Frequency of food allergy in a pediatric population from Spain

We evaluated the prevalence and characteristics of the principal foods implicated in 355 children diagnosed with IgE-mediated food allergy. Diagnosis was established on the basis of positive clinical history for the offending food, positive specific IgE by skin prick test and RAST, and open food challenge. Our results showed the principal foods involved in allergic reactions are: eggs, fish, and cow's milk. These are followed in frequency by fruits (peaches, hazelnuts and walnuts), legumes (lentils, peanuts and chick peas) and other vegetables (mainly sunflower seeds). The legumes demonstrated the highest degree of clinical cross-reactivity. Most patients with food allergy reacted to one or two foods (86.7%). Only 13.3% of patients reacted to 3 or more foods, mostly to legumes and fruits. We found that food allergy begins most frequently in the first (48.8%) and second (20.4%) years of life. Allergy to proteins of cow's milk, egg, and fish begins predominantly before the second year, demonstrating a clear relationship with the introduction of these foods into the child's diet. Allergy to foods of vegetable origin (fruits, legumes and other vegetables) begins predominantly after the second year.;     

Diagnosis of IgE‐mediated food allergy among Swiss children with atopic dermatitis

Diagnosis of food allergy in children with atopic dermatitis (AD) relies on a good knowledge of the prevalence of the disease and of the foods most frequently involved. Our objective was to define these characteristics in a population of Swiss children with AD. Patients referred to a pediatric allergist or a dermatologist for AD were routinely tested by skin‐prick test (SPT) to seven common food allergens (milk, egg, peanut, wheat, soy, fish, and nuts), and to all other foods suspected by history. Patients with positive SPTs were further evaluated for specific serum immunoglobulin E (IgE) antibodies (by using the CAP System FEIA^?). CAP values were interpreted following previously published predictive values for clinical reactivity. Patients with inconclusive results (between the 95% negative predictive value [NPV] and the 95% positive predictive value [PPV]) were challenged with the suspected food. A total of 74 children with AD were screened for food allergies. Negative SPTs excluded the diagnosis in 30 subjects. Nineteen patients were diagnosed by histories suggestive of recent anaphylactic reactions to foods and/or CAP values above the 95% PPV. Forty‐three food challenges (35 open challenges and eight double‐blind, placebo‐controlled in children with persistent lesions of AD despite aggressive topical skin treatment) were performed in patients with positive SPTs but with inconclusive CAP values. Six patients were diagnosed as positive to 15 foods. Challenges were not performed to high‐allergenic foods in young children (under 12 months of age for egg and fish, and under 3 years of age for peanuts and nuts). Altogether, 33.8% (25 of 74) of the AD patients were diagnosed with food allergy. The prevalence of food allergy was 27% (seven of 25) in the group referred to the dermatologist for primary care of AD. The foods most frequently incriminated were egg, milk, and peanuts. The prevalence of food allergy in our population was comparable to that in other westernized countries, suggesting an incidence of food allergy in approximately one‐third of children with persistent lesions of AD. Together with milk and eggs, peanuts were most frequently involved in allergic reactions.     

Multiple food allergy: a possible diagnosis in breastfed infants

Six infants suspected of food allergy during breastfeeding were evaluated using prick tests, total IgE, RASTs and intestinal permeability measurements during fast and provocation with mother's milk. An elimination diet was undertaken in mothers, removing first cow's milk protein (CMP), then, when inefficient, all foods suspected on the clinical history or a positive prick test in the child, followed by oral challenges in mother's diet with the corresponding food. The sole CMP-free diet in mothers always proved insufficient. In four, an additional diet excluding two to three other foods cleared the symptoms. Oral provocations in mother's diet with those foods were positive in all. In two, mothers turned down a diet excluding more than four foods, symptoms cleared while feeding the child with an extensively hydrolysed formula, whereas challenges with mother's milk induced immediate reactions. Intestinal permeability was altered during provocation tests with mother's milk sampled before maternal diet. Food allergy during breastfeeding may be due to multiple foods and the inefficacy of the sole CMP elimination in mothers does not rule out food sensitization.     

