The prevalence of allergy to egg: a population-based study in young children

Correlation between specific immunoglobulin E levels and the severity of reactions in egg allergic patients

Different studies proposed specific immunoglobulin E (IgE) cut-off levels for the diagnosis of egg allergy. Little is known if IgE titres could be helpful for prediction of the severity of the reaction. The aim of this study was to determine whether IgE titres are associated with the severity of the reaction during a standardized egg challenge. We reviewed data obtained during oral challenge tests to egg performed between 2003 and 2005, and attributed a clinical score to the positive reactions. Serum specific IgE levels were analysed in relation with the severity of the reaction. We analysed data from 51 oral food challenges to egg, raw or cooked. Sixteen challenges (31%) were negative and 35 (69%) were positive of which 13 challenges (37% of positive reactions) elicited a severe reaction. IgE levels in our patients ranged from undetectable to 14.90 kU/l. We could determine a cut-off level of 8.20 kU/l for a 90% probability of clinical reactivity. IgE titres were statistically significantly different between the patients with absent, mild and moderate or severe reaction. Patients with negative challenge had IgE levels between 0.35 and 6.41 kU/l (median 1.17), those with mild and moderate reaction had IgE levels ranging from 0.35 to 14.90 (median 2.47) and patients with severe reactions had IgE between 1.18 and 11.00 (median 3.70) (p = 0.006). Our results show a correlation between IgE titres and the severity of the clinical reaction to egg. IgE titres may help to determine the potential risk of a reaction to eggs.

Establishment of a highly sensitive sandwich enzyme-linked immunosorbent assay specific for ovomucoid from hen's egg white

A highly sensitive sandwich enzyme-linked immunosorbent assay (ELISA) kit was established for quantifying ovomucoid from hen's egg white, which has been considered as one of the major allergen in egg white. The detection limit reached 0.041 ng/mL, and linearity ranged from 0.1 to 6.25 ng/mL. Intra- and interassay coefficient variations were all lower than 5% at three concentrations (0.5, 2.5, and 5 ng/mL). No cross-reactivity was observed with bovine serum, horse serum, goat serum, human serum, duck egg white, goose egg white, quail egg white, and pigeon egg white, but a low level of cross-reactivity was found with chicken serum. The ELISA kit was established on the basis of two monoclonal antibodies (mAbs) recognizing different epitopes of ovomucoid. However, these mAbs were generated using commercially purified ovalbumin as immunogen. Studies on the relative allergenicity and antigenicity of egg white protein have been performed by many researchers, but there were controversial opinions reported previously because of the impurity of each egg white protein used in various studies. In the present work we measured the degree of ovomucoid contamination in commercially purified ovalbumin sample, and the value was about 11%. We also determined the ovomucoid residue in influenza vaccine samples for the first time. These data showed that the ELISA kit we established could serve as an effective method for precisely quantifying concentrations of ovomucoid in the egg industry and as a useful tool for the research of allergenicity and antigenicity of hen's egg proteins.

The natural history of egg allergy

BACKGROUND

Egg allergy is very common, affecting 1% to 2% of children. It is generally thought that the majority of children with egg allergy develop tolerance in early childhood; however, this has not been examined in a large cohort with egg allergy.

OBJECTIVE

The purpose of the study was to estimate the proportion of children with egg allergy who develop egg tolerance and to identify predictors of tolerance development.

METHODS

Retrospective chart review of patients with egg allergy seen in a tertiary referral clinic. Patients were considered to have developed egg tolerance if they tolerated concentrated egg.

RESULTS

Kaplan-Meier analysis predicted resolution in 4% of patients with egg allergy by age 4 years, 12% by age 6 years, 37% by age 10 years, and 68% by age 16 years. Patients with persistent egg allergy had higher egg IgE levels at all ages to age 18 years. A patient's highest recorded egg IgE, presence of other atopic disease, and presence of other food allergy were significantly related to egg allergy persistence.

CONCLUSION

A majority of patients with egg allergy will develop egg tolerance, although the rate of tolerance development is slower than described previously. Egg IgE is predictive of allergy outcome and should be used in counseling patients on prognosis.

