Incidence and natural history of challenge-proven cow's milk allergy in European children--EuroPrevall birth cohort

BACKGROUND

Cow's milk allergy (CMA) is one of the most commonly reported childhood food problems. Community-based incidence and prevalence estimates vary widely, due to possible misinterpretations of presumed reactions to milk and differences in study design, particularly diagnostic criteria.

METHODS

Children from the EuroPrevall birth cohort in 9 European countries with symptoms possibly related to CMA were invited for clinical evaluation including cows' milk-specific IgE antibodies (IgE), skin prick test (SPT) reactivity and double-blind, placebo-controlled food challenge.

RESULTS

Across Europe, 12 049 children were enrolled, and 9336 (77.5%) were followed up to 2 years of age. CMA was suspected in 358 children and confirmed in 55 resulting in an overall incidence of challenge-proven CMA of 0.54% (95% CI 0.41-0.70). National incidences ranged from 1% (in the Netherlands and UK) to <0.3% (in Lithuania, Germany and Greece). Of all children with CMA, 23.6% had no cow's milk-specific IgE in serum, especially those from UK, the Netherlands, Poland and Italy. Of children with CMA who were re-evaluated one year after diagnosis, 69% (22/32) tolerated cow's milk, including all children with non-IgE-associated CMA and 57% of those children with IgE-associated CMA.

CONCLUSIONS

This unique pan-European birth cohort study using the gold standard diagnostic procedure for food allergies confirmed challenge-proven CMA in <1% of children up to age 2. Affected infants without detectable specific antibodies to cow's milk were very likely to tolerate cow's milk one year after diagnosis, whereas only half of those with specific antibodies in serum 'outgrew' their disease so soon.

Hazelnut allergy across Europe dissected molecularly: A EuroPrevall outpatient clinic survey

BACKGROUND

Hazelnut allergy is birch pollen-driven in Northern/Western Europe and lipid transfer protein-driven in Spain and Italy. Little is known about other regions and other allergens.

OBJECTIVE

Establishing a molecular map of hazelnut allergy across Europe.

METHODS

In 12 European cities, subjects reporting reactions to hazelnut (n = 731) were evaluated and sensitization to 24 foods, 12 respiratory allergen sources, and latex was tested by using skin prick test and ImmunoCAP. A subset (124 of 731) underwent a double-blind placebo-controlled food challenge to hazelnut. Sera of 423 of 731 subjects were analyzed for IgE against 7 hazelnut allergens and cross-reactive carbohydrate determinants by ImmunoCAP.

RESULTS

Hazelnut allergy was confirmed in 70% of those undergoing double-blind placebo-controlled food challenges. Birch pollen-driven hazelnut sensitization (Cor a 1) dominated in most cities, except in Reykjavik, Sofia, Athens, and Madrid, where reporting of hazelnut allergy was less frequent anyhow. In Athens, IgE against Cor a 8 dominated and strongly correlated with IgE against walnut, peach, and apple and against Chenopodium, plane tree, and mugwort pollen. Sensitization to seed storage proteins was observed in less than 10%, mainly in children, and correlated with IgE to nuts, seeds, and legumes. IgE to Cor a 12, observed in all cities (10% to 25%), correlated with IgE to nuts, seeds, and pollen.

CONCLUSIONS

In adulthood, the importance of hazelnut sensitization to storage proteins, oleosin (Cor a 12), and Cor a 8 is diluted by the increased role of birch pollen cross-reactivity with Cor a 1. Cor a 8 sensitization in the Mediterranean is probably driven by diet in combination with pollen exposure. Hazelnut oleosin sensitization is prevalent across Europe; however, the clinical relevance remains to be established.

Incidence and risk factors for food hypersensitivity in UK infants: results from a birth cohort study

BACKGROUND

The prevalence of food hypersensitivity in the UK is still largely open to debate. Additionally its pathogenesis is also unclear although it is known that there are differing phenotypes. Determining its prevalence, along with identifying those factors associated with its development will help to assess its clinical importance within the national setting and also add to the debate on appropriate prevention strategies.

