BACKGROUND: The prevalence of peanut allergy (PA) among children has increased significantly over the past decade. Even though the prevalence of PA in Singapore is considered low, peanut is the top trigger for food-induced anaphylaxis in Singaporean children.OBJECTIVE: To describe the demographic characteristics and clinical features of children with PA.METHODS: This is a 5-year retrospective review of children diagnosed with PA based on clinical history coupled with a positive skin prick test to peanut or positive oral food challenge results.RESULTS: There were 269 patients (53.9% males) with a clinical diagnosis of PA. The median age at first allergic presentation for the PA group was 24 months old, with interquartile range of 13–39 months. The most common form of peanut introduced was roasted peanut. The rate of peanut anaphylaxis was 7.1%. Concomitant tree nut sensitization was found in 32.3% of this cohort, predominantly to cashew nut. Majority of them have a personal history of atopy – 75.8% with eczema, 63.6% with allergic rhinitis, and 19.7% with asthma.CONCLUSION: This is the first large review of peanut-allergic children in Singapore. Prospective population-based studies are needed to establish the true prevalence and risk factors associated with the development of this potentially life-threatening condition.
Anacardium ; Anaphylaxis ; Arachis ; Asia ; Asthma ; Child ; Cohort Studies ; Diagnosis ; Eczema ; Humans ; Nuts ; Peanut Hypersensitivity ; Prevalence ; Prospective Studies ; Retrospective Studies ; Rhinitis, Allergic ; Risk Factors ; Singapore ; Skin ; Trees

BACKGROUND: Peanut allergy is an increasing problem in Singapore and strict avoidance is difficult as peanut is ubiquitous in Asian cuisine. OBJECTIVE: We aimed to assess the efficacy and safety of peanut oral immunotherapy (OIT) in children with obvious peanut allergy in Singapore. METHODS: This was an open-label study of peanut OIT in children living in Singapore, with 2 weekly dose escalation until final maintenance dose of 3,000 mg of peanut protein and a maintenance phase of 12 months. An oral food challenge was performed at 6 months to assess for desensitisation and at 4 weeks after discontinuation of OIT having completed 12 months of maintenance therapy to assess for possible sustained unresponsiveness. The adverse events were monitored using the symptom diaries. RESULTS: Nine subjects were started on OIT, with 7 managing to complete maintenance phase of therapy. Of these 7, all were able to tolerate at least 3,000 mg of peanut protein by 6 months of maintenance therapy, showing that the OIT was effective. Of these 7, 3 patients complied with the 4-week abstinence period after completion of OIT before another peanut challenge; 2 of the 3 subjects showed a significant decrease from the initial ability to tolerate 3,000 mg of peanut protein. Side effects were mainly gastrointestinal in nature and were more common during the updosing phase than the maintenance phase. No episodes of anaphylaxis were observed in this study. CONCLUSION: Peanut OIT seemed to be effective and safe in our cohort of Singaporean children.
Anaphylaxis ; Arachis ; Asian Continental Ancestry Group ; Child ; Cohort Studies ; Humans ; Hypersensitivity ; Immunotherapy ; Peanut Hypersensitivity ; Pilot Projects ; Probiotics ; Singapore

BACKGROUND: The predictive decision points for both peanut skin prick test (SPT) wheal size and serum IgE concentrations, in peanut-sensitized children, have not been evaluated in Singapore. OBJECTIVE: We aim to derive clinically useful predictive decision points to be used for risk stratification of oral food challenge (OFC) in peanut-sensitized patients. METHODS: Patients with a positive SPT to peanut, performed during a 4-year period between 2012 and 2016, were included in a retrospective chart review. The patients were assessed for their peanut allergy status based on a convincing clinical history. Their first SPT and serum IgE results done at presentation to our centre were used. RESULTS: There were 269 patients with a clinical diagnosis of peanut allergy based on recent immediate reaction to peanut and 59 patients whom were tolerating peanuts regularly. There were 251 patients sensitized to peanut, without prior known peanut exposure. A wheal size of ≥8 mm and a peanut-specific IgE of ≥6 kU/L each provided for a 95% positive predictive value of clinical reaction to peanuts; the larger the wheal size on SPT, the higher the probability. CONCLUSION: The cutoff values derived in this study can help clinicians in the risk assessment of OFC in peanut-sensitized patients. Prospective studies using OFCs for the diagnosis of peanut allergy are needed to confirm the diagnostic performance of these tests in predicting OFC outcomes.
Arachis ; Child ; Diagnosis ; Humans ; Immunoglobulin E ; Peanut Hypersensitivity ; Prospective Studies ; Retrospective Studies ; Risk Assessment ; Singapore ; Skin

