Environmental exposure to endotoxin and its relation to asthma in school-age children

BACKGROUND

In early life, the innate immune system can recognize both viable and nonviable parts of microorganisms. Immune activation may direct the immune response, thus conferring tolerance to allergens such as animal dander or tree and grass pollen.

METHODS

Parents of children who were 6 to 13 years of age and were living in rural areas of Germany, Austria, or Switzerland where there were both farming and nonfarming households completed a standardized questionnaire on asthma and hay fever. Blood samples were obtained from the children and tested for atopic sensitization; peripheral-blood leukocytes were also harvested from the samples for testing. The levels of endotoxin in the bedding used by these children were examined in relation to clinical findings and to the cytokine-production profiles of peripheral-blood leukocytes that had been stimulated with lipopolysaccharide and staphylococcal enterotoxin B. Complete data were available for 812 children.

RESULTS

Endotoxin levels in samples of dust from the child's mattress were inversely related to the occurrence of hay fever, atopic asthma, and atopic sensitization. Nonatopic wheeze was not significantly associated with the endotoxin level. Cytokine production by leukocytes (production of tumor necrosis factor alpha, interferon-gamma, interleukin-10, and interleukin-12) was inversely related to the endotoxin level in the bedding, indicating a marked down-regulation of immune responses in exposed children.

CONCLUSIONS

A subject's environmental exposure to endotoxin may have a crucial role in the development of tolerance to ubiquitous allergens found in natural environments.

Utility of food-specific IgE concentrations in predicting symptomatic food allergy

BACKGROUND

The double-blind, placebo-controlled food challenge is considered the gold standard for diagnosing food allergy. However, in a retrospective analysis of children and adolescents with atopic dermatitis and food allergy, discrete food-specific IgE concentrations were established that could predict clinical reactivity to egg, milk, peanut, and fish with greater than 95% certainty.

OBJECTIVE

The purpose of this investigation was to determine the utility of these 95% predictive decision points in a prospective evaluation of food allergy.

METHODS

Sera from 100 consecutive children and adolescents referred for evaluation of food allergy were analyzed for specific IgE antibodies to egg, milk, peanut, soy, wheat, and fish by using the Pharmacia CAP System FEIA. Food-specific IgE values were compared with history and the results of skin prick tests and food challenges to determine the efficacy of previously established 95% predictive decision points in identifying patients with increased probability of reacting during a specific food challenge.

RESULTS

One hundred children (62% male; median age, 3.8 years; range, 0.4-14.3 years) were evaluated for food allergy. The diagnosis of food allergy was established by means of history or oral food challenge. On the basis of the previously established 95% predictive decision points for egg, milk, peanut, and fish allergy, greater than 95% of food allergies diagnosed in this prospective study were correctly identified by quantifying serum food-specific IgE concentrations.

CONCLUSION

In a prospective study of children and adolescents referred for evaluation of food allergy, previously established 95% predictive decision points of food-specific IgE antibody concentrations for 4 major food allergens were effective in predicting clinical reactivity. Quantification of food-specific IgE is a useful test for diagnosing symptomatic allergy to egg, milk, peanut, and fish in the pediatric population and could eliminate the need to perform double-blind, placebo-controlled food challenges in a significant number of children.

The inverse association between tuberculin responses and atopic disorder

Human immune responses are heterogeneous and may involve antagonism between T helper (TH) lymphocyte subsets and their cytokines. Atopy is characterized by immediate immunoglobulin E (IgE)-mediated hypersensitivity to agents such as dust mites and pollen, and it underlies the increasingly prevalent disorder asthma. Among Japanese schoolchildren, there was a strong inverse association between delayed hypersensitivity to Mycobacterium tuberculosis and atopy. Positive tuberculin responses predicted a lower incidence of asthma, lower serum IgE levels, and cytokine profiles biased toward TH1 type. Exposure and response to M. tuberculosis may, by modification of immune profiles, inhibit atopic disorder.

Distinct patterns of neonatal gut microflora in infants in whom atopy was and was not developing

BACKGROUND

Improved hygiene has altered early microbial exposure by reducing childhood infections, which has been suggested as a cause for the continuously rising prevalence of atopic diseases. On the basis of both intensity and timing of stimulus, it has been hypothesized that exposure to commensal microflora may represent another key protective modulator of immunity against atopy and subsequent atopic diseases.

