Dr. B. J. C. Perera
MBBS(Ceylon), DCH(Ceylon), DCH(England), MD(Paediatrics), FRCP(Edinburgh), FRCP(London), FRCPCH(United Kingdom), FSLCPaed, FCCP, FCGP(Sri Lanka) Consultant Paediatrician
It is a very common occurrence to note that many people use the word "allergy" in a very loose way to attribute many symptoms to it. All kinds of unconnected symptoms are thought to be due to allergies by many people. In fact, even doctors tend to use this term rather indiscriminately and name it as a cause for many different symptoms. Quite unfortunately, in the case of some parents, almost every symptom that a child develops is due to some sort of allergy. However, in stark reality, allergy is a specific hypersensitive disorder of the immune system. It simply means that the body reacts in an abnormal or exaggerated way to substances to which most other people do not react. Allergic reactions occur against normally harmless environmental substances known as allergens and these reactions are acquired, predictable and rapid. Strictly, allergy is one of four forms of hypersensitivity and is called Type I or immediate hypersensitivity. It is characterized by excessive activation of certain white blood cells called mast cells and basophils by a type of antibody known as Immunoglobulin E (IgE). Such an interaction leads to a well recognised and sometimes extreme inflammatory response. Common allergic reactions include eczema, hives, hay fever, asthma attacks, food allergies, and reactions to the venom of stinging insects such as wasps and bees.
Mild allergies like "hay fever" are highly prevalent in the human population and cause symptoms such as allergic conjunctivitis, itchiness and runny nose. Allergies can play a major role in conditions such as asthma. In some people, severe allergies to environmental or dietary allergens or to medication may result in life-threatening anaphylactic reactions. Children with severe allergies can be at risk for a sudden, potentially life-threatening reaction. This reaction can be frightening, a child may feel like his or her throat is closing or may even lose consciousness. It needs urgent and emergency medical care.Seasonal allergies, sometimes called "hay fever" or seasonal allergic rhinitis, are allergy symptoms that occur during certain times of the year, usually when outdoor moulds release their spores or trees, grasses, and weeds release tiny pollen particles into the air to fertilize other plants. The immune systems of people who are allergic to mould spores or pollen treat these particles called allergens as invaders and release chemicals, including several highly active substances, into the bloodstream to defend against them. It is the release of these chemicals that causes allergy symptoms. People can be allergic to one or more types of pollen or mould. The type someone is allergic to determines when symptoms will occur. For example, in the mid-Atlantic states, tree pollination begins in February and lasts through May, grass from May through June, and weeds from August through October. In those areas, children with these allergies are likely to have increased symptoms during those times of the year. Seasonal allergies can start at almost any time, but they usually develop by 10 years of age and reach their peak in the early twenties, with symptoms often disappearing later in adulthood.
Allergy symptoms, which usually come on suddenly and last as long as a person is exposed to a particular allergen, can include sneezing, itchy nose and/or throat, congestion of the nose, runny nose with clear fluid being secreted and coughing. These symptoms are often accompanied by itchy, watery and/or red eyes, which is called allergic conjunctivitis. In some cases these symptoms may be associated with wheezing and asthma. Seasonal allergies are fairly easy to identify because the pattern of symptoms returns from year to year following exposure to an allergen.
To determine an allergy’s cause, doctors in other countries do skin tests in one of two ways. In one, a drop of a purified liquid form of the allergen is dropped onto the skin and the area is pricked with a small pricking device. In the other a small amount of allergen is injected just under the skin. This test stings a little but is not extremely painful. After about 15 minutes, if a lump surrounded by a reddish area similar to a mosquito bite appears at the injection site, then the test is positive. Even if a skin test or a blood test shows an allergy, a child must also have symptoms to be definitively diagnosed with an allergy. For example, a child who has a positive test for grass pollen and sneezes frequently while playing in the grass would be considered allergic to grass pollen.
There is no real cure for seasonal allergies, but it is possible to relieve symptoms. It may be possible in some cases to start by reducing or eliminating exposure to allergens. Children who are prone to allergies should wash hands or shower and change clothing after playing outside. If reducing exposure is not possible or is ineffective, medicines can help ease allergy symptoms. They may include decongestants, antihistamines and nasal spray steroids.
Certain types of allergies present as skin rashes. They are the usual hives where there is elevated wheal- like skin rashes which are intensely itchy. These may occur on contact with certain substances to which the child is allergic or may come on after the child takes by mouth some substance to which he or she is allergic. Sometimes there is marked swelling of the body as well and this particularly affects the face, eyes and lips. Occasionally these symptoms are associated with difficulty in breathing and wheezing. In rare cases they could trigger off a severe life-threatening reaction known as anaphylaxis. It is noteworthy that in susceptible individuals, some drugs too can cause allergic symptoms. The drug concerned should be stopped at once to prevent further progression of the symptoms.
