High incidence of adverse reactions to egg challenge on first known exposure in young atopic dermatitis children: predictive value of skin prick test and radioallergosorbent test to egg proteins

Dietary factors and the risk of atopic dermatitis: a Mendelian randomisation study

Previous studies have revealed an association between dietary factors and atopic dermatitis (AD). To explore whether there was a causal relationship between diet and AD, we performed Mendelian randomisation (MR) analysis. The dataset of twenty-one dietary factors was obtained from UK Biobank. The dataset for AD was obtained from the publicly available FinnGen consortium. The main research method was the inverse-variance weighting method, which was supplemented by MR‒Egger, weighted median and weighted mode. In addition, sensitivity analysis was performed to ensure the accuracy of the results. The study revealed that beef intake (OR = 0·351; 95 % CI 0·145, 0·847; P = 0·020) and white bread intake (OR = 0·141; 95 % CI 0·030, 0·656; P = 0·012) may be protective factors against AD. There were no causal relationships between AD and any other dietary intake factors. Sensitivity analysis showed that our results were reliable, and no heterogeneity or pleiotropy was found. Therefore, we believe that beef intake may be associated with a reduced risk of AD. Although white bread was significant in the IVW analysis, there was large uncertainty in the results given the wide 95 % CI. Other factors were not associated with AD in this study.

Egg Allergy in Children and Weaning Diet

Eggs are a fundamental food in the human diet, and together with cow’s milk, they are the most common food allergen. This work highlights the main nutritional characteristics of eggs to show how their absence from a child’s diet can constitute a serious deficiency. We then analyze the risk factors that facilitate the onset of egg allergy. The third part of the paper reports possible interventions to lower the appearance of food allergy that have been occurred in trials. The last part of the paper is a synthesis of this research study that has been taken from several of the latest guidelines or from position papers.

BSACI 2021 guideline for the management of egg allergy

This guideline advises on the management of patients with egg allergy. Most commonly egg allergy presents in infancy, with a prevalence of approximately 2% in children and 0.1% in adults. A clear clinical history will confirm the diagnosis in most cases. Investigation by measuring egg-specific IgE (by skin prick testing or specific IgE assay) is useful in moderate-severe cases or where there is diagnostic uncertainty. Following an acute allergic reaction, egg avoidance advice should be provided. Egg allergy usually resolves, and reintroduction can be achieved at home if reactions have been mild and there is no asthma. Patients with a history of severe reactions or asthma should have reintroduction guided by a specialist. All children with egg allergy should receive the MMR vaccine. Most adults and children with egg allergy can receive the influenza vaccine in primary care, unless they have had anaphylaxis to egg requiring intensive care support. Yellow Fever vaccines should only be considered in egg-allergic patients under the guidance of an allergy specialist. This guideline was prepared by the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI) and is intended for allergists and others with a special interest in allergy. The recommendations are evidence based. Where evidence was lacking, consensus was reached by the panel of specialists on the committee. The document encompasses epidemiology, risk factors, diagnosis, treatment, prognosis and co-morbid associations.

Non-IgE Mediated Food Allergy

Food allergies, defined as an immune response to food proteins, affect as many as 8% of young children and 2% of adults in western countries, and their prevalence appears to be rising like all allergic diseases. In addition to well-recognized urticaria and anaphylaxis triggered by IgE antibody- mediated immune responses, there is an increasing recognition of cell-mediated disorders, such as eosinophilic esophagitis and food protein-induced enterocolitis. Non-IgE-Mediated gastrointestinal food allergies are a heterogeneous group of food allergies in which there is an immune reaction against food but the primary pathogenesis is not a production of IgE and activation of mast cells and basophils. Those diseases tend to affect mainly the gastrointestinal tract and can present as acute (FPIES) or chronic reaction, such as Eosinophilic Esophagitis (EoE), Food Protein-Induced Allergic Proctocolitis (FPIAP). The role of food allergy in Non-EoE gastrointestinal Eosinophilic disorders (Non- EoE EGID) is poorly understood. In some diseases like EoE, T cell seems to play a major role in initiating the immunological reaction against food, however, in FPIES and FPIAP, the mechanism of sensitization is not clear. Diagnosis requires food challenges and/or endoscopies in most of the patients, as there are no validated biomarkers that can be used for monitoring or diagnosis of Non-IgE mediated food allergies. The treatment of Non-IgE food allergy is dependent on diet (FPIES, and EoE) and/or use of drugs (i.e. steroids, PPI) in EoE and Non-EoE EGID. Non-IgE mediated food allergies are being being investigated.

Food Allergy Testing

Although the gold standard for diagnosis of immunoglobulin E (IgE)-mediated food allergy is an oral food challenge, clinically relevant biomarkers of IgE sensitization, including serum-specific IgE and skin prick testing, can aid in diagnosis. Clinically useful values have been defined for individual foods. More recently, specific IgE to particular protein components has provided additional diagnostic value. In summary, food allergy diagnostics to evaluate IgE sensitization are clinically useful and continue to evolve to improve evaluation of IgE-mediated food allergies.

Red Algae Sulfated Polysaccharides Effervescent Tablets Attenuated Ovalbumin-Induced Anaphylaxis by Upregulating Regulatory T cells in Mouse Models

Red algae sulfated polysaccharides (RASP) were extracted from Porphyra haitanensis and Gracilaria lemaneiformis. RASP were applied to effervescent tablets to develop a type of functional food, termed red algae sulfated polysaccharide effervescent tablets (RASPET), based on the antiallergic activities of RASP. The antiallergic activities and the mechanisms of RASPET were investigated in an ovalbumin (OVA)-induced mouse model of food allergy. The results revealed that RASPET alleviated intestinal villi injury by scanning electron microscopy and anaphylactic symptoms; reduced OVA-specific immunoglobulin E, histamine, and mast cell protease-1 levels in the serum; reduced the level of serum interleukin-4; increased serum interferon-γ level; and decreased B cell and mast cell populations. Remarkably, RASPET increased the levels of serum interleukin-10, transforming growth factor-β, and upregulated splenic CD4⁺foxp3⁺ T cell populations (15.28, 16.82, and 17.58%, respectively) compared to the OVA group (13.17%). In conclusion, RASPET attenuated OVA-induced anaphylaxis via the upregulation of regulatory T cells.

