Allergic babies

By Dr M. YADAV


Allergy is becoming an increasingly prevalent problem in many countries, especially among our young.

ALLERGIC diseases represent a major and increasing health problem in industrialised countries. Over the past five decades, the prevalence of allergic diseases has increased dramatically and the incidence has doubled in the last 20 years in most industrialised countries.

In some countries, for example Australia and Sweden, 40% of young children have allergic disorders.

In Malaysia, about 30% of young children are likely to develop allergic disorders in the first five years of life.

The most common allergic conditions in children and infants are food allergies, eczema, asthma and allergic rhinitis. Allergies are often life-long and although treatable, they tend to recur if the triggers are not strictly avoided. Some food allergies spontaneously improve within three years but are often replaced by respiratory allergies. Thus, it makes sense to try to prevent the development of allergies in early life than trying to treat them later.

Hence, there is great interest to identify the risk factors associated with the development of allergic disorders in early life and modify them to reduce subsequent risks for development of allergy.


Many studies show that breast milk decreases the incidence of allergic eczema compared to cow’s milk.

Risk factors for allergy

The development and appearance of allergic symptoms depends on poorly-understood complex interactions between genetic and environmental factors.

It is evident historically that changing environmental factors have played a major role for the increasing trends in allergy and asthma. Obviously, we have some control over the environmental risk factors but we have practically no control over genetic factors, which have an equal role in the development of allergic disorders.

Families often ask how allergy can be prevented in future offspring. The American Academy of Pediatrics published a clinical report in 2008 with recommendations for those infants at high risk of developing allergic disease. Avoidance of the major risk factors could reduce or prevent the development of allergic disease in most infants. For the avoidance measures to work, the first two years of life are critical and the measures must be applied before the development of allergy in the neonate.

These recommendations do not apply to babies already having food allergy. The major risk factors for the development of allergy in infancy are:

· Strong family history of allergic disease (both parents or one parent plus one sibling with allergy) may significantly increase the risk for allergy in the newborn.

· Exclusive breast feeding is desirable for least four months compared with feeding with intact cow’s milk. Many studies show that breast milk decreases the incidence of allergic eczema compared to cow’s milk.

Partially hydrolysed whey formula, which is hypoallergenic (reduced ability to stimulate and induce an IgE-mediated immune response) formula is preferred as supplementary feed for babies. The hypoallergenic formula is the preferred feed for the baby when the mother is unable to breastfeed. There is no role for soy-based formula in allergy prevention.

· Solid foods should not be introduced before ages four to six months. Early introduction of solid foods increases the risk, but delayed introduction of solid foods beyond six months provides no advantage.

· Exposure as a child or infant to high levels of house dust-mite allergens (allergens are substances, usually proteins, that cause allergy) increases risk to respiratory allergies. Anti-dust mite barrier encasing of mattress and pillows may provided some protection. Regular use of anti-dust mite sprays to reduce the level of dust mite allergens in the home environment is desirable. These procedures are specifically important for Malaysia, which has high dust-mite allergens levels in the home environment.

· Exposure to some indoor mammalian pets (e.g. cat) increases risk in the baby. Keep the pets strictly outside the house away from the baby’s play area and bedroom or remove the pets until the baby is older.

· No smoking should be permitted in the house during pregnancy and lactation. Passive exposure to cigarette smoke during pregnancy or infancy increases the risk for allergy significantly in early life.

· Passive exposures to cigarette smoke during pregnancy or infancy increases the risk for allergy significantly in early life.

· Exposure to environmental pollution as a child or infant (e.g. high levels of car exhaust fumes or fumes from gas heaters) increases the risk.

Maternal diet during pregnancy and lactation The earliest possible nutritional influence on allergy in the infant is the diet of the pregnant mother.

It is well known that food allergens in the diet of the mother can appear in the circulation and be transmitted to the amniotic fluid during pregnancy or breast milk during lactation. The foetus in late pregnancy (when the immune system is immature but functional) can be sensitised (develop the capacity to react to allergens on subsequent exposure) to the food allergens present in the amniotic fluid. In families with a genetic predisposition, there is a good chance that the newborn, when re-exposed to the provoking foods (e.g. cow’s milk), will react with symptoms (e.g. diarrhoea, vomiting, colic, eczema) to the sensitising foods. In families without a genetic allergic-background, the sensitised baby will not react to the provoking allergens.