CLINICAL IMPLICATIONS

Most patients with egg allergy are likely to develop egg tolerance by late childhood, with the exception of patients with an egg IgE greater than 50 kU/L, who are unlikely to develop egg tolerance.

CD4 T cells activated in the mesenteric lymph node mediate gastrointestinal food allergy in mice

A localized Th2 milieu has been observed in the intestine of subjects with food allergic disorders; however, the role of T cells in the pathophysiology of these disorders remains poorly understood. Our aim was to examine sites of T cell activation in response to food challenge, identify potential factors responsible for T cell recruitment to the gut, and determine the role of T cells in disease. BALB/c mice were systemically sensitized to ovalbumin (OVA) and repeatedly fed with OVA to induce allergic diarrhea. Local cytokine and chemokine expressions were assessed by quantitative PCR, and cytokine secretion levels in the mesenteric lymph node (MLN) were determined by ELISA. Homing molecule expression was determined by flow cytometry, and the role of CD4(+) T cells in promoting disease was tested by adoptive transfer. Mice developed diarrhea associated with changes in epithelial ion transport, mast cell infiltration, intestinal IgE secretion, and local upregulation of Th2 cytokines and the Th2 chemokines CCL1, CCL17, and CCL22 in the small intestine. T cell activation occurred in the MLN before symptom onset, and a single feed of OVA induced T cell proliferation, alpha(4)beta(7) upregulation, and CD62L downregulation. Cells from the MLN, including purified CD4(+) T cells, were able to transfer allergic diarrhea to naive mice. A gut-homing phenotype induced in the MLN and selective upregulation of Th2 chemoattractants are likely important factors in the gastrointestinal recruitment of pathological Th2-skewed CD4(+) T cells in food allergy.

Egg allergy

Egg allergy is one of the most common food allergies in infants and young children. The great majority is not life-threatening and management involves exclusion of egg from the diet and regular review with the expectation that the majority of children will outgrow the allergy by school age. Judgment is required as to when the dietary elimination of egg is no longer required. This decision may be helped by demonstrating loss of sensitivity by skin prick or specific IgE testing and in some cases a supervised food challenge. Particular issues in management arise with more severe, potentially life-threatening reactions, with immunization with vaccines prepared in eggs, with the diagnosis of egg hypersensitivity as a cause of delayed exacerbations of eczema which can be non-IgE mediated, and in deciding whether a child can be allowed to ingest small amounts of cooked egg through egg-containing foods while continuing to avoid raw egg or larger amounts of whole egg. Cases which illustrate these issues are presented.

Patterns of immunoglobulin G responses to egg and peanut allergens are distinct: ovalbumin-specific immunoglobulin responses are ubiquitous, but peanut-specific immunoglobulin responses are up-regulated in peanut allergy

BACKGROUND

The clinical significance of food-specific IgG subclasses in food allergy and tolerance remains unclear. Specific IgG titres are often reported in non-standardized units, which do not allow comparisons between studies or allergens.

OBJECTIVE

To quantify, in absolute units, ovalbumin (OVA)- and peanut-specific IgG levels in children with peanut or egg allergy (active or resolved) and in non-allergic controls. Methods Children aged 1-15 years were recruited. Peanut allergy was diagnosed by convincing history and a 95% predictive level of specific IgE; egg allergy or resolution was confirmed by oral challenge. Serum IgG, IgG1 and IgG4 levels (microg/mL) to OVA and peanut extract were quantified by ELISA.

RESULTS

OVA- and peanut-specific IgG was detected in all subjects. In non-allergic controls (n=18), OVA-specific IgG levels were significantly higher than peanut-specific IgG (median microg/mL IgG=15.9 vs. 2.2, IgG1=1.3 vs. 0.6, IgG4=7.9 vs. 0.7; P<0.01). There were no differences in OVA-specific IgG, IgG1 and IgG4 between egg-allergic (n=40), egg-resolved (n=22) and control (n=18) subjects. In contrast, peanut-specific IgG (median microg/mL IgG=17.0, IgG1=3.3, IgG4=5.2) were significantly higher in peanut-allergic subjects (n=59) compared with controls and with non-peanut-sensitized but egg-allergic subjects (n=26). Overall, the range of IgG4 was greater than IgG1, and IgG4 was the dominant subclass in >60% of all subjects.

