FAQ

Allergy

What is an allergy?

An allergy is an abnormal exaggerated physical reaction (with development of any of the following symptoms: diarrhea, vomiting, skin rashes, hives, sneezing, runny nose, asthma, chronic cough, joint pains, puffiness of the eye orbit or face, ear infection, anaphylaxis) to one or more substances called allergens that are harmless to most people. Skin, oral and nose allergy symptoms are associated with intense itch. Sources of common allergens that trigger the allergy symptoms include house dust mites, plant pollens (called hay-fever in temperate regions during spring/summer) mould spores, pet dander (skin scales from pets), foods (for example eggs, peanuts, cows milk, shrimps and many others), drugs (for example penicillin, sulphonamides), venom of stinging insects (for example mosquito bites, wasp sting, ant sting) perfumes (both naturally derived from flowers and artificially synthesized), and many others. Frequent exposure to the provoking allergen will trigger the development of allergy symptoms. Individuals with allergy often have a genetic predisposition with a strong family history of the disease.

What is the mechanism of allergy?

In allergy suffers the immune system produces large amounts of an antibody called Immunoglobulin E (IgE) as part of a confused defense strategy against harmless allergens. Normal individuals do not produce IgE antibody following exposure to allergens. The IgE antibody to the specific allergens enters the blood circulation and distributes to all parts of the body. The IgE antibody has a natural tendency to bind to mast cells present in the skin and mucosal tissues because these cell have special anchoring points for IgE molecule on their surface. Each mast cell may have half-million IgE antibody molecules attached on its surface. Such a person is said to be sensitized to the specific allergen and is ready to react to the allergen on further contact with it. The interaction between the IgE molecules-on-the-mast cell and the allergen causes the mast cell to release powerful chemical mediators (such as histamine, leukotrienes, cytokines and others) that immediately cause inflammation and rash at the site. Thus, two conditions are necessary for allergy to occur: (1) An acute IgE-mediated hypersensitivity to allergens, and (2) Recurrent or continuous exposure to the specific allergen. The absence of either causes the allergy to disappear. In contrast, the taking of medication merely suppresses the symptoms of allergy.

Therefore, the quantities measurement of total IgE levels and allergen-specific IgE antibodies is the key to effective diagnosis and management of allergy

What are the symptoms of allergy?

Allergic symptoms usually appear on the skin and the mucosal surfaces since these tissues are (1) the first to come in contact with the allergen, and (2) also the mast cells are found in large numbers here. Allergy symptoms can take many different forms depending on the reaction of the target organ. Some allergy symptoms are listed below:

Nose:

Allergic rhinitis is 'flu-like' and associated with nasal itching, congestion, sneezing, runny thin watery discharge and postnasal-drip. Sinusitis with headache, facial pain, purulent discharge, is often a complication of rhinitis. Chronic rhinitis may be associated with puffy dark circles underneath the eyes. The triggers in Malaysia are house dust mites and pet dander. Sometime pollens may be involved but are the main seasonal triggers in the temperate regions causing hay-fever. Food allergens can also provoke the symptoms and complicate diagnosis.

Eyes:

Allergic conjunctivitis is associated with itching, redness, swelling and tearing of the eye. The common triggers are house dust mites, pet dander, bird dropping and feathers and pollens. Foods may also be involved.

Lungs:

Asthma symptoms are shortness of breath, wheezing, feeling of tightness in chest and cough. Frequent bronchial infections may be caused by allergy. Airborne allergens (such as, house dust mites, pet dander, bird feathers, perfumes) are the main triggers of IgE-mediated asthma but certain foods may worsen the condition. Some foods such as cows milk may trigger the asthmatic attack in sensitized children.

Skin:

Hives (urticaria) are itchy welts of varying sizes that appear on the skin, lips, inside the mouth and ears. Sometimes there is swelling in the affected parts resulting in symptoms of angioedema. Eczema (atopic dermatitis) is an itchy rash that appears in the skin creases of the arm, leg and neck but may be present in all parts of the body. Foods often play an important role in the development of the condition. Airborne allergens like house dust mites may also participate in the condition. Lately it has been noted that some fungus species that are naturally present on the skin may also be responsible for the development of the skin symptoms.

Digestive tract:

Food allergy symptoms may be associated with stomach cramps, vomiting and diarrhea. Food allergy may also be responsible for eczema, asthma, chronic rhinitis, ear problem, gastrointestinal distress, headache, fatique, hyperactivity and depression. In rare instances foods may cause a life-threatening systemic response called anaphylaxis. For instance peanut allergy can be so severe in some children and adults that it results in anaphylactic shock.

Ears:

Symptoms of recurrent infection or fluid in the middle ear can be provoked by allergic reaction and eventually result in loss of hearing. Both airborne allergens and food allergy can plays a role in many instances.

Emotional factors:

Although allergy is a physical disorder it can be aggravated by intense stress, fear, anxiety, anger, extreme aggravation, and other emotional strains.

Additional provoking factors: Some irritating substances like tobacco smoke, paint solvent, vehicle exhaust, diesel fumes, strong perfumes, chlorine in swimming pools and other chemicals can act as promoters of allergy and worsen the symptoms in many instances.

