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Epidemiology of food allergy/food intolerance in adults: associations with other manifestations of atopy
T. Schafer, E. Bohler et al, Medical University, Lubeck; Environmental Dermatology & Allergy, Munich, Germany
Background: Food allergy and food intolerance (FA/FI) are believed to be frequent medical problems; however, information from epidemiologic studies in adult is scarce.
Objective: The objective was to determine the frequency of FA/FI and allergic sensitisation to food in a large adult sample. Furthermore, the associations between FA/FI and other outcomes of atopy were studied.
Methods: Within a population-based, nested, case-control study, a standardized interview was performed to obtain detailed information on FA/FI and the history of atopic diseases. In addition, a skin prick test with 10 common food and nine aeroallergens was performed.
Results: Overall, 20.8% of the 1537 studied subjects (50.4%) of female, age median 50 years reported FA/FI (women 27.5%, men 14%; OR 2.35, CI 1.80-3.08). Nuts, fruits, and milk most frequently led to adverse effects, and the sites of manifestation were oral (42.9%), skin (28.7%), gastrointestinal (13.0%), systemic (3.2%), and multiple (12.2%). One-quarter of the subjects (25.1%) were senitized to at least one food allergen in the prick test, with hazelnut (17.8%), celery (14.6%), and peanut (11.1%) accounting for most of the positive reactions. The corresponding frequency estimates for the representative study base (n=4178) were 15.5% for reported adverse reactions and 16.8% for allergic sensitisation. Relevant concomitant sensitisation to food and aeroallergens was observed. Food-allergic subjects (positive history and sensitisation to corresponding allergen) suffered significantly more from urticaria, asthma, atopic eczema, and especially hay fever (73.1%) than controls (3.0%). Furthermore, hay fever was treated significantly more often in subjects who suffered from concomitant food allergy.
Conclusions: FA/FI in adults is frequently reported and associated with other manifestations of atopy. Hay fever in conjunction with FA/FI tends to be clinically more severe since therapeutic needs are greater.
Reference: Allergy 2001: 56: 1172-1179
Hidden peanut allergens detected in various foods: findings and legal measures
G. F. Schappi et al, Dept. Dermatology & Allergy, University Hospital, Zurich, Switzerland
Background: Undeclared allergens in foodstuffs represent major health problem for sensitised persons. Until recently, most food control authorities were not in the position to monitor hidden allergens and to take legal measures against the presence in foodstuffs.
Methods: In this study, they employed human sera-based immunoassay techniques, enabling semi quantitative detection of peanut allergens in a variety of foodstuffs.
Results: This study showed the presence of undeclared allergens in products belonging to various food categories, such as cereals, cookies, cakes, and snacks. The detection limit for peanut contamination was in most instances less than 50 mg peanut material per kg, i.e., less than 5 mg peanut allergen per kg. They legally objected to products with more than one part per thousand or 1000 mg/kg of peanut contamination.
Conclusions: In most cases, food producers, confronted with their results, were able to detect and eliminate the sources of the contamination. They implemented measures to prevent the presence of hidden peanut allergens in their products, increasing food safety for sensitised persons and overall food quality.
Reference: Allergy 2001: 56: 1216 - 12
Predictors of positive food challenge outcome in non-IgE-mediated reactions to food in children with atopic dermatitis
Bodo Niggeman et al, Berlin, Germany
Background: Atopic dermatitis is frequently associated with food allergy. In general, clinically manifested food allergy is regarded as IgE mediated. However, there are some children with food allergy for whom IgE hypersensitivity cannot be proven.
Objective: The aim was to evaluate the percentage of children with positive double-blind, placebo-controlled food challenge (DBPCFC) results but without proof of IgE sensitisation and to characterize this subgroup of children.
Methods: 208 DBPCFC were performed in 139 children (median age, 13 months) with atopic dermatitis and suspected food-related clinical symptoms. All children were subjected to skin prick tests (SPTs), determination of specific IgE, and atopy patch tests.
Results: 111 (53%) of 208 oral food challenge results were assessed as positive. Positive challenge results were separated into 2 groups according to IgE positivity: negative SPT and negative specific IgE results in serum (group A, n=12) and positive SPT, specific IgE, or both results in serum (group B, n=99). The atopy patch test results; the distribution of early, late, or both clinical reactions; the age of the children; and total IgE levels all showed no significant differences between the 2 groups. However, wheat challenge results were more often positive among the apparently non-IgE-sensitized children, and hen's egg challenge results were more often positive in the sensitised group (P<. 05).
Conclusions: Around 10% of positive DBPCFC results are not IgE mediated. Therefore not the proof of specific IgE but the suspicion of food-related symptoms should be the indication to perform oral food challenges, especially in the case of wheat. Otherwise, some children will not have their food allergy diagnosed and will be denied the benefit of a specific diet.
Reference: J Allergy Clin Immunol 2001; 108: 1053 - 1058
Adrenaline for the out-of-hospital (first-aid) treatment of anaphylaxis in infants: Is the ampoule/syringe/needle method practical
F. Estelle R. Simons et al, Winnipeg, Manitoba, Canada
Background: Little information is available about administration of an accurate adrenaline dose in infants experiencing anaphylaxis outside the hospital setting.
Objective: Their purpose was to perform a prospective, controlled study of (1) the time needed by parents to draw up an infant adrenaline dose from an ampoule and (2) the dose accuracy.
