is superior to sweeping the room as this may lead to dispersion of allergens into the air. Replacing carpets with hard floor (wood or tiles) are easier to clean than frequent vacuming. While maintaining low humidity (50%) and temperatures (24C) in the room is said to decrease the HDM count, it is not always practical in the tropics. Select furniture made of leather or wood for easy cleaning and avoid soft toys on beds and cots.

And last but no least, select anti-mould paint and low VOC (Volatile Organic Compounds) to decorate the house.

Allergy Medications

Allergy medications are dispensed in many forms, namely tablets, liquids, inhalers, drops, topical creams and even as injections. Now, lets take a brief look at some of them.

1) Antihistamines (AH) - this forms the front line of an allergy. They are classified into many groups acceding to its sedating properties. They work mainly by nullifying the effects of the main allergy chemical in our body i.e. histamine. Some of the more common antihistamines prescribed by doctors are cetrizine (levocetrizine), chlorpeniramine, benadryl, and loratidine (desloratidine). Antihistamines reduces the symptoms of allergy such as itch, runny nose, sneezing and allergic rashes (not eczema). Aside tablet forms, AH is also available as eye/nose/ear drops. Intranasal antihistamine are also gaining popularity.

2) Corticosteroids (CS) - While Steroids may send shivers down the spine of some patients, we have to bear in mind that they are naturally occurring in the human body. Steroids are absolutely essential for the normal functioning of the body. While I will not go in detail on its role, suffice to say that a large part of our hormone are steroids in nature. It is interesting to note that from the diagram above, we can see that Cholesterol is the starting point in chemical pathway for the steroid formation. This is why I always tell my patients that having some cholesterol is essential for the body. Anyway, not to digress, steroids here are used to suppress our hyperactive and confused immune system form overreacting; thus causing allergic symptoms. Having said that, it is also important to note that steroid are not usually the first line treatment by the doctors except in severe cases.

3) Monteleucast (Singulare) - mast cell stabilizers that reduces the release of allergy chemicals forms mast cells. This makes this drug ideal for chronic allergies and asthmatics. It is not used in an acute allergic episode. The drawback of this drug is its cost.

4) Allergy shots - these are actually a form of immunotherapy. Once the offending allergen is known, the allergist will inject carefully titrated doses of allergens every fortnight. The rationale behind this treatment is by allowing the body to accept the allergen and not to fight it. These injections are very costly, and are not given as a routine.

5) Immunotherapy - is the cutting edge of allergy treatment. It can be said allergy treatment is leading the way in possible future treatment of all illness. For the first time, we can actually modify our immune system not to overreact to allergens. So far there are immunotherapy to treat allergies to house dust mite, bee/wasp stings and tree pollen allergens. Immunotherapy can be injected as a fortnightly injections for 2-3 years (Ouch!) to make our immune tolerate to pollen or bee sting. Currently Immunotherapy for house dust mite and tree pollens can be administered as drops below the tongue daily. This method has gained more acceptance and is proving to be a success in North America & Europe. Its use is limited in Asia due to its cost (about Rm 400-500/months x 2 years).

6) Epipen - This is a life saving device prescribed to patients with history of a serious Anaphylatic reaction. An anaphylactic reaction is the most serious form (life threatening) of allergy. Symptoms of an anaphylactic reactions include chocking, coughing, vomiting and shortness of breath on exposure of allergy. It usually occurs to food allergy such as seafood, nuts and even some fruits. Epipen is an automatic injection that is pre filled with epinephrine. The patient is thought to recognize symptoms of anaphylaxis and how to use the epipen device. In Malaysia, its availability is scarce and many doctors are not trained in its use.

Your Allergy Treatment Options

When your allergy or allergies have been diagnosed, the allergy specialist will try to identify which body systems are involved and how severe are the allergies. An individual may have a mono (single) or multiple allergies, involving different organs in our body. Classically, allergy involves a few organ systems (Table 1).