Atopic dermatitis: clinical relevance of food hypersensitivity reactions

Forty-six patients with atopic dermatitis ranging from mild to severe were evaluated for food hypersensitivity with double-blind placebo-controlled food challenges. Twenty-eight (61%) patients had a positive prick skin reaction to one of the foods tested. Sixty-five food challenges were performed; 27 (42%) were interpreted as positive in 15 (33%) patients. Egg, milk, and peanut accounted for 78% of the positive reactions. As in previous studies, patients developed skin (96%), respiratory (52%), or gastrointestinal (30%) symptoms during the challenge. These studies indicate that children who have atopic dermatitis unresponsive to routine therapy or who continue to need daily treatment after several months would benefit from evaluation for food hypersensitivity.     

Food related, exercise induced anaphylaxis

Four children under 12 years of age with food dependent, exercise induced anaphylaxis (EIAn) were investigated. These children and five controls performed exercise challenges when fasting and one hour after a meal without food suspected to predispose to the reaction. Patients then performed exercise tests after intake of each suspected food. Three out of 15 food-exercise combination challenges were positive, but no reactions were provoked after exercise without prior intake of suspected foods. Patients underwent skin prick tests to foods and serum total and specific IgE antibodies were measured. Skin prick test results were positive and RAST results were positive in two of three instances. In case 3, food-exercise combination challenges did not provoke any clinical reaction. The diagnosis of food dependent EIAn should be considered in young children with EIAn of unknown origin.     

Food Allergy in Children: An Overview

The estimated prevalence of food allergy amongst children in the west is around 6–8% but there is paucity of data in the Indian population. There is a complex interplay of environmental influences and genetic factors in the immuno-pathogenesis and manifestations of food allergy. A reliable thorough clinical history, combined with positive skin prick tests or food-specific IgE, is essential for a more precise diagnosis of food allergy. Currently there is no cure for food allergy. The management of food allergy usually includes strict avoidance, patient education and provision of emergency medication (adrenaline-autoinjectors). Emerging therapies based on evolving research are focused on a more active approach to management which includes early introduction of potentially allergenic foods, anticipatory testing and desensitisation to food allergens. Lack of food labelling policy and non availability of adrenaline auto-injectors is a huge limiting factor for effective management of food allergy among children in India. The present review focuses on IgE mediated food allergy.     

婴幼儿鸡蛋与牛奶过敏食物皮肤点刺试验的诊断价值

目的 通过对皮肤点刺试验疹团平均直径与开放性食物激发试验的相关性研究,获得有确诊食物过敏价值的皮肤点刺试验界值点,为简化临床诊断程序提供依据.方法 采用前瞻性研究,选择重庆医科大学附属儿童医院儿保科可疑食物过敏儿童173名,均进行皮肤点刺试验及开放性食物激发试验.测量并记录皮肤点刺试验疹团平均直径,通过开放性食物激发试验确诊食物过敏患儿.采用SPSS 13.0软件包进行统计学处理.将开放性食物激发试验作为诊断的金标准,通过四格表计算疹团平均直径的敏感度、特异度、阳性预测值及阴性预测值.通过受试者工作特征曲线及曲线下面积对疹团平均直径诊断价值进行评价;同时获取具有100%诊断价值的平均直径界值点.结果 173名婴幼儿年龄范围1～24个月,平均(9.39±5.67)个月共进行271次食物激发试验(其中阳性结果123次),99例婴幼儿被确诊为食物过敏.食物激发试验诱发症状主要表现为皮肤症状(87.0%),其次是胃肠道症状(9.8%).蛋白、蛋黄、牛奶皮肤点刺试验的受试者工作特征曲线的曲线下面积分别为0.794、0.804及0.904.当皮肤点刺试验疹团平均直径≥3 mm时,敏感度在71%～87%之间,特异度在31%～57%之间.当蛋白、蛋黄、牛奶皮肤点剌试验疹团平均直径分别≥8.5、5.5、5.5 mm时,皮肤点刺试验对食物过敏的诊断准确率可达100%.结论 皮肤点刺试验疹团平均直径对食物过敏的临床诊断准确性较好,通过其100%诊断界值点,可避免部分可疑食物过敏患儿进行食物激发试验.