CONCLUSION

OVA-specific IgG levels of egg-allergic, egg-resolved or control groups are not distinguishable. Higher peanut-specific IgG levels are associated with clinical allergy, but the range of IgG titres of the allergic and control groups overlapped. Hence, OVA and peanut-specific IgG measurements do not appear to be of diagnostic value. Strong IgG responses to OVA may be a normal physiological response to a protein frequently ingested from infancy, whereas up-regulated IgG responses in peanut allergy may be indicative of a dysregulated immune response to peanut allergens.

Anaphylaxis to foods

Three crucial areas of the management of anaphylaxis due to food allergy are discussed: making a diagnosis, deciding who needs a self-injectable adrenaline device and spotting the novel allergen. Managing children and teenagers with anaphylaxis is challenging due to the lack of available evidence that specific addresses these issue. The available evidence is presented and discussed.

Proteomic analysis of ovomucoid hypersensitivity in mice by two-dimensional difference gel electrophoresis (2D-DIGE)

There is a need to develop reliable methods to assess the safety of genetically modified and other novel foods. The aim of this study was to identify protein biomarkers of food allergy in mice exposed to ovomucoid (OVM), a major food allergen found in chicken egg white. BALB/c mice were repeatedly sensitized by gavage with OVM and cholera toxin (CT) and control mice were exposed to a mixture of amino acids with CT. At the endpoint, all mice were challenged intraperitoneally with OVM and alum. Type-1 hypersensitivity was confirmed in OVM-sensitized mice by observation of clinical signs of anaphylaxis and elevated levels of plasma histamine, OVM-specific IgE and OVM-specific IgG by ELISA. Differential protein expression was assessed in albumin-depleted plasma as well as in mesenteric lymph node, liver, spleen, and ileum by two-dimensional difference gel electrophoresis (2D-DIGE). Differentially expressed proteins were identified by liquid chromatography with tandem mass spectrometry. Plasma proteins overexpressed in OVM-sensitized mice included haptoglobin (41-fold), serum amyloid A (19-fold) and peroxiredoxin-2 (1.9-fold). Further validation of these plasma proteins in other animal models of food allergy with different food allergens is required to assess their potential as candidate biomarkers for use in evaluating the allergenicity of novel foods.

Genetically glycosylated ovomucoid third domain can modulate Immunoglobulin E antibody production and cytokine response in BALB/c mice

BACKGROUND

Food allergies are on the rise and it is estimated that in North America, 8% of the children and 4% of the adults have food allergies. Food allergies tend to occur more often in children than in adults due to their immature digestive and immune systems. Hen's egg is among the most common cause of food-induced allergic reactions in North America.

OBJECTIVE

The present study was undertaken to investigate the role of N-glycans of the third domain of ovomucoid in IgE binding and modulation of allergen-specific immune response in BALB/c mice.

METHODS

The cDNA encoding the third domain of ovomucoid was inserted into the yeast genome and expressed in Pichia pastoris X-33 cells, under the control of the glyceraldehyde-3-phosphate (GAP) dehydrogenase promoter for constitutive expression to obtain a post-translationally modified and functionally active ovomucoid third domain. Upon expression, the protein was secreted into the extracellular medium and was purified by size exclusion chromatography. The recombinant protein was produced at 10 mg/L of the culture supernatant. BALB/c mice were sensitized with the recombinant and native forms of glycosylated ovomucoid third domain antigen. The allergic response of the native and the recombinant glycosylated forms of ovomucoid third domain antigens were compared using antibody and cytokine measurements.