METHODS

A population based birth cohort study conducted in Hampshire, UK as part of the EuroPrevall birth cohort study. 1140 infants were recruited with 823 being followed up until 2 years of age. Infants with suspected food reactions were assessed including specific IgE measurement and skin prick testing. Diagnosis of food hypersensitivity was by positive double-blind, placebo-controlled food challenge (DBPCFC) where symptoms up to 48 h after the end of the food challenge were considered indicative of a food hypersensitivity. Factors associated with food hypersensitivity and its two phenotypes of IgE-mediated and non-IgE-mediated disease were modelled in a multivariable logistic regression analysis.

RESULTS

Cumulative incidence of food hypersensitivity by 2 years of age was 5.0 %. The cumulative incidence for individual food allergens were hens' egg 2.7 % (1.6-3.8); cows' milk 2.4 % (1.4-3.5); peanut 0.7 % (0.1-1.3); soy 0.4 % (0.0-0.8); wheat 0.2 % (0.0-0.5) and 0.1 % (0.0-0.32) for fish. The cumulative incidence of IgE-mediated food allergy was 2.6 % with 2.1 % reacting to hens' egg. For non-IgE-mediated food allergy the cumulative incidence was 2.4 % (cows' milk 1.7 %). Predictors for any food hypersensitivity were wheeze, maternal atopy, increasing gestational age, age at first solid food introduction and mean healthy dietary pattern score. Predictors for IgE mediated allergy were eczema, rhinitis and healthy dietary pattern score whereas for non-IgE-mediated food allergy the predictors were dog in the home, healthy dietary pattern score, maternal consumption of probiotics during breastfeeding and age at first solid food introduction.

CONCLUSIONS

Just under half the infants with confirmed food hypersensitivity had no demonstrable IgE. In an exploratory analysis, risk factors for this phenotype of food hypersensitivity differed from those for IgE-mediated food allergy except for a healthy infant diet which was associated with less risk for both phenotypes.

Comparative Study of Food Allergies in Children from China, India, and Russia: The EuroPrevall-INCO Surveys

BACKGROUND

A clear understanding of the differences in the epidemiology of food allergy between rural and urban populations may provide insights into the causes of increasing prevalence of food allergy in the developed world.

OBJECTIVE

We used a standardized methodology to determine the prevalence and types of food-specific allergic sensitization and food allergies in schoolchildren from urban and rural regions of China, Russia, and India.

METHODS

The current study is a multicenter epidemiological survey of children recruited from 5 cities in China (Hong Kong and Guangzhou), Russia (Tomsk), and India (Bengaluru and Mysore) and 1 rural county in Southern China (Shaoguan). A total of 35,549 children aged 6 to 11 years from 3 countries participated in this survey. Random samples of children from 3 countries were first screened by the EuroPrevall screening questionnaire. Children with and without a history of adverse reactions to foods were then recruited for the subsequent case-control comparative studies. We determined the prevalence rates of food-specific IgE sensitization and food allergies using the predefined criteria.

RESULTS

The prevalence rates of food-specific IgE sensitization (≥0.7 kU/L) to at least 1 food were 16.6% in Hong Kong, 7.0% in Guangzhou, 16.8% in rural Shaoguan, 8.0% in Tomsk, and 19.1% in India. Using a definition of probable food allergy as reporting allergic symptoms within 2 hours of ingestion of a specific food plus the presence of allergic sensitization to the specific food (positive IgE and/or positive skin prick test result), the prevalence of food allergy was highest in Hong Kong (1.50%), intermediate in Russia (0.87%), and lowest in Guangzhou (0.21%), Shaoguan (0.69%), and India (0.14%). For children recruited from Hong Kong, both sensitization and food allergy were significantly higher in children who were born and raised in Hong Kong when compared with those who were born in mainland China and migrated to Hong Kong, highlighting the importance of early-life exposures in affecting the subsequent development of food sensitization and food allergy.

CONCLUSIONS

There are wide variations in the prevalence of food-specific IgE sensitization and food allergy in the 3 participating countries. Food allergy appears to be less common when compared with developed countries. The variations in the prevalence of food allergen sensitization cannot be explained by the differences in the degree of urbanization. Despite the high prevalence of food-specific IgE sensitization in India and rural China, food allergy is still extremely uncommon. In addition to IgE sensitization, other factors must play important roles resulting in the clinical manifestations of food allergies.