Abstract：

Objective Mean diameter is the most common used parameter for wheal response assessment after skin prick test.This study aimed to investigate the diagnostic capacity of mean diameter according to the outcome of oral food challenge, and to determine the cut-off points that could render food challenges unnecessary.Method Data of 173 children referred to the Division of Primary Child Health Care for the evaluation of suspected food allergy were prospectively studied.All children underwent skin prick test and open food challenge to the relevant food(s) in clinic.The mean wheal diameter of skin prick test was measured, and open food challenge was performed to confirm food allergy. The SPSS software package version 13.0 for windows ( SPSS, Chicago, IL,USA) was used for all statistical analysis.Open food challenge was taken as the gold standard for diagnosis.Diagnostic capacity of skin prick test, including the sensitivity, specificity, positive predictive value, negative predictive value, was calculated by cross-table.In addition, receiver operating characteristic curve ( ROC ) was plotted and area under the curve ( AUC ) was calculated to quantify the accuracy of the parameter.Result For the 173 children,271 open food challenges were performed with egg white, egg yolk and cow's milk, In which 123 were positive, 99 children were diagnosed as food allergy.Cutanuous symptoms ( 87.0% ) were most common, followed by gastrointestinal symptoms (9.8% ).The AUC of mean diameter was 0.794 for egg white, 0.804 for egg yolk and 0.904 for cow's milk.The sensitivity of skin prick test with a cut-off value of ≥3 mm was ranged from 71% to 87%,while the specificity was between 31% and 57%.The authors also defined food specific skin prick test mean diameters that were 100% diagnostic for allergy to egg white ( ≥8.5 mm), egg yolk ( ≥5.5 mm), cow's milk ( ≥5.5 mm).Conclusion Predictive decision points for a positive outcome of food challenges can be calculated for egg and cow's milk using mean diameter.It may help to simplify the diagnostic procedure of food allergy.     

Epidemiology of atopy patch tests with food and inhalant allergens in an unselected population of children

Atopy patch test (APT) has been used as a diagnostic tool in patients with suspected food or inhalant allergy. This study assessed the prevalence of positive APT with food or inhalant allergens in an unselected population of schoolchildren. We also evaluated the link between positive APT reactions and skin‐prick tests (SPT) for food and inhalant allergens, circulating eosinophils and histamine skin reactivity. We studied an unselected population of 380 children aged 9 or 13 yr living in Rome, Italy. APTs were carried out with food (native or standardized) and inhalant allergens. All the children also underwent skin‐prick testing with five common inhalant and four food allergens. We also measured eosinophil cell counts and histamine skin reactivity. The prevalence of positive APT reactions for foods in unselected children ranged between 4% and 11% for hen’s egg, tomato, and wheat flour and was similar for both age groups studied. The prevalence of positive APT for milk was significantly lower in children aged 13 than in children aged 9 (p = 0.013). No concordance emerged between positive APT and SPT for foods. Conversely, APT and SPT for inhalant allergens yielded statistically significant concordance (p < 0.001). APT produces positive reactions for food or inhalant allergens in a significant number of subjects in the general population of schoolchildren. Age influences the prevalence of positive APTs with cow’s milk to some extent. Inhalant allergens probably induce a positive APT reaction through an immunoglobulin E‐linked process, while food allergens probably do not.     

Diagnosis of food allergy in children: toward a standardization of food challenge

Adverse reactions to food represent a common complaint in childhood; however, only a small proportion of children have proven clinically relevant food allergy. The foods most commonly involved in food allergy are cow's milk, hen's eggs, peanuts, tree nuts, seeds, soy, wheat, fish, and crustaceans. The diagnostic workup of suspected food allergy includes the patient's history, skin prick testing, the measurement of food-specific immunoglobulin E antibodies, and, more recently, the atopy patch test. Because none of these parameters can accurately predict tolerance, the gold standard for diagnosing food allergy is still the double-blind, placebo-controlled food challenge. Although numerous efforts have been made to standardize the procedure, there is a need for improvement. This review presents the current status of the indication and performance of controlled oral food challenges in children with suspected food-related symptoms. It covers aspects of indications and contraindications, blinding, diet before the challenge, the practical performance, the handling of medication, the interpretation of test results, suitable locations for testing, safety considerations, and the procedure after a period of avoidance. Efforts to standardize oral food challenges to achieve the best possible decision on a diet are important to avoid an unnecessary diet that may be harmful to the child.     