Allergy Test

Since avoidance of the provoking allergen/s is the best therapy it is vital to identify the offending allergens accurately as soon as possible. In many cases a careful and systemic history combined with clinical examination may provide useful clues to the nature of the potential allergens. Avoidance based on guesswork may cause more harm to the child or adult in question. Allergy tests should be performed quickly to identify the suspected allergen triggering the symptoms. There are two types of allergy test available: (1) Skin Prick Test, and (2) Allergy Blood Test, based on 'Cap RAST' performed on a blood sample. The blood test using the Cap RAST is the preferred method since it is accurate and is unaffected by the medication being taken by the patient. Secondly, the new Cap RAST blood assay technique is more sensitive than the skin prick test for foods and some types of aeroallergens.

Skin Prick Test

In this test small drops of allergens in variable concentration is placed on the forearm and the dermis punctured with a special lancet. The development of a raised area (called wheal) similar to a mosquito bite appears within minutes and the area surrounding the wheal becomes reddened (flare). The response is compared to negative and positive controls run at the same time. A positive reaction for the allergen is confirmed when the swelling reaches a certain size which is bigger than the negative control.

In some laboratories, if the skin prick test is negative further test using the intradermal test is used. In the intradermal test large quantities of allergen is injected just under the dermis of the skin using a small bore hypodermics. This test is different from the skin prick test since the large amount of allergen is injected. The allergen can trigger the mast cell specifically via the specific-IgE on the surface of mast cells or through non-specific mechanism (lectins in the foods cross-links carbohydrate moieties present on the antibodies) or other non-specific mechanism. The intra-dermal test may give false positive results for allergy.

The skin prick test has many limitations. Skin testing is dangerous in highly sensitive patients and there have been fatalities recorded in the past. Patients must stop taking anti-histamines for at least 7 to 28 days (depending on drug) because the drug suppresses the skin reaction causing the development of a false negative result. The skin test is not useful for babies and the elderly. The skin in patients with a skin condition is hypersensitive and may give a false positive result with the skin prick test. In general skin prick tests are not useful indicators for food allergies because of the frequent false positive reactions. Skin testing is being rapidly replaced with allergy blood testing using advanced Cap RAST technology.

Allergy Blood Tests:

There are many types of cheap allergy blood testing methods available but most of them have poor reproducibility. Moreover, these tests normally report the results with fancy colourful charts which appear impressive but provide little information to the professionals. These tests often give false positive or false negative results that may cause more harm than good. In general, hospitals worldwide do not use these types of allergy testing methods but use the cap RAST technique as the only method of choice.

The Cap RAST method uses a state-of-the-art technique that is accepted world wide as the in-vitro Gold Standard. Moreover, the IgE level estimated by the equipment is standardized against the World Health Organization immunology standards for IgE maintained by them. The cap RAST reports the results in both quantitative and qualitative terms for professional assessment. Therefore, the allergy blood test using the cap RAST is the method of choice because it is sensitive, accurate, safer, convenient and unaffected by medication taken by the patient. The allergy blood test can be performed in babies and elderly and in persons with severe eczema in whom it is difficult to do the skin test.

The choice of the allergens selected for test depends on the clinical history. Usually the doctor may select about 12 to 15 allergens based on his experience but in some cases he may select less number of allergens for testing. Skill and experience is required to interpret the result and in most cases the test results often fit the clinical observation and confirm the diagnosis. Appropriate avoidance measures should be immediately implemented. The benefits of the avoidance measures usually become apparent within the first few days.

Can the risk for allergy be determined at birth?

It is now possible to identify babies at risk for allergy at birth. Two factors are usually considered, namely (1) Family history, and (2) Cord blood total serum IgE level. Epidemiological studies have shown that when one parent has allergy the risk for the baby is 20 percent but if both parents have allergy the risk for the baby developing an allergic disorder increase to 70%. The risk of allergy is four times higher if the mother has allergy compared if the father has allergy. If there is a family history, even when grandparents have allergic symptoms, it is advisable to plan to reduce exposure to allergens for the baby even during the pregnancy.

In recent years research studies have revealed that the foetus develops in an immunological environment biased for the humoral response during pregnancy. This means that genetically predisposed foetus has a very high risk for being sensitized to allergens during pregnancy. Therefore, it is likely that the serum IgE levels may be elevated in the high-risk baby's blood. Thus, the risk for allergy can be easily determined by estimating the total serum IgE level in the cord blood at birth. A high IgE concentration in the cord blood suggests that the baby has a high risk for the development of allergy. This information pre-warns the paediatrician of the possibility of allergy symptoms in the baby appearing anytime after birth depending on the exposure to allergens. Therefore, avoidance measures can be taken early even before the symptoms appear and reduce the chances for allergy symptoms appearing in the predisposed baby.

At birth an infant's immune system is immature and the neonate is dependent on many factors present in breast milk for immune protection. Depriving the baby of breast milk may speed up the development of allergy in pre-disposed infants.

The Allergy March

Young babies who develop food-induced eczema before one year have almost 50 percent risk of developing asthma by age 5 years. This is specifically true of babies who have been exposed to high levels of house dust mite allergens. Another study revealed that children who wheeze before age 3 years and continue to wheeze at age 6 years have diminished lung function and a 2- to 3-fold increased risk of having asthma at age 11 years. These studies indicate that intervention for asthma must be initiated very early in childhood to change the course of history of the disease.