PURPOSE: Clinical features of peanut allergy can range from localized to systemic reactions. Because peanut and birch pollen have cross-reactivity, peanut can lead to localized allergic reaction in Fagales pollen-sensitized oral allergy syndrome (OAS) patients without peanut sensitization per se. The purpose of this study was to discriminate true peanut food allergy from cross-reactive hypersensitivity in birch-sensitized peanut allergy. METHODS: Birch-sensitized (n=81) and peanut anaphylaxis patients (n=12) were enrolled. Peanut-related allergic reactions and sensitization profiles were examined. Specific IgE to Fagales tree pollens (birch, oak), peanut, and their component allergens (Bet v 1, Bet v 2, Ara h 1, Ara h 2, Ara h 3, Ara h 8, and Ara h 9) were evaluated. Based on these specific IgEs and clinical features, the patients were classified into 4 groups: group 1 (Fagales pollen allergy without OAS), group 2 (Fagales pollen allergy with OAS), group 3 (OAS with peanut anaphylaxis), and group 4 (peanut anaphylaxis). RESULTS: After peanut consumption, one-third of OAS patients experienced oral symptoms not associated with peanut sensitization. Ara h 1 or Ara h 2 was positive in peanut anaphylaxis patients, whereas Ara h 8 was positive in OAS patients. There were 4 patients with both peanut anaphylaxis and OAS (group 3). Both Ara h 2 and Ara h 8 were positive in these patients. Foods associated with OAS in Korea showed unique patterns compared to Westernized countries. CONCLUSIONS: Ara h 2 and Ara h 8 may be important component allergens for discriminating peanut allergy.
Allergens* ; Anaphylaxis ; Arachis* ; Betula ; Food Hypersensitivity ; Humans ; Hypersensitivity ; Immunoglobulin E ; Korea* ; Peanut Hypersensitivity* ; Pollen ; Rhinitis, Allergic, Seasonal ; Trees

PURPOSE: The purpose of this study was to establish the diagnostic decision point (DDP) of peanut specific IgE (sIgE) for predicting the outcome of oral food challenge (OFC). We also evaluated the usefulness of sIgE to peanut components (Ara h 1, 2, 3, 8, and 9) in diagnosing peanut allergy. METHODS: Korean children aged over 12 months with a suspected peanut allergy were enrolled. Diagnosis of peanut allergy was confirmed by an open OFC or through the convincing history of anaphylaxis. Cutoff levels of sIgE to peanut and peanut components were determined by analyzing receiver operating characteristic curves. RESULTS: Forty-eight children (22 boys and 26 girls) with a suspected peanut allergy were enrolled. The previously established DDP for peanut-sIgE antibodies (14 kU/L) showed a sensitivity of 22.7%, specificity of 100%, positive predictive value (PPV) of 100%, and negative predictive value of 60.4% in our study population. The median levels of peanut-sIgE (5.4 kU/L vs 1.1 kU/L, P<0.001) and Ara h 2-sIgE (0.8 kU/L vs 0 kU/L, P<0.001) were significantly higher in the peanut allergy group than in the peanut tolerance group. The peanut-sIgE concentration indicating a PPV of 100% was 10.3 kU/L. The Ara h 2-sIgE level of 4.0 kU/L had a PPV of 100%. CONCLUSIONS: Our results showed that the cutoff levels for peanut (10.3 kU/L) and Ara h 2 (4.0 kU/L) established in this study is useful for the diagnosis of peanut allergy in Korean children.
Anaphylaxis ; Antibodies ; Child* ; Diagnosis ; Food Hypersensitivity ; Humans ; Immunoglobulin E* ; Peanut Hypersensitivity* ; ROC Curve ; Sensitivity and Specificity

Food allergy is common with the prevalence of 5%??% in Korean children. The development of food allergy is likely to reflect interactions between genetic factors and environmental exposure. To prevent food allergy, early exposure to food allergens through maternal and infant diet have been investigated. Recently, guidelines for primary prevention of food allergy have been updated, and consensus communication on early peanut introduction has been demonstrated. For the first 4?? months after birth, exclusive breast-feeding is recommended, and if impossible, extensively or partially hydrolyzed infant formula can be recommended in high-risk infants. Introducing complementary foods is recommended between 4 and 6 months of age, even in case of potentially allergenic foods such as egg, milk, and wheat. For the prevention of peanut allergy, early peanut introduction could be better than late peanut introduction in selected high-risk infants. However, infants who developed food allergy should avoid ingestion of specific offending foods.
Allergens ; Child ; Consensus ; Diet ; Eating ; Environmental Exposure ; Food Hypersensitivity* ; Humans ; Infant Formula ; Infant* ; Milk ; Ovum ; Parturition ; Peanut Hypersensitivity ; Prevalence ; Primary Prevention ; Triticum

