[Allergology in Denmark 2005].
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Allergy and Immunology↗
Biomedical subjects
Susanne Halken
Publications and source records attributed to Susanne Halken.
[The influence of environmental factors on the development of allergy].
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Adult↗
[Allergy testing of children].
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Allergens↗
Primary prevention of food allergy in infants who are at risk.
PURPOSE OF REVIEW: Allergic diseases represent a major burden of health problems in industrialized countries. Though several studies have focused on possible preventive measure and strategies much controversy still exists on this topic. The aim of this review is to discuss the recent literature on primary prevention of food allergy. RECENT FINDINGS: In prospective observational controlled studies of high quality of birth cohorts, exclusive breastfeeding for at least 4 months combined with introduction of solid foods after 4 months of age is associated with a reduced risk of food allergy and atopic dermatitis, particularly in high-risk infants. When breastfeeding for 4-6 months is not possible or insufficient, randomized controlled trials have shown a significant reduction in food allergy and atopic dermatitis in high-risk infants fed a documented hypoallergenic hydrolysed formula. SUMMARY: Breastfeeding should be encouraged for 4-6 months. In high-risk infants a documented hypoallergenic hydrolysed formula is recommended if exclusively breastfeeding is not possible for the first 4 months. As regards primary prevention of food allergy there is no evidence for preventive dietary intervention during neither pregnancy nor lactation. Likewise, preventive dietary restrictions after the age of 4-6 months are not scientifically documented.
Animals↗
What causes allergy and asthma? The role of dietary factors.
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Asthma↗
Dietary prevention of allergic diseases in infants and small children. Part I: immunologic background and criteria for hypoallergenicity.
The role of primary prevention of allergic diseases has been a matter of debate for the last 40 years. In order to shed some light into this issue, a group of experts of the Section of Pediatrics EAACI critically reviewed the existing literature on the subject. In this paper, the immunology of the fetus and newborn is reviewed as well as the post-natal development of the immune system. The influence of post-natal environment and breastfeeding on tolerance induction and sensitization are examined. Allergic diseases result from a strong relationship between genetic and environmental factors. Sensitization to food allergens occurs in the first year of life and cow's milk allergy is the first food allergy to appear in the susceptible infants. Hypoallergenicity of food formulas to be used is a critical issue both for treatment of cow's milk-allergic children and for prevention. Methods to document hypoallergenicity are discussed and evaluated in the preclinical and clinical steps.
Breast Feeding↗
Dietary prevention of allergic diseases in infants and small children. Part III: Critical review of published peer-reviewed observational and interventional studies and final recommendations.
The role of primary prevention of allergic diseases has been a matter of debate for the last 40 years. In order to shed some light on this issue, a group of experts of the Section of Pediatrics EAACI reviewed critically the existing literature on the subject. An analysis of published peer-reviewed observational and interventional studies was performed following the statements of evidence as defined by WHO. The results of the analysis indicate that breastfeeding is highly recommended for all infants irrespective of atopic heredity. A dietary regimen is unequivocally effective in the prevention of allergic diseases in high-risk children. In these patients breastfeeding combined with avoidance of solid food and cow's milk for at least 4-6 months is the most effective preventive regimen. In the absence of breast milk, formulas with documented reduced allergenicity for at least 4-6 months should be used.
Breast Feeding↗
Dietary prevention of allergic diseases in infants and small children. Part II. Evaluation of methods in allergy prevention studies and sensitization markers. Definitions and diagnostic criteria of allergic diseases.
The role of primary prevention of allergic disease has been a matter of debate for the last 40 years. In order to shed some light into this issue a group of experts of the Section of Pediatrics EAACI critically reviewed the existing literature on the subject. The design of observational and interventional studies was evaluated with relevance to the important factors influencing outcome of studies on allergy development/prevention. in this analysis the statements of evidence as defined by WHO were applied. Best evidence of recommendations are those fulfilling the criteria for statements category 1 and 2 and grade of recommendations A and B as proposed by WHO. This survey include target group for dietary prevention and methods and diagnostic criteria of atopic dermatitis, asthma and food allergy for prevention studies.
Asthma↗
Prevention of allergic disease in childhood: clinical and epidemiological aspects of primary and secondary allergy prevention.