In predisposed infants in the first few months the initial symptom of allergy manifest in the skin as eczema and the severity of the symptoms slowly decrease with age giving the impression that the allergy is getting cured. Often the eczema is followed by allergic disorder of the gastrointestinal tract and when it appears that the symptoms are disappearing respiratory allergic disorder begins. The respiratory allergy initially manifest as rhinitis but soon is followed by wheezing often ending up as asthma. This is called the Allergy March. The symptoms of allergy begin in the skin and spread to the gastrointestinal tract and later persist in the respiratory system. Do not ever be complacent when the child develops an allergic symptom in early life. Immediately find the cause and manage it through avoidance. Early in life management of the allergy will prevent or reduce the risk significantly for the child developing asthma later in childhood.

What are the benefits of breast milk?

Breast milk is unique and is the ideal food for the baby. It fosters proper growth to the newborn. The composition of human breast milk among others includes nutrition, growth factors, hormones, enzymes, blood cells that fight infections and immune-protective factors. The lactation is robust and mother's breast milk is adequate in essential nutrients, even when her own nutrition is inadequate. Mature breast milk usually has constant levels of about 7g/dL carbohydrate and about 0.9g/dL proteins. But the composition of fats essential for neonatal growth, brain development, and retinal function varies according to a woman's intake, the length of gestation, and the period of lactation. Vitamins and minerals also vary according to maternal intake. However, even when these nutrients are lower in breast milk than in formulas, their higher bioactivity and bioavailability nearly meet the complete needs of neonates than provided by even the best infant formulas. Also, in many instances human milk components compensate for immature function, such as a neonate's inability to produce certain digestive enzymes, immunoglobulin A (IgA), taurine, nucleotides, and long-chain polyunsaturated fatty acids. In addition, the breast milk contains various cells (such as macrophages, neutrophils and lymphocytes) that play a critical role in the immune protection of the baby.

Babies on breast milk have lower risk for the development of allergy. Human milk lacks inflammatory mediators, and contains anti-inflammatory agents such as antiproteases, antioxidants, and enzymes that degrade inflammatory mediators and modulators of leukocyte activation. Furthermore, IgE (the principal immunoglobulin responsible for immediate hypersensitivity reactions), basophils, mast cells, eosinophils (the principal effector cells in these reactions) are absent in breast milk. The mediators from these cells are also absent in human milk. Immune and nonimmune protecting agents are present in milk throughout lactation and some, such as lysozyme, are present at higher concentrations during prolonged lactation than during the early stages. Therefore, although it is advocated that breast-fed infants receive solid food supplements after 4 to 6 months of exclusive breast-feeding, it is advisable to continue breast-feeding for longer periods even when on a weaning diet.

Moreover, the breast milk promotes the development of healthy gut flora that acts to suppress the development of the allergic reaction.

What is the alternative to breastfeeding?

If possible the babies should be breast fed. However, there are many mothers for one or other reasons cannot breast feed their babies. There is wide range of cows milk formulas' available. Until recently there was not much difference between these cows milk formulas. Nowadays various components are added, for instance essential fatty acids, healthy bacteria and vitamins to competitively market these foods. Moreover the composition of the cows milk formula is adjusted to be as close to the breast milk composition.

Nonetheless, cow's milk is a highly allergenic food and the first foreign protein given in large quantities to the immunologically-immature newborn baby. Therefore, it is not surprising to find cows milk is the major cause of milk allergy in about 10% of the infants.

Recently, a new infant formula containing partially hydrolyzed cows milk whey (Nan HA) has been introduced.

The highly allergenic proteins in the cows milk have been treated enzymatically to make them less allergenic. Over 20 research studies throughout the world including Singapore, demonstrates that this hypoallergenic formula significantly reduces the development of allergy. The use of partially hydrolyzed whey formula in infants for the first four to six months of life significant reduced the manifestations of allergic diseases for 5 to 10 years.

In a study performed in Singapore a significant reduction in atopic disorders at 12, 24, 36 and 60 months was found in infants who were on partially-hydrolyzed hypoallergenic milk formula for the initial 4 months of their life. These observations suggest long term benefits detectable way past the period of direct intervention with the partially hydrolyzed milk formula. Some studies have suggested that partially hydrolyzed cows milk formula should be preferentially introduced for at least 4 months to all babies if the infant's mother opts not to breast feed.

Can totally breastfed babies develop devere allergy symptoms?

In a family with a history of allergy special care is needed to avoid allergens during pregnancy and also during the early development of the baby. Even babies who are totally breast fed can develop allergic reactions. Food allergens in the mother's diet can appear in her breast milk within 2 to 6 hours. Even aeroallergens such as pollen allergens and house dust mite allergens that the mother is exposed to can appear in the breast milk. The allergens in the breast milk can sensitize the baby or provoke symptoms in babies who are already sensitized. Allergy symptoms can develop in predisposed infants continuously exposed to food allergens or aeroallergens in breast milk.