OBJECTIVE

We sought to investigate whether differences in early gut microflora precede the later development of atopic sensitization.

METHODS

Intestinal microflora from 76 infants at high risk of atopic diseases were analyzed at 3 weeks and 3 months of age by using conventional bacterial cultivation and 2 culture-independent methods, gas-liquid chromatography of bacterial cellular fatty acids and quantitative fluorescence in situ hybridization of bacterial cells. Infants evincing at least one positive skin prick reaction at 12 months were grouped as atopic subjects, and those without positive reactions were grouped as nonatopic subjects.

RESULTS

Atopic sensitization was observed in 22 (29%) of 76 children. At 3 weeks, the bacterial cellular fatty acid profile in fecal samples differed significantly between infants in whom atopy was and was not developing (P =.005). By using fluorescence in situ hydridization, atopic subjects had more clostridia (geometric mean [95% confidence interval]: 9.3 x 10(7) [3.8-22.9 x 10(7)] vs 3.3 x 10(7) [1.8-6.1 x 10(7)], P =.04) and tended to have fewer bifidobacteria (1.8 x 10(9) [0.4-7.6 x 10(9)] vs 6.1 x 10(9) [2.5-14.6 x 10(9)], P =.11) in their stools than nonatopic subjects, resulting in a reduced ratio of bifidobacteria to clostridia (P =.03). The differences were not detected by bacterial cultivation.

CONCLUSION

Differences in the neonatal gut microflora precede the development of atopy, suggesting a crucial role of the balance of indigenous intestinal bacteria for the maturation of human immunity to a nonatopic mode.

Allergy development and the intestinal microflora during the first year of life

BACKGROUND

The intestinal microflora is a likely source for the induction of immune deviation in infancy.

OBJECTIVE

The purpose of this study was to prospectively relate the intestinal microflora to allergy development in 2 countries differing with respect to the prevalence of atopic diseases.

METHODS

Newborn infants were followed prospectively through the first 2 years of life in Estonia (n = 24) and Sweden (n = 20). By that age, 9 Estonian and 9 Swedish infants had developed atopic dermatitis and/or positive skin prick test results. Stool samples were obtained at 5 to 6 days and at 1, 3, 6, and 12 months, and 13 groups of aerobic and anaerobic microorganisms were cultivated through use of standard methods.

RESULTS

In comparison with healthy infants, babies who developed allergy were less often colonized with enterococci during the first month of life (72% vs 96%; P <.05) and with bifidobacteria during the first year of life (17% to 39% vs 42% to 69%; P <.05). Furthermore, allergic infants had higher counts of clostridia at 3 months (median value, 10.3 vs 7.2 log(10); P <.05). The prevalence of colonization with Staphylococcus aureus was also higher at 6 months (61% vs 23%; P <.05), whereas the counts of Bacteroides were lower at 12 months (9.9 vs 10.6 log(10); P <.05).

CONCLUSION

Differences in the composition of the gut flora between infants who will and infants who will not develop allergy are demonstrable before the development of any clinical manifestations of atopy. Because the observations were made in 2 countries with different standards of living, we believe that our findings could indicate a role for the intestinal microflora in the development of and protection from allergy.

Food allergy

Adverse immune responses to foods affect approximately 5% of young children and 3% to 4% of adults in westernized countries and appear to have increased in prevalence. Food-induced allergic reactions are responsible for a variety of symptoms and disorders involving the skin and gastrointestinal and respiratory tracts and can be attributed to IgE-mediated and non-IgE-mediated (cellular) mechanisms. Genetic disposition and environmental factors might abrogate oral tolerance, leading to food allergy. Disease outcomes are influenced by the characteristics of the immune response and of the triggering allergen. Diagnosis is complicated by the observation that detection of food-specific IgE (sensitization) does not necessarily indicate clinical allergy. Therefore diagnosis requires a careful medical history, laboratory studies, and, in many cases, an oral food challenge to confirm a diagnosis. Novel diagnostic methods, including ones that focus on immune responses to specific food proteins or epitopes of specific proteins, are under study. Currently, management of food allergies consists of educating the patient to avoid ingesting the responsible allergen and to initiate therapy (eg, with injected epinephrine for anaphylaxis) in case of an unintended ingestion. Improved therapeutic strategies under study include oral and sublingual immunotherapy, Chinese herbal medicine, anti-IgE antibodies, and modified vaccines.