Peanut-specific IgE antibodies in asymptomatic Ghanaian children possibly caused by carbohydrate determinant cross-reactivity

Background

The prevalence of peanut allergy has increased in developed countries, but little is known about developing countries with high peanut consumption and widespread parasitic infections.

Objective

We sought to investigate peanut allergy in Ghana.

Methods

In a cross-sectional survey among Ghanaian schoolchildren (n = 1604), data were collected on reported adverse reactions to peanut, peanut sensitization (serum specific IgE and skin reactivity), consumption patterns, and parasitic infections. In a subset (n = 43) IgE against Ara h 1, 2, 3, and 9 as well as cross-reactive carbohydrate determinants (CCDs) was measured by using ImmunoCAP. Cross-reactivity and biological activity were investigated by means of ImmunoCAP inhibition and basophil histamine release, respectively.

Results

Adverse reactions to peanut were reported in 1.5%, skin prick test reactivity in 2.0%, and IgE sensitization (≥0.35 kU/L) in 17.5% of participants. Moreover, 92.4% of those IgE sensitized to peanut (≥0.35 kU/L) had negative peanut skin prick test responses. Schistosoma haematobium infection was positively associated with IgE sensitization (adjusted odds ratio, 2.29; 95% CI, 1.37-3.86). In the subset IgE titers to Ara h 1, 2, 3, and 9 were low (<1.3 kU/L), except for 6 moderately strong reactions to Ara h 9. IgE against peanut was strongly correlated with IgE against CCDs (r = 0.89, P < .0001) and could be almost completely inhibited by CCDs, as well as S haematobium soluble egg antigen. Moreover, IgE to peanut showed poor biological activity.

Conclusions

Parasite-induced IgE against CCDs might account largely for high IgE levels to peanut in our study population of Ghanaian schoolchildren. No evidence of IgE-mediated peanut allergy was found.

Prevalence of food sensitization and probable food allergy among adults in India: the EuroPrevall INCO study

BACKGROUND

Data are lacking regarding the prevalence of food sensitization and probable food allergy among general population in India. We report the prevalence of sensitization and probable food allergy to 24 common foods among adults from general population in Karnataka, South India.

METHODOLOGY

The study was conducted in two stages: a screening study and a case-control study. A total of 11 791 adults in age group 20-54 were randomly sampled from general population in South India and answered a screening questionnaire. A total of 588 subjects (236 cases and 352 controls) participated in the case-control study involving a detailed questionnaire and specific IgE estimation for 24 common foods.

RESULTS

A high level of sensitization (26.5%) was observed for most of the foods in the general population, higher than that observed among adults in Europe, except for those foods that cross-react with birch pollen. Most of the sensitization was observed in subjects who had total IgE above the median IgE level. A high level of cross-reactivity was observed among different pollens and foods and among foods. The prevalence of probable food allergy (self-reports of adverse symptoms after the consumption of food and specific IgE to the same food) was 1.2%, which was mainly accounted for cow's milk (0.5%) and apple (0.5%).

CONCLUSION

Very high levels of sensitization were observed for most foods, including those not commonly consumed in the general population. For the levels of sensitization, the prevalence of probable food allergy was low. This disassociation needs to be further explored in future studies.

The EuroPrevall outpatient clinic study on food allergy: background and methodology

BACKGROUND

The EuroPrevall project aimed to develop effective management strategies in food allergy through a suite of interconnected studies and a multidisciplinary integrated approach. To address some of the gaps in food allergy diagnosis, allergen risk management and socio-economic impact and to complement the EuroPrevall population-based surveys, a cross-sectional study in 12 outpatient clinics across Europe was conducted. We describe the study protocol.

METHODS

Patients referred for immediate food adverse reactions underwent a consistent and standardized allergy work-up that comprised collection of medical history; assessment of sensitization to 24 foods, 14 inhalant allergens and 55 allergenic molecules; and confirmation of clinical reactivity and food thresholds by standardized double-blind placebo-controlled food challenges (DBPCFCs) to milk, egg, fish, shrimp, peanut, hazelnut, celeriac, apple and peach.

