Immunology and allergy Archives - Page 4 of 4

Immunology and allergy, Paediatrics, Women's health

Podcasts

Formula 101: When whole protein formulas are not tolerated

How to evaluate feed tolerance and when to be clinically concerned

Expert/s: Dr Jeremy Rajanayagam

Immunology and allergy

Podcasts

Mammalian meat allergy following tick bites

Mammalian meat allergy is the most common reason patients carry an Epipen in the Northern Beaches of Sydney

Expert/s: Clinical A/Prof Sheryl Van Nunen

Immunology and allergy

Podcasts

Update on clinical aspects of anaphylaxis – Lecture

Dr Wainstein will cover the definition, clinical presentation, diagnosis and management of anaphylaxis. The common causes and epidemiology of anaphylaxis and anaphylaxis related fatalities will be discussed.

Expert/s: Dr Brynn Wainstein

Immunology and allergy

Clinical Articles

Always screen asthma patients for allergic rhinitis, especially children

According to Allergist and Medical Rhinologist, Dr Jessica Tattersall, up to 80% of asthmatic children will also have allergic rhinitis.

Expert/s: Dr Linda Calabresi

Immunology and allergy

Clinical Articles

We all know that the previous avoidance strategy to prevent young children developing food allergies has been turned on its head. But out there in the real world, many new parents remain very nervous about feeding their six-month-old cooked egg or letting them taste peanut butter. As much as we would like to think a word of reassurance from their trusted GP is all that is needed, such reassurance is likely to carry much more weight if it is accompanied by a written resource from a reputable source. Enter the Prevent Allergies website. Among many other resources available on the site, there is a very succinct, definitive, printable brochure - entitled ‘Nip Allergies in the Bub’ - that clearly outlines the latest evidence-based information about what parents should be feeding their child and when with regard to lowering their risk of food allergies.

Expert/s: Dr Linda Calabresi

Immunology and allergy

Clinical Articles

It’s only been around a few years, but this little bit of technology has already received world wide acclaim for its ability to improve the safety of vaccines in the real-world setting. In simple terms, Smartvax is a program practices install into their software system that sends an SMS directly to patients three days after they receive a vaccination. Patients are asked if they experienced an adverse reaction to the vaccine. A straightforward Yes (Y) or No (N) is all that is required. A No reply ends the conversation, but a Yes will trigger a brief questionnaire that examines the nature of the adverse reaction. If the reaction resulted in the need to seek medical attention this is then flagged in the GP’s software inbox as well as with the local health authority. In practical terms this means adverse reactions are tracked in real time and act as an early warning signal that something could be amiss with a vaccine. Smartvax was developed by Perth GP, Dr Alan Leeb and Ian Peters, following a spate of serious and unexpected adverse reactions among young children who received one brand of flu vaccine back in 2010. It was apparent that a better, more time-sensitive system of monitoring side effects to vaccines was needed to ensure the safety of patients. With the widespread use of mobile phones, the day three post vax text has proven a very effective means of tracking reactions, with a high level of acceptance by patients. In a study from one NSW general practice, the response rate to the SMS text was 85% post-childhood vaccination, and even in the over 65 year age range the response rate was 74%. Smartvax has now been adopted by more than 280 practices around Australia. The technology can also be used as a reminder system to prompt patients when their next vaccine is due. This is such a clever idea and as general practice becomes more and more tech savvy one can envisage a day when Smartvax is a basic requirement for all clinics that provide vaccinations. >> Access the resource here

Expert/s: Dr Linda Calabresi

Immunology and allergy

Clinical Articles

Peanut Allergies: Research Shows ‘Oral Immunotherapy’ is Safe for Preschoolers

“We don’t have to live in fear anymore.” That’s the common refrain from hundreds of parents of preschoolers with peanut allergy that my colleagues and I have successfully treated with peanut “oral immunotherapy” over the past two years. Oral immunotherapy (OIT) is a treatment in which a patient consumes small amounts of an allergenic food, such as peanut, with the dose gradually increased to a target maximum (or maintenance) amount. The goal for most parents is to achieve desensitization — so their child can ingest more of the food without triggering a dangerous reaction, protecting them against accidental exposure. A recent study published in The Lancet has suggested that this treatment may make things worse for children with peanut allergies. The researchers behind the meta-analysis argue that children with peanut allergies should avoid peanuts. This study has limitations however. It did not include a single child under the age of five years old. And it runs the risk of confusing parents. My colleagues and I have seen firsthand that oral immunotherapy is not only safe, but is well tolerated in a large group of preschool children. We published data demonstrating this recently in the Journal of Allergy and Clinical Immunology: In Practice.