The development and phenotypic expression of atopic diseases depends on a complex interaction between genetic factors, environmental exposure to allergens,and non-specific adjuvant factors, such as tobacco smoke, air pollution and infections. Preventive measures may include both exposure to allergens and adjuvant risk/protective factors and pharmacological treatment. These measures may address the general population, children at risk for development of atopic disease (high-risk infants), children with early symptoms of allergic disease or children with chronic disease. The objective for this review was to evaluate possible preventive measures as regards prevention of development of allergic disease in childhood--primary prevention--and also some aspects of the effect of specific allergy treatment as regards secondary prevention in children with allergic asthma and allergic rhinoconjunctivitis. In one prospective observational study of a birth cohort of unselected infants we evaluated possible predictive/risk factors. In two prospective intervention studies including 1 yr birth cohorts of high-risk(HR) infants we investigated the effect of feeding HR infants exclusively breast milk (BM) and/or hydrolyzed cow's milk-based formula the first 4-6 months as regards: (i) the allergy preventive effect of BM/extensively hydrolysed formula (eHF) compared with ordinary cow's milk-based formula, (ii) the effect of two different eHFs, a whey (Profylac) and a casein-based (Nutramigen) formula, as regards development of cow's milk protein allergy (CMA), and (iii) a comparison of the preventive effect of eHF (Profylac/Nutramigen) with a partially hydrolyzed cow's milk-based formula (pHF) (NanHA) as regards development of CMA. None of the mothers had a restricted diet during pregnancy or lactation period. In two prospective randomized intervention studies we evaluated the preventive effect of specific allergen avoidance and specific immunotherapy (SIT) in children with allergic asthma and allergic rhinoconjunctivitis, respectively. The combination of atopic heredity and elevated cord blood IgE resulted in the best predictive discrimination as regards development of allergic disease. The optimal high-risk group was defined by either double parental atopic predisposition or single atopic predisposition, the latter combined with a cord blood IgE > or = 0.3 kU/1. 66% of unselected infants were daily exposed to tobacco smoke, which was a significant risk factor for recurrent wheezing until the age of 1.5 yr. HR infants were breastfed for a longer period and less exposed to tobacco smoke than unselected infants. Exclusively BM/eHF for at least 4 months was associated with a significantly reduced cumulative prevalence of CMA [3.6% (5/141) vs. 20%(15/75) in the control group] up to 5 yr. The effect of the two different eHFs was similar. Exclusively breastfed infants were significantly less exposed to tobacco smoke and pets, had solid foods introduced later and belonged to higher social classes. pHF was significantly (p = 0.05) less effective than eHF as regards prevention of development of CMA. A diet period of 4 months seems to be as efficient as 6 months or more as regards development of CMA. A few ongoing prospective, randomized intervention studies have produced the first indication that avoidance of indoor allergens such as house dust mite (HDM) in HR infants may reduce the incidence of severe wheeze and sensitization during the first 1-4 yr of age. Long-term follow-up is awaited. In a prospective, double-blind placebo-controlled study in children with doctors diagnosed asthma and documented HDM allergy, we found that semipermeable polyurethane mattress and pillow encasings (Allergy Control) when compared with placebo encasings resulted in a significant perennial reduction of HDM exposure and a significant reduction in the needed dose of inhaled steroids by approximately 50% (mean dose: 408 microg--227 microg/day) after 1-yr follow-up. In another randomized prospective study we investigated the possible preventive effect of SIT in children with allergic rhinoconjunctivitis and grass/birch pollen allergy as regards development of asthma. Among those without asthma significantly fewer in the SIT group developed asthma when compared with the control group (19/79 = 24% vs.32/72 = 44%) after the first 3 yr; and methacholinebronchial provocation test results improved significant in the SIT group. The results of our studies support the evidence that the risk for development of early allergic manifestations e.g. CMA and atopic dermatitis can be reduced significantly by simple dietary measures for the first4 months of life. In all infants breastfeeding should beencouraged for at least 4-6 months, and exposure to tobacco smoke should be avoided during pregnancy and early childhood. In HR infants a documented hypoallergenic formula (at present eHF) is recommended if exclusive breastfeeding is not possible for the first 4 months. In homes of HR-infants, current evidence supports measures to reduce the levels of indoor allergens. e.g. HDM and pets. In symptomatic children allergen-specific treatment may influence both the symptoms and the prognosis. Allergen avoidance can reduce the need for pharmacological treatment, SIT may have the potential for preventing the development of asthma in children with allergic rhinoconjunctivitis. and it may be possible to interfere with the natural course of allergic diseases.