RESULTS

ELISA tests indicated a significant decrease in specific IgE antibodies to the recombinant N-linked glycosylated form (P-Gly), when compared with the native glycosylated form (DIII+) using mice sera. Immunization with P-Gly induced the production of IFN-gamma [T-helper type 1 (Th1) response] and lowered the production of IL-4 (Th2 response), and a skewed balance towards the Th1 cytokine demonstrated that P-Gly has a modulating ability on Th1/Th2 balance to down-regulate Th2 response. Furthermore, N-linked glycan (N28) in the third domain of ovomucoid was shown to be associated with suppression of the allergic response.

CONCLUSION

Therefore, we can conclude that P-Gly facilitates and contributes to the discovery of new molecular target for the development of a safe and specific therapeutic vaccine for the treatment of egg allergy, and oligosaccharides do seem to play a major role in the suppression of IgE-binding activity.

Egg allergy: are all childhood food allergies the same?

Egg allergy is one of the most common food allergies in childhood affecting about 1-2% of preschool children and differs in a number of ways from other common childhood food allergies such as cows milk and peanut. Common egg allergens are altered both by heat and gastric enzymes. Compared with peanuts/tree nuts and milk, egg allergy appears less likely to cause severe life-threatening reactions or fatal anaphylaxis. Children are much more likely to outgrow egg allergy by school age as compared with peanut allergy. While the MMR vaccine is no longer contraindicated in egg allergy, influenza vaccine is contraindicated in children with anaphylaxis to egg. An understanding of the similarities and differences in these common food allergies of childhood is helpful in the management of these common and increasing problems.

Incidence of parentally reported and clinically diagnosed food hypersensitivity in the first year of life

BACKGROUND

There are very few population-based studies investigating the incidence of food hypersensitivity during the first year of life.

OBJECTIVE

To determine the incidence of parentally reported food hypersensitivity and objectively diagnosed food hypersensitivity during the first year of life.

METHODS

A birth cohort was recruited (n = 969). At 3, 6, 9, and 12 months, information regarding feeding practices and reported symptoms of atopy were obtained. At 1 year, infants underwent a medical examination and skin prick testing to a battery of allergens. Symptomatic infants underwent food challenges.

RESULTS

Adverse reactions to foods were reported by 132 (14.2%) parents at 3, 83 (9.1%) at 6, 49 (5.5%) at 9, and 65 (7.2%) at 12 months. Of the subjects, 1.0% (8/763) were sensitized to aeroallergens and 2.2% (17/763) to food allergens. Between 6 and 9 months and 9 and 12 months, 1.4% (14/969) and 2.8% (27/969) infants were diagnosed with food hypersensitivity on the basis of open food challenges and 0.9% (9/969) and 2.5% (24/969) on the basis of double-blind, placebo-controlled food challenges. Cumulative incidence of food hypersensitivity by 12 months was 4% (39/969; 95% CI, 2.9% to 5.5%) on the basis of open food challenges and 3.2% (31/969; 95% CI, 2.2% to 4.5%) on the basis of double-blind, placebo-controlled food challenges.

CONCLUSION

Between 2.2% and 5.5% of infants have food hypersensitivity in the first year of life. The rate of parental perception of food hypersensitivity is higher than the prevalence of atopic sensitization to main food allergens or objectively assessed food hypersensitivity.

CLINICAL IMPLICATIONS

In the first year of life, the rate of parentally perceived food hypersensitivity is considerably higher than objectively assessed food hypersensitivity.

The prevalence of food hypersensitivity in an unselected population of children and adults

A rising prevalence of food hypersensitivity (FHS) and severe allergic reactions to food has been reported the last decade. To estimate the prevalence of FHS to the most common allergenic foods in an unselected population of children and adults. We investigated a cohort of 111 children <3 yr of age, 486 children 3 yr of age, 301 children older than 3 yr of age and 936 adults by questionnaire, skin prick test, histamine release test and specific immunoglobulin E followed by oral challenge to the most common allergenic foods. In total, 698 cases of possible FHS were recorded in 304 (16.6%) participants. The prevalence of FHS confirmed by oral challenge was 2.3% in the children 3 yr of age, 1% in children older than 3 yr of age and 3.2% in adults. The most common allergenic foods were hen's egg affecting 1.6% of the children 3 yr of age and peanut in 0.4% of the adults. Of the adults, 0.2% was allergic to codfish and 0.3% to shrimp, whereas no challenges with codfish and shrimp were positive in the children. The prevalence of clinical reactions to pollen-related foods in pollen-sensitized adults was estimated to 32%. This study demonstrates the prevalence of FHS confirmed by oral challenge to the most common allergenic foods in an unselected population of children and adults.