One particular type of allergy, though quite rare, is important as it causes quite a few problems. This is allergy to cow milk. Almost all infants are fussy at times. But some are excessively fussy because they have an allergy to the protein in cow’s milk, which is also the basis for most commercial baby formulas. A person of any age can have milk allergy but it is more common among infants, perhaps around 1 to 2 percent of babies. Milk allergy occurs when the immune system of the body mistakenly sees the milk protein as something the body should fight off. This starts an allergic reaction, which can cause an infant to be fussy and irritable and cause an upset stomach and other symptoms. Most children who are allergic to cow’s milk also react to several other forms of animal milk. Infants who are breastfed have a lower risk of developing a milk allergy than those who are formula fed from a very early age. However, researchers do not fully understand why some develop a milk allergy and others do not, though it is believed that in many cases, the allergy is genetic. Typically, a milk allergy goes away on its own by the time a child is 3 to 5 years old but in some rare cases, some children never grow out of it. A milk allergy is not the same thing as lactose intolerance which is due to an inability to digest the sugar lactose, a compound that is present in all forms of animal and human milk.
Symptoms of cow’s milk protein allergy will generally appear within the first few months of life. An infant can experience symptoms either very quickly after feeding (rapid onset) or not until 7 to 10 days after consuming the cow’s milk protein (slower onset). The slower-onset reaction is more common. Symptoms may include loose stools, sometimes containing blood, vomiting, gagging, refusing food, irritability, abdominal colics and skin rashes. This type of reaction is more difficult to diagnose because the same symptoms may occur with other health conditions. Rapid-onset reactions come on suddenly with symptoms that can include irritability, vomiting, wheezing, swelling, hives, other itchy bumps on the skin and bloody diarrhoea. In very rare cases, a potentially severe allergic reaction such as anaphylaxis can occur and affect the baby’s skin, stomach, breathing and blood pressure. Anaphylaxis is much more common with other food allergies than with cow milk allergy.
Several tests may be needed to confirm the diagnosis of milk allergy. In addition to a stool tests and blood tests, the diagnosis can be confirmed with a special skin test. In that test a small amount of the milk protein in injected just under the surface of the child’s skin with a needle. If a raised spot called a wheal emerges, the child may have a milk allergy. This test is so far not freely available in Sri Lanka. It is also necessary to perform an oral challenge test. After stopping all types of cow milk for about a week, the infant will be given a test dose of the milk. If the symptoms reappear, it confirms the diagnosis.
If an infant has a milk allergy and the mother is breastfeeding, it is also important to restrict the amount of dairy products that the mother takes because the milk protein that is causing the allergic reaction can cross into the breast milk. All food makers must clearly state on package labels whether the foods contain milk or milk-based products, indicating this in or next to the ingredient list on the packaging. If the baby is formula-fed, it may be necessary to switch over to a soy protein based formula. The other alternative is to use a hypo-allergenic formula milk in which the proteins are broken down into particles so that the formula is less likely to trigger an allergic reaction. All these milks are quite expensive.
Two major types of hypoallergenic formulas are available:
1. Extensively hydrolyzed formulas have cow’s milk proteins that are broken down into small particles so that they become less allergenic than the whole proteins in regular formulas. Most infants who have a milk allergy can tolerate these formulas, but in some cases, they may still provoke allergic reactions.
2. Amino acid-based infant formulas, which contain protein in its simplest form. These amino acids are the building blocks of proteins. This may be recommended if the baby’s condition does not improve even after a switch to a hydrolyzed formula.
Once the diagnosis is confirmed and the milk replaced by an appropriate preparation, the symptoms should settle down pretty quickly. The baby should become quite normal. The replacement formula should be continued right up to about the end of the first year after which one could try out some cow milk again. Many children tend to grow out of this type of allergy and may be able to tolerate cow milk as they grow older. If there is a recurrence of symptoms, then of course one may need to keep off cow milk for a further period of time before performing a challenge again.
In general, many types of allergies that occur in children, even the rarer and more severe ones, can be effectively treated and controlled with certain medications. It may be necessary for the parents to keep certain medicines at home with specific instructions as to how and when to use them if and when certain allergic manifestations develop. If such a situation arises, it is extremely important for the parents and other members of the household to clearly understand how and when to administer these drugs. It should be undertaken only under strict medical supervision.
KEY POINTS
* The word "allergy" should not be used loosely to account for all kinds of symptoms.
* It is a specific entity that is associated with an abnormal and exaggerated reaction of the body to certain substances.
* The manifestations of allergy can be mild but troublesome and in some cases quite severe and even life-threatening.
* The commonest manifestations are those affecting the upper respiratory passages and symptoms of hay fever.
* Allergy to cow milk proteins is rare but important in view of the symptoms that this condition causes.
* Many children tend to grow out of the cow milk protein allergy with advancing age.
Courtesy - The Island
