Explaining allergy

When the body’s immune system overacts, we have what is called an allergy.

An allergy is not an infection. It manifests because of your own body’s immune response.

All our bodies are primed to defend against foreign substances invading it, such as bacteria, viruses etc. This is a natural protective mechanism.

Sometimes, we have an exaggerated immune response when our body is in contact with certain foreign substances. These substances cause most people no harm, but our bodies sometimes see it as harmful. Thus, we are “allergic” or “atopic” to that particular substance.

These foreign substances that produce allergies in allergic people are called “allergens”.

The word allergy was coined in 1905 by an Austrian paediatrician named Clemens Pirquet. It is derived from the Greek words “allos”, meaning different or changed, and “ergos”, meaning work or action. Thus allergy roughly means “altered reaction”.

But I thought allergies were only confined to people with asthma?

No. There are many types of “allergic” diseases, including asthma and allergic rhinitis, and all come under the broad spectrum of allergy.



How does allergy manifest? Is it only itching? Or does it involve sneezing?

The parts of the body that are prone to react to allergies are the nose, skin, eyes, lungs, and stomach.

For example, in allergic rhinitis (commonly known as “hay fever”), you have runny nose, blocked or stuffy nose, sneezing, itching, and sometimes a lot of throat clearing because the liquid drips from behind your nose into your throat.

Allergic rhinitis is the most common of the allergic diseases. Some people have it seasonally, especially during spring, where a lot of pollen is released. Some people have it all through the year, and this is usually caused by indoor allergens such as dust mites, animal dander, or moulds.

Asthma is another very common allergic disease. Here, there is shortness of breath, wheezing and chest tightness caused by the inflammation and spasm (narrowing) of the lung’s air passages (bronchial airways). A lot of people also have cough.

The eye is another commonplace for allergies. Allergic conjunctivitis is the inflammation of the conjunctiva, which causes redness, watery and itchy eyes and swelling.

In the skin, it manifests itself as “hives” (called urticaria). These are intensely itchy swellings that can occur on any part of your body.

Allergic reactions can also manifest as allergic eczema (atopic dermatitis). There is redness, itching, and dryness of the skin. This is common in children.



Do people die from allergies? I remember seeing this TV programme about a man who ate a peanut. He started to swell. He was dead within minutes.

This sounds a bit drastic, but yes, people have been known to die from allergies. Allergic shock (anaphylactic shock) sends the body into massive immune response overload, causing the tissues and organs to swell and the blood pressure to drop dramatically because the blood vessels turn leaky. This is usually in response to a food being eaten or a sting (for example, a bee or scorpion sting).



How will I know if I’m allergic to something? It would be very difficult to pinpoint the source.

You are right. It can be very difficult. You have to go back to the patterns of your behaviour, or whether there has been a new addition to your household.

For example, you were never allergic to anything before. Suddenly, a new dog arrives. Then you begin to sneeze violently and have watery eyes. But your wife and children have no reaction.

Solution: you are very likely allergic to the dog’s hair (animal dander)!

Apparently, there was a period of “sensitisation” to the dog hair that had occurred in you in the past that you weren’t aware of. It may range from months to years. You have previously been in prior contact with dog hair and your body began to develop an immune reaction to it.

So when the new dog came into your house – wham! Allergic reaction.

source:thestar.com.my