Similar prevalence, different spectrum: IgE-mediated food allergy among Turkish adolescents

Recognition of nuts and seeds in children with/without food allergies and their mothers: A reflection of culinary culture

BACKGROUND

Nuts and seeds are among the leading causes of food allergy. Effective food allergy management hinges on the ability to identify and avoid relevant foods.

AIM

To evaluate the nut/seed recognition ability in both children and mothers.

METHODS

Primary caregivers (mothers) and their children (6-18 years old) with/without food allergies were shown photographs of nuts/seeds, and their products with visible/hidden allergens to assess their ability to recognize accurately.

RESULTS

A total of 196 children and 184 mothers participated. The median ages of the children and mothers were 7.6 (6.8-10) and 37.8 (33.1-41.5) years, respectively. Over 75% of the children/adolescents and over 90% of the mothers accurately identified the kernel forms of nuts/seeds, except pine nuts. Walnuts, hazelnuts, almonds, and cashews were the most accurately recognized kernel forms by both populations. Generally, the kernel forms were recognized 5-20% more accurately than their in-shell forms, followed by products with visible and hidden forms, respectively. Some Turkish culinary-specific products with visible/hidden allergens were recognized as frequently as the kernel/in-shell forms by both study groups. Although there was a similar recognition pattern between study groups and subgroups (nut/seed allergy, other food allergy, controls), higher rates of recognition were found in mothers than in their children and adolescents than in schoolchildren.

CONCLUSION

In Eastern Mediterranean region, nuts and sesame seeds are highly recognized by both mothers and their children. Accurate identification of these foods is likely a culinary feature, but not the result of increased awareness. More information is needed on whether this ability reduces the risk of exposure.

Prevalence of tree nut allergy in Europe: A systematic review and meta-analysis

In 2014, the European Academy of Allergy and Clinical Immunology (EAACI) published the first systematic review that summarized the prevalence of food allergy (FA) and food sensitization in Europe for studies published 2000-2012. However, only summary estimates for tree nut allergy (TNA) were feasible in that work. In the current update of that systematic review, we summarized the prevalence of tree nut allergy/sensitization to individual tree nuts. Six databases were searched for relevant papers published 2012-2021 and 17 eligible studies were added to the 15 studies already identified between 2000 and 2012, giving a total of 32 studies. Of the investigated tree nuts, meta-analysis was possible for hazelnut, walnut, almond, and in few cases, for cashew, and Brazil nut. The lifetime self-reported prevalence was 0.8% (95% CI 0.5-1.1) for hazelnut and 0.4% (0.2-0.9) for walnut. The point self-reported prevalence was 4.0% (2.9-5.2) for hazelnut, 3.4% (2.0-4.9) for Brazil nut, 2.0% (1.1-2.9) for almond, and 1.8% (1.1-2.5) for walnut. Point prevalence of food challenge-confirmed TNA was 0.04% (0.0-0.1) for hazelnut and 0.02% (0.01-0.1) for walnut. Due to paucity of data, we could not identify any meaningful and consistent differences across age groups and European regions.

Prevalence estimates of eight big food allergies in Europe: Updated systematic review and meta-analysis

In 2014, the European Academy of Allergy and Clinical Immunology published prevalence estimates for food allergy (FA) and food sensitization (FS) to the so-called eight big food allergens (i.e. cow's milk, egg, wheat, soy, peanut, tree nuts, fish and shellfish) in Europe for studies published between 2000 and 2012. The current work provides 10-year updated prevalence estimates for these food allergens. A protocol was registered on PROSPERO before starting the research (reference number CRD42021266657). Six databases were searched for studies published 2012-2021, added to studies published up to 2012, resulting in a total of 93 studies. Most studies were graded as at moderate risk of bias. The overall pooled estimates for all age groups of self-reported lifetime prevalence were as follows: cow's milk (5.7%, 95% confidence interval 4.4-6.9), egg (2.4%, 1.8-3.0), wheat (1.6%, 0.9-2.3), soy (0.5%, 0.3-0.7), peanut (1.5%, 1.0-2.1), tree nuts (0.9%, 0.6-1.2), fish (1.4%, 0.8-2.0) and shellfish (0.4%, 0.3-0.6). The point prevalence of food challenge-verified allergy were as follows: cow's milk (0.3%, 0.1-0.5), egg (0.8%, 0.5-1.2), wheat (0.1%, 0.01-0.2), soy (0.3%, 0.1-0.4), peanut (0.1%, 0.0-0.2), tree nuts (0.04%, 0.02-0.1), fish (0.02%, 0.0-0.1) and shellfish (0.1%, 0.0-0.2). With some exceptions, the prevalence of allergy to common foods did not substantially change during the last decade; variations by European regions were observed.