IgG1+ B-cell immunity predates IgE responses in epicutaneous sensitization to foods

BACKGROUND

The generation of IgE-mediated food allergy in humans is silent and only diagnosed upon manifestation of clinical symptoms. While experimental models have been used to investigate some mechanisms of allergic sensitization, the generation of humoral immunity and memory remains to be elucidated. Here, we defined the evolution of allergen-specific B-cell responses during epicutaneous sensitization to foods.

METHODS

Wild-type and genetic knockout animals, and drug or antibody strategies for cell depletion and immunoglobulin signaling blockade were used to investigate epicutaneous sensitization and disease progression; we analyzed allergen-specific germinal centers and IgG1⁺ memory B cells by flow cytometry, evaluated humoral responses, and determined clinical reactivity (anaphylaxis).

RESULTS

Epicutaneous sensitization caused microscopic skin damage, inflammation, and recruitment of activated dendritic cells to the draining lymph nodes. This process generated allergen-specific IgG1⁺ germinal center B cells, serum IgG1, and anaphylaxis that was mediated by the alternative pathway. Whether we used peanut and/or ovalbumin from the egg white for sensitization, the allergen-specific IgG1⁺ memory compartment predominantly exhibited an immature, pro-germinal center phenotype (PDL-2^- CD80^- CD35⁺ CD73⁺ ). Subsequent subclinical exposures to the allergen induced IgE⁺ germinal center B cells, serum IgE, and likely activated the classical pathway of anaphylaxis.

CONCLUSIONS

Our data demonstrate that IgG1⁺ B-cell immunity against food allergens in epicutaneous sensitization precedes the generation of IgE responses. Therefore, the assessment of allergen-specific cellular and humoral IgG1⁺ immunity may help to identify individuals at risk of developing IgE-mediated food allergy and hence provide a window for therapeutic interventions.

The Initiation of Th2 Immunity Towards Food Allergens

In contrast with Th1 immune responses against pathogenic viruses and bacteria, the incipient events that generate Th2 responses remain less understood. One difficulty in the identification of universal operating principles stems from the diversity of entities against which cellular and molecular Th2 responses are produced. Such responses are launched against harmful macroscopic parasites and noxious substances, such as venoms, but also against largely innocuous allergens. This suggests that the established understanding about sense and recognition applied to Th1 responses may not be translatable to Th2 responses. This review will discuss processes and signals known to occur in Th2 responses, particularly in the context of food allergy. We propose that perturbations of homeostasis at barrier sites induced by external or internal subverters, which can activate or lower the threshold activation of the immune system, are the major requirement for allergic sensitization. Innate signals produced in the tissue under these conditions equip dendritic cells with a program that forms an adaptive Th2 response.

Early introduction of allergenic foods for the prevention of food allergy from an Asian perspective-An Asia Pacific Association of Pediatric Allergy, Respirology & Immunology (APAPARI) consensus statement

Emerging evidence for the early introduction of allergenic foods for the prevention of food allergies, such as peanut allergy in Western populations, has led to the recent publication of guidelines in the USA and Europe recommending early peanut introduction for high-risk infants with severe eczema or egg allergy. Peanut allergy is, however, much less prevalent in Asia compared to the West. Varying patterns of food allergy are seen even within Asian countries-such as a predominance of wheat allergy in Japan and Thailand and shellfish allergy in Singapore and the Philippines. Customs and traditions, such as diet and infant feeding practices, also differ between Asian populations. Hence, there are unique challenges in adapting guidelines on early allergenic food introduction to the Asian setting. In this paper, we review the evidence and discuss the possible approaches to guide the timely introduction of allergenic food in high-risk infants in Asia.

Diagnostic values for egg white specific IgE levels with the skin prick test in Turkish children with egg white allergy

BACKGROUND

The diagnostic values for the skin prick test (SPT) diameters and egg white-specific IgE (EW-sIgE) levels that will allow us to predict the result of the oral food challenge test (OFC) in the diagnosis of egg white allergy vary by the community where the study is carried out.

OBJECTIVE

This study aimed to determine the diagnostic values of SPT and EW-sIgE levels in the diagnosis of egg white allergy.

METHODS

59 patients followed with the diagnosis of egg allergy September 2013 to September 2015 were included in our retrospective cross-sectional study. The patients were investigated in terms of egg and anaphylaxis history or the requirement of the OFC positivity. The demographic, clinical and laboratory findings of the cases were recorded, and they were compared with the patients with the suspected egg allergy but negative OFC (n=47).

RESULTS

In the study, for all age groups, the value of 5mm in SPT was found to be significant at 96.4% positive predictive value (PPV) and 97.8% specificity and the value of 5.27kU/L for EW-sIgE was found to be significant at 76% PPV and 86.6% specificity for egg white. The diagnostic power of the SPT for egg white (AUC: 72.2%) was determined to be significantly higher compared to the diagnostic power of the EW-sIgE (AUC: 52.3%) (p<0.05).

CONCLUSION

Along with the determination of the diagnostic values of communities, the rapid and accurate diagnosis of the children with a food allergy will be ensured, and the patient follow-up will be made easier.

Nutrition and skin: Kids are not just little people

There has been a surge of new data regarding the pathophysiology of skin diseases. We are appreciating the sophisticated interplay among the skin, the immune system, and the environment. More elegant and highly specific medicines have been designed to target certain immune mediators of the adaptive immune system. In parallel fashion, we are learning more about the elegance of the innate immune system and how nutrition as early as the prenatal period can affect the priming of other immune cells. Concerns about the long-term impact of new immune-modulating medicines-especially in the pediatric population-have patients asking their dermatologists for nutritional alternatives to medical therapies. Nutrients and nutritional therapies appear to play a role at different ages for different dermatoses. Probiotics are showing promise as a therapeutic option for patients older than 1 year for atopic dermatitis. Systemic contact allergens appear to be a bigger burden on the adult population with atopic dermatitis. Obesity is a growing concern for both children and adults with psoriasis. Milk and high glycemic foods have a strong impact on the teenage acne population. Vitamins A and D are addressed as piece of the alopecia areata puzzle. Zinc and homeopathy are presented finally as possible treatments to the everlasting wart.