Prior to 2008, the American Academy of Pediatrics had recommended avoidance of peanuts, cow’s milk, soy milk, fish and eggs during pregnancy and lactation to reduce the risk for allergy to these foods in the baby.



However, in January 2008, the American Academy of Pediatrics reversed their position on maternal avoidance of specific foods. The current position, based on evidence from large number of research studies, does not support maternal avoidance of allergenic foods during pregnancy or lactation. Moreover, maternal avoidance of specific nutrition during pregnancy may not be conducive for the healthy growth of the baby.

Low levels of maternal dietary food-allergens present in breast milk may cause allergic symptoms (e.g. eczema) in exclusively breastfed babies. Our studies in Malaysia show that exclusively breastfed babies with skin symptoms are mostly reactive to cow’s milk and egg white proteins. However, in some babies, additional allergens such as wheat, peanuts, soy bean, sesame seeds, banana, chicken meat, garlic and many others were also contributory to the development of allergic eczema. In all these babies, there was a family history of allergy.

The continued breastfeeding and maternal avoidance of the provoking foods is normally advised when the infant is less than four to six months. In older infants, breast milk can be stopped and the weaning diet should exclude the provoking foods.

In all such cases it is essential to identify the provoking food allergens through blood allergy tests on the baby based on the maternal diet. Any delay in seeking allergy services may potentially lead to adverse clinical outcome due to unacceptable diagnostic oversight.

Food allergy in Malaysian children Investigations into food allergy in Malaysia were pioneered by Dr N. Iyngkaran and his colleagues, including myself, in the mid-70s at the then University Hospital.

At that time, chronic diarrhoea in infants was a major cause of morbidity and mortality. In a series of experimental studies, it was demonstrated that cow’s milk was the primary cause of the chronic gastroenteritis diarrhoea in young infants. These infants suffered from symptoms of vomiting, diarrhoea and colic. Moreover, the associated lactose intolerance was recognised as secondary to the intestinal mucosal damage inflicted by the cow’s milk allergic reaction. This was an important contribution because for the first time the relationship between cow’s milk allergy, intestinal mucosal damage, lactose intolerance and clinical symptoms became clear. The group went on to demonstrate that many other proteins, such as egg protein and soy protein, which caused allergic reactions in young infants and children, were also responsible for marked intestinal mucosal aberrations.

One interesting study performed by the group showed that about 40% of infants with cow’s milk allergy developed allergic reaction to soy milk even if the baby had not been exposed to soy products previously. Only in recent years has it become clear that cow’s milk casein shares common allergens with soy protein and hence infants sensitised to casein will eventually react to soy if it is used as a substitute in infants allergic to cow’s milk.

Adverse reactions to cow’s milk are frequently seen in the first year of life in infants on bottle feed. Cow’s milk allergy is present in 3-5% of infants and 85% will outgrow the milk allergy by the third year.

However, in some children, particularly those with high titres of IgE antibody and severe symptoms, the milk allergy will persist longer, usually into adolescence and sometimes into adulthood.

The symptoms of cow’s milk allergy usually starts in the first weeks of life. The main symptoms of cow’s milk allergy are:

gastrointestinal in about half the infants; skin eczema in two-third of infants; and respiratory problems in about quarter of infants. In many infants, all three symptoms may be present.

Young children with eczema are at a higher risk of developing food allergy, particularly those infants and toddlers whose skin disease is more severe or recalcitrant to therapy. Generally, the younger the patient and the more severe the eczema, the more likely food allergy is a causative factor.

Parental perceptions with regards to food allergy in their children are notoriously inaccurate. Parents often have very strongly held beliefs that certain foods cause a variety of symptoms, many of which are inconsistent with an immune-mediated process.

In fact, when the diagnosis of IgE-mediated food allergy are performed in an established laboratory using approved allergy tests, only about 40% of patients’ histories of food-induced reactions can be verified. Thus it is very important to conduct an allergy test at a centre managed by professionals.