RESULTS

A standardized methodology for a comprehensive evaluation of food allergy was developed and implemented in 12 outpatient clinics across Europe. A total of 2121 patients (22.6% <14 years) reporting 8257 reactions to foods were studied, and 516 DBPCFCs were performed.

CONCLUSIONS

This is the largest multicentre European case series in food allergy, in which subjects underwent a comprehensive, uniform and standardized evaluation including DBPCFC, by a methodology which is made available for further studies in food allergy. The analysis of this population will provide information on the different phenotypes of food allergy across Europe, will allow to validate novel in vitro diagnostic tests, to establish threshold values for major allergenic foods and to analyse the socio-economic impact of food allergy.

The influence of early feeding practices on healthy diet variety score among pre-school children in four European birth cohorts

OBJECTIVE

The present study examined whether maternal diet and early infant feeding experiences relating to being breast-fed and complementary feeding influence the range of healthy foods consumed in later childhood.

DESIGN

Data from four European birth cohorts were studied. Healthy Plate Variety Score (HPVS) was calculated using FFQ. HPVS assesses the variety of healthy foods consumed within and across the five main food groups. The weighted numbers of servings consumed of each food group were summed; the maximum score was 5. Associations between infant feeding experiences, maternal diet and the HPVS were tested using generalized linear models and adjusted for appropriate confounders.

SETTING

The British Avon Longitudinal Study of Parents and Children (ALSPAC), the French Etude des Déterminants pre et postnatals de la santé et du développement de L'Enfant study (EDEN), the Portuguese Generation XXI Birth Cohort and the Greek EuroPrevall cohort.

SUBJECTS

Pre-school children and their mothers.

RESULTS

The mean HPVS for each of the cohorts ranged from 2.3 to 3.8, indicating that the majority of children were not eating a full variety of healthy foods. Never being breast-fed or being breast-fed for a short duration was associated with lower HPVS at 2, 3 and 4 years of age in all cohorts. There was no consistent association between the timing of complementary feeding and HPVS. Mother's HPVS was strongly positively associated with child's HPVS but did not greatly attenuate the relationship with breast-feeding duration.

CONCLUSIONS

Results suggest that being breast-fed for a short duration is associated with pre-school children eating a lower variety of healthy foods.

Fish oil in infancy protects against food allergy in Iceland-Results from a birth cohort study

BACKGROUND

Consumption of oily fish or fish oil during pregnancy, lactation and infancy has been linked to a reduction in the development of allergic diseases in childhood.

METHODS

In an observational study, Icelandic children (n = 1304) were prospectively followed from birth to 2.5 years with detailed questionnaires administered at birth and at 1 and 2 years of age, including questions about fish oil supplementation. Children with suspected food allergy were invited for physical examinations, allergic sensitization tests, and a double-blind, placebo-controlled food challenge if the allergy testing or clinical history indicated food allergy. The study investigated the development of sensitization to food and confirmed food allergy according to age and frequency of postnatal fish oil supplementation using proportional hazards modelling.

RESULTS

The incidence of diagnosed food sensitization was significantly lower in children who received regular fish oil supplementation (relative risk: 0.51, 95% confidence interval: 0.32-0.82). The incidence of challenge-confirmed food allergy was also reduced, although not statistically significant (0.57, 0.30-1.12). Children who began to receive fish oil in their first half year of life were significantly more protected than those who began later (P = .045 for sensitization, P = .018 for allergy). Indicators of allergy severity decreased with increased fish oil consumption (P = .013). Adjusting for parent education and allergic family history did not change the results.

CONCLUSION

Postnatal fish oil consumption is associated with decreased food sensitization and food allergies in infants and may provide an intervention strategy for allergy prevention.

Opisthorchis felineus negatively associates with skin test reactivity in Russia-EuroPrevall-International Cooperation study

BACKGROUND

Most studies on the relationship between helminth infections and atopic disorders have been conducted in (sub)tropical developing countries where exposure to multiple parasites and lifestyle can confound the relationship. We aimed to study the relationship between infection with the fish-borne helminth Opishorchis felineus and specific IgE, skin prick testing, and atopic symptoms in Western Siberia, with lifestyle and hygiene standards of a developed country.