Consensus Conference on Clinical Management of pediatric Atopic Dermatitis

The Italian Consensus Conference on clinical management of atopic dermatitis in children reflects the best and most recent scientific evidence, with the aim to provide specialists with a useful tool for managing this common, but complex clinical condition. Thanks to the contribution of experts in the field and members of the Italian Society of Pediatric Allergology and Immunology (SIAIP) and the Italian Society of Pediatric Dermatology (SIDerP), this Consensus statement integrates the basic principles of the most recent guidelines for the management of atopic dermatitis to facilitate a practical approach to the disease. The therapeutical approach should be adapted to the clinical severity and requires a tailored strategy to ensure good compliance by children and their parents. In this Consensus, levels and models of intervention are also enriched by the Italian experience to facilitate a practical approach to the disease.

Is it possible to make a diagnosis of raw, heated, and baked egg allergy in children using cutoffs? A systematic review

The diagnosis of IgE-mediated egg allergy lies both on a compatible clinical history and on the results of skin prick tests (SPTs) and IgEs levels. Both tests have good sensitivity but low specificity. For this reason, oral food challenge (OFC) is the ultimate gold standard for the diagnosis. The aim of this study was to systematically review the literature in order to identify, analyze, and synthesize the predictive value of SPT and specific IgEs both to egg white and to main egg allergens and to review the cutoffs suggested in the literature. A total of 37 articles were included in this systematic review. Studies were grouped according to the degree of cooking of the egg used for OFC, age, and type of allergen used to perform the allergy workup. In children <2 years, raw egg allergy seems very likely when SPTs with egg white extract are ≥4 mm or specific IgEs are ≥1.7 kUA /l. In children ≥2 years, OFC could be avoided when SPTs with egg white extract are ≥10 mm or prick by prick with egg white is ≥14 mm or specific IgE is ≥7.3 kUA /l. Likewise, heated egg allergy can be diagnosed if SPTs with egg white extract are >5 and >11 mm in children <2 and ≥2 years, respectively. Further and better-designed studies are needed to determine the remaining diagnostic cutoff of specific IgE and SPT for heated and baked egg allergy.

Egg Allergy in Adolescent and Adult Patient Suffering from Atopic Dermatitis – Association with Concomitant Allergic Diseases

Background: A few reports demonstrate the occurrence of egg allergy in adolescent and adult patients suffering from atopic dermatitis and the association of this allergy to other food and aeroallergens. Aims and Objectives: The aim of this study is to evaluate the occurrence of egg allergy in patients suffering from atopic dermatitis at the age 14 years and older and to evaluate the relationship between egg allergy or egg sensitisation and the sensitisation to dust, mites, feather, and animal dander. Materials and Methods: Complete dermatological and allergological examination was performed. These parameters were examined: food allergy and food sensitisation to egg white and yolk, to mites, animal dander (mixture), feather and dust. The statistical evaluation of the relations among egg allergy, egg sensitisation and sensitisation to mites, animal dander (mixture), feather and dust was performed. Two hundred and eighty eight patients were included in the study (90 men, 198 women, with the average age 25.2). Results and Conclusion: Egg allergy was recorded in 5% and egg sensitisation in 20% of patients; sensitisation to dust is recorded more often in patients with positive results in sIgE for egg white and/or yolk.

Allergenicity of pasteurized whole raw Hen's egg compared with fresh whole raw Hen's egg

BACKGROUND

Oral food challenges for diagnosis and management of egg allergy using fresh egg are common; however, to limit the risk of foodborne infection, many allergy units use pasteurized raw egg. Pasteurization and drying processes have the potential to affect the structure of egg proteins in egg powder and thus the allergenicity when compared to fresh egg. Our aim was to compare the binding of serum IgE from egg-allergic children to in vitro digested and undigested pasteurized whole raw egg powder with unpasteurized fresh whole raw egg.

METHODS

Egg proteins from in vitro digested or undigested pasteurized whole raw egg powder, fresh whole egg, egg white and egg yolk were separated by SDS-PAGE, transferred onto nitrocellulose membrane and incubated overnight with pooled sera from egg-allergic children.

RESULTS

In both the raw egg samples and the pasteurized whole egg powder, protein bands corresponding to known molecular weights of the major egg allergens were present. Pasteurized whole raw egg powder was bound by serum IgE in a similar manner to unpasteurized whole raw egg and was unaffected by in vitro digestion. Serum IgE also bound egg yolk, indicating sensitization to both egg yolk and egg white proteins.

CONCLUSIONS

The main egg allergens are present in pasteurized whole raw egg powder, and serum IgE of egg-allergic children binds to them in a similar pattern to those in fresh whole raw egg. Pasteurized whole raw egg powder is a suitable substitute for raw egg in clinical practice for oral food challenges.

Eczema in early childhood, sociodemographic factors and lifestyle habits are associated with food allergy: a nested case-control study

BACKGROUND

Studies suggest an increase in food allergy prevalence over the last decade, but the contributing factors remain unknown. The aim of this study was to evaluate the association between the most common food allergies and atopic history, sociodemographic characteristics and lifestyle habits.

METHODS

We conducted a case-control study nested within the SPAACE study (Surveying Prevalence of Food Allergy in All Canadian Environments) – a cross-Canada, random telephone survey. Cases consisted of individuals with probable food allergy (self-report of convincing symptoms and/or physician diagnosis) to milk, egg, peanut, tree nut, shellfish, fish, wheat, soy, or sesame. Controls consisted of nonallergic individuals, matched for age. Cases and controls were queried on personal and family history of atopy, sociodemographic characteristics and lifestyle habits. Multivariate logistic regression was used to evaluate the association between atopy, sociodemographic characteristics and lifestyle habits with probable food allergy.