Safe for preschoolers

For any parent of a child with severe allergy, the idea of giving them even a small amount of the allergenic food might give them pause. I don’t blame them — giving a child a known allergen is a daunting thought. Some allergists share this fear and do not offer OIT to patients in their clinics due to safety concerns. To assess the safety of oral immunotherapy, we followed 270 children across Canada between the ages of nine months and five years who were diagnosed with peanut allergy by an allergist. The children were fed a peanut dose, in a hospital or clinic, that gradually increased at every visit. Parents also gave children the same daily dose at home, between clinic visits, until they reached the maintenance dose. We found that 243 children (90 per cent) reached the maintenance stage successfully. Only 0.4 per cent of children experienced a severe allergic reaction. Out of over 40,000 peanut doses, only 12 went on to receive epinephrine (0.03 per cent). Our research provides the first real-world data that OIT is safe for preschool-aged children with peanut allergy when offered as routine treatment in a hospital or clinic, rather than within a clinical trial.

The Lancet study was of older children

So why does the meta-analysis published in The Lancet show that peanut OIT increases allergic reactions, compared with avoidance or placebo? The researchers behind this study argue that avoidance of peanut is best for children with peanut allergy. They describe that in older children, the risk of anaphylaxis is 22.2 per cent and the risk of serious adverse events is 11.9 per cent. It is important for parents to note that The Lancet study only assessed children aged five and older participating in clinical trials (average age nine years old), and the researchers don’t even mention this as a limitation of their analysis. Our study, on the other hand, assessed preschool children (average age just under two years old) in the real world outside of research. While I agree that there are certainly more safety concerns in older children, and more research is needed to see which of them would most benefit, our results demonstrate with real-world data that, in preschoolers, OIT is a game-changer.

For many patients, benefits outweigh risks

It isn’t rocket science that avoiding what one is allergic to will be safer than eating it. An analogy is knee replacement surgery. Of course, not having knee replacement surgery would be “safer” than having the surgery. But not having knee replacement surgery doesn’t provide any potential of benefits and also provides little hope for families. Likewise, telling parents of children with peanut allergy that avoidance is the only option outside research fails to take into account the negative long-term consequences of avoidance — such as poor quality of life, social isolation and anxiety. Allergists and the medical community as a whole must stop confusing parents with endless mixed messages about OIT both within and outside of research. The fact is, many allergists are already offering OIT outside of research. In our current era of basing medical treatment decisions on a comparison of risks versus benefits, there is simply no one-size-fits-all approach. Rather than concluding that all children with peanut allergy should be managed with avoidance, we should be concluding that there are some patients, such as preschoolers, for whom the benefits of offering this treatment outweigh the risks. OIT has proven to be effective in many studies, and we will similarly follow the progress of our patients long term to track effectiveness. The bottom line is this: OIT is safe for preschool children and should be considered for families of those very young children with peanut allergy who ask for it.

- Edmond Chan, Pediatric Allergist; Head & Clinical Associate Professor, Division of Allergy & Immunology, Department of Pediatrics, Faculty of Medicine; Investigator, BC Children's Hospital Research Institute, University of British Columbia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Expert/s: Dr Edmond Chan

Immunology and allergy

Clinical Articles

Guide to Allergy Testing

Allergic disorders result from an inappropriate, usually IgE-mediated, immune response upon exposure to either environmental or food allergens. Common manifestations of allergy include rhinoconjunctivitis, asthma, eczema, acute urticaria and anaphylaxis. Disorders, such as chronic urticaria, hereditary angioedema and T-cell contact dermatitis (metal allergy), while clinically similar in some ways, are not IgE-mediated. Allergic disease manifests in different ways through life and the likely causative agents can also change with age (see Table 1).

Tests used in the diagnosis of IgE-mediated allergy

Total IgE Higher levels of total IgE are often found in patients with allergic conditions. However, normal total IgE does not exclude allergy. Total IgE is also elevated in other conditions including parasitic infections and allergic bronchopulmonary aspergillosis. It is used increasingly in determining anti-IgE therapy in moderate to severe asthmatics. Allergen-specific IgE Allergen-specific IgE can be detected for a large variety of allergens. The presence of a specific IgE to allergen can suggest allergic disease and is detected via a blood test (RAST or radioallergosorbent test) or skin prick test. RAST tests detect many of the different proteins within an individual allergen. Recombinant allergen testing Of the many proteins within a substance, only a few may cause allergic symptoms. Recombinant allergen testing looks for specific characterised protein within an allergen. Interpretation of RAST tests The presence of detectable specific IgE to an allergen does not confirm the patient is allergic to that substance. All results must be interpreted in conjunction with the clinical history of the patient. Low levels of detectable specific IgE can confirm the presence of allergy in the right clinical context. RAST testing aids in the assessment of, and identification of allergic sensitisation, but is not to be used alone as the deciding factor for inclusion or exclusion of allergy. As the level of specific IgE increases, the likelihood of clinical relevance also increases. As shown in Table 2, different allergens have different specific IgE level cutoffs at which serious allergy is >95% likely (positive predictive value or PPV). The range of values is vastly different between allergens and is affected by age and also by geographic region. Table 2 defines levels at which exposure, or a challenge, would be highly hazardous for a patient. Importantly, many patients could have serious reactions at much lower levels. [table id=1 /] [table id=2 /]