METHODS

Schoolchildren aged 7-11 years were sampled from one urban and two rural regions. Skin prick tests (SPT) and specific IgE (sIgE) against food and aeroallergens were measured, and data on allergic symptoms and on demographic and socioeconomic factors were collected by questionnaire. Diagnosis of opisthorchiasis was based on PCR performed on stool samples.

RESULTS

Of the 732 children included, 34.9% had opisthorchiasis. The sensitization to any allergen when estimated by positive SPT was 12.8%, while much higher, 24.0%, when measured by sIgE. Atopic symptoms in the past year (flexural eczema and/or rhinoconjunctivitis) were reported in 12.4% of the children. SPT was positively related to flexural eczema and rhinoconjunctivitis, but not to wheezing. Opisthorchiasis showed association with lower SPT response, as well as borderline association with low IgE reactivity to any allergen. However, the effect of opisthorchiasis on SPT response was not mediated by IgE, suggesting that opisthorchiasis influences SPT response through another mechanism. Opisthorchiasis also showed borderline association with lower atopic symptoms.

CONCLUSIONS

There is a negative association between a chronic helminth infection and skin prick test reactivity even in a developed country.

Estimating the Risk of Severe Peanut Allergy Using Clinical Background and IgE Sensitization Profiles

Background: It is not well-understood why symptom severity varies between patients with peanut allergy (PA). Objective: To gain insight into the clinical profile of subjects with mild-to-moderate and severe PA, and investigate individual and collective predictive accuracy of clinical background and IgE to peanut extract and components for PA severity. Methods: Data on demographics, patient history and sensitization at extract and component level of 393 patients with probable PA (symptoms ≤ 2 h + IgE sensitization) from 12 EuroPrevall centers were analyzed. Univariable and penalized multivariable regression analyses were used to evaluate risk factors and biomarkers for severity. Results: Female sex, age at onset of PA, symptoms elicited by skin contact with peanut, family atopy, atopic dermatitis, house dust mite and latex allergy were independently associated with severe PA; birch pollen allergy with mild-to-moderate PA. The cross-validated AUC of all clinical background determinants combined (0.74) was significantly larger than the AUC of tests for sensitization to extract (0.63) or peanut components (0.54-0.64). Although larger skin prick test wheal size, and higher IgE to peanut extract, Ara h 1 and Ara h 2/6, were associated with severe PA, and higher IgE to Ara h 8 with mild-to-moderate PA, addition of these measurements of sensitization to the clinical background model did not significantly improve the AUC. Conclusions: Models combining clinical characteristics and IgE sensitization patterns can help establish the risk of severe reactions for peanut allergic patients, but clinical background determinants are most valuable for predicting severity of probable PA in an individual patient.

Allergic sensitization to foods in India and other Low-Middle-income countries

Food allergy is an important cause of morbidity, significantly affecting the quality of life of the sufferer. Most food allergy research has been undertaken in high-income countries. Here, we summarize literature regarding food allergy in India and other low-middle-income countries (LMIC). We provide summaries of self-reported adverse food reactions and food sensitization in these regions by reviewing published community-based studies of prevalence, burden, and risk factors. We identified 2 community-based studies of food allergy prevalence in Karnataka, India, which estimate that food allergy affects just 0.14% of children and 1.2% of adults. The overall prevalence of allergic sensitization to 'any' food was 26.5% in adults and 19.1% in children by serum-specific IgE; but only 4.48% in children by skin prick test. We identified a further 28 studies in other LMICs, mainly from China but also Turkey, South Africa, Ghana, Mexico, Brazil, Thailand, Philippines, and Korea. The overall prevalence of allergic sensitization to 'any' food ranged from 0.11% to 16.8% in children using serum-specific IgE and 0.14% to 9.6% in children by skin prick test. The questionnaires and skin prick testing materials used and number of allergens tested varied significantly between studies. Other than Karnataka, there is no information on prevalence of food sensitization and probable food allergy in the community in India. Similar lack of information is noted among the majority of the 136 LMICs. Where community-based studies have been undertaken, there is wide variation in the prevalence and patterns of food sensitization across different LMICs, at least partly due to variations in study methodology. International collaboration is required in order to formally assess food allergy prevalence and burden across representative samples from multiple LMICs.