RESULTS

Between September 2010 and September 2011, 480 cases and 4,950 controls completed the questionnaire. For all 9 allergens, factors associated with a higher risk of probable allergy were as follows: (1) personal history of eczema (in the first 2 years of life), asthma or hay fever (odds ratio, OR 2.3, 95% CI 1.6-3.5; OR 2.8, 95% CI 2.2-3.6, and OR 2.3, 95% CI 1.8-3.0, respectively), (2) maternal, paternal or sibling's food allergy (OR 3.7, 95% CI 2.5-5.6; OR 3.0, 95% CI 1.8-5.1, and OR 3.1, 95% CI 2.2-4.2), (3) high household income (top 20%; OR 1.5, 95% CI 1.2-2.0). Males and older individuals were less likely to have food allergy (OR 0.7, 95% CI 0.6-0.9, and OR 0.99, 95% CI 0.99-1.00). Eczema in the first 2 years of life was the strongest risk factor for egg, peanut, tree nut and fish allergy.

CONCLUSIONS

This is the largest population-based nested case-control study exploring factors associated with food allergies. Our results reveal that, in addition to previously reported factors, eczema in the first 2 years of life is consistently associated with food allergies.

Nutritional management of food protein-induced enterocolitis syndrome

PURPOSE OF REVIEW

To summarize the latest information on the nutritional management of food protein-induced enterocolitis syndrome (FPIES), focusing on the foods implicated and how to avoid these whilst maintaining a nutritionally sound diet.

RECENT FINDINGS

A number of foods are implicated in FPIES such as milk, soy and grains, particularly rice. The number of foods implicated in FPIES per individual differs, but the majority of reported cases have two or fewer food triggers involved.

SUMMARY

FPIES is a complex presentation of non-IgE-mediated food allergy. Dietary management is complicated as both common food allergens as well as atypical food allergens can trigger FPIES. Sound nutritional advice is required to ensure appropriate food avoidance, adequate consumption of other foods and sufficient nutritional intake to maintain and ensure growth and development.

Tolerance to egg proteins in egg-sensitized infants without previous consumption

BACKGROUND

Egg-sensitized infants who have never eaten egg may react at first ingestion. We sought to determine the association between skin prick test (SPT) and specific IgE (sIgE) to egg proteins (EP) and oral food challenge (OFC) outcomes to find cut-off points which can diagnose egg allergy.

METHODS

One hundred and fifty-four infants up to 18 months, with cow's milk allergy (CMA) and/or atopic dermatitis (AD) without previous egg consumption, were recruited. SPT to EP were performed. If it was positive, sIgE was performed. If positive SPT and/or sIgE (n = 94), OFC was performed between 12 and 18 months. Receiver operating characteristic (ROC) curves were plotted, and the outcome of the OFC was related to SPT and sIgE. The cut-off points with the best diagnostic accuracy were found.

RESULTS

Ninety-four patients were sensitized to egg (69%) and 60 nonsensitized (31%). Of the sensitized, 27 tolerated cooked (CE) and raw egg (RE) (28.7%). Sixty-seven were allergic (71.3%): 29 reacted to CE, seven to egg yolk (EY) and 22 to egg white (EW) and 38 reacted to RE. 69.2% tolerated CE. EW SPT and ovalbumin (OVA) sIgE have the best area under the curve (AUC). The higher positive predictive values (PPV) were obtained for EW SPT and EW sIgE.

CONCLUSIONS

In egg-sensitized infants with EW SPT ≥8 mm and/or EW sIgE ≥8.36 KU/l, egg diagnostic OFC can be avoided as there is 94% probability of becoming positive. In the other patients, OFC should be performed safely and early to avoid unnecessary diets.

The skin prick test is not useful in the diagnosis of the immediate type food allergy tolerance acquisition

BACKGROUND

Some studies have been reported about positioning of SPT in the diagnosis of food allergy. On the other hand, it is not yet clear about the positioning of SPT in the diagnosis of tolerance acquisition of the immediate type food allergy.

METHODS

The retrospective study had been conducted for 236 egg allergic children (51.3 months in mean), 127 milk allergic children (53.4 months), and 96 wheat allergic children (42.6 months). The retrospective analysis of serum nonspecific and antigen-specific IgE levels, SPT, and OFC had been conducted for each allergic patient. All OFC had been conducted to verify the acquisition of tolerance against eliminated food.

RESULTS

The OFC was positive in 61 (25.8%) hen's egg allergies, 34 (26.8%) milk allergies and 33 (34.4%) wheat allergies. The greatest AUC for each allergen is as following; hen's egg for egg white specific IgE at 0.745, milk/histamine (wheal) index at 0.718, and wheat for wheal size at 0.597. For the predictive decision points, the highest accuracy rate was at 25.8% for an egg white wheal of 9.5mm, at 26.8% for a milk wheal of 9.5mm, and at 34.4% for a wheal of 6.5mm.

CONCLUSIONS

As a result of this analysis, the diagnostic accuracy of SPT had not been satisfactory to judge the acquisition of tolerance in allergic children for eggs, milk and wheat. Therefore, this is not a strong evidence to testify the tolerance of the immediate type food allergy.

Risk of adverse IgE-mediate reaction at the first egg ingestion in children with atopic dermatitis. Results of a case-control study

BACKGROUND

Studies have reported that children with atopic dermatitis (AD) have a high risk of adverse reactions at first egg ingestion.

METHODS

We enrolled 79 children with AD retrospectively and 45 children without AD (control group) prospectively, who had never eaten egg. All children underwent skin prick tests (SPT) with commercial extracts and prick by prick with natural food (raw and boiled egg). Oral food challenge (OFC) was performed in SPT positive patients.

RESULTS

Sixty-six percent (52/79) of AD group and 11% (5/45) of Control group had at least one positive SPT (p<0.001), Relative Risk (RR)=5.9 and Odds Ratio=15.4. Of the 46/52 sensitised children in the AD group, 36 children ate egg for the first time in hospital during an OFC and 10 children ate egg at home because of their parents' choice, with 19/46 (41%) resulting in allergic reactions to raw and/or boiled egg. Four/five sensitised children in the control group underwent OFC and three of them (75%) showed an allergic reaction to raw, but not boiled egg. Thirty percent (14/46) of AD group had a systemic reaction vs. 25% (1/4) of Control group.