Allergy Avoidance

Once the offending allergens have been identified, the easier way to 'cure' your allergies would be to avoid the allergen. It is often easier said than done but a little effort in cleaning your home or office by wet mop or water based vacuum cleaner goes a long way in reducing respiratory symptoms such as sneeze, runny nose and even asthma. Frequent housekeeping and clearing of rooms of unused furniture reduce the deposition of house dust mites (HDM) and pet fur. However, the largest collection of HDM can be found within the mattress and pillows that we sleep on every night. Vacuuming beddings have shown to have some degree of improvement for asthmatics, it is indeed a laborious task and many parents usually abandon this rigorous task in the long run. Changing bedsheets and pillow covers have usually minimal effect since the HDM resides deep within the mattress.

It is interesting to note that HDM allergy is not provoked by the mite per se but rather its droppings which are few microns in size. The droppings therefore can easily pass through the woven fabric of beed and pillow covers and float freely in the air. Fans and closed windows help circulate these droppings within the bedroom atmosphere. Another common items HDM breed are soft toys, often hugged by the sleeping child. It is recommended to clear bedrooms of all fabric toys and pets. Windows should be opened for ventilation. Soft toys should be frequently washed and throughly dried in direct sunlight for more than 4 hours. Some doctors advocate the use of eucalyptus oil and detergent to presoak the toys for a few hours prior to wash.

The use of HDM proof beddings is gaining popularity. Indeed some mattress manufacturers incorporate "anti dust mite " features built in . What this essentially means that the mattress fabric is usually infused with acaricides (Anti HDM) chemicals that kill the HDM on contact. While this may sound good, be aware that there have not be any large studies detailing the effects of these chemicals on the human body. There are however newer Anti dust mite sheets that are chemical free and relies on high tech weaving that prevents the free movement of mites or droppings from the mattress to the surface.

Next: A look at medications.

Table 1: Common Allergies and the organs involved

: Organs involved	Symptoms	Allergic Disease
Respiratory: Nose Lungs	Itchy, runny and blocked nose, Watery Nose and sneezing. Chest tightness, shortness of breath, Wheezing, Dry cough.	Rhinitis, hypertrophied Nasal Turbinate Deviated nasal Septum. Asthma, chronic dry Cough. Allergic Bronchitis
Skin	Itch, Rash, Skin Swelling.	Urticaria, eczema, pruritic rash
Digestive System	Lip/tongue numbness and swelling, Diarrhea, Vomiting and sensitive Stomach.	Angioedema
Eyes	Red Eyes, Eyelid swelling, Watery Eyes.	Allergic conjunctivitis

If you believe you have allergies, it makes sense to find out what your allergies are. Locating a doctor who specializes in allergy (Allergist) in Malaysia is not an easy task as there are only a handful doctors who offer the service.

Allergy tests today are more convenient and accurate than before. Before we go into the various tests available, its important to understand these two terms:

Sensitized: means your body is 'primed' to an allergen. A positive skin test therefore indicates that you are sensitized to the allergen while you may not necessarily have the allergic symptoms. Confused? This means that you may test positive for peanuts by allergy test; although you have never developed any allergic symptoms to peanut before. In another words, sensization to peanuts means you have the potential to develop peanut allergy in the future, even if you never had peanut allergy. More confused? Read on and I will explain.

Allergy: means definite reaction to allergen. This means when the doctor says you are allergic to peanuts (as an example), eating peanuts will surely provoke allergic symptoms (itchy rash, puffy face and eyes or choking).

The interpretation of allergy test to identify the offending allergen is best left to allergist or doctors trained in allergy - to avoid any misinformation. An allergist is trained to distinguish between a sensitization and a true allergy by taking a careful allergy history and interpreting the allergy test. In addition, the allergist is to treat a person with multiple allergies involving different organs. A patient may be suffering from skin, dust and food allergies at the same time and it is important to identify and treat all the allergies simultaneously.

Now, lets talk about the different allergy tests.

Allergy testing involve skin and/or blood test to identify allergens that is causing your allergy. Allergy test can be broadly classified into two groups, namely Skin Prick Test and Blood Test.

Skin Prick Test

Skin Prick Tests (SPT) can be done as an outpatient procedure in an allergy alinic. This is the most preferred test method as the results can be known in 15 to 20 minutes and its cheaper than blood tests.