Prevalence of asthma and atopy in two areas of West and East Germany

The German reunification offers a unique opportunity to study the impact of environmental factors on the development of childhood respiratory and allergic disorders in ethnically similar populations. We investigated the prevalence of asthma, hay fever, atopy, and bronchial hyperresponsiveness (BHR) in 9- to 11-year old children in West Germany (n = 5,030) and East Germany (n = 2,623). A self-administered questionnaire was distributed to the parents. Children underwent cold air challenge and allergy skin prick tests. Atopic sensitization was considerably more frequent in West German children than in their peers in East Germany (36.7% versus 18.2%; odds ratio [OR] = 2.6, p < 0.0001). The prevalence of current asthma and hay fever was significantly higher in West Germany when compared with that in East Germany (5.9% versus 3.9%; OR = 1.5, p < 0.0001 and 8.6% versus 2.7%; OR = 3.4, p < 0.0001, respectively). Bronchitis, however, was more prevalent in East Germany than in the western part of the country. The prevalence of BHR as assessed by cold air challenge was higher in West Germany compared with that in East Germany (8.3% versus 5.5%, OR = 1.6, p < 0.001). Logistic regression showed that the West German study area was no longer a significant independent determinant of asthma once sensitization to mites, cats, and pollen was taken into account. We conclude that sensitization to aeroallergens is strikingly more frequent in West Germany than in East Germany and this may explain the differences in the prevalence of asthma and hay fever between the two parts of the country.

Perennial allergen sensitisation early in life and chronic asthma in children: a birth cohort study

BACKGROUND

Reduced lung function is a feature of chronic asthma, which becomes apparent at school age. Unknown factors between birth and school age determine the progressive loss of pulmonary function in children with persistent asthma. We investigated the role of allergic sensitisation and allergen exposure early in life.

METHODS

The German Multicentre Allergy Study followed 1314 children from birth to 13 years of age. We regularly interviewed parents about their child's asthma and measured IgE levels. Allergen exposure was assessed at age 6 months, 18 months, and at 3, 4, and 5 years; lung function was assessed at 7, 10, and 13 years; post-bronchodilator response at 10 and 13 years; and a bronchial histamine challenge was done at 7 years.

RESULTS

90% of children with wheeze but no atopy lost their symptoms at school age and retained normal lung function at puberty. By contrast, sensitisation to perennial allergens (eg, house dust mite, cat and dog hair) developing in the first 3 years of life was associated with a loss of lung function at school age. Concomitant exposure to high levels of perennial allergens early in life aggravated this process: forced expiratory volume in 1 s (FEV1) to forced vital capacity (FVC) ratio was 87.4 (SD 7.4) for those sensitised and with high exposure compared with 92.6 (6.0) for those not sensitised, p<0.0001; and maximal expiratory flow at 50% (MEF50) 86.4 (25.1) for sensitised and with high exposure compared with 101.5 (23.2; p=0.0031) for those not sensitised. Such exposure also enhanced the development of airway hyper-responsiveness in sensitised children with wheeze. Sensitisation and exposure later in life had much weaker effects and sensitisation to seasonal allergens did not play a part.

INTERPRETATION

The chronic course of asthma characterised by airway hyper-responsiveness and impairment of lung function at school age is determined by continuing allergic airway inflammation beginning in the first 3 years of life. However, children with a non-atopic wheezing phenotype lose their symptoms over school age and retain normal lung function at puberty.

Decreased atopy in children infected with Schistosoma haematobium: a role for parasite-induced interleukin-10

BACKGROUND

Most of the effort directed at understanding the role infections have in preventing allergy has focused on bacteria and viruses and their ability to divert the immune system towards T-helper-1 responses and away from proallergic T-helper-2 responses. However, helminth infections, highly prevalent in large parts of the developing world, where allergy is uncommon, stimulate strong T-helper-2 responses. We investigated the influence of chronic helminth infections on the prevalence of atopy and aimed to understand the relation at a detailed immunological level.

METHODS

520 Gabonese schoolchildren were tested for skin reaction to house-dust mite and other allergens, for Schistosoma haematobium eggs in urine, and for microfilariae in blood samples. Total and mite-specific IgE antibodies were measured. A subsample selected on the basis of their skin test to house-dust mite received detailed immunological investigations.