Previously, several allergy symptoms including regurgitation, vomiting, colic, diarrhoea, and eczema have been reported in breast feed infants. Elimination of the offending food allergens from the mother's diet corrected the symptoms in the babies. In Malaysia we have found allergic skin reaction in exclusively breast fed infants. We tested the infant's blood for specific IgE antibodies to common foods in the mother's diet. We have found IgE-mediated response to cows milk, eggs, and wheat in different infants. In one infant with severe allergic disorder of skin the IgE antibody response in the baby was directed to many allergens in the mother's diet. Thus parents need to be aware of the possibility of allergy symptoms developing in their infant via the breast milk particularly in families with a history of allergy. We recommend that special dietary precautions be taken during lactation for mothers of high-risk families.

In North Europe many parents with history of allergy plan their babies so that the later part of the pregnancy and early lactation falls outside spring and early summer when the air pollen counts are high, to reduce exposure to pollen allergens.

Allergy to house dust mites

House dust mites are the most common cause of asthma, allergic rhinitis and sometimes eczema. In Malaysia, house dust mites are found in all localities surveyed with 80% homes containing several species of mite in high numbers. One Malaysian survey of homes throughout the country recorded millions of mites multiplying in the mattresses of most homes. The three most prominent house dust mites found locally are Blomia tropicalis, Dermatophagoides farinae and Dermatophagoides pteronyssinus. These three species have unique allergens but some cross-reacting allergens exist between D. farinae and D. pteronyssinus and only one need to be tested. However, Blomia tropicalis does not share any antigenic determinant with the other two and hence need to be tested separately in a patient suspected of house dust mite allergy. About 85% of patients allergic to dust mites react to both species (Blomia tropicalis and Dermatophagoides species) but the other 15% react to one or the other species.

Dust mites feed mainly on skin scales (derived from humans or mammalian pets), fungi, hair/fur and body fragments of dead insects. The life span of the adult mite is about 2 to 3 months and during this period it will lay about 50 eggs per month. These eggs hatch and mature in about twenty-five days in the tropics. The major allergen of the house dust mite is derived from the fecal pellets (each dust mite defecates about 50 pellets daily) and dead dust mite parts. The fecal pellets are about 20 microns in size and can reach the upper airways of people breathing them. Fecal allergens contain enzymes that allow the allergen to penetrate mucosal surfaces rapidly and cause immune allergic sensitization.

Exposure to high levels of house dust mite allergens during infancy increases the risk of allergic sensitization and the development of asthma in later life. In Malaysia about 90% of children with asthma or allergic rhinitis are positive for house dust mites. In adults with asthma the prevalence rate of mite sensitization is close to 70%. Many adults with non-specific chronic cough are often positive to house dust mite allergens. Many patients with eczema also react to house dust mites. All patients with asthma or allergic rhinitis should undergo allergy tests for house dust mites to identify the causal factors for long term management of their clinical symptoms. Many studies have emphatically demonstrated that reduction of exposure to the mites in the home environment significantly lead to the improvement of allergic symptoms. Only one company (Approved Allergy Fighters) in Malaysia has experience in home management of house dust mites. They also supply allergy products (such as, mattress/pillow allergicovers, anti-dust mite sprays and air-filters)

Management of house dust mites

Professor Dr TA Platts-Mills, a world-leading allergy expert and medical doctor in United States, stresses that total encasing the mattresses and pillows with anti-mite barrier material is the only sure way of reducing the dust mite-allergen load. Encasing of the mattresses and pillows is the first essential remedial step towards management of dust mite allergy and asthma. Other prominent allergy researchers endorse and state, ' Using a combination of allergen barriers on mattress and regular washing routine can significantly lower the number of dust mites found in the bedrooms in humid regions'. There are several good controlled clinical trials with patients showing that allergen barriers effectively reduce symptoms of dust mite allergy and asthma. In many of these studies the dust mite allergen concentration decreased by as much as 90 percent in the bedroom when dedicated procedures were followed. Partial encasing, for example covering the top half of the mattresses, caused no change in mite exposure and therefore was not effective as a barrier to protect the patients.

When managing house dust mites it is essential to also consider other items in the bedroom and living room that could contribute to the house dust mite allergen load. Carpets, upholstered furniture, blankets-duvets, furry toys, rugs, and dust-collecting items may substantially contribute to the house dust mite load in the house. Thus, it is essential to take stringent measures contributed by these items to reduce the house dust mite allergen load in home environment. Thus, management of house dust mites in the home environment must take all these issues into consideration otherwise any success achieved in the bedroom would be compromised.

House dust mite allergy is the most common cause of allergic asthma and perennial rhinitis in Malaysia. The relationship between exposure and asthma symptoms in sensitized individuals is complex, with some patients reacting to very low doses of allergen, whereas others are able to tolerate rather large doses. Nonetheless, exposure to higher allergen levels is associated with more severe asthma and rhinitis symptoms in dust mite-sensitized patients. Avoidance of house dust mite allergen exposure seems to be the most logical way to treat children and adults with asthma and allergic rhinitis due to house dust mite allergens. Marked improvement of symptoms and reduction of use of medication is associated with successful management of house dust mite allergens.

The following is suggested as essential steps towards the management of house dust mites in the Malaysian homes.

