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Immunology and allergy

Preventing allergy
Dr Linda Calabresi
Clinical Articles iconClinical Articles

Preventing allergy

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
Simple blood test a mortality predictor
Dr Linda Calabresi
Clinical Articles iconClinical Articles

Smartvax

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
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Dr Edmond Chan
Clinical Articles iconClinical 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.The Conversation 

- 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
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Sullivan Nicolaides Pathology
Clinical Articles iconClinical 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 IgEHigher 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 IgEAllergen-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 testingOf 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 testsThe 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, PeanutAge >2 years: Milk, Egg, Peanut, Dust miteAdditional allergens or an extended RAST combined allergy panel may be ordered.Asthma and allergic rhinoconjunctivitis Dust mite, Grass mix, Animal danderAdditional 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 providedAge <5 years: Dust mite, Grass mix, Food MixAge >5 years: Dust mite, Grass mix, Animal MixAnaphylaxis 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
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Dr Linda Calabresi
Clinical Articles iconClinical Articles

Vaccinating the Immunosuppressed – Who, What and When

Vaccination in immunosuppressed adult patients has many facets and can be challenging for GPs who don’t deal with these cases regularly.But there are a few key considerations that can help guide clinicians, says Associate Professor Michael Woodward, Melbourne-based geriatrician, writer, researcher and passionate advocate for health promotion.Firstly, not all immunosuppression is equal. It is important to ascertain the degree of immunosuppression, as some people may be being unnecessarily denied vaccines because they are taking medication that can suppress the immune system but only at higher doses or in different formulations.“For instance, someone who is on inhaled corticosteroids for their asthma or on low dose (less than 20mg) prednisolone daily for just a few weeks is not significantly immunosuppressed and can be vaccinated in the same way as other people,” said Professor Woodward in an interview following his presentation at Healthed’s recent Annual Women's and Children’s Health Update in Perth.However, those on higher doses of steroids or on steroids more long-term, as well as those people who have conditions associated with immunosuppression such as haematological malignancy do need special consideration when it comes to vaccination.Most importantly, live vaccines are not to be given to this group. This includes the new herpes zoster vaccine (Zostavax), which absolutely contraindicated in severely immunocompromised patients. The consequences of inadvertently administering this vaccine to an immunosuppressed patient hit the headlines some months ago, highlighting the importance of this guideline.The other question often asked is whether patients who are known to be immunosuppressed, and therefore at greater risk of significant infections actually need more or stronger doses of the vaccines they are able to have.In some cases that is a very real and worthwhile consideration if you want to achieve the objective of immunoprotection, Professor Woodward said.For example, you might consider giving an immunosuppressed patient the pneumococcal vaccine (Prevenar 13) as opposed to the polysaccharide pneumococcal vaccine (Pneumovax 23).“The conjugate vaccine is generally slightly more likely to produce an immune response [than the polysaccharide vaccine],” he said.The other scenario where GPs might need to be considering vaccination in association with immunosuppression, is in patients who are scheduled for an elective splenectomy. The lack of a spleen is known to be associated with a reduction of the body’s ability to respond to a vaccine, so it is currently recommended that people who are about to undergo a splenectomy have the influenza, pneumococcal and the newer zoster vaccine. In addition, they should be vaccinated against H. influenza B and receive the two meningococcal vaccines currently available.All these are detailed as part of the pre-splenectomy recommendations on the spleen.org.au website, with the exception of the zoster vaccine, as the guidelines have yet to be updated. However, Professor Woodward says most health professionals in this area are advocating the inclusion of the zoster vaccine. Some of these vaccinations may also be given shortly after the removal of the spleen in cases where the splenectomy has been urgent, but this is generally not the remit of the GP.In general, the question of vaccination in the immunosuppressed patient can be complicated. It is a highly specialised area and Professor Woodward suggested, if in doubt GPs might want to seek input from a specialist in this area such as an immunologist or a rheumatologist.

Expert/s: Dr Linda Calabresi

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