FINDINGS

Children with urinary schistosomiasis had a lower prevalence of a positive skin reaction to house-dust mite than those free of this infection (odds ratio 0.32 [95% CI 0.16-0.63]). The degree of sensitisation to house-dust mite could not explain this difference in skin-prick positivity. Schistosome-antigen-specific concentrations of interleukin-10 were significantly higher in infected children, and higher specific concentrations of this anti-inflammatory cytokine were negatively associated with the outcome of skin-test reactivity to mite (0.53 [0.30-0.96]). No association between polyclonal IgE antibodies and skin-test results was found.

INTERPRETATION

The anti-inflammatory cytokine, interleukin-10, induced in chronic schistosomiasis, appears central to suppressing atopy in African children.

Respiratory symptoms and atopy in Aberdeen schoolchildren: evidence from two surveys 25 years apart

OBJECTIVE

To estimate changes in the prevalence of respiratory symptoms and the reported diagnoses of asthma, eczema, and hay fever in primary school children in Aberdeen between 1964 and 1989.

DESIGN

Determination of incidence prevalence and prevalence from survey data.

SETTING

Aberdeen, Scotland.

PARTICIPANTS

2743 primary school children (aged 8-13) from 1964 and 4003 [corrected] from 1989.

MAIN OUTCOME MEASURES

Survey data on whether, according to the parent or guardian, the child wheezed or was troubled with shortness of breath; the number of episodes of breathlessness in the past year; and whether asthma, eczema, or hay fever had ever been diagnosed.

RESULTS

Questionnaires were completed by the parents of 2510 children in 1964 and 3403 children in 1989. The prevalence of wheeze rose from 10.4% in 1964 to 19.8% in 1989, and the prevalence of episodes of shortness of breath increased from 5.4% to 10.0%. In both surveys wheeze and shortness of breath were more prevalent in boys than in girls. The reported diagnosis of asthma rose from 4.1% to 10.2%, hay fever from 3.2% to 11.9%, and eczema from 5.3% to 12%. The proportion of boys suffering from eczema rose from 47.7% to 60.0%. Hay fever showed a similar increase, from 49.4% to 60.1%, in boys over the 25 year period. Though the parents of a higher proportion of children with wheeze were aware of the diagnosis of asthma in 1989, because of the increased prevalence of wheeze the absolute number of parents of wheezy children who were not aware of a diagnosis of asthma increased from 7.4% to 9.6% of the population studied.

CONCLUSION

The higher diagnosis rate for asthma is due not simply to changes in diagnostic fashion but reflects an increase over the past 25 years in the prevalence of respiratory symptoms, which in turn may reflect a more general change in the prevalence of atopy, the increase in which was particularly noticeable in boys. This increase explains some of the increase in hospital admission rates for children with asthma.

The genetics of asthma and allergic disease: a 21st century perspective

Asthma and allergy are common conditions with complex etiologies involving both genetic and environmental contributions. Recent genome-wide association studies (GWAS) and meta-analyses of GWAS have begun to shed light on both common and distinct pathways that contribute to asthma and allergic diseases. Associations with variation in genes encoding the epithelial cell-derived cytokines, interleukin-33 (IL-33) and thymic stromal lymphopoietin (TSLP), and the IL1RL1 gene encoding the IL-33 receptor, ST2, highlight the central roles for innate immune response pathways that promote the activation and differentiation of T-helper 2 cells in the pathogenesis of both asthma and allergic diseases. In contrast, variation at the 17q21 asthma locus, encoding the ORMDL3 and GSDML genes, is specifically associated with risk for childhood onset asthma. These and other genetic findings are providing a list of well-validated asthma and allergy susceptibility genes that are expanding our understanding of the common and unique biological pathways that are dysregulated in these related conditions. Ongoing studies will continue to broaden our understanding of asthma and allergy and unravel the mechanisms for the development of these complex traits.

High rates of autoimmune and endocrine disorders, fibromyalgia, chronic fatigue syndrome and atopic diseases among women with endometriosis: a survey analysis

BACKGROUND

Women with endometriosis may also have associated disorders related to autoimmune dysregulation or pain. This study examined whether the prevalence of autoimmune, chronic pain and fatigue and atopic disorders is higher in women with endometriosis than in the general female population.