Frequency of food allergy in Europe: An updated systematic review and meta-analysis

Food allergy (FA) is increasingly reported in Europe, however, the latest prevalence estimates were based on studies published a decade ago. The present work provides the most updated estimates of the prevalence and trends of FA in Europe. Databases were searched for studies published between 2012 and 2021, added to studies published up to 2012. In total, 110 studies were included in this update. Most studies were graded as moderate risk of bias. Pooled lifetime and point prevalence of self-reported FA were 19.9% (95% CI 16.6-23.3) and 13.1% (95% CI 11.3-14.8), respectively. The point prevalence of sensitization based on specific IgE (slgE) was 16.6% (95% CI 12.3-20.8), skin prick test (SPT) 5.7% (95% CI 3.9-7.4), and positive food challenge 0.8% (95% CI 0.5-0.9). While lifetime prevalence of self-reported FA and food challenge positivity only slightly changed, the point prevalence of self-reported FA, sIgE and SPT positivity increased from previous estimates. This may reflect a real increase, increased awareness, increased number of foods assessed, or increased number of studies from countries with less data in the first review. Future studies require rigorous designs and implementation of standardized methodology in diagnosing FA, including use of double-blinded placebo-controlled food challenge to minimize potential biases.

Evaluating the influence of cold plasma bubbling on protein structure and allergenicity in sesame milk

BACKGROUND

Sesame is a traditional oilseed comprising essential amino acids. However, the presence of allergens in sesame is a significant problem in its consumption; thus, this study attempted to reduce these allergens in sesame oilseeds.

OBJECTIVE

The present study aimed to evaluate the effect of cold plasma processing on structural changes in proteins, and thereby the alteration of allergenicity in sesame milk. Method: Sesame milk (300 mL) was processed using atmospheric pressure plasma bubbling unit (dielectric barrier discharge, power: 200 V, and airflow rate: 16.6 mL/min) at different exposure times (10, 20, and 30 min).

RESULTS

The efficiency of plasma-bubbling unit as measured by electron paramagnetic resonance in terms of producing reactive hydroxyl (OH) radicals proved that generation of reactive species increased with exposure time. Further, the plasma-processed sesame milk subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and differential scanning calorimetery analysis revealed that plasma bubbling increased the oxidation of proteins with respect to bubbling time. The structural analysis by Fourier transform infrared spectroscopy and circular dichroism revealed that the secondary structure of proteins was altered after plasma application. This change in the protein structure helped in changing the immunoglobulin E (IgE)-binding epitopes of the protein, which in turn reduced the allergen-binding capacity by 23% at 20-min plasma bubbling as determined by the sandwich-type enzyme-linked immunosorbent assay. However, 30-min plasma bubbling intended to increase allergenicity, possibly because of increase in IgE binding due to the generation of neo epitopes.

CONCLUSION

These changes proved that plasma bubbling is a promising technology in oxidizing protein structure, and thereby reducing the allergenicity of sesame milk. However, increase in binding at 30-min bubbling is to be studied to facilitate further reduction of the binding capacity of IgE antibodies.

IgE mediated legume allergy in east Mediterranean children: A reflection of multiple food allergies

BACKGROUND

Legumes are nutritionally valuable as an inexpensive protein source, but may cause severe allergic reactions. This study aimed to identify the characteristics of legume allergies (LAs) in Turkish children.

METHODS

A total of 87 children (4.9 (3.1-7.0) years) with LAs confirmed by either oral food challenge (OFC) or consistent history were reviewed.