Diagnostik und Therapie der Nahrungsmittelallergie im Kindesalter

Food allergy is a common problem in infants and children, prevalences of 2–5% being reported. While immediate-type allergic reactions to foods can be diagnosed quite easily, the diagnosis of late-phase reactions, e.g. in atopic dermatitis, is often challenging. The aim of this review article is to present a practical procedure for diagnosing food allergy in infants and children. Once the classic diagnostic procedures, such as history, skin prick tests, atopy patch test, and determination of specific IgE in the serum have been exhausted, double-blind, placebo-controlled food challenges are seen as the gold standard. After the subject has been fed an oligo-allergenic diet, suspected foods or placebo are given in a titrated manner until a clear clinical reaction is seen or the highest dose is reached. An observation period of 48 h is required in each phase in the case of atopic dermatitis. Constant monitoring of clinical reactions is mandatory. Dietetic recommendations are given, and once these have been followed for 12 months the position should be reassessed. The effort involved in such a procedure is justified, since it can help to avoid clinically relevant food allergens in some cases and in others can prevent children from being exposed unnecessarily to diets that may be harmful to them. Therapeutic options in the case of cow's milk allergy include feeding with extensively hydrolysed formulae or, when intolerance to these is observed, with amino acid formulae, on both of which children generally thrive.     

Sensitization to food allergens in Iranian children with mild to moderate persistent asthma

Background

Asthma is the most common chronic respiratory disease in childhood. The clinical presentation of asthma may worsen after food allergen ingestion in sensitized patients. To avoid nonspecific dietary restrictions in children with asthma, laboratory-based advice about foods is potentially helpful. The purpose of this study was to determine food sensitization in children with asthma.

Methods

Seventy-nine children with mild to moderate persistent asthma were included in this study. Commercial food allergens including cow??s milk, egg white, almond, potato, and soybean were used in skin prick tests. Specific IgE to 20 common food allergens was also measured in serum.

Results

Twelve (15.2%) of the patients had a positive skin prick test to at least one of the five food extracts. Sensitization was detected by skin prick tests to cow??s milk and egg white (each 6.3%), almond (3.8%), potato (2.5%) and soybean (1.3%). Specific IgE levels ??0.35 kAU/L were detected in the serum of 47% of the children with asthma. The most common food allergens were cow??s milk (26.6%), hazelnuts (25.3%), wheat flour (15.2%) and egg white (12.6%). Patients with a history of at least one hospital admission due to asthma attack had a higher rate of sensitization to egg.

Conclusions

In our study, food sensitization was frequent in Iranian children with asthma. Although clinical food allergy could not be evaluated because food challenge tests were not used in our study, skin prick tests and serum-specific IgE to common food allergens might be helpful in identifying children with food sensitization.     

In vivo studies of residual allergen activity of hydrolysate feeding]

The capacity of food proteins to induce IgE-mediated reactions can be reduced by hydrolysis, heat treatment or ultrafiltration. It was the aim of our study to investigate the capacity of hydrolysates used for dietary purposes in cow's milk allergy to induce allergic symptoms in cow's milk sensitive children. Six different hydrolysates were tested by skin prick test and oral provocation test in 17 cow's milk sensitive children. Our data indicate that certain hydrolysates induce positive skin reactions as well as allergic symptoms after oral challenge. Casein hydrolysates were found to have the least residual allergenic activity. From our data we conclude that hydrolysates should be tested by titrated oral challenges before used in the diet of cow's milk sensitive children.     

Natural history of food hypersensitivity in children with atopic dermatitis

Patients with atopic dermatitis and food hypersensitivity who were adhering to an elimination diet underwent repeat double-blind, placebo-controlled oral food challenges annually for follow-up of their food allergy. After 1 year, 19 of 75 patients lost all signs of clinical food hypersensitivity (15 of 45 patients allergic to one food, and 4 of 21 allergic to two foods). Of the individual foods, 38 of 121 no longer elicited symptomatic responses. After 2 years, patients underwent a second rechallenge; 4 of 44 patients tested lost their clinical food hypersensitivity. In 20 patients undergoing a third rechallenge, no food hypersensitivity was lost. Loss rate of food hypersensitivity varied among foods; after 1 year, there was a 26% loss of symptomatic food allergy to five major allergens (egg, milk, soy, wheat, and peanut) compared with a 66% loss rate to other food allergens. Loss of symptomatic allergy was not affected by the patient's age at diagnosis, except with milk allergy, for which older patients were more likely to lose clinical food hypersensitivity (p less than 0.05). Total serum IgE and prick skin tests were not useful for predicting loss of symptomatic food hypersensitivity. There was no significant decrease in skin test wheal size corresponding to loss of clinical food hypersensitivity. Patients developing only skin symptoms during the initial challenge were most likely to lose symptomatic food hypersensitivity.     

