Fish and shellfish allergy in children: Review of a persistent food allergy

The increased consumption of fish and shellfish has resulted in more frequent reports of adverse reactions to seafood, emphasizing the need for more specific diagnosis and treatment of this condition and exploring reasons for the persistence of this allergy. This review discusses interesting and new findings in the area of fish and shellfish allergy. New allergens and important potential cross‐reacting allergens have been identified within the fish family and between shellfish, arachnids, and insects. The diagnostic approach may require prick to‐prick tests using crude extracts of both raw and cooked forms of seafood for screening seafood sensitization before a food challenge or where food challenge is not feasible. Allergen‐specific immunotherapy can be important; mutated less allergenic seafood proteins have been developed for this purpose. The persistence of allergy because of seafood proteins’ resistance after rigorous treatment like cooking and extreme pH is well documented. Additionally, IgE antibodies from individuals with persistent allergy may be directed against different epitopes than those in patients with transient allergy. For a topic as important as this one, new areas of technological developments will likely have a significant impact, to provide more accurate methods of diagnosing useful information to patients about the likely course of their seafood allergy over the course of their childhood and beyond.     

The diagnosis of IgE-mediated food allergy in childhood

IgE-mediated food allergy is a common condition in childhood and a recognized public health concern. An accurate diagnosis of food allergy facilitates the avoidance of the allergen – and cross-reactive allergens – and allows for safe dietary expansion. The diagnosis of food allergy relies on a combination of rigorous history, physical examination, allergy tests [skin prick tests (SPT) and/or serum-specific IgE] and oral food challenges. Diagnostic cut-off values for SPT and specific IgE results have improved the diagnosis of food allergy and thereby reduced the need to perform oral food challenges. This clinical case series seeks to highlight a contemporary approach to the diagnosis of food allergy in children strategies.     

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.     

Peanut and tree nut allergy in childhood

Peanut and tree nut allergies present multiple challenges in their presentation and management. These challenges have become increasingly relevant in recent years, as these allergies appear to have become more common. An estimated 1–2% of the population in the USA is allergic to peanut or tree nuts. Peanut allergy typically presents with symptoms in one of the first few exposures to peanut. Diagnosis is based on clinical history along with skin prick test, or quantitation of allergen-specific immunoglobulin E (IgE), and oral food challenges when indicated. Once the diagnosis is confirmed, the only current management approach is strict avoidance of the food. This is clearly an imperfect option as it can be difficult to avoid completely peanut and tree nuts and accidental exposures are not uncommon. Only about 20% of those with peanut allergy, and <10% of those with tree nut allergy, are reported to acquire tolerance. Additionally, peanut allergy can recur, with one study finding a recurrence rate of 8%. Peanut and tree nuts are the foods most frequently associated with fatal episodes of anaphylaxis. This is of particular concern in adolescents and young adults, among whom life-threatening and fatal food allergy-related reactions are most common.     

Role of food allergy in childhood atopic dermatitis

The interplay between atopic dermatitis (AD) and food allergy is complex and subject to significant misconceptions both by the general public and the medical community. Childhood AD is a very prevalent disorder. In its moderate and severe forms, AD is a challenging disorder to manage from the perspective of the child, parent and treating doctor. As AD is one of the disease manifestations of atopy, it is unsurprising that many children with AD also have a coexisting IgE‐mediated food allergy. It is a common misconception that food allergy is causal in the setting of AD. However, in a proportion of sufferers, food allergy does play a role in triggering or exacerbating pre‐existing AD by immune‐mediated mechanisms and potentially by non‐immune mechanisms. It is, therefore, important to differentiate causality, co‐existent disease and disease modifiers in this context. This paper seeks to clarify the role of food allergy in childhood AD, and to outline a rational framework for the diagnosis and approach to food allergy in the context of the management of a child with problematic AD.     

上海地区720例特应质儿童食物过敏临床分析

目的 探讨上海地区特应质儿童中食物过敏的发病情况和临床特点,以及食物过敏与其他过敏性疾病的关系.方法 采用国际上经典的食物过敏诊断方法 进行研究,对2007年7月-2008年7月因过敏症状在上海儿童医学中心过敏/免疫专科就诊的720例2个月～17岁特应质儿童,进行病史收集、皮肤点刺试验、排除性饮食试验和开放式食物激发试验.结果 最后确诊食物过敏59例(发生率8.19%).初次发生食物过敏的平均年龄为(0.40±0.33)岁.引起过敏的主要食物为鸡蛋(5.83%)、牛奶(2.78%),虾(1.67%)、鱼(1.25%);3岁以下儿童对鸡蛋过敏多见,≥3岁对虾过敏多见(P<0.01);94.92%的儿童对一种或二种食物过敏.食物过敏100%可引起皮肤症状,25%的特应质儿童因食物过敏引起湿疹;消化道症状发生率为3.39%;呼吸道症状发生率为1.69%;过敏性休克发生率为1.69%.≥3岁仍食物过敏的儿童吸入性过敏原阳性、患哮喘和过敏性鼻炎/结膜炎的人数均显著多于3岁以下的食物过敏儿童(P<0.01).结论 上海地区的特应质儿童中,食物过敏的发生率高,发生年龄小.对有皮肤过敏症状的儿童,应首先考虑食物过敏可能.早期诊断并阻断食物过敏,可预防其他严重过敏性疾病的发生.     