RESULTS

The median age of onset was 19 (12-38) months. The most frequent LA was lentil (n = 57, 66%), followed by peanut (n = 53, 61%), chickpea (n = 24, 28%), pea (n = 21, 24%), bean (n = 7, 8%), and soybean (n = 1, 1%). From these, it was observed that 60% had multilegume (≥2) allergies and the age of onset occurred earlier compared with the single LA subgroup (18 (11-30) vs. 28 (17-42) months, p = .042). Single LA was present in peanut (51%) and lentil (16%) allergies, but not chickpea, pea, and bean. Fifteen patients had tolerated lentils before their first allergic reaction. The majority of children with LA (91.9%) were allergic to multiple foods including tree nuts (71%), hen's egg (66%), and cow's milk (49%). Seventy-eight patients (89.7%) also presented with atopic comorbidities concerning atopic dermatitis (70%), asthma (40%), and allergic rhinitis (30%). Patients with anaphylactic type of reaction (20%) had higher frequency of aeroallergen sensitization (p = .001). Lip dose challenge with legume paste predicted the result of OFC with a diagnostic accuracy of 81.82% and a positive likelihood ratio of 10.8.

CONCLUSION

In Turkey, LA is a reflection of multiple food allergies and the presence of allergy to a least frequently encountered legume is a sign of multiple LA.

From Allergen Molecules to Molecular Immunotherapy of Nut Allergy: A Hard Nut to Crack

Peanuts and tree nuts are two of the most common elicitors of immunoglobulin E (IgE)-mediated food allergy. Nut allergy is frequently associated with systemic reactions and can lead to potentially life-threatening respiratory and circulatory symptoms. Furthermore, nut allergy usually persists throughout life. Whether sensitized patients exhibit severe and life-threatening reactions (e.g., anaphylaxis), mild and/or local reactions (e.g., pollen-food allergy syndrome) or no relevant symptoms depends much on IgE recognition of digestion-resistant class I food allergens, IgE cross-reactivity of class II food allergens with respiratory allergens and clinically not relevant plant-derived carbohydrate epitopes, respectively. Accordingly, molecular allergy diagnosis based on the measurement of allergen-specific IgE levels to allergen molecules provides important information in addition to provocation testing in the diagnosis of food allergy. Molecular allergy diagnosis helps identifying the genuinely sensitizing nuts, it determines IgE sensitization to class I and II food allergen molecules and hence provides a basis for personalized forms of treatment such as precise prescription of diet and allergen-specific immunotherapy (AIT). Currently available forms of nut-specific AIT are based only on allergen extracts, have been mainly developed for peanut but not for other nuts and, unlike AIT for respiratory allergies which utilize often subcutaneous administration, are given preferentially by the oral route. Here we review prevalence of allergy to peanut and tree nuts in different populations of the world, summarize knowledge regarding the involved nut allergen molecules and current AIT approaches for nut allergy. We argue that nut-specific AIT may benefit from molecular subcutaneous AIT (SCIT) approaches but identify also possible hurdles for such an approach and explain why molecular SCIT may be a hard nut to crack.

Clinical phenotypes of childhood food allergies based on immune mechanisms: A multicenter study

Background: Food allergies (FA) are an important public health concern that place a major burden on the lives of children and their families. The complex pathogenesis of FAs results in multisystemic and heterogenous clinical presentations. Objective: To evaluate, according to immune mechanisms, the characteristics and risk factors of childhood FA in Turkey. Methods: This descriptive multicenter study included 1248 children with FA, aged < 18 years,, who were evaluated by pediatric allergists in 26 different centers. Results: Immune mechanisms of FA were immunoglobulin E (IgE) mediated in 71.8%, non-IgE mediated in 15.5%, and mixed IgE/non-IgE mediated in 12.7% of the patients. An episode of anaphylaxis had occurred in 17.6% of IgE-mediated FA. The most common food allergens were classified into five categories (in order of decreasing frequency): cow's milk, egg, tree nuts and/or peanut, wheat, and seafood. Allergies to cow's milk and egg declined significantly with age, whereas tree nuts and/or peanut allergies increased with age. The 0-2 year age group accounted for 62.5% of the cases. The most frequent cause of FA and food anaphylaxis was cow's milk before age 13 years and tree nuts and/or peanut during adolescence (ages 13-18 years). Compared with other phenotypes, male sex (odds ratio [OR] 1.486; p = 0.032), sibling(s) (OR 1.581; p = 0.021), and maternal atopy (OR 1.531; p = 0.045) increased the likelihood of IgE-mediated FA, whereas high household income (OR 1.862; p = 0.026) increased the likelihood of non-IgE-mediated FA in multivariate regression analysis. Conclusion: This study showed that the clinical findings of FA were highly variable, depending on age and underlying immune mechanism. Knowing the population characteristics will enable better management of FA in children.