Food allergy: When and how to perform oral food challenges

In many situations, the diagnosis of food allergy rests simply upon a history of an acute onset of typical symptoms, such as hives and wheezing, following the isolated ingestion of a suspected food, with confirmatory laboratory studies of positive prick skin tests or RASTs. However, the diagnosis is more complicated when multiple foods are implicated or when chronic diseases, such as asthma or atopic dermatitis, are evaluated. The diagnosis of food allergy and identification of the particular foods responsible is also more difficult when reactions are not mediated by IgE antibody, as is the case with a number of gastrointestinal food allergies. In these latter circumstances, well‐devised elimination diets followed by physician‐supervised oral food challenges are critical in the identification and proper treatment of these disorders. Since childhood food allergies to common allergenic foods such as milk, egg, wheat and soy are usually outgrown, oral food challenges are also an integral part of the long‐term management of these children.     

Sensitization to turnip rape and oilseed rape in children with atopic dermatitis: a case-control study

Turnip rape and oilseed rape 2S albumins are new allergens in children with atopic dermatitis suspected for food allergy. We recently found that 11% (206/1887) of these children had a positive skin prick test to seeds of oilseed rape ( Brassica napus ) and/or turnip rape ( Brassica rapa ). In the present case-control study we examined how the children with atopic dermatitis sensitized to turnip rape and oilseed rape had been breast-fed and whether they had some common sensitization pattern to certain foods or pollens. A total of 64 children with atopic dermatitis and a positive skin prick test to turnip rape and/or oilseed rape (≥5 mm) were examined. Sixty-four age- and sex-matched children with atopic dermatitis but negative skin prick tests to turnip rape and oilseed rape served as case controls. The turnip rape and/or oilseed rape sensitized children with atopic dermatitis had significantly more often positive skin prick tests reactions and IgE antibodies to various foods (cow's milk, egg, wheat, mustard; p < 0.01) and pollens (birch, timothy, mugwort; p < 0.01) than the control children. They had been exclusively breast-fed for a longer period (median 4 months; p < 0.05) and had more often associated asthma (36%) and allergic rhinitis (44%). Children with atopic dermatitis sensitized to oilseed rape and turnip rape had high frequency of associated sensitizations to all foods and pollens tested showing that oilseed plant sensitization affects especially atopic children who have been sensitized to multiple allergens.     

Sensitization to turnip rape and oilseed rape in children with atopic dermatitis: a case-control study.

Turnip rape and oilseed rape 2S albumins are new allergens in children with atopic dermatitis suspected for food allergy. We recently found that 11% (206/1887) of these children had a positive skin prick test to seeds of oilseed rape (Brassica napus) and/or turnip rape (Brassica rapa). In the present case-control study we examined how the children with atopic dermatitis sensitized to turnip rape and oilseed rape had been breast-fed and whether they had some common sensitization pattern to certain foods or pollens. A total of 64 children with atopic dermatitis and a positive skin prick test to turnip rape and/or oilseed rape (>or=5 mm) were examined. Sixty-four age- and sex-matched children with atopic dermatitis but negative skin prick tests to turnip rape and oilseed rape served as case controls. The turnip rape and/or oilseed rape sensitized children with atopic dermatitis had significantly more often positive skin prick tests reactions and IgE antibodies to various foods (cow's milk, egg, wheat, mustard; p < 0.01) and pollens (birch, timothy, mugwort; p < 0.01) than the control children. They had been exclusively breast-fed for a longer period (median 4 months; p < 0.05) and had more often associated asthma (36%) and allergic rhinitis (44%). Children with atopic dermatitis sensitized to oilseed rape and turnip rape had high frequency of associated sensitizations to all foods and pollens tested showing that oilseed plant sensitization affects especially atopic children who have been sensitized to multiple allergens.     