Methods: They gave 18 parents written instructions and asked them to draw up adrenaline 0.09 ml. They timed them by means of a stopwatch and measured the adrenaline content in (micrograms) in each dose by using HPLC-UV. 18 resident physicians, 18 general duty nurses, and 18 emergency department nurses served as controls.
Results: The parents took significantly longer (p< 0.05) than the controls to draw up the dose; the mean (+/- SEM) times were 142 +/- 13 seconds (range, 83-248) for the parents, 52 +/- seconds (range, 30-83) for the physicians, 40 +/- 2 seconds (range, 26-71) for the general duty nurses, and 29 +/- 0.09 seconds (range, 27-33) for the emergency department nurses. The control groups did not differ significantly from each other in speed (p > .05). The adrenaline content of the doses drawn up by the parents ranged 40-fold in contrast to the physicians' doses (7- to 8- fold), general duty nurses' doses (3-fold), and emergency department (2-fold). The mean adrenaline content did not differ significantly (p >.05) among the 4 groups.
Conclusions: Most parents were unable to draw up an infant adrenaline dose rapidly or accurately. Most health care professionals drew up the dose rapidly; however, their accuracy was compromised by inherent variations of adrenaline concentrations in the ampoules (US Pharmacopeia compendial limits, 90% to 115%) and the inherent difficulty of measuring low volumes (<0.1ml) of adrenaline. User-friendly premeasured adrenaline doses suitable for infants should be developed.
Reference: J Allergy Clin Immunol 2001; 108:1040-4
Elevated serum concentrations of beta- tryptase, but not alpha- tryptase, in Sudden Infant Death Syndrome (SIDS). An investigation of anaphylactic mechanisms
M. G. Buckley et al, Sheffield Children's Hospital, Sheffield, UK.
Background: Sudden Infant Death Syndrome, (SIDS) or cot death, remains the most common category of post-perinatal death in the UK. By definition, the cause of death is unknown, but a long-standing theory is that some of these deaths could be the result of anaphylaxis.
Objective: To investigate the potential contribution of anaphylactic mechanisms to death in infancy by determining relative levels of - and tryptases and both total and allergen-specific IgE in sera from groups of infants whose deaths were attributed to SIDS or to other causes.
Methods: Serum samples were collected at the time of post-mortem examination from infants whose deaths were classed as SIDS (n=40) and from a comparison group in which cause of death was established (n=32). Serum tryptase concentrations were measured by radioimmunoassay with monoclonal antibody G5 which detects primarily or an ELISA with antibody AA5 which has equal sensitivity for a- and â-tryptase. Levels for total IgE and IgE specific for casein, b-lactoglobulin, house dust mite and mould were determined.
Results: Analysis of these results of the two assays for tryptase indicated that the levels of the beta-like tryptase (the form secreted on anaphylactic degranulation) were significantly higher in serum from infants with SIDS compared with those whose deaths were explained. There was no evidence for an increase in levels of a-tryptase (the variant secreted constitutively from mast cells). Total level of serum IgE did not differ between the two groups and, reflecting the low circulating IgE concentrations in infancy an elevation in IgE specific for the panel was not detected.
Conclusions: In a proportion of SIDS victims there may be increased serum levels of beta-like tryptase, a marker for anaphylaxis. The failure to detect an increase in alpha-tryptase would suggest that mast cell hyperplasia is not a feature of cot death. The nature of the inciting agents remains unclear, but anaphylaxis deserves serious consideration as a possible cause of sudden death in infancy.
References: Clinical and Experimental Allergy, Vol 31, and pp. 1696 - 1704
Concordance and inter-relationship of atopic diseases and markers of allergic sensitisation among adult female twins.
David P. Strachan et al London, UK
Background: Previous twin studies of asthma and allergy implicate both genetic and environmental factors in disease risk, but few have related the occurrence of clinical disease to objective markers of allergic sensitisation in twins.
Objective: They sought to investigate the concordance and interrelationships of self-reported allergic diseases and total and aeroallergen-specific IgE levels within pairs of British adult female twins.
Methods: 340 monozygotic and 533 dizygotic pairs, aged 18 to 72 years, completed questionnaires about allergic diseases. Of these, 282 monozygotic and 270 dizygotic pairs were tested for total IgE and specific IgE to Der p 1 (house dust mites), mixed grass pollen, and cat dander by means of fluoro immunoassay.
Results: Concordance rates for all variables were higher for monozygotic than for dizygotic twins, significantly (p<. 05) so for hay fever, eczema, and specific IgE positivity but not (p>.05) for self-reported asthma or allergies. Within-pair correlations of log-transformed IgE were 0.59 for monozygotic twins and 0.29 for dizygotic twins, implying heritability at 60%. Within both monozygotic and dizygotic pairs discordant for hay fever or reported allergies, affected twin had significantly higher total and specific IgE levels. Within pairs who were doubly discordant for 3 allergic diseases, associations between diseases were of similar strength for monozygotic and dizygotic pairs.
Conclusions: These results confirm that genetic factors influence susceptibility to aeroallergen sensitisation and clinical allergic disease. However, genetically identical twins are often discordant in their expression of atopy, suggesting a substantial modifying role for environmental factors.
Reference: J Allergy Clin Immunol 2001; 108:901-7
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