Adolescent↗
Early sensitisation and development of allergic airway disease - risk factors and predictors.
The development and phenotypic expression of allergic airway disease depends on a complex interaction between genetic and several environmental factors, such as exposure to food, inhalant allergens and non-specific adjuvant factors (e.g. tobacco smoke, air pollution and infections). The first months of life seem to be a particularly vulnerable period and there is evidence that sensitisation is related to the level of allergen exposure during early life. At present, the combination of atopic heredity and elevated cord-blood IgE seems to result in the best predictive discrimination as regards development of allergic disease at birth. Early sensitisation, cow's milk allergy and atopic eczema are predictors for later development of allergic airway disease. Exposure to indoor allergens, especially house dust mite allergens, is a risk factor for sensitisation and development of asthma later in childhood in high-risk infants and infants with early atopic manifestations.
Age Factors↗
Effect of mattress and pillow encasings on children with asthma and house dust mite allergy.
BACKGROUND: House dust mite (HDM) allergy is a frequent cause of allergic asthma in children. Reduction of exposure seems to be the most logical way to treat these patients. OBJECTIVE: Our aim was to investigate whether mattress and pillow encasings resulted in an effective long-term control of HDM allergen levels, thereby reducing the need for asthma medication in children with asthma and HDM allergy. METHODS: In a prospective, double-blind, placebo-controlled study 60 children (age range, 6-15 years) with asthma and HDM allergy were randomized to active (allergy control) or placebo mattress and pillow encasings. After a 2-week baseline period, follow-up was performed every 3 months for 1 year. During the entire study period, the dose of inhaled steroids was tapered off to the lowest effective dose according to well-defined criteria. RESULTS: Fifty-two patients completed the trial, and 5 were excluded, leaving data from 47 children (26 in the active treatment group and 21 in the placebo group) for analysis. A significant perennial reduction in HDM allergen concentrations was seen only for the active treatment group. Also, a significant decrease in the dose of inhaled steroids (mean, 408 to 227 microg/d; P <.001) was found for the active treatment group only, with significant differences between groups after 9 and 12 months. After 1 year, the dose of inhaled steroids was reduced by at least 50% in significantly more children in the active treatment group than in the placebo group (73% vs 24%, P <.01). CONCLUSION: Encasing of mattresses and pillows resulted in a significant long-term reduction in HDM allergen concentrations in mattresses and in the need for inhaled steroids in children with asthma and HDM allergy.
Adolescent↗
Practical aspects of allergy-testing.
Allergy-testing is a prerequisite for specific allergy treatment, including specific allergen avoidance measures, relevant pharmacotherapy and specific allergy vaccination. All children with persisting, recurrent or severe possible "allergic symptoms" or those with a need for continuous treatment should be tested, irrespective of the child's age. Allergy-testing includes a careful case history and a determination of IgE sensitisation by skin prick test or the measurement of allergen-specific IgE in serum by standardised and validated methods. The diagnosis of food allergy cannot usually be based solely on the case history and IgE sensitisation; the diagnosis has to be confirmed by controlled food elimination and food challenge procedures. The diagnosis of inhalant allergic disease requires only confirmatory nasal, conjunctival or bronchial challenges in equivocal cases or before specific allergy treatment such as extensive allergen avoidance measures or allergy vaccination.
Allergens↗
Case 5: assessment. Recurrent wheezing.
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Asthma↗
Pollen immunotherapy reduces the development of asthma in children with seasonal rhinoconjunctivitis (the PAT-study).