METHODS AND RESULTS

A cross-sectional survey was conducted in 1998 by the Endometriosis Association of 3680 USA members with surgically diagnosed endometriosis. Almost all responders had pain (99%), and many reported infertility (41%). Compared with published rates in the general USA female population, women with endometriosis had higher rates of hypothyroidism (9.6 versus 1.5%, P < 0.0001), fibromyalgia (5.9 versus 3.4%, P < 0.0001), chronic fatigue syndrome (4.6 versus 0.03%, P < 0.0001), rheumatoid arthritis (1.8 versus 1.2%, P = 0.001), systemic lupus erythematosus (0.8 versus 0.04%, P < 0.0001), Sjögren's syndrome (0.6 versus 0.03%, P < 0.0001) and multiple sclerosis (0.5 versus 0.07%, P < 0.0001), but not hyperthyroidism or diabetes. Allergies and asthma were more common among women with endometriosis alone (61%, P < 0.001 and 12%, P < 0.001 respectively) and highest in those with fibromyalgia or chronic fatigue syndrome (88%, P < 0.001 and 25%, P < 0.001 respectively) than in the USA female population (18%, P < 0.001 and 5%, P < 0.001 respectively).

CONCLUSIONS

Hypothyroidism, fibromyalgia, chronic fatigue syndrome, autoimmune diseases, allergies and asthma are all significantly more common in women with endometriosis than in women in the general USA population.

Rhinitis as an independent risk factor for adult-onset asthma

BACKGROUND

For many years, the association between asthma and rhinitis has primarily been attributed to a common allergic background. Recently, it has been suggested that asthma and rhinitis are associated in the absence of atopy. The nature of this association is not well known.

OBJECTIVE

The purpose of this study, which was performed in a large, longitudinal community population, was to determine the extent to which rhinitis is an independent risk factor for adult-onset asthma.

METHODS

We carried out a nested case-control study from the longitudinal cohort of the Tucson Epidemiologic Study of Obstructive Lung Diseases. One hundred seventy-three incident patients with physician-confirmed asthma were compared with 2177 subjects who reported no asthma or shortness of breath with wheezing. Potential risk factors, including the presence of rhinitis, were assessed before the onset of asthma (patients) or before the last completed survey (control subjects).

RESULTS

Rhinitis was a significant risk factor for asthma (crude odds ratio, 4.13; 95% confidence interval, 2.88-5.92). After adjustment for years of follow-up, age, sex, atopic status, smoking status, and presence of chronic obstructive pulmonary disease, the magnitude of the association was reduced but still highly significant (adjusted odds ratio, 3.21; 95% confidence interval, 2.19-4.71). After stratification, rhinitis increased the risk of development of asthma by about 3 times both among atopic and nonatopic patients and by more than 5 times among patients in the highest IgE tertile. Patients with rhinitis with persistent and severe nasal symptoms and a personal history of physician-confirmed sinusitis had an additional increased risk of asthma development.

CONCLUSION

We conclude that rhinitis is a significant risk factor for adult-onset asthma in both atopic and nonatopic subjects. The nature of the association between rhinitis and asthma is open to interpretation.

Measles and atopy in Guinea-Bissau

BACKGROUND

Epidemiological studies have led to speculation that infections in early childhood may prevent allergic sensitisation but evidence to support this hypothesis is lacking. We investigated whether measles infection protects against the development of atopy in children of Guinea-Bissau, West Africa.

METHODS

We conducted a historical cohort study in Bandim, a semi-rural district of Bissau, the capital of Guinea-Bissau. 395 young adults, first surveyed in 1978-80 aged 0-6 years, were followed up in 1994. Our analyses were restricted to 262 individuals still living in Bandim for whom a measles history, documented in childhood, was judged to be reliable. We defined atopy as skin-prick test positivity (> or = 3 mm weal) to one or more of seven allergens.

FINDINGS

17 (12.8 percent) of 133 participants who had had measles infection were atopic compared with 33 (25.6 percent) of 129 of those who had been vaccinated and not had measles (odds ratio, adjusted for potential confounding variables 0.36 [95 percent CI 0.17-0.78], p=O.O1). Participants who had been breastfed for more than a year were less likely to have a positive skin test to housedust mite. After adjustment for breastfeeding and other variables, measles infection was associated with a large reduction in the risk of skin-prick test positivity to housedust mite (odds ratio for Dermatophagoides pteronyssinus 0.20 [0.05-0.81], p=0.02; D farinae 0.20 [0.06-0.71], p=0.01).

INTERPRETATION

Measles infection may prevent the development of atopy in African children.

