Saturday, 23 July 2011

Dealing with Allergies

Published in "Panaorama"

Tackling Allergies

Sami was fed up with having to take large doses of steroids, antibiotics, antihistamines and nasal sprays to tackle the symptoms of rhinitis and sinusitis which had become chronic now. Yet, all these medications only suppressed the symptoms but did nothing to alleviate the problem. Investigations revealed he was extremely allergic to house dust mite and household sprays. Following his physician’s advice, he removed the carpets from his apartment and stopped using household sprays. The effect was dramatic. Sami’s bouts of rhinitis and sinusitis reduced significantly in frequency and intensity.

30 year old David was rushed to the hospital was he suddenly developed violent skin rashes and experienced laboured breathing. Fortunately, the timely medical aid had saved his life! He was found allergic to peanuts, which he had consumed prior to this attack!

What is food to one may be a fierce poison to another. It is believed that approximately 1.5% of the U.S and U.K populations suffers from serious food allergies which could often be serious enough to be fatal! The commonest agent affecting vast numbers of people world over are grass and tree pollen, leading to Hayfever or Seasonal Allergic Rhinitis. The problem is often seasonal usually the most prevalent during the summer months. Individuals could be allergic to minute particles of fur, skin or animal dander from pets such as cats, dogs and even birds.

What is allergy and why do some people develop allergies? Dr.Anil P. Mummigatti, ENT Surgeon, Zulekha Hospital, Sharjah explains, “An allergy is an adverse reaction to a normally harmless substance which may be food or environmental agents such as pollen, dust or chemical pollutants. While the reason why some people suffer from allergies is still not fully understood, the tendency to develop an allergy in most instances is inherited. Of course people may suffer specific allergies where there is no hereditary factor involved.”

What happens in the body to set off allergic reactions? Allergies happen because of a misdirected response of the immune system to invading bacteria, viruses, and hosts of other hazardous intruders or antigens. The immune system produces antibodies to fight these antigens, particularly Immunoglobulin E (IgE) which participates in allergic reactions. Every individual has various IgE antibodies and each allergen stimulates the production of a particular form of IgE. For instance, an IgE meant to respond to pollen of oak, will not respond to ragweed pollen or any other type of pollen.

Within the body of allergy victims, there exist millions of IgE antibodies to specific allergens. These are attached to certain types of circulating white blood cell or to mast cells lining the respiratory & gastrointestinal tracts or to the subcutaneous layer of the skin. When IgE antibodies come in contact with the allergen they are designed to fight, a chain of events occur in the body; they signal the mast cells or white blood cells to unleash histamine and other chemicals to the site of allergen invasion. These chemicals and histamines instigate the distressful symptoms of allergic reactions. “The histamines cause vaso-dilatation and when this happens, there is an increased blood supply in the region. So there is definitely a redness and a sort of heat in the area. There might be itching and swelling. The heat could be localized or there could be feverish feeling also. For instance, when the histamine is released in the nose, eyes and sinuses, it stimulates running nose and watery eyes, sneezing, etc. If released in the skin, it gives rise to rashes and hives; if lungs are the site of release, it narrows and inflames the lining of the airways and increases mucus secretion; in the digestive tract, it leads to stomach cramps, diarrhoea, vomiting, etc., explains Dr.Anil.

Can food allergies produce respiratory symptoms?
“Most certainly,” says Dr.Anil. Classic example may be of peanuts wherein if a person is allergic to it, eating even one peanut might produce reactions whereby he might go into sudden respiratory arrest and even die if timely help is not rendered. Having said that, fatalities due to allergic reactions in modern times are very rare.”

Can the symptoms of an allergic reaction mimic symptoms of other diseases, making diagnosis difficult? Dr.Anil clarifies, “Generally speaking, we can make out an allergic reaction from other disorders. However, when the nose is involved, sometimes when a patient complains of having a cold: so many times, in the acute phase where the IgE is released, if you look at the nose, the appearance is same as during a normal cold. But if that acute phase has passed, say in 3-4 hours, and then the patient comes to you, then yes, we can make out the allergic cold from a normal cold because the nasal skin inside the nose will show more of a bluish tinge or appear pale if allergy is involved. On the other hand, in a viral cold or flue, the nose will be red and angry; but this is after the acute phase has passed. During an acute episode, it is difficult to make out if the patient is having allergic reaction or suffering from flue. Also, in cold due to allergy, there may be only mild grade fever unlike in cold from flue where fever is high. But this again is very subjective for correct diagnosis to be made.”

Can we classify allergic reactions as being mild, moderate and severe? Dr.Anil explains, “The first rule is what we call as all or none phenomenon. That is, if there is a threshold and any allergen reaches that threshold irrespective of what is above that threshold, the reaction will be the same. It is complete, that is, it doesn’t come in degrees. The other thing is, unless taken care of, it gets worse. We call this unamnestic reaction, that is, non-forgettable. The body gets sensitized to something; hence it remembers. Which means, every time the body is exposed to that similar agent, the threshold keeps coming down. For instance, if during the first episode of an allergic reaction, the individual needed 10 gms of allergen the cause the reaction, the next time, this may come down to 1 gm; the 3rd time to 1 mg. In this sense, we talk of mild, moderate or severe reactions.”

While there is a definite heredity factor involved in allergies, the first allergy episode can occur anytime in an individual’s life, reveals Dr.Anil. “Normally after 60 years of age, the first time allergies are not very well known. But before that, anybody can develop allergies to anything at any age.”

Is it then possible that the allergic reactions disappear as suddenly as they appeared without any treatment? Dr.Anil cautions: “Yes, this might happen. At the same time, if left unchecked, it has got anamnestic reaction, and keeps increasing. This is the reason we must control it.”

How are allergies diagnosed? This is done based on several factors including taking the person’s family history, physical examination and allergy testing for sensitivity to specific allergens. Skin testing is used to diagnose immediate-type hypersensitivity allergy, the commonest type of allergic reaction where the symptoms occur very quickly after being exposed to the allergen. This involves injecting small amounts of the suspected allergy triggers through the skin. Raised, red, itchy bumps will show up, usually within 15 minutes of the substances being injected, confirming the allergy.

Elimination diet is used to help isolate sensitivity to specific foods, explains Dr.Anil. This involves removing certain food items suspected of causing the allergic reaction, from the diet. Alternatively, the radioallergosorbet test (RAST) and related blood tests use radioactive or enzyme markers to detect levels of IgE antibodies.”

Treatment of allergies on the one hand involves avoidance of allergy-producing foods or other agents wherever these are identifiable. Dr.Anil explains, “Where patients are seasonally allergic, we know the period of the year when they are going to suffer the reactions. We start them on anti-histamine medication, one week or 10 days prior to the change of season. Over the years, with this kind of treatment, these people have the reactions reduced dramatically in terms of frequency and intensity. The problem may even disappear after years, but this does not happen in everybody.”

How safe are the anti-histamine drugs themselves? Dr.Anil is reassuring. “I generally put the patients on a 15-day course with the latest anti-histamines, the third generation anti-histamines which do not have the adverse effects associated with the earlier I and II generation antihistamines, even though these two are also being used today. If someone is having hypertension, we have to be careful in giving the I and II generation antihistamines because they might themselves increase the blood pressure and also have a direct effect on the heart and they may interact with the drugs given for hypertension.”

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