Effective therapy of childhood atopic dermatitis allays food allergy concerns

BACKGROUND

Roughly one third of children with atopic dermatitis (AD) have IgE-mediated food allergy. Most parents and pediatricians assume foods also cause the eczema, a focus that diverts proper skin therapy and has negative outcomes including nutritional deficiency, costly referrals, and unnecessary testing. This project investigates the relationship between food allergy and AD, both before and after treatment in an established AD population. During an open trial of topical tacrolimus we observed a decrease in parental food allergy concern during good control of their child's eczema. We tested this observation by follow-up interviews and a questionnaire study to compare parental estimates of food allergy concerns after therapy with concerns before beginning the trial. Study subjects were children 11 years old and younger with AD and suspicion of food allergy. AD and food allergy parameters, pre- and post-treatment, were retrospectively assessed by a questionnaire given to the parents.

RESULTS

Twenty-three patients were enrolled: 16 had positive food allergy tests (7 RAST and/or 10 skin prick tests) and 30% had a definite history of immediate IgE reactions to foods. Ninety-five percent of parents felt that food allergy exacerbated their child's AD. Treatment durations were 3 to 45 months. Parental concern of food allergy decreased significantly from 7.7 to 4.0 on a 10 point scale (P < .001). Additionally, estimated food reactions decreased by approximately 80% during 1- and 6-month periods (P = .001).

CONCLUSIONS

In this selected university-based childhood AD population, nearly all parents were convinced their child had food allergy and further that the food contributed to the AD. The level of concern about food reactions was significantly decreased and the number of food reactions declined during effective topical therapy. This preliminary assessment of parental perceptions suggests that successful, stable therapy of AD reduces perceived food reactions and allays parental concerns about food allergy. Such therapy may encourage parents to refocus on direct skin care as the primary effort in AD therapy. We conclude that the effect of successful AD treatment on food allergy and food allergy concern are of interest and worthy of further study.

Is delivery by cesarean section a risk factor for food allergy?

BACKGROUND

Cesarean delivery might delay the colonization of the newborn intestine. A delayed or aberrant colonization process has been offered as an explanation for the increase in allergic diseases.

OBJECTIVE

The aim of this study was to examine whether cesarean delivery and the use of antibiotics were associated with subsequent food allergy.

METHODS

In a population-based birth cohort of 2803 children, information regarding mode of delivery, maternal or infant use of antibiotics, and information on potential confounders was obtained prospectively from parental reports and the Norwegian Birth Registry. Parentally perceived reactions to egg, fish, or nuts, as well as objectively confirmed reactions to egg at the age of 2 1/2 years, were chosen as outcomes.

RESULTS

Among children whose mothers were allergic, cesarean section was associated with a 7-fold increased risk of parentally perceived reactions to egg, fish, or nuts (odds ratio, 7.0; CI, 1.8-28; P =.005) and a 4-fold increased risk of confirmed egg allergy (odds ratio, 4.1; CI, 0.9-19; P =.08) in a logistic regression analysis, adjusting for pregnancy complications, birth weight, gestational length, and socioeconomic factors. Among children whose mothers were not allergic, the association was much weaker and not significant. Maternal or infant use of antibiotics was not associated with an increased risk of food allergy.

CONCLUSION

The results indicate that in predisposed children cesarean section might increase the risk of development of food allergy, which supports the theory that factors interfering with the colonization process might play a role in the development of food allergy.