Encase completely the mattress and the pillow in Demitze Allergicover dust-mite barrier and zip it with protective flap next to the mattress. The allergicover material prevents any house dust mite allergens escaping out of the barrier. Do not remove unless soiled. The allergicover can be washed in detergent water and dried in air or sun within 2 hours. Before encasing the mattress again, thoroughly vacuum the upper surface of the mattress to remove dead mites and fecal allergens. Some people like to spray the mattress with anti-mite spray (Benzyl benzoate) before encasing the mattress.
Wash all bed linen (bed-sheets and pillow-cases) in hot water (60 degree Centigrade) once a week. Some people like to add anti-mite solution to the detergent in the washing-machine.
Remove carpets, rugs and furry toys from the bedroom and also other parts of the house. If unable to remove carpets or rugs from the house for any reason it is advised to regularly steam-sanitize (140 degree Centigrade) wall-to-wall carpets, rugs, and fabric upholstery at least twice a year.
The floor preferably made of parquet or tiles should be wet-mopped daily. Anti-dust mite solution may be added to the wash solution.
A non-toxic Acaricide (Demitze anti-mite spray) may be sprayed on soft furnishing surfaces, carpets, rugs, upholstery and similar items to kill dust mites. The sprayed items need to be vacuumed one week after spraying the items. Protection against dust mites lasts for about 4 months. Replacing the upholstered furniture with leather covered furniture considerably reduces the sites where dust mites can multiply.
Since dust mite fecal pellets (they are potent allergens) are easily airborne the use of a true HEPA filter in the bedroom when sleeping may reduce allergen exposure substantially from airborne particles.

What is the disadvantage of Pyrothroid-impregnated nets

No allergist anywhere in the world has proposed the use of such nets for allergic or asthmatic patients to control house dust mites present in large numbers in mattresses or pillows. Anyhow do not use permethrin-treated products if you have an allergy to chrysanthemums or are hypersensitive to chemicals. The use of pyrethroid containing products in the home environment may do more harm for chemical-sensitive individuals. There are several other reasons that argue against the use of such netting in the home.

The netting is placed over the top part of the mattress and the argument is that when the dust mites come in contact at night with the net they would be killed by the chemical. There is only one study conducted with normal individuals using the net. The net had the ability to kill a proportion of the dust mites in the mattress but the mites continued to proliferate in the mattress throughout the period of the study over several months showing that the net does not totally eliminate the mites from the mattress. The accumulation of dead mites and their fecal pellets on the mattress may be a hazard for patients with asthma since this high load of dust mite allergen could trigger an attack.

The impregnated-net is marketed with the suggestion that it is effective for a period of 24 months but no study exists to substantiate this point. According to World Health Organization sources the half-life of pyrethroid impregnated-net is about 8 months and therefore the chemical is effective for that period only. After this period the net must be recharged with the chemical or the netting replaced with a new one. Obviously replacing the product every 6 to 8 months becomes an expensive option but recharging with the chemical may be a cheaper option.

However, there are other reasons to avoid exposure to pyrethroid chemicals because of health concerns particularly for the young. Naturally derived pyrethrins are well recognized sensitizers and people can develop hypersensitive reactions to them. Similar sensitizing potential of synthetic pyrethroids has also been noted. Outbreak of several cases of urticaria occurring in children due to pyrethroid chemical has been reported in the literature (Vet Hum Toxicol. 1999, 41:92-3).

Moreover recent experimental studies show that some pyrethroids, including permethrin, are endocrine-modulating chemicals and can accumulate in breast milk. On lactational delivery to the newborn the chemicals can accumulate in the brain causing activity-dependent gene expressions in cerebellar neuronal cells to be repressed. These studies suggest that lactational exposure to pyrethroids might negatively affect the postnatal development of the mammalian brain (Arch Toxicol. 2002,76:392-7).

A 45 year old female animal keeper who was exposed to pyrethroid insecticides over a period of 13 years at her workplace in activities (such as feeding, maintenance of hygienic conditions, and application of insecticides) developed what is called the pyrethroid syndrome. Clinical history revealed mainly neurologic and allergy like symptoms which developed in a progressive manner through exposure to pyrethroid chemicals over years. She also developed pain syndrome in muscles and joints. These symptoms had been apparent for about 5 years. Furthermore, the patient suffered from abnormalities of the neural behavior (e.g., loss of strength and performance, abnormal tiredness, loss of interest, sensation of coldness, dysphoria, heart arrhythmia, rapid pulse, malfunction of memory and concentration, nausea, headache, decreased olfactory sensitivity, and low blood pressure), hair loss, hypothyreosis, and vitiligo. The animal keeper was incapable of work due to the severity of the complaints and required regular medication for her condition.

Recently, in a report by BBC News Online the insecticide permethrin was shown to cause a series of chemical changes in brain that could lead to the development of Parkinson's disease (research conducted by Virginia Polytechnic University and presented at the American Chemical Society). Researchers studied changes in brain chemicals in mice exposed to different levels of permethrin, often used on clothing and netting to kill and repel ticks and mosquitoes. The study found that exposure to the insecticide resulted in reduced levels of the chemical transmitter dopamine in the brains of the mice. It also found that permethrin led to increased production of a protein that is a major component of fibrous tangles found in the brains of people with Parkinson's disease. Just a small dose of the insecticide was enough to cause these chemical changes in the brains of the experimental mice.