IgE-mediated food allergy throughout life

Food allergy (FA) has become an increasing problem throughout the world. Over the last 2 decades, the frequency of FA has increased in both children and adults. The prevalence differs according to the research methodology, age, and geographic regions, ranging between 2.0% and 10.0%. The most common form of FA is immunoglobulin E (IgE)-mediated FA. In this form, patients may present with life-threatening conditions, such as anaphylaxis, or milder conditions, such as urticaria, angioedema, sneezing, and nausea alone. The gold standard in the diagnosis of FA is oral provocation tests. Epidermal skin prick tests and specific IgE measurements, as well as component-resolved diagnostic techniques are helpful in the diagnosis and follow-up of patients. In this review, the epidemiology, diagnosis, follow-up, and prognosis of IgE-mediated FA in children and adults were discussed and some specific forms of FA, such as pollen FA syndrome, alpha-gal allergy, and food-dependent exercise-induced anaphylaxis were explained.

Phenotypical characterization of tree nuts and peanut allergies in east Mediterranean children

INTRODUCTION/OBJECTIVES

The characteristics of tree nuts (TNs) and peanut (PN) allergies vary in different regions of the world. We aim to identify the characteristics of TNs/PN allergies in Turkish children.

PATIENTS AND METHODS

A total of 227 children [4.8 (3.2-6.8) years] with TN and/or PN allergies were included. The phenotypical features of TNs/PN allergic children and the risk factors for multiple TNs/PN allergies were evaluated.

RESULTS

Allergy to TNs/PN developed at a median age of 12.0 (10.0-18.0) months. The most common TNs/PN responsible for food allergies were the hazelnut (63.9%) and the pistachio (54.6%). Of TNs/PN allergic children, 54.2% experienced reactions with at least two types of . Current ages 6-10 years [OR:2.455, 95% CI:1.255-4.852, p=0.009] and family history of atopy [OR:2.156, 95% CI:1.182-3.932, p=0.012] were the risk factors for multiple TNs/PN allergies. Most of the patients with cashew nut and pistachio allergies exhibited co-sensitization and co-allergy to both of these TNs/PN. Although the rarest TNs/PN allergy was seen with almond, the possibility of allergy to other TNs or PN was highly increased in the patients with almond allergy compared to other TNs/PN.

CONCLUSIONS

Children with TNs/PN allergy living in an East Mediterranean region differ from the counterparts living in Western countries by an earlier age of onset of the TNs/PN allergy symptoms, increasing possibility to have multiple TNs/PN allergy at older ages, and different spectrum of TN/PN allergies (hazelnut followed by pistachio/cashew) that all indicate the consumption habits which are important determinants of TN/PN allergy development.

Challenges of managing food allergy in the developing world

Food allergy (FA) is currently a significant health care problem in the developing world. Widely varying study populations and methodologies, the use of surrogate markers such as self report or hospitalization rates due to anaphylaxis rather than objective methods, limits robust estimation of FA prevalence in low income settings. Also, allergy is under-recognized as a clinical specialty in the developing world which compromises the chance for accurate diagnosis. In this review, most published data on food allergens from developing or low income countries are displayed. The diagnostic challenges and limitations of treatment options are discussed. It seems that FA is an under-appreciated health care issue in the developing world, and accurate determination of its burden in low-income settings represents an important unmet need. Multicenter surveillance studies, using standardized methodologies, are, therefore, needed to reveal the true extent of the problem and provide epidemiological clues for prevention. Preventive strategies should be tailored to fit local circumstances in different geographic regions. In addition, studying the gene environment interactions and impact of early life microbiota on the expression of FA in developing communities would be worthwhile. Efforts and resources should be directed toward public health education and training of health care providers dealing with food allergic patients.