Food allergy in children is most likely to manifest between one and three years. In Malaysian infants less than one year old, the foods causing allergy in order of importance are cow’s milk, soy milk, chicken eggs and fish.

On the other hand, in children more than two years old, the foods causing allergy in order of importance are shellfish (prawns/shrimp), cow’s milk, chicken eggs, wheat, soy and peanuts. In 70% of children, chicken egg allergy lasts until the twelfth year.

Peanut allergy tends to be long-lasting, with 20% infants resolving by the ninth year, but in the rest, it may be life-long. Avoidance of the provoking foods is essential for success in treating food allergy.

The only objective method of measuring IgE antibodies is to use technology that is calibrated against established reference preparations. The CAP RAST blood test is scientifically considered superior to any other allergy test for the detection of the provoking allergen in the infant’s diet. It is a quantitative test with each run incorporating controls which are standardised against WHO standards. The blood allergy test is not affected by medications, including anti-histamines.

Elimination of the food allergen is the only proven effective therapy at this time. Strict dietary avoidance is generally recommended once a food allergy is diagnosed.

If the mother is breastfeeding, she must also strictly eliminate the causal foods from her diet. Clinical tolerance can develop over time, more commonly to some foods (milk, egg, soy, wheat) over others (peanut, tree nuts, seafood). In time, the baby will outgrow the allergy brought on by the provoking food (e.g. cow’s milk or chicken eggs) and show no food-specific IgE-antibody. Only then can the problematic food be successfully reintroduced into the diet of the child without worrying about the development of adverse reactions. In rare cases, some food (e.g. chicken egg, shrimp/prawn, bird’s nest soup) may cause severe systemic life-threatening reaction (called anaphylaxis) within minutes of ingestion of the provoking food. The symptoms appear rapidly, usually with minutes of exposure to the provoking food. The symptoms include: (1) skin or mucosal involvement (e.g. generalised hives or swelling of oral mucosa), (2) respiratory compromise (e.g. dyspnea, wheeze), (3) persistent gastrointestinal symptoms (e.g. vomiting), (4) hypotension (e.g. hypotonia, fainting).

Epinephrine, which is dispensed in special syringes called Epipen, is clearly the treatment of choice for anaphylaxis. Following epinephrine treatment, the individual should be rushed to the hospital.

Certainly, having signs of hypotension (even without accompanying symptoms) is an indication for epinephrine administration, particularly in a child with known food allergy. It is important to identify the provoking foods through food allergy tests if any one has had this experience of anaphylaxis since such episodes tend to reappear in reactive individuals. Avoiding the trigger resolves the problem.

Food allergy in infancy predicts respiratory allergy in mid-childhood.

Food allergy in infants less than one year old predicts the development of respiratory allergy and asthma in children five to eight years old.

There are ways for physicians to increase the predictive value of the allergy test. One factor is the level of specific IgE antibody in serum, which can affect the presence, persistence and severity of the allergic disease. Thus the risk of developing asthma increases with increasing specific antibody levels.

A sensitised infant with specific IgE antibody to food allergens (e.g. cow’s milk, chicken egg) and/or aeroallergens (e.g. cat dander, dust mite) summing up to a total of 0.5 kilounits per litre (kU/L) has 20% risk of developing persistent wheezing/asthma, but if the summed antibody level is greater than 10 kU/L in early life, the predictive value for wheezing/asthma increases to 90% at five years of age.

This definitely calls for quantification of IgE antibody levels if allergy is suspected in the young baby for assessing the severity of the disease. Allergy is not a simple yes or no phenomenon of allergy tests. Recent studies show that prediction and diagnosis of allergy needs to be based on several factors, including quantitative of IgE antibody levels.

Conclusion

In Malaysia, food allergies in infancy are increasing rapidly. In young infants, the most common foods causing allergies are cow’s milk and chicken eggs. The next commonest are soy milk, wheat, fish and peanuts.

In older children, shellfish (e.g. shrimp/prawns, crab), in addition to the other foods noted in infancy, is most important.

The majority of children with food allergy in the first year of life will develop respiratory allergy to house dust mites during mid-childhood. Thus, early measures to prevent the risk for development of allergy are desirable.

For further information, e-mail starhealth@thestar.com.my. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this column. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.