Pasini, G., B. Simonato, M. Giannattasio, C. Gemignani, A. Curioni, 2000. IgE binding to almond proteins in two CAP-FEIA-negative patients with allergic symptoms to almond as compared to three CAP-FEIA-false-positive subjects. Allergy. 55:955-958.
Background: Allergy to almonds has been frequently reported, but data on the identification of the almond allergens, as well as on the reliability of the methods for in vitro detection of specific IgE for these allergens, are scant. This study aimed to identify the almond allergens and to evaluate the reliability of the CAPFEIA as the standard system for detection of almond-specific IgE with clinical significance. Methods: Immunoblotting performed with an almond-protein extract was carried out on the sera of five patients who had previously been tested by the CAP-FEIA system; two of these patients had tested negative with the CAP-FEIA system but suffered life-threatening laryngeal edema after eating almonds, whereas the other three subjects, who had tested positive with CAP-FEIA, did not present any symptoms subsequent to almond ingestion. Results: The sera of the two symptomatic CAP-FEIA-negative patients had IgE that bound only to a 37-kDa protein in immunoblotting. On the contrary, the sera of the three asymptomatic subjects all showed IgE binding to two almond proteins of 62 and 50 kDa, corresponding to the glycosylated components of the extract. Conclusions: The results here presented suggest that, at least for the examined subjects, the positivity to almond, as measured with a standard laboratory method, is due to the presence of the 62/50-kDa glycoproteins with little or no immunologic significance, and not to the binding to the 37-kDa polypeptide, which appears to be a true almond allergen.
Eigenmann, P.A., A.-M. Calza, 2000. Diagnosis of IgE-mediated food allergy among Swiss children with atopic dermatitis. Pediatr Allergy Immunol. 11: 95-100.
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 speci®c 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 ®sh, 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.
Ortolani, C., B.K. Ballmer-Weber, K.S. Hansen, M. Ispano, B. Wüthrich, C. Bindslev-Jensen, R. Ansaloni, L. Vannucci, V. Pravettoni, J. Scibilia, L.K. Poulsen, E.A. Pastorello, 2000. Hazelnut allergy: A double-blind, placebo-controlled food challenge multicenter study. J Allergy Clin Immunol. 105:577-581.
Background: Tree nuts are a common cause of food allergy in Europe. However, few studies deal with real food allergy to hazelnuts in subjects believed to be allergic to this food. Objective: We sought to select subjects with a history of allergic reactions on ingestion of hazelnut and determine how many of these have true allergy by means of the double-blind, placebo-controlled food challenge (DBPCFC). Methods: Eighty-six subjects with a history of symptoms after hazelnut ingestion were recruited from 3 allergy centers (Milan, Zurich, and Copenhagen). All subjects underwent skin prick tests (SPTs) with aeroallergens and hazelnut, as well as having their specific hazelnut IgE levels determined. Diagnosis of clinical relevant food allergy was made on the basis of the DBPCFC. Results: Sixty-seven (77.9%) of 86 subjects had a positive DBPCFC result; 8 were placebo responders, and 11 were nonresponders. Of the 11 nonresponders, 4 had positive open-challenge test results. Of the DBPCFC-positive subjects, 87% also had positive skin test responses to birch pollen extract. Specific IgE determination for hazelnut (positive CAP response ≥0.7 kU/L [ie, class 2]) showed a sensitivity of 0.75, a positive predictive value (PPV) of 0.92, a specificity of 0.16, and a negative predictive value (NPV) of 0.05. Skin tests with commercial hazelnut extract produced a sensitivity of 0.89, a PPV of 0.92, a specificity of 0.05, and an NPV of 0.05. Skin tests with natural food produced a sensitivity of 0.88, a PPV of 0.94, a specificity of 0.27, and an NPV of 0.15. Conclusion: This study shows that hazelnut is an allergenic source that can cause real food allergy, as confirmed by DBPCFC. Skin and IgE tests demonstrated reasonable sensitivity and PPV but a very low specificity and NPV, thus implying that these should not be used to validate the diagnosis of food allergy to hazelnut.