Food allergy: an overview

Food allergy affects between 5% and 7.5% of children and between 1% and 2% of adults. The greater prevalence of food allergy in children reflects both the increased predisposition of children to develop food allergies and the development of immunologic tolerance to certain foods over time. Immunoglobulin (Ig) E-mediated food allergies can be classified as those that persist indefinitely and those that are predominantly transient. Although there is overlap between the two groups, certain foods are more likely than others to be tolerated in late childhood and adulthood. The diagnosis of food allergy rests with the detection of food-specific IgE in the context of a convincing history of type I hypersensitivity-mediated symptoms after ingestion of the suspected food or by eliciting IgE-mediated symptoms after controlled administration of the suspected food. Presently, the only available treatment of food allergies is dietary vigilance and administration of self-injectable epinephrine.

Current issues with influenza vaccination in egg allergy

Influenza infection, with its accompanying morbidity and mortality, represents a major public health concern yearly to the elderly and high-risk groups, including asthmatic patients. Active prevention with vaccination consistently falls short of reaching optimal immunization rates in all risk groups. Asthmatic patients and others with concomitant egg allergy might be denied active immunization because of the risk of inducing adverse reactions with a vaccine derived from egg embryo tissue. Evidence supports the relatively safe administration of influenza vaccine to individuals with egg allergy in whom vaccination is indicated when specific protocols are followed under the supervision of experienced physicians. A practical protocol that includes incremental dosing of influenza vaccine is presented to guide clinicians in influenza vaccination in this high-risk group.

Food allergy

Food allergy encompasses a range of disorders that result from adverse immune responses to dietary antigens. This group of conditions includes acute, potentially fatal reactions, and a host of chronic diseases that mainly affect the skin and gastrointestinal tract. Tools for diagnosis and management have not changed much in the past two decades, and include the clinical history, physical examination, tests for specific IgE antibody to suspected foods, elimination diets, oral food challenges, and provision of medications such as epinephrine for emergency treatment. However, much research in the past few years has enhanced our understanding of the clinical, epidemiological, and immunological aspects of these disorders. In this review I will discuss these advances and incorporate them into an improved diagnostic and management scheme. Additionally, emergent diagnostic, treatment, and prevention strategies are reviewed.

Can we determine a threshold level for allergenic foods by statistical analysis of published data in the literature?

BACKGROUND

The aim of this paper was to investigate whether a statistical model could be developed to estimate a "threshold" dose for foods eliciting allergic reactions in susceptible patients. The threshold dose is defined to be one that elicits allergic reactions in a given (small) proportion of susceptible patients, using data from published studies.

METHODS

Based on data available from the literature, we developed a statistical model using the actual allergen content in the four foods, where data for allergen content are available (peanut, soy, egg, milk).

RESULTS

The model demonstrated that the threshold doses giving a reaction of one in a million in susceptible patients were within the same order of magnitude for egg, milk and soy, but were an order of magnitude lower for peanut flour: 0.005 mg of cow's milk, 0.002 mg of fresh hen's egg, 0.0007 mg of peanut, or 0.0013 mg of soy flour.

CONCLUSIONS

Although several assumptions were made in creating this statistical model, we demonstrated that the previously published differences in threshold doses for various foods can be largely eliminated by comparing actual allergen content; this may therefore serve as a model for further studies.

Prediction of tolerance on the basis of quantification of egg white-specific IgE antibodies in children with egg allergy

BACKGROUND

It is thought that the natural evolution of food allergy has a good tolerance prognosis. However, there are few follow-up studies that determine the exact probability of tolerance to a given food or that analyze prognostic factors that can help us to understand the evolution of a child who begins life with a food allergy.

OBJECTIVE

We sought to determine the likelihood that children younger than 2 years of age with allergy to egg would eventually have tolerance to it and to analyze several prognostic predictors using egg white-specific IgE level as the main variable.