BACKGROUND: In peanut and tree nut allergic children a history of anaphylaxis is associated with subsequent severe reactions. OBJECTIVE: We aimed to prospectively rechallenge peanut and tree nut allergic children with a history of mild/moderate reactions to assess their allergy over time. METHODS: In this cohort study peanut and tree nut allergic children with a history of mild/moderate reactions during a controlled oral challenge were invited to have a follow-up oral challenge to the same food at least 1 year later. RESULTS: Twenty-six children participated in the study. The mean time interval between the first and second challenge for all participants was 35.5 months. Peanut or tree nut allergy resolved in 38.5% of participants. Those with persistent peanut or tree nut allergy showed a decrease in their reaction threshold and/or increased severity in 81% of cases. There were no demographic features or skin test results that were predictive of changes in severity over time. CONCLUSION: Peanut and tree nut allergic children with a history of mild/moderate reactions who remained allergic demonstrated a high rate of more severe reactions and/or reduced thresholds upon rechallenge over a year later, however, the rate of resolution of allergy in this group may be higher than previously reported.
Anaphylaxis ; Arachis ; Child ; Cohort Studies ; Follow-Up Studies ; Humans ; Hypersensitivity ; Nut Hypersensitivity ; Nuts ; Peanut Hypersensitivity ; Prospective Studies ; Skin Tests ; Trees

With the exception of shellfish, the overall food allergy rates in Singapore have not reached the epidemic proportions of the West. The rates of egg, milk and fish allergies remain low. However, the patterns of some food allergies in Singapore have changed over the last decade. For example, peanut allergy, once rare in Singapore, is now the most common cause of anaphylaxis in children. Studies analysing lifestyle practices, particularly with respect to prevention of food allergy, are necessary in order for practitioners to understand global differences and maintain this low prevalence.
Anaphylaxis ; diagnosis ; Child ; Child, Preschool ; Egg Hypersensitivity ; Fish Products ; Food Hypersensitivity ; diagnosis ; epidemiology ; prevention & control ; Humans ; Infant ; Infant, Newborn ; Milk Hypersensitivity ; Peanut Hypersensitivity ; Singapore ; epidemiology ; Surveys and Questionnaires

Food allergies continue to increase exponentially and therapies that can modify the natural course of disease is a recent top priority of the research. IgE-mediated food allergy represents both a promising and an intriguing disease of application for allergen specific immunotherapy. In particular, oral immunotherapy (OIT) may offer a novel effective therapeutic modality for persistent and severe forms of food allergies. In such patients, avoidance of the causative foods only may be insufficient because of the risk of unplanned exposure to causative foods. In patients with cow's milk, hen's egg, and peanut allergies, several recently published studies, including meta-analysis, confirmed the overall benefit of OIT. However, the definitive evidence of efficacy and safety with long-term therapeutic or disease-modifying effects is limited. In current protocols, entry indications, and initial-escalating-maintenance doses, the form of antigens, durations, and follow-up periods await to be standardized. Most of the clinical trials of OIT demonstrate effective desensitization, but the ability for inducing long-term tolerance remains to be improved, and the ratio of risks versus benefits of OIT should be considered in detail. The ultimate goal is extending OIT to primary care practice, but at this time, OIT remains within the purview of allergy specialists in terms of associated risk-benefit ratios, related safety, and long-term tolerance induction.
Food Hypersensitivity* ; Humans ; Hypersensitivity ; Immunotherapy* ; Milk ; Ovum ; Peanut Hypersensitivity ; Primary Health Care ; Specialization

Regional dietary habits and cooking methods affect the prevalence of specific food allergies; therefore, we determined the effects of various pH conditions on major peanut allergens. Peanut kernels were soaked overnight in commercial vinegar (pH 2.3) or acetic acid solutions at pH 1.0, 3.0, or 5.0. Protein extracts from the sera of seven patients with peanut-specific IgE levels >15 kUA/L were analyzed by SDS-PAGE and immunolabeling. A densitometer was used to quantify and compare the allergenicity of each protein. The density of Ara h 1 was reduced by treatment with pH 1.0, 3.0, or 5.0 acetic acid, or commercial vinegar. Ara h 2 remained largely unchanged after treatment with pH 5.0 acetic acid, and was decreased following treatment with pH 1.0, 2.3, or 3.0 acetic acid. Ara h 3 and Ara h 6 appeared as a thick band after treatment with pH 1.0 acetic acid and commercial vinegar. IgE-binding intensities to Ara h 1, Ara h 2, and Ara h 3 were significantly reduced after treatment with pH 1.0 acetic acid or commercial vinegar. These data suggest that treatment with acetic acid at various pH values affects peanut allergenicity and may explain the low prevalence of peanut allergy in Korea.
Acetic Acid ; Allergens ; Arachis ; Cooking ; Electrophoresis, Polyacrylamide Gel ; Food Habits ; Humans ; Hydrogen-Ion Concentration ; Immunoglobulin E ; Korea ; Peanut Hypersensitivity ; Prevalence