Food hypersensitivity and atopic dermatitis: evaluation of 113 patients

One hundred thirteen patients with severe atopic dermatitis were evaluated for food hypersensitivity with double-blind placebo-controlled oral food challenges. Sixty-three (56%) children experienced 101 positive food challenges; skin symptoms developed in 85 (84%) challenges, gastrointestinal symptoms in 53 (52%), and respiratory symptoms in 32 (32%). Egg, peanut, and milk accounted for 72% of the hypersensitivity reactions induced. History and laboratory data were of marginal value in predicting which patients were likely to have food allergy. When patients were given appropriate restrictive diets based on oral food challenge results, approximately 40% of the 40 patients re-evaluated lost their hypersensitivity after 1 or 2 years, and most showed significant improvement in their clinical course compared with patients in whom no food allergy was documented. These studies demonstrate that food hypersensitivity plays a pathogenic role in some children with atopic dermatitis and that appropriate diagnosis and exclusionary diets can lead to significant improvement in their skin symptoms.     

Shellfish allergy in children

Food allergies affect approximately 3.5–4.0% of the world's population and can range from a mere inconvenience to a life-threatening condition. Over 90% of food allergies in childhood are caused by eight foods: cow's milk, hen's egg, soy, peanuts, tree nuts, wheat, fish, and shellfish. Shellfish allergy is known to be common and persistent in adults, and is an important cause of food induced anaphylaxis around the world for both children and adults. Most shellfish-allergic children have sensitivity to dust mite and cockroach allergens. Diagnostic cut-off levels for skin prick testing in children with shrimp allergy exist but there are no diagnostic serum-specific immunoglobulin E (IgE) values. All patients with symptoms of IgE-mediated reactions to shellfish should receive epinephrine autoinjectors, even if the initial symptoms are mild. In this study, we review three cases of clinical presentations of shellfish allergy in children.     

Comparison of results of skin prick tests, enzyme-linked immunosorbent assays and food challenges in children with respiratory allergy

The present study was undertaken to investigate if enzyme-linked immunosorbent assays (ELISA) alone or in combination with skin tests could provide a better indicator of clinical food hypersensitivity in children with respiratory allergy. Skin prick tests (SPT) were performed on 64 children with crude antigenic food extracts. Oral food challenges were administered to children to confirm or rule out allergenicity of the food(s) incriminated, on the basis of the clinical history and/or a positive skin test. ELISA tests were then performed on the serum samples of all 64 children of study group as well as 32 children of the control group. SPT was found to be more sensitive as it detected a greater number of food challenge positive patients as compared to ELISA (92.85 vs 28.57 per cent). However, ELISA was found to have better specificity than SPT (88.04 vs 64.30 per cent). Clinically significant in our patients were 18.86 per cent of positive SPT and 4.81 per cent of positive ELISA. Our study shows that an ELISA value within the normal range is a reliable predictor of non-allergy, whereas IgE determination as a screening test for allergy is not reliable. Moreover, ELISA in itself or in combination with SPT had no advantage over SPT alone in correctly diagnosing food hypersensitivity.     

Prospective appraisal of complaints of adverse reactions to foods in children during the first 3 years of life

To examine the natural history of adverse reactions to foods, 480 children were followed prospectively from birth to their third birthdays. Foods thought to be causing symptoms were evaluated by elimination of suspected foods, open challenges, and double-blind food challenges. Foods producing symptoms were reintroduced into the diet at 1- to 3-month intervals until the symptoms no longer occurred. Of the 480 children completing the study, 28% were thought to have symptoms produced during food ingestion, but in only 8% were these reactions reproduced (excluding fruit and fruit juices). During the first year of life 80% of the initial complaints occurred. The most striking finding was the brief duration during which reactions could be reproduced. The majority of foods were replaced in the diet within 9 months of their incrimination. A long list of foods was reported to produce many symptoms, but only a few foods reproducibly evoked gastrointestinal and skin symptoms, with respiratory symptoms being infrequent. Of great interest was that 75 children were reported to react to fruit or fruit juice, and 56 of these children had reproducible symptoms. This study has found that most food reactions occur during the first year of life, but rechallenge at regular intervals has shown that the food can be reintroduced into the diet by the third year without risk. Almost all reactions that were reproduced appear to be non-immunoglobulin E mediated.