Atopy in children of families with an anthroposophic lifestyle

BACKGROUND

Increased prevalence of atopic disorders in children may be associated with changes in types of childhood infections, vaccination programmes, and intestinal microflora. People who follow an anthroposophic way of life use antibiotics restrictively, have few vaccinations, and their diet usually contains live lactobacilli, which may affect the intestinal microflora. We aimed to study the prevalence of atopy in children from anthroposophic families and the influence of an anthroposophic lifestyle on atopy prevalence.

METHODS

In a cross-sectional study, 295 children aged 5-13 years at two anthroposophic (Steiner) schools near Stockholm, Sweden, were compared with 380 children of the same age at two neighbouring schools in terms of history of atopic and infectious diseases, use of antibiotics and vaccinations, and social and environmental variables. Skin-prick tests were done for 13 common allergens, and we took blood samples from children and their parents for analysis of allergen-specific serum IgE-antibodies.

FINDINGS

At the Steiner schools, 52% of the children had had antibiotics in the past, compared with 90% in the control schools. 18% and 93% of children, respectively, had had combined immunisation against measles, mumps, and rubella, and 61% of the children at the Steiner schools had had measles. Fermented vegetables, containing live lactobacilli, were consumed by 63% of the children at Steiner schools, compared with 4.5% at the control schools. Skin-prick tests and blood tests showed that the children from Steiner schools had lower prevalence of atopy than controls (odds ratio 0.62 [95% CI 0.43-0.91]). There was an inverse relation between the number of characteristic features of an anthroposophic lifestyle and risk of atopy (p for trend=0.01).

INTERPRETATION

Prevalence of atopy is lower in children from anthroposophic families than in children from other families. Lifestyle factors associated with anthroposophy may lessen the risk of atopy in childhood.

Changing prevalence of asthma in Australian children

OBJECTIVE

To investigate whether prevalence of asthma in children increased in 10 years.

DESIGN

Serial cross sectional studies of two populations of children by means of standard protocol.

SETTING

Two towns in New South Wales: Belmont (coastal and humid) and Wagga Wagga (inland and dry).

SUBJECTS

Children aged 8-10 years: 718 in Belmont and 769 in Wagga Wagga in 1982; 873 in Belmont and 795 in Wagga Wagga in 1992.

MAIN OUTCOME MEASURES

History of respiratory illness recorded by parents in self administered questionnaire; airway hyperresponsiveness by histamine inhalation test; atopy by skin prick tests; counts of house dust mites in domestic dust.

RESULTS

Prevalence of wheeze in previous 12 months increased in Belmont, from 10.4% (75/718) in 1982 to 27.6% (240/873) in 1992 (P < 0.001), and in Wagga Wagga, from 15.5% (119/769) to 23.1% (183/795) (P < 0.001). The prevalence of airway hyperresponsiveness increased twofold in Belmont to 19.8% (173/873) (P < 0.001) and 1.4-fold in Wagga Wagga to 18.1% (P < 0.05). The prevalence of airway hyperresponsiveness increased mainly in atopic children only, but the prevalence of atopy was unchanged (about 28.5% in Belmont and about 32.5% in Wagga Wagga). Numbers of house dust mites increased 5.5-fold in Belmont and 4.5-fold in Wagga Wagga.

CONCLUSIONS

We suggest that exposure to higher allergen levels has increased airway abnormalities in atopic children or that mechanisms that protected airways of earlier generations of children have been altered by new environmental factors.

Cross sectional retrospective study of prevalence of atopy among Italian military students with antibodies against hepatitis A virus

OBJECTIVE

To investigate the working hypothesis that common infections occurring early in life prevent atopy.

DESIGN

Cross sectional, retrospective study of young Italian men with results for hepatitis A serology and atopy.

SETTING

Air force school of military students in Caserta, Italy.

SUBJECTS

1659 male students aged 17-24, most of whom (90%) were from central and southern Italy.

MAIN OUTCOME MEASURES

Skin sensitisation and specific IgE antibodies to locally relevant airborne allergens; diagnosis of respiratory allergy (asthma or rhinitis, or both); hepatitis A seropositivity.