Epidemiology of Food Allergy

Understanding the epidemiology of food allergy is complicated by the difficulty of identifying it on a large scale. The prevalence of food allergy is higher in younger age groups and decreases with age. Allergy to peanut and egg seems to be more common in Northern Europe, the United States, Canada and Australia compared with Southern Europe, Eastern Europe and Asia, whereas shellfish and fish allergies may be more common in Asia. The rate of transient unrecognized food allergy may be high and variable recognition of food allergy may explain some of the differences seen in food allergy prevalence.

Food Allergy in South Africa

PURPOSE OF THE REVIEW

Whilst food allergy seems to have increased significantly in many developed countries in the past few decades, quality data on the burden of food allergy in many developing countries is scanty. Until recently, South Africa had a dearth of robustly designed food allergy studies. This article summarizes some of the recent research and observations regarding food allergy from the South African setting.

RECENT FINDINGS

South Africa has recently seen two important food allergy prevalence studies in selected and unselected populations. Both show allergy rates in keeping with those in several westernized countries. The major difference between sensitization and allergy rates in these studies emphasizes the vital role of the food challenge in differentiating true food allergy from asymptomatic sensitisation in equivocal cases. Eczema, young age and living in an urban population are important risk factors for food allergy in South Africa. Egg and peanut allergy are the most common food allergies in both selected and unselected populations in South Africa. In peanut allergy, Ara h 2 is the most useful component in differentiating true allergy from tolerance in peanut-sensitized patients. Use of internationally derived 95% positive predictive values for peanut and egg allergy produced many false positives in South African studies. Studies in South Africa show a trend towards more conservative introduction of peanut in eczema patients, which needs to be addressed in the light of recent studies showing a protective effect of earlier introduction of peanut. "Novel" allergies such as galactose-alpha-1,3-galactose allergy, food protein-induced enterocolitis syndrome and eosinophilic oesophagitis are being described with increasing frequency in South Africa. The surprisingly high prevalence of food allergy in South Africa points towards possible involvement of South Africa in the so-called "food allergy epidemic". This has major implications on the planning of health services in the allergy sector. Food challenges will form a vital role in allergy services. Ninety-five percent positive predictive values for peanut and egg allergy may need revision to be more applicable to the local population.

Prevalence of fish and shellfish allergy: A systematic review

BACKGROUND

Accurate information on the prevalence of food allergy facilitates a more evidence-based approach to planning of allergy services and can identify important geographic variations.

OBJECTIVE

To conduct a systematic review to assess the age-specific prevalence of fish and shellfish allergy worldwide.

METHODS

Searches were conducted using Web of Science and PubMed. Population-based cross-sectional studies and cohort studies that examined the prevalence of fish and shellfish allergy (IgE mediated and non-IgE mediated) at an identifiable point in time were eligible for inclusion in the study. Reviewers extracted general study information and study design, type of food allergy considered, food(s) assessed, method of diagnosis, sampling strategy, and sample characteristics. Raw data were extracted and percentage prevalence and 95% confidence intervals calculated.

RESULTS

A total of 7,333 articles were identified of which 61 studies met the inclusion criteria and were included in this review. The prevalence of fish allergy ranged from 0% to 7% and the prevalence of shellfish allergy from 0% to 10.3%, depending on the method of diagnosis. Where food challenges were used, the prevalence for fish allergy was found to be 0% to 0.3% and for shellfish allergy was 0% to 0.9%.

CONCLUSION

Few studies have established the prevalence of fish or shellfish allergy using the gold standard double-blind, placebo-controlled challenge criteria, with most instead relying on self-reported questionnaire-based methods. The limited data available suggest that fish allergy prevalence is similar worldwide; however, shellfish allergy prevalence may be higher in the Southeast Asia region.