Sicherer SH, A. Muñoz-Furlong, A.W. Burks, H.A. Sampson, 1999. J Allergy Clin Immunol. 103(4):559-562.
Allergy to peanuts and tree nuts (TNs) is one of the leading causes of fatal and near-fatal food-induced allergic reactions. These allergies can be lifelong and appear to be increasing in prevalence. Despite the seriousness of these allergies, the prevalence of peanut and TN allergy in the general population is unknown. OBJECTIVE: We sought to determine the prevalence of peanut and TN allergy among the general population of the United States. METHODS: We used a nationwide, cross-sectional, random digit dial telephone survey with a standardized questionnaire. RESULTS: A total of 4374 households contacted by telephone participated (participation rate, 67%), representing 12,032 individuals. Peanut or TN allergy was self-reported in 164 individuals (1.4%; 95% confidence interval [CI], 1.2%-1.6%) in 151 households (3.5%; 95% CI, 2.9%-4.0%). The prevalence of reported allergy in adults (1.6%) was higher than that found in children under 18 years of age (0.6%). In 131 individuals, details of the reactions were obtained. When applying criteria requiring reactions to be typical of IgE-mediated reactions (hives, angioedema, wheezing, throat tightness, vomiting, and diarrhea) within an hour of ingestion, 10% of these subjects were excluded. Among the remaining 118 subjects, allergic reactions involved 1 organ system (skin, respiratory, or gastrointestinal systems) in 50 subjects, 2 in 45 subjects, and all 3 in 23 subjects. Forty-five percent of these 118 respondents reported more than 5 lifetime reactions. Only 53% of these 118 subjects ever saw a physician for the allergic reaction, and only 7% had self-injectable epinephrine available at the time of the interview. The prevalence of peanut and TN allergy was adjusted by assuming that 10% of the remaining 33 subjects without a description of their reactions would also be excluded and correcting for a 7% false-positive rate for the survey instrument. A final “corrected” prevalence estimate of 1.1% (95% CI, 1.0%-1.4%) was obtained. CONCLUSIONS: Peanut and/or TN allergy affects approximately 1.1% of the general population, or about 3 million Americans, representing a significant health concern. Despite the severity of reactions, about half of the subjects never sought an evaluation by a physician, and only a few had epinephrine available for emergency use.
Sampson, H.A., 1999. Food allergy. Part 1: Immunopathogenesis and clinical disorders. J Allergy Clin Immunol. 103:717-728.
Up to 8% of children less than 3 years of age and approximately 2% of the adult population experience food-induced allergic disorders. A limited number of foods are responsible for the vast majority of food-induced allergic reactions: milk, egg, peanuts, fish, and tree nuts in children and peanuts, tree nuts, fish, and shellfish in adults. Food-induced allergic reactions are responsible for a variety of symptoms involving the skin, gastrointestinal tract, and respiratory tract and may be caused by IgE-mediated and non-IgE-mediated mechanisms. In part 1 of this series, immunopathogenic mechanisms and clinical disorders of food allergy are described.
Pumphrey, R.S.H., P.B. Wilson, E.B. Faragher, S.R. Edwards, 1999. Specific immunoglobulin E to peanut, hazelnut and brazil nut in 731 patients: similar patterns found at all ages. Clin Exp Allergy. 29:1256-1259.
Background: Previous studies have reported reactions to an increasing range of nuts as patients with nut allergy grow older. Most patients with symptoms suggesting nut allergy have specific IgE to more than one nut. Furthermore, fatal reactions have followed eating nuts different from any causing the deceased’s previous reactions. Objective: To explore the pattern of specific IgE to three distantly related nuts in patients of all ages with nut allergy. Methods: This study includes all patients referred to our laboratory for nut allergy testing from January 1994 to August 1998 who were tested for peanut, hazelnut and brazil nut, and had specific IgE to at least one of these nuts. All tests were performed using the Pharmacia Unicap system. Results: Seven hundred and thirty-one patients (age 7 months to 65 years, median 6.6 years) had specific IgE > 0.35 kUA/L to at least one of these three nuts: 282 had IgE to one nut, 130 to two nuts, and 319 to all three nuts. When analysed by gender and age quartile, very similar patterns were found in all subgroups though significant age trends and age interactions were found for IgE to individual nuts and combinations of nuts. Conclusions: The probability of a patient with nut allergy having specific IgE to a particular combination of peanut, hazelnut and brazil nut is similar, whatever their age or sex. The apparent increase in multiple nut reactivity with increasing age may therefore be due to exposure of previously unchallenged sensitivity. The frequency of multiple-nut specificity is sufficiently high that patients should always be tested for allergy to a range on nuts if they have a history of reacting to any nut.