RESULTS

443 of the 1659 subjects (26.7%) were positive for hepatitis A virus antibody. Atopy was less common among seropositive than seronegative subjects according to skin sensitization (weal reaction > or = 3 mm) to one or more allergens (21.9% (97/443) v 30.2% (367/1216), P < 0.001); polysensitisation (sensitive to three or more allergens) (2.7% (12/443) v 6.4% (78/1216), P < 0.01); high specific IgF concentration (9.7% (43/443) v 18.4% (224/1216), P < 0.00005); and lifetime prevalence of allergic rhinitis or asthma, or both (8.4% (37/443) v 16.7% (203/1216), P < 0.001). Hepatitis A seropositivity remained inversely associated with atopy after adjusting for father's education, the number of older siblings, and the area of residence (based on the number of inhabitants). The prevalence of atopy was constantly low among seropositive subjects, whatever the number of older siblings; by contrast, it increased with a decreasing number of older siblings among seronegative subjects.

CONCLUSION

Indirect but important evidence is added to the working hypothesis as common infections acquired early in life because of the presence of many older siblings (among seronegative subjects) or because of unhygienic living conditions (among seropositive subjects) may have reduced the risk of developing atopy.

Skin test reactivity and number of siblings

OBJECTIVE

To investigate the relation between skin test reactivity in children and number of siblings.

DESIGN

Cross sectional survey among schoolchildren aged 9-11 years. Skin prick tests in the children and self completion of written questionnaire by their parents.

SUBJECTS

5030 children in Munich and 2623 children in Leipzig and Halle, Germany.

MAIN OUTCOME MEASURES

Atopic status assessed by skin prick tests.

RESULTS

After possible confounders were controlled for, the prevalence of atopic sensitisation decreased linearly with increasing number of siblings (odds ratio = 0.96 for one sibling, 0.67 for five or more siblings; P = 0.005). In atopic children the severity of the skin test reaction as assessed by the weal size was not associated with the number of siblings.

CONCLUSIONS

Factors directly or indirectly related to the number of siblings may decrease the susceptibility of children to become atopic. Thus, declining family size may in part contribute to the increased prevalence of atopic diseases reported in Western countries over the past few decades.

The prevalence of childhood atopic eczema in a general population

BACKGROUND

Atopic eczema has become more common during recent decades, but few studies have looked at its prevalence in the general community.

OBJECTIVE

Our purpose was to ascertain the prevalence of atopic eczema, its age of onset, and its relationship to breast-feeding and ear piercing in a general practice population.

METHODS

Children (N = 1104), aged 3 to 11 years, were identified from a computerized register in a socially and ethnically mixed English general practice population of 13,314. Of these, 1077 children (97.6% recruitment) were interviewed with parents or guardians, and the resultant data were recorded on a survey form.

RESULTS

The lifetime occurrence of atopic eczema was 20% in boys (12% in the past year) and 19% in girls (11% in the past year). Prevalence in the past year was 10% to 14% in boys aged 3 to 11 years but fell in girls from 15% at 3 to 5 years to 8% at 9 to 11 years. Atopic eczema developed in the first 12 months of life in 60% of the children who had the condition, and it developed in the first 6 months of life in three quarters of these children. Ear piercing had been performed in 35% of girls and 3% of boys and was most prevalent in social classes 3, 4, and 5. More than half the girls aged 9 to 11 years had pierced ears. Breast-feeding did not affect the prevalence of atopic eczema.

CONCLUSION

The lifetime prevalence of atopic eczema was 20% in children aged 3 to 11 years. There was no evidence that ear piercing perpetuated eczema in this age group. Breast-feeding did not protect against the development of atopic eczema.

Epidemiology of anaphylaxis in Olmsted County: A population-based study

BACKGROUND

Awareness of the clinical features of anaphylaxis and its causative triggers is important if recurrent episodes are to be avoided. The incidence of anaphylaxis in the general population is often underreported, and epidemiologic studies are few. Because an accurate profile of anaphylaxis could heighten awareness of this problem, we investigated the epidemiology of anaphylaxis in the general population of Olmsted County, Minn.

OBJECTIVE

The purpose of this study was to describe the epidemiology of anaphylaxis in Olmsted County residents from 1983 through 1987.

METHODS

This was a retrospective population-based cohort study. The medical records of 1255 Olmsted County residents identified by computer-linked, medical diagnostic indices (the Rochester Epidemiology Study) were reviewed retrospectively to identify residents whose clinical episodes met the criteria for anaphylaxis. We determined the incidence and rate of occurrence of anaphylaxis, rate of recurrence, prevalence of atopy, cause of anaphylaxis, frequency of referral to an allergy specialist, hospital admission rate, and case-fatality rate.