CONCLUSION

A child with AD has a RR of sensitisation to egg six times higher than a child without AD, before the first known ingestion. We propose to test sensitisation to egg in every child with AD who has never eaten egg, and to perform OFC in those with positive SPT in hospital setting.

The natural history of IgE-mediated food allergy: can skin prick tests and serum-specific IgE predict the resolution of food allergy?

IgE-mediated food allergy is a transient condition for some children, however there are few indices to predict when and in whom food allergy will resolve. Skin prick test (SPT) and serum-specific IgE levels (sIgE) are usually monitored in the management of food allergy and are used to predict the development of tolerance or persistence of food allergy. The aim of this article is to review the published literature that investigated the predictive value of SPT and sIgE in development of tolerance in children with a previous diagnosis of peanut, egg and milk allergy. A systematic search identified twenty-six studies, of which most reported SPT or sIgE thresholds which predicted persistent or resolved allergy. However, results were inconsistent between studies. Previous research was hampered by several limitations including the absence of gold standard test to diagnose food allergy or tolerance, biased samples in retrospective audits and lack of systematic protocols for triggering re-challenges. There is a need for population-based, prospective studies that use the gold standard oral food challenge (OFC) to diagnose food allergy at baseline and follow-up to develop SPT and sIgE thresholds that predict the course of food allergy.

Position document: IgE-mediated allergy to egg protein

Egg is the food that most often causes allergy in young Spanish children, with an incidence of 2.4-2.6% in the first 2 years of life. The prevalence of sensitisation and allergy to egg is greater in children with allergy to cow's milk and in those suffering atopic dermatitis. The protein component from egg white is the cause of the allergic response in child. The major allergens in egg white are ovomucoid and ovalbumin. Most of the allergic reactions affect the skin, followed by gastrointestinal and respiratory systems. Egg allergy is one of the most common causes of severe anaphylaxis. The diagnosis of egg allergy is based on the existence of a suggestive clinical history, a positive allergy study and the subsequent application of controlled exposure testing, which represents the gold standard for confirming the diagnosis. The treatment of egg allergy is based on the avoidance of egg protein intake. A subgroup of egg-allergic patients are tolerant to cooked egg. In these cases, only uncooked egg must necessarily be avoided. Maintaining a diet with strict egg avoidance is difficult, and transgressions are relatively common. The patient, family, and school environment should receive education and training in the avoidance of egg and in the management of possible allergic reactions. With an avoidance diet, up to 15-20% of children will remain allergic and the severity of the reactions will increase over the years. In these more severe cases of egg-allergy, it becomes more difficult to adhere to the avoidance diet over the years, with a significant decrease in patient quality of life. Oral tolerance induction can be regarded as a therapeutic option for IgE-mediated egg allergy. The anti-IgE, omalizumab, might become another genuine therapeutic option for food allergy, not only to prevent allergic reactions after a contact with egg, but also as a complementary treatment to oral tolerance induction for egg allergy, with the purpose of reducing adverse reactions. The administration of influenza vaccine to children with egg allergy is safe in children that do not manifest severe reactions after egg intake, and in children who tolerate cooked egg. The triple viral vaccine (MMR) can be given to egg-allergic children in their usual vaccination centre, with no added risk. Different medicinal products can be formulated with egg proteins, and therefore should be avoided in children with egg allergy.

Skin prick test responses and allergen-specific IgE levels as predictors of peanut, egg, and sesame allergy in infants

BACKGROUND

Ninety-five percent positive predictive values (PPVs) provide an invaluable tool for clinicians to avoid unnecessary oral food challenges. However, 95% PPVs specific to infants, the age group most likely to present for diagnosis of food allergy, are limited.

OBJECTIVE

We sought to develop skin prick test (SPT) and allergen-specific IgE (sIgE) thresholds with 95% PPVs for challenge-confirmed food allergy in a large population-based cohort of 1-year-old infants with challenges undertaken irrespective of SPT wheal size or previous history of ingestion.

METHODS

HealthNuts is a population-based, longitudinal food allergy study with baseline recruitment of 1-year-old infants. Infants were recruited from council-run immunization sessions during which they underwent SPTs to 4 allergens: egg, peanut, sesame, and cow's milk/shrimp. Any infant with a detectable SPT response was invited to undergo oral food challenge and sIgE testing.

RESULTS

Five thousand two hundred seventy-six infants participated in the study. Peanut SPT responses of 8 mm or greater (95% CI, 7-9 mm), egg SPT responses of 4 mm or greater (95% CI, 3-5 mm), and sesame SPT responses of 8 mm or greater (95% CI, 5-9 mm) had 95% PPVs for challenge-proved food allergy. Peanut sIgE levels of 34 kUA/L or greater (95% CI, 14-48 kUA/L) and egg sIgE levels of 1.7 kUA/L or greater (95% CI, 1-3 kUA/L) had 95% PPVs for challenge-proved food allergy. Results were robust when stratified on established risk factors for food allergy. Egg SPT responses and sIgE levels were poor predictors of allergy to egg in baked goods.

CONCLUSION

These 95% PPVs, which were generated from a unique dataset, are valuable for the diagnosis of food allergy in young infants and were robust when stratified across a number of different risk factors.

Early regular egg exposure in infants with eczema: A randomized controlled trial

BACKGROUND

Observational studies suggest that early regular ingestion of allergenic foods might reduce the risk of food allergy.

OBJECTIVE

We sought to determine whether early regular oral egg exposure will reduce subsequent IgE-mediated egg allergy in infants with moderate-to-severe eczema.

METHODS

In a double-blind, randomized controlled trial infants were allocated to 1 teaspoon of pasteurized raw whole egg powder (n = 49) or rice powder (n = 37) daily from 4 to 8 months of age. Cooked egg was introduced to both groups after an observed feed at 8 months. The primary outcome was IgE-mediated egg allergy at 12 months, as defined based on the results of an observed pasteurized raw egg challenge and skin prick tests.