Allergy to mammalian pets

Many families have experienced the joy of owning a mammalian pet such as dog or cat. Children become emotionally attached to the animal giving them free run of the house. Unfortunately, some people are allergic to certain pet allergens. The allergens are found in the pet's saliva, hair, urine, and dander (dried skin flakes or scales). In general cats produce more severe allergic reactions than dog. Other household pets or pests such as hamsters, rabbits, guinea pig, rats and mice carry allergens that could trigger respiratory allergies especially asthma.

When pets have the run of the house they will shed their dander on the carpets, beds and upholstery. Allergens will build up in carpets, mattresses, cushions, and curtains and can be a constant source of provocation to sensitized individuals. In predisposed sensitized individuals the allergic symptoms can occur within minutes of being exposed to the pet. The sensitized individuals can even react to people who have close contacts with pets through allergens adhering to their clothes. In some individuals the symptoms will build up over several hours and be most severe at 12 hours after contact with the pet. In some cases the respiratory reaction to the pet allergens can be life threatening. In Malaysians, the prevalence of allergy to cat dander is about 30% and dog dander is about 20% for patients with asthma and rhinitis.

The normal voice can change significantly in individuals with allergy of the respiratory system.

In one particular individual who frequently lost his voice, the allergy profile revealed that the person had severe allergic reaction to several aeroallergens including house dust mites, dog dander, cat dander, and mouse-associated allergens. In recent years, it has become evident that practically all respiratory animal allergens (horse, cow, dog, cat, mouse, rat and cockroach) characterized at the molecular level belong to the lipocalin family of proteins.

If you are considering buying a pet then it may be advisable for the family to visit a pet shop several times to make sure that no one in the family develops an allergy to the pet you intend to bring home. However, if you are predisposed to allergy it may be advisable to buy pets that do not have fur such as turtle, fish or reptile. You may need to take some strict measures if you severely allergic to your dog or cat but cannot part with it. Washing the dog or cat twice a week considerably reduces the dander shed in the house. Ask a non-allergic member to wash, brush and vacuum the fur of your pet to reduce the allergens released.

Do not allow the pets into the house and certainly not in the bedroom. Encase the mattress with anti-static allergicover so that pet dander does not reach the mattress fabric. An air filter with HEPA attachment in the bed room will rapidly reduce the airborne pet dander particles in the room. Individuals with allergy to pets should consider immunotherapy which reduces the allergic symptoms in time.

Pollen Allergy

Hayfever is a commonly used term for pollen allergy normally experienced in the temperate regions during spring and early summer when the pollen counts in the air are very high due to the flowering season. Nose allergy is predominant with frequent sneezing bouts accompanied with runny or clogged nose. The nose mucosal membrane, the eye conjunctiva and the throat are very itchy. Moreover, the membrane lining the eyelid become inflamed and cause red-rimmed eyes. The eyes water continuously. Hay fever susceptible individuals are miserable during Spring-Summer period when most people are enjoying the beauty of nature.

In Malaysia there is no fixed flowering season but individuals with allergic rhinitis and rhinoconjunctivitis do show reaction to local pollens. Grass pollens account for about 40% of total particle counts in the air in Kuala Lumpur city area and these grass pollen counts reach peak levels during the month of March and September. Allergy tests in asthmatics showed that 22 % reacted to grass pollens and a similar number reacted to tree pollens, specifically Acacia species and oil palm pollens, in the city. On the other hand in Kelantan 18% of patients with perennial rhinitis were positive to grass pollens probably related to rice plant pollens. In one study it was observed that the patients with allergic disease reacted to oil-palm pollen (Elaeis guineensis) with high frequency (22 %), followed by resam-fern spores (34%), sea-teak pollen (34%) and fungal spores (32%). Positive responses to these allergens correlated with total serum IgE levels of the subjects. The grasses most often implicated were Bahia, Bermuda and rough pigweed.

Many types of grasses have been introduced into the country for lawns and golf courses and the pollens generated from these grasses may pose a risk factor for some people. These studies, however, clearly demonstrate that pollens from tropical plants, both grasses and trees, play an important role as potential causal factor in allergic rhinitis, allergic conjunctivitis and asthma.

In addition, allergenic cross-reactivity has been described for different species of palm pollens. Cross-reacting allergens are present in palm pollens from betel nut, coconut, royal palm, date palm, oil palm and other palms trees. Thus the evaluation of response to pollens should consider aspects of cross-reactivity between related plants in triggering the allergic reaction.

Rice pollen allergy is important in parts of the world where rice is cultivated extensively. In Malaysia rice is cultivated in Northern parts of the country particularly some areas of Perak and Selangor, Kedah Perlis and Kelantan. Rice pollen proteins do elicit a specific reaction in asthmatics children and is an important causal factor for allergic rhinitis. Rice pollen allergy should be distinguished from "Rice Millers' Syndrome" which due to irritant effect from the husk particles.

Asthma

Asthma is a disease of the lung's airways. About 1 person in 40 is the world has asthma. Its prevalence and severity among children has increased steadily in the past 40 years. A World Health Organization report indicates that 10 to 15 % of children in the world suffer from the disease. In Malaysia a clinical survey done in 1997 of school children aged 7 to 12 years in the Kelang Valley showed that 17 % had asthma but in many cases their parents were not aware of their children's condition.