RAST tests

RAST tests are available for a range of allergens, however Medicare criteria limits rebates based on the number, type and frequency of tests. Medicare Australia limits rebates for RAST tests to a maximum of four specific allergens and/or mixes per pathology request and a maximum of four RAST test episodes per year. When ordering RAST tests, it is advisable to include allergens the patient feels are relevant and those likely for the clinical scenario. For common clinical scenarios we recommend the following: Childhood eczema Age <2 years: Milk, Egg, Wheat, Peanut Age >2 years: Milk, Egg, Peanut, Dust mite Additional allergens or an extended RAST combined allergy panel may be ordered. Asthma and allergic rhinoconjunctivitis Dust mite, Grass mix, Animal dander Additional allergens may be ordered or substituted if relevant (e.g. cat dander instead of animal dander). An extended RAST inhalant panel is also available. Default panel if no allergens are specified and no clinical notes are provided Age <5 years: Dust mite, Grass mix, Food Mix Age >5 years: Dust mite, Grass mix, Animal Mix Anaphylaxis Anaphylaxis is a severe life-threatening allergic reaction. It is recommended these patients require specialist assessment by a clinical immunologist or allergist. Initial testing should look for the causative allergen if possible. It is important to note that a negative RAST test does not exclude the allergen tested. RAST testing recommendations

Test individual likely causative allergen i.e. food, stinging insect.
Tryptase, if done within 2-6 hours of reaction, can support the occurrence of an allergic reaction.
Useful as an assessment of mastocytosis (condition with increased numbers of mast cells)

Extended RAST panels

Extended RAST panels have been developed to represent the common allergens encountered clinically in practice. They are particularly relevant in our geographic region and replace the skin prick test panel which is no longer available. Additional allergens may also be requested. All results must be interpreted in conjunction with the patient’s clinical history. Extended RAST Food Panel

Covers common food-related allergens
Almond; Hazelnut; Sesame seed; Banana; Mango; Shrimp (prawn); Cashew; Milk (cow); Soybean; Codfish; Peanut; Walnut; Egg white; Rice; Wheat

Extended RAST Nut Allergy Panel

Broad collection of commonly consumed nuts, including peanuts
Individual nut testing with appropriate clinical history is preferred
Recommend to discuss results with a clinical immunologist or allergist
Almond; Macadamia; Pine nut; Brazil; Peanut; Sesame seed; Cashew; Peanut (Ara-h2); Walnut; Hazelnut; Pecan

Extended RAST Combined Allergy Panel

Combination of common food and environmental allergens
Replaces the skin prick test panel (no longer available)
Almond; Dust mite; Mould mix; Cashew nut; Egg white; Peanut; Cat dander; Grass mix; Shrimp (prawn); Codfish; Hazelnut; Soy; Dog dander; Milk (cow); Wheat
* Preferable for children (<12 years) due to low serum volume

Extended RAST Inhalant Panel

Covers common environmental allergens
Useful for asthma and allergic rhinitis
Acacia (wattle); Blomia tropicalis; Dust mite; Alternaria alternate; Cat dander; Eucalyptus; Aspergillus fumigatus; Cladosporium; Horse dander; Bahia grass; Common ragweed; Johnson grass; Bermuda grass; Dog dander; Perennial rye grass

Recombinant allergens

Omega-5 gliadin

A component of wheat
Associated with anaphylaxis
Often in the context of eating wheat and physical activity within 1-2 hours

Alpha-gal (mammalian meat allergy) 

Associated with anaphylaxis; often delayed following consumption of meat (beef, lamb, pork)
Related to tick bites

Peanut Allergy Risk Assessment

Peanuts like all food is made up of many different proteins
Ara-h2 is associated with anaphylaxis to peanut
Can assist with risk assessment and should be done in conjunction with a clinical immunologist or allergist
A negative Ara-h2 in peanut positive patient does not imply there is no risk to anaphylaxis
Results of RAST tests can also be of use in monitoring ongoing allergy in patients in conjunction with their treating clinician

How to order allergy tests

RAST tests - standard panels Medicare Australia limits rebates for RAST tests to a maximum of four specific allergens and/or mixes per pathology request and a maximum of four RAST test episodes per year. Extended RAST tests (Medicare rebate + $120* per panel)

Extended RAST Food
Extended RAST Nut
Extended RAST Combined
Extended RAST Inhalant

Please note, extended RAST panels are not bulk billed. Recombinant allergen tests (Medicare rebate + $60* each)

Alpha-gal
Omega-5 gliadin
Peanut (Ara-h2)
Peanut Allergy Risk Assessment

General Practice Pathology is a regular column each authored by an Australian expert pathologist on a topic of particular relevance and interest to practising GPs. The authors provide this editorial free of charge as part of an educational initiative developed and coordinated by Sonic Pathology.

Expert/s: Sullivan Nicolaides Pathology