The SPT comes in a kit form with small bottles of laboratory prepared allergens. The doctor selects the allergens to be tested (usually up to 10 allergens ) and apply a very tiny drop of the allergen on your forearm. The doctor then makes a tiny needle prick on the skin surface through the applied allergen drop (don't be afraid-it does not hurt as the needle rest only on the skin surface). There is usually no blood seen during the test.

Each suspected allergen is tested by individual pricks. Usually up 10 allergens can be tested on a single sitting. A small swell at the site of the needle prick ( more than 3mm diameter) within 15 minutes is said to be a positive test for that allergen. (image below).

Remember: These tests only denotes sensitization and not necessarily allergy.

Another modified skin prick test is called the prick-prick test which is usually done for fresh food or fruits. A small slice of the food is pricked with the needle before pricking onto the skin. A swelling at the site may indicate allergy to the said fruit.

Blood Test : The Rast or Immunoabsorbant assay

This test involves drawing blood from the forearm and dispatching it to labs that do allergy testing. After a couple of days , the results will indicate the level of antibody for the tested allergens. The allergen specific antibody called IgE (Immunonoglobulin) will be raised if your are sensitive to the allergen. Again, this is a sensitization test- a high level IgE is indicative of sensitization but not necessarily allergic to the allergen.

Patch Test

Patch test is usually done to detect contact dermatitis. This includes testing for metal, chemical, leather and latex allergies.There are a few types of test kits available in the market. It comes with a standard of 10-20 common pre-filled metals, chemicals and other materials that commonly causes skin allergies such as eczemas and dermatitis. These are then applied to the back of the torso and left for 24-48 hours before reading for reactions. The stronger the reaction the more pronounced is the redness. Sometimes, the reactions can be so strong that it causes a bleb or a wound at the site. The patient is usually warned to remove the patch if there is pain.

The type or the quantity of test selected by the allergist is dependent on the disease; based on a good clinical history and medical examination. A consent is a must before any test can be performed.

Next chapter: What are your treatment options?

Allergy- Lets Start from the Beginning!

Why do some people get allergy while others don't? Well, simply, people with allergies have a confused immune system!

You see, our immune system is designed to protect us from the many thousands of harmful bacteria, virus, fungi and even chemicals. The main defensive army of our immune system are the white blood cells (WBC). Like soldiers, there are many varieties - army,navy, air force etc., the WBC varieties include the the neutrophils, lymphocytes, eosinophils, monocytes and platlets. Without going into details, suffice to say their job is to defend our body against infection around the clock 24/7/365.

The WBC are able to identify and distinguish between a friendly cell (such as our own organ cells called self cells and an enemy cell such as bacteria and viruses called non-self cells). Not all of the invading cells are harmful; indeed a large percentage of these non-self cells are harmless bystanders that neither help nor harm our body. Examples of these 'innocent bystanders' include what we call as allergens such as dust mite droppings, animal furs and tree pollen inhaled when we go about our daily activities.

The confused WBCs attack these 'innocent bystanders' thinking that they are bacteria or viruses. And hence, an allergic reaction produce similar effects of a common flu such as nose itch, sneeze and runny nose. The eyes are often involved too, with red watery discharge.

It's believed that similar responses occurs within the skin causing contact dermatitis and in the lungs as in asthma. Over time, research into immune system revealed the highly complex pathways that allergy develop, i.e. right from the time of contact with the allergens to the development of symptoms. In fact, new research shows there may be many other complex pathways and chemicals involved in forming allergies of other systems, such as food and eczemas.

To develop allergies, one needs to have the allergy genes within their DNA. However, possessing the allergic genes alone does not confer one to suffer allergies. Exposure to allergens is a vital ingredient to developing allergy. Prolonged exposure to allergens (months or even years) may be necessary to provoke an allergic response. This may be the reason why many patients find it hard to believe the house they lived in or their pet FiFi is a source of their rhinitis or asthma!

I hope this sheds some simplistic light into the basic mechanism of allergy. I must admit, it has been a challenge and a learning experience for me to simplify the immune mechanism of allergy.

Up next: How do we find out if we have allergies