The prevalence, natural history and time trends of peanut allergy over the first 10 years of life in two cohorts born in the same geographical location 12 years apart

BACKGROUND

The aim of this study was to explore the natural history of peanut allergy in childhood in two birth cohorts from the same geographical region in the South of England.

METHODS

The FAIR birth cohort was established on the Isle of Wight (UK) between 2001 and 2002 (n = 969). Children were followed up prospectively, skin prick tested (SPT) to peanut allergens at 1, 2, 3 and 10 years and food challenges performed. The Isle of Wight (IOW) birth cohort was established in 1989 (n = 1456). SPTs were performed at 1, 2, 4 and 10 years. Peanut allergy was based on positive SPT and a good clinical history.

RESULTS

In the FAIR cohort, the prevalence of sensitization to peanut was 0.4%, 2.0%, 2.0% and 2.4% at 1, 2, 3 and 10 years, respectively. At 10 years of age, 12 of 828 (1.5%) children were diagnosed with peanut allergy. One child (8%) outgrew her peanut allergy between 3 and 10 years and two children (15%) presented with new onset peanut allergy. Over the first 10 years of life, 13 of 934 (1.4%) children were diagnosed with peanut allergy. In the IOW cohort, 6 of 1034 (0.58%) were diagnosed with peanut allergy at 10 years. We found no significant differences between the FAIR and the IOW birth cohort for any of the time points studied.

CONCLUSION

Peanut allergy appears to be stable over the first 10 years of life in our cohorts. There was no significant difference in peanut sensitization or clinical peanut allergy between 1989 and 2001.

Prevalence of sensitization to food allergens and challenge proven food allergy in patients visiting allergy centers in Rawalpindi and Islamabad, Pakistan

In this study, we estimated the prevalence of food allergy in the adult allergic patients of Rawalpindi and Islamabad , Pakistan, based on self-report, skin prick test (SPT) and oral food challenge test (OFC). SPT was used for the estimation of sensitization to wheat, egg, milk, beef, chicken, mutton, fish, corn, lentils, rice, soya, peanut and banana. Among 689 patients, 39.19 % showed sensitivity to one or more foods, where, sensitization to wheat (156; 22.6 %) was highest, followed by egg (148; 21.48 %) and milk (138; 20.03 %). Sensitization to various proteins ranged between 15.53–15.97 %, while lentils, corn, rice, soya and peanut sensitization was 15.4, 16, 12.5, 12 and 11.5 % respectively. Only 7.1 % patients were SPT positive for banana allergen. SPT was performed in patients with self-reported food allergy (341/689) and also with no self-reported history of food allergy (348/689). SPT results were positive in 69.8 % of the self-report group, whereas, in the patients with no self-reported food allergy 9.2 % were found sensitized to one or more tested food allergens. 101 patients were recruited for OFC, 61 % of these were confirmed of food allergy. The prevalence of food allergy in the study population was 9 %. Food specific OFC results show that wheat allergy is affecting 1.6 % (95 % CI 0.9–2.84 %) of the total allergy patients, followed by egg allergy 1.31 % (95 % CI 0.70–2.47 %). Furthermore, corn allergy, rice allergy and peanut allergy were 1.02, 0.87 and 0.73 %, respectively. In conclusion, wheat allergy is the most prevalent, followed by egg, chicken, beef and fish allergy, respectively.

Prevalence and cumulative incidence of food hyper-sensitivity in the first 10 years of life

BACKGROUND

Prevalence, incidence and natural history of food hypersensitivity (FHS) and its trends in an unselected cohort of older children are unclear.

METHODS

A birth cohort born on the Isle of Wight (UK) between 2001 and 2002 was followed up prospectively. Children were clinically examined and skin prick tested at set times and invited for food challenges when indicated. At 10 years of age, children were also invited for a blood test.

