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.
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