Eggesbø, M., R. Halvorsen, K. Tambs, G. Botten, 1999. Prevalence of parentally perceived adverse reactions to food in young children. Pediatr Allergy Immunol. 10:122-132.
A substantial number of parents perceive that their children have adverse reactions to food, but it is well documented that objective assessments agree with only one-quarter to one-half of parentally reported reactions. In order to prevent wrong diagnoses and curtail unnecessary or inadequate diets, primary health care providers need to deal with the parental perception of adverse reactions to food. A description of the prevalence and pattern of parentally perceived adverse reactions to food in children is needed to meet this challenge. The aim of the present study was to estimate the prevalence, incidence and cumulative incidences of parentally perceived adverse reactions to food in children younger than 2 years of age, and to study the duration of the reactions. A population-based cohort of 3623 children born in Norway was followed from birth until the age of two. At 6-month intervals, the parents completed questionnaires regarding the occurrence and type of any reaction to food. Information was available on the outcome measure at all age points for 77.4% of the families and these were used in the analyses; 3.8% of the cohort were entirely lost to follow-up. The cumulative incidence of adverse reactions to food was 35% by age two. Fruits, milk and vegetables accounted for nearly two-thirds of all reported reactions. Milk was the single food item most commonly incriminated, the cumulative incidence being 11.6%. The cumulative incidences of reported reactions to fruits and vegetables were 20.4% and 7.3%, respectively, with citrus fruits, strawberry and tomatoes as the most common food items in these groups. The cumulative incidences were less for food reactions associated with eggs (4.4%), fish (3%), nuts (2.1%) and cereals (1.4%). The duration of the reactions was short ± approximately two-thirds of the reactions were not reported again 6 months later. However, the probability of remission depended on the food item concerned, the age at onset of reactions, and whether the reaction had been reported previously or not. Adverse reactions to food are reported by the parents of one-third of children in Norway before the age of two. The most striking feature of this study is the short duration of the food reactions, as approximately two-thirds of the reactions are not reported again 6 months later. Nevertheless, the high frequency of reactions attributable to milk is of concern. Milk is an important part of the Norwegian diet for children, and if removed from the diet its nutritional value is not easily replaced. Further studies are needed to assess the degree to which parents alter the diet of their children based upon perceived reactions to food.
Altman, D.R., L.T. Chiaramonte, 1996. Public perception of food allergy. J Allergy Clin Immunol. 97(6):1247-1251.
BACKGROUND: Although studies that use the double-blind placebo-controlled food challenge suggest that the prevalence of food allergy is about 2%, public belief in food allergy appears to be considerably higher. OBJECTIVE: The study was undertaken to determine the magnitude and features of the American public’s belief in food allergy by surveying a large, demographically balanced population. METHODS: A simple question about food allergy was incorporated into a broad, self-reported, mailed consumer questionnaire. Five thousand demographically representative American households were surveyed by means of quota sample in 1989, 1992, and 1993. RESULTS: The response rates were 79%, 75%, and 74%, respectively. Of responding households, 16.2%, 16.6%, and 13.9%, respectively, reported an average of 1.17 household members with food allergy. Individuals reported to be allergic to foods were more likely to be female, particularly adult women. Male individuals with reported food allergy tended to be young, whereas no such skew was noted among female subjects. Geographic differences were observed in reported food allergy, with the highest rate in the Pacific region. Milk and chocolate were the individual foods most frequently implicated in food allergy. Trends were consistent over the period studied. CONCLUSIONS: Perceived food allergy is widespread and persistent. The characteristics and demographic patterns of this belief are not reflective of known food allergy epidemiology derived from studies in which the double-blind placebo-controlled food challenge is used.