BACKGROUND: Children with allergic rhinitis are likely to develop asthma. OBJECTIVE: The purpose of this investigation was to determine whether specific immunotherapy can prevent the development of asthma and reduce bronchial hyperresponsiveness in children with seasonal allergic rhinoconjunctivitis. METHODS: From 6 pediatric allergy centers, 205 children aged 6 to 14 years (mean age, 10.7 years) with grass and/or birch pollen allergy but without any other clinically important allergy were randomized either to receive specific immunotherapy for 3 years or to an open control group. All subjects had moderate to severe hay fever symptoms, but at inclusion none reported asthma with need of daily treatment. Symptomatic treatment was limited to loratadine, levocabastine, sodium cromoglycate, and nasal budesonide. Asthma was evaluated clinically and by peak flow. Methacholine bronchial provocation tests were carried out during the season(s) and during the winter. RESULTS: Before the start of immunotherapy, 20% of the children had mild asthma symptoms during the pollen season(s). Among those without asthma, the actively treated children had significantly fewer asthma symptoms after 3 years as evaluated by clinical diagnosis (odds ratio, 2.52; P <.05). Methacholine bronchial provocation test results improved significant in the active group (P <.05). CONCLUSION: Immunotherapy can reduce the development of asthma in children with seasonal rhinoconjunctivitis.
Adolescent↗
Clinical course of cow's milk protein allergy/intolerance and atopic diseases in childhood.
A cohort of 1,749 newborns from the municipality of Odense, born during 1995 at the Odense University Hospital, were followed up prospectively for the development of cow's milk protein allergy/intolerance (CMPA/I) during the first year of life. Once a diagnosis of CMPA/I was confirmed, a milk-free diet was continued until a new milk challenge had shown development of tolerance. All infants with CMPA/I were rechallenged at 12 months of age and, in the event of continued clinical sensitivity to cow's milk protein, controlled rechallenges were performed every 6 months up to 3 years of age; and thereafter every 12 months until the age of 15 years. From the same birth cohort, 276 infants were randomly selected at birth for prospective non-interventional follow-up in order to investigate the natural course of sensitization and development of atopic disease during childhood. Standardized questionnaires on atopic heredity, environmental factors and presence of atopic symptoms were answered at 0, 6, 12 and 18 months and at 5, 10 and 15 years of age. Interviews on atopic history and environmental factors as well as physical examination were carried out at 18 months, 5, 10 and 15 years of age. Skin prick test and specific sIgE (Pharmacia CAP) testing were performed at 18 months, 5, 10 and 15 years of age against a panel of inhalant allergens (birch, grass, mugwort, dog, cat, horse, Dermatophagoidespteronyssinus, Dermatophagoides farinae, alternaria and cladosporium herbarum). Furthermore, lung function measurements were performed in children when 10 and 15 years of age. Based on controlled milk elimination and challenge procedures, the diagnosis of CMPA/I was confirmed in 39 out of 117 infants, with symptoms suggestive of CMPA/I, thus resulting in a 1-year incidence of CMPA/I of 2.2%. The overall prognosis of CMPA/I was good, with a total recovery of 56% at 1 year, 77% at 2 years, 87% at 3 years, 92% at 5 and 10 years and 97% at 15 years of age. In children younger than 10 years of age, 41% developed asthma and 31% rhinoconjunctivitis. Children with non-IgE-mediated CMPI had a good prognosis, whereas children with IgE-mediated CMPA in early childhood had a significantly increased risk for persistent CMPA, development of other food allergies, asthma and rhinoconjunctivitis. During early infancy, recurrent wheezing was the most prevalent disease (20%), followed by atopic dermatitis (14%) and food allergy (7%) at 18 months of age. Physician diagnosed asthma increased from 2% at 1.5 years of age to 9% at 10 years of age. Rhinoconjunctivitis increased from <1% at 1.5 years of age to 9% at 10 years of age. Overall, the current prevalence of any atopic disease was 20% at 1.5 years of age, declining to 14% at 5 years of age and followed by an increase to 25% at 10 years of age. Sensitization to inhalant and/or food allergens (specific IgE of > or = class 2; CAP RAST) showed a low rate of sensitization among asymptomatics (3%, 10% and 12%) compared with higher rates of sensitization of 8%, 39% and 30% among symptomatic atopics at 1.5, 5 and 10 years of age respectively. The highest rate of sensitization (53%) was found among children with current asthma at 10 years of age.
Cohort Studies↗