The world’s growing allergy problem, how to find out if you have one and what do if it’s a food allergy

Allergies affect up to 40 per cent of the world’s population, according to the World Health Organisation, and the proportion of sufferers in big cities and industrialised countries is rising. They can cause chronic illness and, in the case of some food allergies, can be fatal.

More than one in two people in Hong Kong suffer from one or more allergic diseases, according to the Hong Kong Institute of Allergy, which will hold events to raise public awareness about allergies to mark World Allergy Week that begins today.

Why children’s allergies are on the rise and how dirt may hold key to reducing cases

Children born in Hong Kong have an elevated risk of developing allergies, for two reasons. Babies delivered by caesarean section are five times more likely to suffer from common allergies than those born by vaginal delivery, according to Dr Lee Tak-hong, director of the Allergy Centre at Hong Kong Sanatorium & Hospital in Happy Valley. Hong Kong has one of the highest rates of birth by caesarean section in the world, with more than four in 10 babies born by C-section, double the proportion in the developed world. Secondly, says Lee, the risk of allergies is four times higher in infants fed with cow’s milk formula than breastfed children. “Breastfeeding for a minimum of six months is the best prevention strategy,” he says. Yet in Hong Kong only 2.3 per cent of mothers exclusively breastfed their baby for six months, according to a 2013 survey of babies born in 2012 by the Department of Health.

Around 5 per cent of Hong Kong children aged under 14 have food allergies, according to the Allergy Alliance, and nearly one in six of these are estimated to be at risk of going into anaphylactic shock – a severe, potentially life-threatening allergic reaction – if they eat something to which they are allergic.

However, being born allergic to something does not condemn you to suffer from allergies all your life. Doctors say infants can be desensitised to allergies, thereby avoiding problems as they get older, as long as their allergic reactions are detected early enough.

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“A child’s immune system develops during the prenatal period. The 270 days during pregnancy until two years, or rather the first 1,000 days [from conception] provide a window of opportunity to prevent allergy,” Lee says.

Dr Adrian Wu, registered specialist in immunology and allergy, Centre for Allergy and Asthma Care, Hong Kong, in Central, says: “It is possible to desensitise to many allergens, which will arrest the development of allergic diseases. For example, allergen immunotherapy (desensitisation) can prevent the onset of asthma in children with allergic rhinitis.” Hong Kong has one of the highest rates of allergic rhinitis in the world; the nasal allergy is aggravated by air pollution.

The risk of children with a high chance of suffering from food allergies developing allergic reactions can be greatly reduced if they start eating foods to which they are likely to be allergic (such as peanuts and tree nuts) early, Wu says, citing recent studies.

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Even in children who are already sensitised to certain foods, the risk of them developing a clinical allergy to them can be reduced if they are fed these foods regularly. Doctors need to carry out “food challenges” to exclude children who are already clinically allergic.

Hong Kong chef Shane Osborn, founder of Arcane restaurant in Central, has a personal and professional interest in food allergies. He says the most common allergies he encounters in Hong Kong are to lactose (present in dairy products) and gluten (present in wheat, barley and rye).

“My personal experience is that some businesses don’t take the issue seriously,” he says. “I have seafood allergies, my wife is coeliac [meaning gluten triggers an adverse autoimmune reaction] and my daughter has severe nut allergies. Going to restaurants is always very stressful and waiters can be very vague and at times not interested in checking with the kitchen.”

What does he advise diners with allergies? “Dine at restaurants with quality professional chefs, as they take the diners’ health very seriously. Also try to speak with the manager at the restaurant – hopefully he/she can be more reassuring,” says Osborn. “It also helps to have the allergies translated into Cantonese – for my daughter we have a laminated piece of paper with a list of her allergies.”

Time to revise infant eating guidelines to tackle rise in allergies, Hong Kong experts say

During World Allergy Week the World Health Organisation seeks to raise awareness of allergic disease and related disorders and advocates the provision of training and resources to diagnose, manage, and prevent them. To mark World Allergy Week, the Hong Kong Institute of Allergy and Hong Kong Allergy Association will hold two public workshops – one on April 8 about anaphylaxis and food allergies and another one today about urticaria (commonly known as hives). They will also hold a patient sharing session today about the common daily problems encountered by allergic patients. All the events will be held at the association’s headquarters at 394 Shanghai Street, Yau Ma Tei, Kowloon.

Are you allergic?

Patients need to be wary of the many tests on the market that claim to diagnose allergies. Dr Wu says laboratory testing is not regulated in Hong Kong, and this results in a lot of unvalidated tests. Some may lack any scientific basis, he says. None of them have been approved as diagnostic tests by any national health agencies (such as the Food and Drug Administration in the United States or the European Medicines Agency in the European Union) and the EMA in Europe).

“We have increasingly been seeing patients who try to self-diagnose by seeking out these tests, and even some GPs are offering these tests to their patients,” he says. “This has resulted in unnecessary anxiety and even harmful dieting, as these tests would generally recommend all their customers to avoid all the most common food allergens (in case some of them actually do have food allergy).

“I have also had patients being falsely reassured by the result of these tests, only to find out that they are actually allergic to a food when they ended up having a severe allergic reaction.”

There is no test that can diagnose an allergy, says Yuen, since the condition requires a clinical diagnosis. “Tests only give some information that can help the clinician make a diagnosis, but there are a lot of nuances to interpreting even the most reliable laboratory tests. Therefore, patients with troublesome symptoms should consult a specialist.”

Four things to do if you have a food allergy

Denise Fair, a dietitian at Central Health Medical Practice in Central, offers these tips for those with food allergies.

1. Learn to read labels and ingredient lists. There are many different names for some foods, for example milk. You need to know these names and if they contain the allergen, avoid them.

2. Be careful about cross contamination. People with severe allergies can have a reaction if they consume even a small molecule of the allergen. A small amount of peanut oil left on a child’s pencil that a child with a severe peanut allergy then picks up may be all that it takes. Surfaces must be cleaned regularly; use separate cooking utensils and dishes to avoid triggering an allergic reaction. With severe allergies it is best to eliminate the allergen from the house or flat permanently. Wash everything in hot soapy water.

3. Be very picky when dining out. When you aren’t making the food yourself there is a dramatic increase in the possibility of eating a dish containing something to which you are allergic. You have to be careful that the allergen isn’t in the food you ordered and that the dish and its ingredients have not been in contact with any food containing something to which you are allergic. Always talk to the manager and relay the severity of the issue. Plan ahead and call beforehand to see if they can guarantee you are at no risk of exposure to an allergen.

4. Make sure you have some sort of identification on you indicating your allergy (an ID bracelet for example) and carry a card listing important information (name, allergy, emergency call number, use/location of medical devices such as Epipen [an injector for treating anaphylactic shock]).