RESULTS

A high proportion (31% [15/49]) of infants randomized to receive egg had an allergic reaction to the egg powder and did not continue powder ingestion. At 4 months of age, before any known egg ingestion, 36% (24/67) of infants already had egg-specific IgE levels of greater than 0.35 kilounits of antibody (kUA)/L. At 12 months, a lower (but not significant) proportion of infants in the egg group (33%) were given a diagnosis of IgE-mediated egg allergy compared with the control group (51%; relative risk, 0.65; 95% CI, 0.38-1.11; P = .11). Egg-specific IgG4 levels were significantly (P < .001) greater in the egg group at both 8 and 12 months.

CONCLUSION

Induction of immune tolerance pathways and reduction in egg allergy incidence can be achieved by early regular oral egg exposure in infants with eczema. Caution needs to be taken when these high-risk infants are first exposed to egg because many have sensitization already by 4 months of age.

Food allergy: temporal trends and determinants

This review summarizes studies discussing temporal trends in the prevalence of food allergy as well as potential factors associated with the development of food allergy. In addition, we will address the potential hypotheses accounting for the apparent increase in food allergy prevalence. Studies suggest increased prevalence of food allergy. However, relatively little is known about its pathogenesis. This review aims to assess temporal trends in the prevalence of food allergy and discuss potential genetic, environmental, and demographic determinants. The search strategy examined the medical literature database MEDLINE (using PubMed) for the time period of January 1, 2002 to January 31, 2012. In recent decades, the prevalence of food allergy in general has increased by 0.60 % [95 % confidence interval (CI), 0.59 %-0.61 %] and the prevalence of peanut allergy by 0.027 % (95 % CI, 0.026 %-0.028 %), but it has now likely stabilized in developed countries. Genes, the environment, and demographic characteristics play a role in the pathogenesis of food allergy. Numerous environmental and demographic factors as well as gene-environment interactions may account for this increase in prevalence, but further studies are required to tease out their relative contribution.

IgE-mediated cow milk allergy and infantile colic: diagnostic and management challenges

Cow milk allergy (CMA) is a common problem affecting 2-3% of children and is the most prevalent food allergy in infancy. Infantile colic is also a common problem in the first year of life. A frequent practice among physicians is to recommend a dairy-free diet to breast-feeding mothers and infants in cases of infantile colic. However, recent studies suggest that late introduction of potentially allergenic foods may increase the risk of developing a life-threatening food allergy. We describe two infants managed with dairy-free diet to control symptoms of colic in whom CMA developed. It is possible that unnecessary cow milk restriction may have contributed to the development of food allergy in these infants.

Oral food challenge: safety, adherence to guidelines and predictive value of skin prick testing

BACKGROUND

The diagnostic gold standard of food allergy is the oral food challenge (OFC). Data on severe reactions and drug use during OFC are scarce. Our aims were (i) to investigate the prevalence and spectrum of reactions' severity during OFC and to assess drug use and epinephrine use in anaphylaxis due to OFC; (ii) to investigate the predictive value of the skin prick test wheal size for the outcome of OFCs.

METHODS

A retrospective charts review of children undergoing OFC at three Allergy Centres between January 2007 and December 2008 was performed.

RESULTS

A total of 544 OFCs were analysed. Most frequently involved foods were egg, milk and wheat. 254/526 (48.3%) were positive. 167 (65.7%) were defined mild reactions, 81 (31.9%) multiorgan reactions and 6 (2.4%) anaphylaxis. No patients had cardiovascular symptoms. Data on treatments were available in 98.8% OFCs. In half of them antihistamines were used vs. 10% cases in which steroids were preferred. Six children (2.4%) were treated with Epinephrine inhalation, 5 (2%) with beta-2 inhalation, 8 (3.1%) with steroid inhalation. One child was treated with IM Epinephrine + IV fluids. Skin prick tests predictive cut-off were 9 mm for albumen, 7 for yolk, 13 for fresh albumen, 10 for α-lactalbumin, seven for casein, eight for β-lactoglobulin, 20 for cow's milk and 10 for fresh cow's milk.

CONCLUSION

OFCs performed in controlled settings by expert Allergists are safe. Consideration needs to be given as to whether the Anaphylaxis' Guideline need to be modified when applied in treating patients undergoing OFC.

Absence of clinical symptoms upon introduction of egg into the diet of milk-allergic infants not previously sensitised to egg

BACKGROUND

It is unclear how many children suffering from IgE mediated cow's milk allergy are sensitised to egg in early life and what the clinical implication of this sensitisation is. It is also unclear if those not sensitised to egg in early life, do later on develop sensitisation and clinical allergy to egg.

METHODS

This study examines the prevalence of egg sensitisation among infants with allergy to cow's milk, prior to and following the introduction of egg and what this sensitisation clinically means.

RESULTS

The percentage of egg-sensitised children seen among the group of children with cow's milk allergy was 43.2%, and predictive factors for egg sensitisation are discussed. 81.8% of the sensitised patients presented with symptoms when exposed to egg in at least one of its forms, although up to 54.5% of patients tolerated boiled egg and egg-based products. Of the non-sensitised patients, the vast majority (92.5%) did not present with symptoms after the introduction of egg in their diet.

CONCLUSIONS

Coexistence of allergy to egg and milk allergy is common, and it is recommended that these patients be monitored, since children who are sensitised to egg despite having never been exposed to it in their diet, may present with symptoms immediately following first ingestion. Most children who are initially non-sensitised to egg do not require special care, and it is not generally recommended to delay or monitor these children, although a small number may have subsequently reacted to egg.

The predictive value of skin prick testing for challenge-proven food allergy: a systematic review

Immunoglobulin E-mediated (IgE) food allergy affects 6-8% of children, and the prevalence is believed to be increasing. The gold standard of food allergy diagnosis is oral food challenges (OFCs); however, they are resource-consuming and potentially dangerous. Skin prick tests (SPTs) are able to detect the presence of allergen-specific IgE antibodies (sensitization), but they have low specificity for clinically significant food allergy. To reduce the need for OFCs, it has been suggested that children forgo an OFC if their SPT wheal size exceeds a cutoff that has a high predictability for food allergy. Although data for these studies are almost always gathered from high-risk populations, the 95% positive predictive values (PPVs) vary substantially between studies. SPT thresholds with a high probability of food allergy generated from these studies may not be generalizable to other populations, because of highly selective samples and variability in participant's age, test allergens, and food challenge protocol. Standardization of SPT devices and allergens, OFC protocols including standardized cessation criteria, and population-based samples would all help to improve generalizability of PPVs of SPTs.