Asthma is defined as follows:

Airways obstruction that is reversible (but not completely in some individuals) either spontaneously or by treatment;
the presence of inflammation in the airways mucosa by inflammation-causing cells such as eosinophils, mast cell, macrophages, and T-lymphocytes; and
increased airway responsiveness to a variety of stimuli. The abnormal hyperactivity of the airway may be caused by many non-specific stimuli including: aero-irritants (cigarette smoke, diesel fumes, nitrous oxide and others), weather changes, stress, drugs (aspirin, antibiotics and others), emotions and viral infections.

These stimuli cause increased production of mucus and contraction of the bronchial muscles resulting in difficulty in breathing out. Asthmatic individuals develop clinical symptoms such as chronic cough, wheezing and hoarse voice, after exposure to allergens, environmental irritants, viral infections, cold air or exercise.

Asthma may be broadly grouped into allergic asthma and non-allergic asthma. Some asthmatics may have both types. In Malaysia about 80 to 90% are allergic asthma mostly noted in children and young adults, and 20% are non-allergic asthma that is frequently found in middle-aged and elderly individuals. In allergic asthma, inhalation of allergens such as house dust mites, cockroach or cat dander, is the most important stimulus known to trigger the disease. In sensitized individuals the allergens trigger an immediate asthmatic response during which bronchi-constriction develops within 10 minutes, reaches maximal contractions in 30 minutes and then usually resolves in 1 to 3 hours. In about 50% of adults and 80% of children with the response, a late asthmatic response (bronchi-constriction) follows. The asthmatic attack recurs at 3 hours and lasts for 24 hours if untreated. Patients with late phase asthma triggered by allergens, go on to develop hyper-responsiveness that last for days or weeks.

From the Malaysian context, analysis of the response to specific allergens in children with asthma showed that 90% reacted to house-dust mites allergens, 67% reacted to cockroach allergens, 23% to cat dander or dog epithelium allergens, and 10 to 22% to cows milk, soya bean, egg, peanut, fish, shrimp, crab, banana, and wheat. Thus, it is important to obtain a complete allergen profile for the asthma patient so that appropriate avoidance measures can be taken as part of the management programme for the disease.

Two approaches are needed for the successful management of the asthma, namely, non-pharmacological reduction of risk factors and pharmacological intervention through medication. Bronchoconstriction is reversed by long acting bronchodilators (e.g. Salmeterol, formoterol) and may be used in children greater than 5 years old. As the disease progresses, exacerbation caused by inflammation of the bronchial mucosal tissue, specifically eosinophils, is an early and important feature of asthma. Thus, anti-inflammatory drugs specifically inhaled corticosteroids (e.g. nebulized budesonide) are widely used for the long-term control of asthma.

Anaphylaxis

A small number of highly allergic individuals are susceptible to a most serious form of allergic reaction known as anaphylaxis. It is an acute life-threatening condition and requires immediate medical attention. The systemic allergic reaction occurs rapidly and involves many organs of the body, such as the skin, respiratory tract, gastrointestinal tract, and cardiovascular system. Thus, symptoms normally appear rapidly, usually within seconds or minutes, after exposure to an allergen. In rare cases the anaphylactic reaction may be delayed for 12 to 24 hours. Generally, most anaphylactic events occur at home in infants, children and adults. Many types of agents, for example drugs, foods, and insect venoms, can cause anaphylaxis. The mechanism of anaphylaxis could be IgE mediated or non-IgE mediated but the IgE-mediated anaphylaxis can be fatal if emergency measures are not taken.

The anaphylaxis triggered by various agents can cause different types of clinical manifestations but the most frequent symptoms involve the respiratory system (78%) with breathing difficulty and the skin with manifestation of hives (90%). Individuals with episodes of anaphylaxis are advised to carry emergency kit (e.g Anahelp) and also wear a bracelet warning of their condition.

Allergen immunotherapy

Allergen immunotherapy (also called desensitization, hyposensitisation) is the technique of treating specific IgE-mediated disease with increasing doses of the causal provoking allergen in order to decrease the sensitivity to the offending allergen. The desensitization process is associated with the production of IgG-blocking antibodies that interfere with the function of IgE antibodies. Patients who have multiple allergy symptoms that are severe, year-round, and not adequately controlled by conventional drugs combined with avoidance measures should consider management of the symptoms through immunotherapy. However, not all types of allergy conditions can be managed through immunotherapy. A number of conditions particularly unstable asthma, food allergy, certain types of eczema or urticaria, are poor candidatea for this treatment. Many research studies have shown that allergen immunotherapy gives good result for airborne allergens, such as, house dust mites, pollens and pet dander.

Oral allergen immunotherapy, now usually referred to as sublingual immunotherapy (SLIT), is a promising alternative to traditional injection immunotherapy. The sublingual allergen immunotherapy is generally preferred because it has less-risks with side reactions including anaphylaxis, compared to injection allergen immunotherapy. Allergen immunotherapy should be considered only when the standard management through avoidance is not successful. However, many allergens cannot be adequately avoided through controlling the patient's environment and these individuals are good candidates for immunotherapy.