Nutritional problems related to food allergy in childhood

Food allergy is becoming an increasing problem worldwide with an estimated 6–8% of children affected at some point in their childhood. The perceived prevalence of food allergy is even higher with an estimated 20% of children adhering to some form of elimination diet. Against this background, accurate diagnosis is essential to prevent the imposition of unnecessarily restrictive diets on young children. Raising clinical awareness amongst health professionals as to the clinical characteristics, epidemiology, investigation, and management of food allergic disorders is key to tackling this growing problem. In this article, three separate cases of children with poor nutrition and secondary morbidity are presented, highlighting the varying scenarios in which these conditions can be encountered. In the first child, the features clinically displayed were hypocalcemic seizures and rickets due to prolonged breast feeding, poor weaning, and inadequate dietary supplementation. The second case reveals the dangers of complementary diagnostic allergy testing leading to poor nutrition as a consequence of an unsupervised elimination diet. The last report describes a child with multiple food allergies, failure to thrive, and protein losing enteropathy to highlight the diversity of nutritional problems faced by allergists and to underline the importance of specialist dietetic input in the management of a child with food allergy.     

Food allergy after liver transplantation in children: a prospective study

Food allergy has been increasingly reported in children who had orthotopic liver transplantation (OLT). We aimed to conduct a prospective study to investigate the prevalence of sensitizations and food allergy in pediatric OLT recipients. We also aimed to identify potential risk factors. The study group consisted of 28 children (14 male, 14 female, mean age 4.96 ± 0.76 yrs) who had OLT. Total eosinophil count (TEC), total IgE, and specific IgEs were studied before and 3, 6, 12 months after OLT. Six patients (21%) developed multiple food allergies. Mean age of six patients at OLT who developed food allergy was younger compared to the non‐food allergy group (10.2 months vs. 68.9 months, p < 0.05). Food allergy has been developed within 1 yr in 5, and in 20 months in one patient after OLT. All six patients had cow’s milk and egg allergy after OLT. Five children developed wheat, one children developed lentil and another one developed peach allergy in addition to cow’s milk and egg allergy. Out of six food‐allergic patients after OLT, four children developed Epstein–Barr virus (EBV) infection prior to food allergy. Before OLT, TECs and total IgE levels were not differed among food allergic and non‐food allergic patients (p > 0.05). Mean of TECs were significantly higher in food allergic group compared to non‐food allergic group at each time point after OLT (p < 0.05). Though statistically insignificant, mean of total IgE levels were also higher in the food allergic group (p > 0.05). These findings suggest that food allergy should be considered after OLT in patients who are younger than 1 yr of age, who developed hypereosinophilia, high total IgE levels or EBV viremia.     

Prevalence of food allergy among preschool children in northern Thailand

Background: The epidemiology and clinical spectrum of food allergies (FA) confirmed by oral food challenge tests (OFC) in the Southeast Asian countries are limited. The aim of the present study was to examine the prevalence and characteristics of FA among preschool children in northern Thailand. Methods: Five hundred and forty‐six children aged 3–7 years living in Chiang Mai, Thailand participated in this study. A cross‐sectional parent questionnaire survey was conducted. Families with children reporting FA were invited to undergo further investigations with skin prick testing, serum specific IgE, and OFC. Results: A total of 452 out of 546 questionnaires (82.8%) were returned. Forty‐two children (9.3%) were reported to have FA. The five leading allergic foods reported were shrimp, cow's milk, fish, chicken eggs, and ant eggs. The most commonly reported symptom was a skin rash (78.0%), followed by abdominal pain and vomiting (31.1%). Anaphylaxis was found in two children (3.4%), from ant eggs allergy. Eighteen children underwent OFC; five of them were positive to shrimp, fish, and crab. Either skin prick test or serum‐specific IgE was positive in these children. Factors associated with parent‐reported FA included personal and family history of atopic dermatitis. Conclusions: The prevalence of IgE‐mediated FA confirmed on OFC was ≥1.11% (95% confidence interval: 0.41–2.98%). The most common causative food was shrimp. Ant eggs were a unique food allergen causing severe reactions in preschool children in northern Thailand.     

Milk allergy school: Nutritional therapy in group for parents of children with cow''s milk allergy/intolerance in Primary Health Care

The objective of this study was to create a method for group nutritional therapy for parents of children with cow's milk allergy/intolerance in a paediatric primary care setting to increase accessibility to nutritional therapy. A second objective was to evaluate a milk allergy school. Follow-up time after the group session was 3 yr. All parents to newly diagnosed children (n=98) with cow's milk allergy/intolerance in the Primary Health Care system in the city of Goteborg during an 11-month period were invited. The majority of the families chose to participate (n=84, 86%). The mean age of the children was 9 months (3 months to 5 yr). The number of participants obtaining nutritional treatment within a month after diagnosis has significantly increased. Seventy-four families (88%) could be re-contacted 3 yr after participation for a second evaluation. Seventy-eight per cent of the children no longer had cow's milk allergy/intolerance. Most participants expressed satisfaction with the information obtained in the meeting. The milk allergy school does not replace but complements individual counselling. The milk allergy school seems to meet the families' needs for information, has few administrative routines and is cost-efficient. This activity has become permanent, is being offered weekly and can be recommended.