RESULTS

A total of 969 children were recruited at 12 weeks of pregnancy, and 92.9%, 88.5%, 91.6% and 85.3% were assessed at 1, 2, 3 and 10 years. Prevalence of sensitization to any allergen over 10 years was 186 of 969 (19.2%; 95% CI: 16.84-21.8) and 108 of 969 (11.2%; 95% CI: 9.31-13.29) children were sensitized to at least one predefined food allergen. Excluding wheat (due to cross-reactivity with pollen), 40 of 969 (4.1%; 95% CI: 3.19-5.32) children were sensitized to a predefined food allergen. Using food challenges and/or a good clinical history, the cumulative incidence of food hypersensitivity (FHS) in the first decade of life was 64 of 947 (6.8%, 95% CI: 5.2-8.4), while the prevalence of FHS at 10 years was 30 of 827 (3.6%, 95% CI: 2.54-5.15). The vast majority, 25 of 827 (3.0%, 95% CI: 1.8-4.2), suffered from IgE-mediated food allergy, while 5 of 827 (0.6%, 95% CI: 0.07-1.3) had non-IgE-mediated food allergy/food intolerance.

CONCLUSIONS

By the age of 10 years, 6.8% of children suffered from FHS based on food challenges and a good clinical history. There was a large discrepancy between reported and diagnosed FHS.

The Prevalence of Tree Nut Allergy: A Systematic Review

Tree nuts are one of the most common foods causing acute allergic reactions and nearly all tree nuts have been associated with fatal allergic reactions. Despite their clinical importance, tree nut allergy epidemiology remains understudied and the prevalence of tree nut allergy in different regions of the world has not yet been well characterised. We aimed to systematically review the population prevalence of tree nut allergy in children and adults. We searched three electronic databases (OVID MEDLINE, EMBASE and PubMed) from January 1996 to December 2014. Eligible studies were categorised by age, region and method of assessment of tree nut allergy. Of the 36 studies identified most were in children (n = 24) and from Europe (n = 18), UK (n = 8) or USA (n = 5). Challenge-confirmed IgE-mediated tree nut allergy prevalence was less than 2 % (although only seven studies used this gold standard) while probable tree nut allergy prevalence ranged from 0.05 to 4.9 %. Prevalence estimates that included oral allergy syndrome (OAS) reactions to tree nut were significantly higher (8-11.4 %) and were predominantly from Europe. Prevalence of individual tree nut allergies varied significantly by region with hazelnut the most common tree nut allergy in Europe, walnut and cashew in the USA and Brazil nut, almond and walnut most commonly reported in the UK. Monitoring time trends of tree nut allergy prevalence (both overall and by individual nuts) as well as the prevalence of OAS should be considered given the context of the overall recent rise in IgE-mediated food allergy prevalence in the developed world.

A global survey of changing patterns of food allergy burden in children

While food allergies and eczema are among the most common chronic non-communicable diseases in children in many countries worldwide, quality data on the burden of these diseases is lacking, particularly in developing countries. This 2012 survey was performed to collect information on existing data on the global patterns and prevalence of food allergy by surveying all the national member societies of the World Allergy Organization, and some of their neighbouring countries. Data were collected from 89 countries, including published data, and changes in the health care burden of food allergy. More than half of the countries surveyed (52/89) did not have any data on food allergy prevalence. Only 10% (9/89) of countries had accurate food allergy prevalence data, based on oral food challenges (OFC). The remaining countries (23/89) had data largely based on parent-reporting of a food allergy diagnosis or symptoms, which is recognised to overestimate the prevalence of food allergy. Based on more accurate measures, the prevalence of clinical (OFC proven) food allergy in preschool children in developed countries is now as high as 10%. In large and rapidly emerging societies of Asia, such as China, where there are documented increases in food allergy, the prevalence of OFC-proven food allergy is now around 7% in pre-schoolers, comparable to the reported prevalence in European regions. While food allergy appears to be increasing in both developed and developing countries in the last 10-15 years, there is a lack of quality comparative data. This survey also highlights inequities in paediatric allergy services, availability of adrenaline auto-injectors and standardised National Anaphylaxis Action plans. In conclusion, there remains a need to gather more accurate data on the prevalence of food allergy in many developed and developing countries to better anticipate and address the rising community and health service burden of food allergy.