Generally, the patient should meet three important conditions for consideration of allergen immunotherapy. Firstly, there must be a convincing history of clinical symptoms severe enough to justify the time commitment, cost, and risks of immunotherapy. Secondly, the patterns of symptoms are not well controlled by avoidance measures and acceptable levels of drug therapy, or both. Thirdly, the patient should show an immediate IgE-mediated allergic response (detected through cap RAST tests) to specific allergens that can be used for immunotherapy. Multiple allergen reactions need detailed consideration of the potential long-term benefits of immunotherapy with one or more causal allergen. Variety of health and other conditions may render the patients a poor candidate for allergen immunotherapy and these should be weighed carefully before initiating the immunotherapy.

Food Intolerance (non-immune mediated reaction)

Food intolerance, unlike food allergy, does not involve the immune system. For instance, symptoms of stomach cramps, bloating due to gas and diarrhea can develop if there is a lack of lactase enzyme in the gastrointestinal tract to digest lactose sugar normally present in cows milk. Intolerance to food means that our body does not have the appropriate enzyme to digest certain proteins present in the food. People intolerant to certain foods can take a small amount of the offending food but ingestion beyond a particular threshold causes them to react with severe allergy-like symptoms. Other symptoms of food intolerance may include irritation of the gut, recurrent hives and swelling, headache, lethargy, severe joint pains, unpredictable mood changes and hyperactive behaviour changes.

Intolerance to chemical component present in foods is much more common than true food IgE-mediated allergies. The reaction is caused by various natural chemicals found in various foods. Fruits, vegetables, meats and seafoods are endowed with many natural chemicals that provide the specific smell and flavour to the food. However these very chemicals can cause symptoms because of intolerance to them.

Articificial preservatives, food colouring or flavouring are cause for concern for people with intolerance.

Intolerance can occur in people from families with genetic predisposition to allergy and families with no such risk. Some individuals can have both intolerance and allergy condition coexisting. Symptoms can begin at any age, either suddenly or slowly over years. Sometimes, changes in diet can trigger the response but more commonly a viral infection or serious illness is the trigger. Heavy exposure to certain foods such as coffee, spicy foods, chocolate, alcohol, shellfish or junk food (during a party or function) could be contributory in initiating the reaction. Asthmatics can develop severe symptoms after exposure to sodium preservatives, aspirin or monosodium glutamate.

A wide variety of chemical are added to processed foods. Some food additives known to cause allergy-like reaction include: Histamine, tyramine, tryptamine, serotonin, dopamine, and phenylethylamine found in many foods; Salicylates found in many spices; Sulphites and Metabisulphites found in processed fruits, dried fruits, vegetables, meats, fish, poultry products, wines, alcoholic and fruit drinks; Benzoic acid and Paraben are found naturally in berries, concentrated tomato products, spices but often added to wide variety of processed foods; Colours (artificial colours, natural colours, and mineral colours) are used extensively for the presentation of the foods; Nitrates and nitrites are used as a preservative in processed plastic-packed meats and some cheeses but can cause harmful effect by direct toxicity to intestinal microvilli; and the list for food additives is extensive.

Allergy and intolerance in autistic children

Autism is a developmental disorder characterized by a spectrum of symptoms ranging from decreased verbal skills and social withdrawal, to restrictive repetitive behavior and uncontrolled outbursts. The etiopathology of this life-lasting disability is poorly defined but there are many possible factors linked to the behavioral characteristics of this syndrome. Both true allergies (IgE-mediated trigger) and allergy-like or intolerance (non-immune mediated trigger) conditions may be present in children with these disorders. Consistent with this observation is the fact that the immune system shows abnormalities involving altered antibody production with a skewed pattern of T lymphocytes biased for allergy type reaction, aberrant cytokine profiles, and other impairments consistent with chronic inflammation and autoimmunity.

There is growing evidence that many children with autism are allergic to certain foods. In some children the IgE-mediated allergic reaction may be severe but in others it may be mild. In one of our case the child had a significantly elevated IgE level of 2100 Kilounits per litre (KU/L) compared to normal levels of less than 25 KU/L. This child had both skin and respiratory allergy. The child reacted to many foods including egg white, cows milk, fish, wheat, peanut, soya bean, rice, chicken meat, potato, barley, oats, maize, sesame seed, pea, lentil, coconut, garlic, onion, cheese, cucumber, egg plant, chillipepper, red kidney bean, goat milk, crab, shrimp, pacific squid, tuna, sardine, abalone, scallop, oyster, tomato, orange, melon, mango fruit, banana, apple, lemon, papaya and jack fruit. It is rare for autistic children to react to many-food but in the majority the response is limited to few foods. Avoidance is the best approach for the management of IgE-mediated allergic problems.

In addition, in our brain a natural peptide called enkephalins function as neurotransmitters and participate as a natural painkillers. Enkephalin peptide also resembles the morphine structure. Research studies show that partial gastrointestinal digestion of certain proteins (cows milk casein, wheat gluten) result in peptides with opiate-like activity similar to enkephalin. It appears that autistic children may be more prone to the production of such opiate-like peptides form incompletely digested food proteins. These opiate-like peptides are found in large quantities in the urine of about 80% of autistic children. These unnatural peptides tend to accumulate in the brain over months because specific enzymes to break them down are not present. As the peptides increase in brain they bind to receptors specific to enkephalin and cause adverse reaction with mind-altering problem.

The total avoidance of dairy products and gluten foods has remarkable beneficial effects in these susceptible children.

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