Current understanding of egg allergy

Egg is one of the most important allergens in childhood feeding, and egg allergy can pose quality-of-life concerns. A clear clinical history and the detection of egg white-specific immunoglobulin E (IgE) will confirm the diagnosis of IgE-mediated reactions. Non-IgE-mediated symptoms, such as those of eosinophilic diseases of the gut, might also be observed. Egg avoidance and education regarding the treatment of allergic reactions are the cornerstones of management of egg allergy. This article discusses epidemiology, risk factors, diagnosis, treatment, and natural history of egg allergy.

In utero anaphylaxis

Late fetal demise and hypoxic-ischemic neurologic injury after previously normal in utero development remain devastating outcomes of pregnancy, for which no cause is identified in many cases. Based on a case encountered, I propose that some of these incidents may be due to in utero anaphylaxis to food antigens that cross the placenta. Potential allergens to which pregnant women are exposed can be transported across the placenta, and the fetus is capable of producing IgE, the antibody responsible for anaphylaxis in humans. Whether this IgE is antigen specific is controversial with some studies indicating the ability to generate IgE to food antigens prenatally. Indirect evidence for in utero production of specific IgE is the high percentage of food reactions that occur on the first postnatal exposure to the food. I propose that some cases of stillbirth and prenatal hypoxic-ischemic injury may be due to in utero anaphylaxis.

Results of the oral egg-challenge test performed on two different groups of children. One group with a history, suggestive of allergic reaction with egg intake and the other group sensitised to hen's egg without previous egg intake

INTRODUCTION

Egg allergy is an adverse immune-system reaction of an IgE-mediated type, which can happen in children after egg intake and several times after their first egg intake.

OBJECTIVES

Compare the results of the oral egg-challenge test in two groups of egg-sensitised children, with and without prior intake.

PATIENTS AND METHODS

Retrospective study of two egg-sensitised groups (72 subjects). Group 1: 22 children without prior egg-intake. Group 2: 50 children with a clinical history of adverse reactions after egg intake. Skin prick tests, egg-white specific IgE (sIgE) and yolk specific IgE, were performed on all children. The oral egg-challenge tests were performed after a period of egg-avoidance diet and when egg-white specific IgE levels were lower than 1.5K U/L.

RESULTS

31.8% of the children in Group 1 did not tolerate egg-intake whereas 38% of the children in Group 2 did not tolerate egg-intake. Egg-avoidance periods lasted 19.5 and 18 months, respectively. Egg-white specific IgE levels went down in both groups after an egg-avoidance diet. No statistically significant differences were found between the groups and the positivity of oral egg-challenge test.

CONCLUSIONS

No statistically significant differences were found in the behaviour of the two groups studied. Given the high risk of adverse reactions, it was recommended that any egg-introduction tests were to be performed in a hospital environment on the children who were sensitised to hen's egg (including children without prior egg intake).

Childhood Food Allergy: A Singaporean Perspective

Food allergy is defined as reaction to a food which has an immunologic mechanism. Its prevalence is increasing in children globally and is therefore of increasing clinical importance. A useful clinical approach is to distinguish food allergic reactions by the timing of clinical reaction in relation to food exposure and classified as immediate (generally IgE-mediated) and delayed (generally non-IgE-mediated), with the exception of eczema and eosinophilic gastrointestinal disease, which, when associated with food allergy may be associated with either mechanism. This review is aimed at providing the clinician with a Singaporean perspective on the clinical approach and management of these disorders. Key words: Asia, Children, Food allergy

State of the art and new horizons in the diagnosis and management of egg allergy

Egg allergy is one of the most frequent food allergies in children below the age of three. Common symptoms of egg allergy involve frequently the skin as well as the gut and in more severe cases result in anaphylaxis. Non-IgE-mediated symptoms such as in eosinophilic diseases of the gut or egg-induced enterocolitis might also be observed. Sensitization to egg white proteins can be found in young children in absence of clinical symptoms. The diagnosis of egg allergy is based on the history, IgE tests as well as standardized food challenges. Ovomucoid is the major allergen of egg, and recent advances in technology have improved the diagnosis and follow-up of patients with egg allergy by using single allergens or allergens with modified allergenic properties. Today, the management of egg allergy is strict avoidance. However, oral tolerance induction protocols, in particular with egg proteins with reduced allergenic properties, are promising tools for inducing an increased level of tolerance in specific patients.

Clinical practice: Breastfeeding and the prevention of allergy

The increase in allergic disease prevalence has led to heightened interest in the factors determining allergy risk, fueled by the hope that by influencing these factors one could reduce the prevalence of allergic conditions. The most important modifiable risk factors for allergy are maternal smoking behaviour and the type of feeding. A smoke-free environment for the child (to be), exclusive breastfeeding for 4-6 months and the postponement of supplementary feeding (solids) until 4 months of age are the main measures considered effective. There is no place for restricted diets during pregnancy or lactation. Although meta-analyses suggest that hypoallergenic formula after weaning from breastfeeding grants protection against the development of allergic disease, the evidence is limited and weak. Moreover, all current feeding measures aiming at allergy prevention fail to show effects on allergic manifestations later in life, such as asthma. In conclusion, the allergy preventive effect of dietary interventions in infancy is limited. Counselling of future parents on allergy prevention should pay attention to these limitations.

Food allergy: review, classification and diagnosis

Food allergies, defined as an immune response to food proteins, affect as many as 8% of young children and 2% of adults in westernized countries, and their prevalence appears to be rising like all allergic diseases. In addition to well-recognized urticaria and anaphylaxis triggered by IgE antibody-mediated immune responses, there is an increasing recognition of cell-mediated disorders such as eosinophilic esophagitis and food protein-induced enterocolitis. New knowledge is being developed on the pathogenesis of both IgE and non-IgE mediated disease. Currently, management of food allergies consists of educating the patient to avoid ingesting the responsible allergen and initiating therapy if ingestion occurs. However, novel strategies are being studied, including sublingual/oral immunotherapy and others with a hope for future.