METHODS

We performed a prospective study of 58 children younger than 2 years of age with egg allergy, who were studied periodically until tolerance developed or until the end of the study. During the follow-up period, open challenge tests were carried out according to previously established criteria to verify tolerance to egg. Factors such as egg white-specific IgE level, serum total IgE level, symptoms after egg ingestion, size of skin prick test reactions to egg white, atopic dermatitis, and sex were analyzed as prognostic markers. Kaplan-Meier survival curves were used to calculate cumulative tolerance probability. Predictor influence and relative prognostic importance were estimated with the Cox proportional regression model.

RESULTS

The median time from the appearance of the first symptoms to tolerance was 35 months. Cumulative tolerance probability was 16% at 12 months of follow-up, 28% at 24 months, 52% at 36 months, 57% at 48 months, and 66% at 60 months. The relative weight of prognostic factors, expressed as the hazard ratio, was 50.95 for symptoms and 3.74 for the size of skin prick test reactions, with both being independent effects. The hazard ratio was 1.173 for every 0.1-unit decrease in the concentration log (decimal logarithm) of specific IgE level, with this effect being associated with tolerance only in children with cutaneous symptoms.

CONCLUSIONS

Half of the children younger than 2 years of age with egg allergy will tolerate the food at 35 months of follow-up, and the proportion could be 66% after 5 years. At that age, the main predictors were the symptoms experienced after egg ingestion, followed by the size of skin prick test reactions. In addition, the specific IgE antibody level is an important prognostic marker in children who only had cutaneous symptoms.

Improving in-vitro tests for the diagnosis of food hypersensitivity

Food hypersensitivity reactions affect up to 8% of children under 3 years of age and approximately 2.5% of the general United States population. Food allergic disorders may be subdivided into either IgE-mediated or cell-mediated reactions. The diagnostic 'gold standard' of 'symptomatic' food allergies remains the blinded oral food challenge because of the poor specificity of patient histories, skin testing and standard radioallergosorbent tests, and the outcomes of elimination diets. Little progress has been made in the development of in-vitro tests for the diagnosis of cell-mediated food hypersensitivities. However, new developments in in-vitro technologies have improved the capabilities of these tests to diagnose IgE-mediated reactivity and perhaps predict the development of future 'tolerance', i.e. 'outgrowing' the allergy.

Restricted diets in children with reactions to milk and egg perceived by their parents

The aim of this study was to investigate the degree to which parents alter the diets of their children on the basis of perceived reactions. From a population-based sample of 2979 2-year old children with reactions to egg or milk perceived by their parents, one third had strict limitations on the intakes of these foods, representing 2.5% of the children in the cohort. In approximately 1 of 6 families the strict diets were initiated without consulting a doctor, and in a substantial proportion the restrictions were unwarranted. High maternal education level and irritability attributed to food were among the risk factors for unwarranted diets. On the other hand, many children, in whom an adverse reaction was verified, lacked appropriate diet restrictions. We conclude that the handling of adverse reactions to food frequently occurs outside the medical care system at the cost of correct diagnosis and appropriate diets.

The prevalence of CMA/CMPI in young children: the validity of parentally perceived reactions in a population-based study

BACKGROUND

The present study aimed to estimate the prevalence of adverse reactions to milk, as population-based prevalence estimates based on objective diagnostic procedures are rare.

METHODS

Children with parentally reported reactions to milk were selected for further examination from a population-based cohort of 2721 children. At the age of 2(1/2) years, they underwent a stepwise diagnostic procedure that included diet trials at home, skin prick tests, and open and double-blind, placebo-controlled food challenges. A sample of children with symptoms not attributed to milk was selected for assessment of unrecognized reactions.

RESULTS

The estimated point prevalence of cow's milk allergy and cow's milk protein intolerance (CMA/CMPI) in children with parentally perceived reactions at the age of 2(1/2) years was estimated to be 1.1% (CI 0.8-1.6). However, this was an underestimate, as unrecognized reactions were detected. Most reactions were not IgE-mediated. The positive predictive value of a parentally perceived reaction depended on the number of times it had been reported and was good for reactions reported three times (at 12, 18, and 24 months of age).

CONCLUSION

The present study confirms previous findings that parents overestimate milk as a cause of symptoms in their children; however, it also indicates that unrecognized reactions may be a problem as well.