Egg allergy in childhood: an update

PURPOSE OF REVIEW

Allergy to hen's egg is common in infancy and childhood. The management of egg allergy involves dietary avoidance of egg-containing foods, implementation of anaphylaxis precautions and ongoing monitoring for tolerance development. In this article, we review the recent literature regarding the immunology, clinical presentation, diagnosis, management and natural history of egg allergy.

RECENT FINDINGS

Retrospective studies suggest that most egg-allergic children will become tolerant over time. Regular ingestion of small quantities of cooked egg in baked products is often well tolerated and may hasten tolerance development. Influenza vaccination of egg-allergic patients remains controversial, and immunization of patients with previous significant reactions or anaphylaxis to egg is currently not recommended. In recent years, there has been increasing success in clinical trials of specific oral tolerance induction to egg, but concerns regarding the safety and long-term efficacy still preclude the use of oral immunotherapy in clinical practice.

SUMMARY

Egg allergy generally has a good prognosis. Despite recent advances in oral immunotherapy trials, the treatment of egg allergy currently relies on avoidance of egg-containing foods until tolerance has developed. It remains unclear whether the ongoing low-dose exposure to egg proteins in cooked foods improves the natural history of egg allergy.

Food allergy: is strict avoidance the only answer?

It is an immunological paradigm that avoidance of food allergen may reduce the risk or prevent immunological reactions and conversely that a greater exposure increases the magnitude of the immune response. Consequently, food allergen avoidance has been recommended to reduce the risk of sensitization in infants and to prevent clinical reactions in children with positive skin prick tests (SPT). In the latter setting, it is hoped that avoidance may either promote or at least not retard the development of tolerance. Animal studies, however, have demonstrated that tolerance to food allergens may be induced by either large (high zone tolerance) or small (low zone tolerance) doses, whereas doses in between may actually stimulate immune responses. In this review, we discuss whether strict allergen avoidance is always the most appropriate strategy for preventing or managing IgE-mediated food allergy.

Skin prick tests and allergy diagnosis

Skin testing remains an essential diagnostic tool in modern allergy practice. A significant variability has been reported regarding technical procedures, interpretation of results and documentation. This review has the aim of consolidating methodological recommendations through a critical analysis on past and recent data. This will allow a better understanding on skin prick test (SPT) history; technique; (contra-) indications; interpretation of results; diagnostic pitfalls; adverse reactions; and variability factors.

Ready-to-use introduction schedules for first exposure to allergenic foods in children at home

BACKGROUND

The vast majority of children will undergo their first exposure to common allergenic foods at home. However, the first exposure may lead to clinical reactions. It has been proposed to introduce allergenic foods gradually into the diets of children at risk for food allergy, but no practical dietary advice has been devised.

OBJECTIVE

The aim of this study was to devise safe introduction schedules for common allergenic foods for use at home, based on the challenge doses as administered in double-blind, placebo-controlled food challenge (DBPCFCs) in children who were never exposed previously to these foods.

METHODS

Seventy-two DBPCFCs were performed in 63 children as a first known exposure. The incrementing challenge doses were converted into equivalent portions of these foods in their usual household form and incorporated in introduction schedules. The feasibility of the introduction scales was tested in parents of the children attending our clinic.

RESULTS

Based on the results of the positive challenges (37) in which severe reactions did not occur, detailed introduction schedules and a reference photograph of the required increasing amounts of food were devised for use at home. Feasibility testing showed that, when using these introduction schedules, parents portioned the initial doses significantly lower than without detailed instructions.

CONCLUSIONS

The introduction schedules and reference photograph provide information for parents to introduce the required amounts of allergenic foods in initial low doses at home. This is expected to improve the safety of this procedure.

Skin prick test predictive value on the outcome of a first known egg exposure in milk-allergic children

Children with milk allergy have higher incidence of other food allergies, especially egg allergy. The objective of this study was to ascertain the accuracy of the prick test in children with IgE-mediated milk allergy for diagnosing egg allergy. Children under the age of 1 yr who came consecutively to Allergy Department 2003-05, and were diagnosed with IgE-mediated milk allergy were selected for this study. Egg introduction was completely avoided until the age of 14 months when clinical history, skin prick tests (SPT), specific-IgE antibodies determination and egg challenge test were performed. One hundred and four milk-allergic children were included. At least one positive prick test to any egg allergen was found in 65 out of the 104 (62.5%). Thirty-eight (36.5%) were allergic to egg proteins as well. Prick tests with egg white and ovomucoid (OVM) had the best diagnostic performances showing the largest areas under the receiver operating characteristic curve. The optimal diagnosis cut-off point was 6 mm for egg white and 5 mm for OVM. The positive likelihood ratios for these cut-off points were: 2.95 (95% CI: 1.74-4.99) for egg white prick test, and 20 (95% CI: 2.9-143.7) for OVM prick test. Children with specific IgE-mediated cow's milk allergy must be closely followed as a risk group for egg allergy. Early diagnosis is necessary and the SPT has shown itself to be a very useful tool for diagnosing immediate IgE reactions to egg on first known exposure.

Egg allergy

Egg allergy is one of the most common food allergies in infants and young children. The great majority is not life-threatening and management involves exclusion of egg from the diet and regular review with the expectation that the majority of children will outgrow the allergy by school age. Judgment is required as to when the dietary elimination of egg is no longer required. This decision may be helped by demonstrating loss of sensitivity by skin prick or specific IgE testing and in some cases a supervised food challenge. Particular issues in management arise with more severe, potentially life-threatening reactions, with immunization with vaccines prepared in eggs, with the diagnosis of egg hypersensitivity as a cause of delayed exacerbations of eczema which can be non-IgE mediated, and in deciding whether a child can be allowed to ingest small amounts of cooked egg through egg-containing foods while continuing to avoid raw egg or larger amounts of whole egg. Cases which illustrate these issues are presented.