RESULTS

There were 133 residents who experienced 154 anaphylactic episodes during the 5-year period: 116 residents had 1 episode of anaphylaxis, 13 residents had 2 episodes, and 4 residents had 3 episodes. The anaphylaxis occurrence rate was 30 per 100,000 person-years (95% confidence interval, 25-35). There were 110 residents who had a first lifetime episode of anaphylaxis (that was medically evaluated) during the years 1983 to 1987. The average annual incidence rate of anaphylaxis was 21 per 100,000 person-years (95% confidence interval, 17-25). Atopy was present in 53% of the cohort, and allergy consultation was obtained in 52%. A suspect allergen was identified in 68% of the cohort, most frequently a food, medication, or insect sting. The hospitalization rate was 7%, and 1 patient died.

CONCLUSION

The incidence of anaphylaxis is less than 1%, and death rarely occurs. People with atopy experience anaphylaxis more frequently than people without atopy. Anaphylaxis frequently is not recognized by patients and physicians.

Sleepless in America: inadequate sleep and relationships to health and well-being of our nation's children

OBJECTIVE

Our goal was to identify characteristics associated with inadequate sleep for a national random sample of elementary school-aged children (6-11 years) and adolescents (12-17 years).

METHODS

Data from 68418 participants in the 2003 National Survey of Children's Health were analyzed by using weighted bivariate and multivariate regression models. The dependent variable was report of not getting enough sleep for a child of his or her age >or=1 night of the past week. Independent variables included demographic characteristics, child health, school and other activities, and family life.

RESULTS

Parents of elementary school-aged children with inadequate sleep were more likely to report that their child was having problems at school or had a father with fair or poor health. Parents of adolescents with inadequate sleep were more likely to report that their child had an atopic condition, frequent or severe headaches, a parent with less-than-excellent emotional health, or experienced frequent parental anger. Inadequate sleep in both age groups was associated with parental report that their child usually or always displayed depressive symptomatology, family disagreements involved heated arguing, or parental concern that the child was not always safe at home, at school, or in their neighborhood.

CONCLUSIONS

Approximately 15 million American children are affected by inadequate sleep. Primary care providers should routinely identify and address inadequate sleep and its associated health, school, and family factors.

The European Community Respiratory Health Survey II

The European Community Respiratory Health Survey (ECRHS) II will determine the incidence of and risk factors for the development of allergic disease, atopy and rapid loss of lung function in middle-aged adults living in Europe. From 1991-1993, >18,000 individuals took part in ECRHS I and provided information on symptoms and exposure to known or suspected risk factors for asthma. Blood samples for assessment of specific immunoglobulin E to environmental allergen were taken and lung function and bronchial responsiveness to methacholine were assessed. From 1999-2001, study participants were re-contacted to determine symptom status and exposure to a variety of factors, including tobacco smoke, animals, occupational agents and air pollutants (including particulate matter). In a subsample of responders, exposure to house dust-mite allergen was assessed by analysis of dust samples taken from participants' mattresses. In addition, blood samples suitable for deoxyribonucleic acid extraction were collected and stored. Currently, European Community Respiratory Health Survey II is being conducted in 29 centres in 14 countries. At the time of writing this paper, 27 centres had begun the study and approximately 12,000 participants had completed a short postal questionnaire, approximately 9,000 had completed a more detailed health assessment and 3,500 participants had provided dust samples. Historical air-pollution data have been collated and the programme of monitoring particles with a 50% cut-off aerodynamic diameter of 2.5 microm has been completed in 21 centres in 10 countries.

The prevalence of and risk factors for atopy in early childhood: a whole population birth cohort study

OBJECTIVES

A birth cohort was followed-up to age 4 years to record the development of allergic disorders and to study the influence of genetic and environmental factors.

METHODS

Information on family history and environmental factors was obtained at birth, and serum cord IgE was measured. At age 4 years, 1218 children were reviewed.

RESULTS

By age 4 years, 27% of the children had symptoms of allergic disease. Period prevalence of asthma increased from 8.7% in infancy to 14.9% at 4 years. Family history of atopy was the single most important risk factor for atopy in children. Sibling atopy was a stronger predictor of clinical disease than maternal or paternal atopy, whereas paternal atopy, male sex, and high cord IgE were significant for the development of allergen sensitization. Children of asthmatic mothers were three times more likely to have asthma (odds ratio [OR]: 3.0, 95% confidence interval [CI]: 1.6-5.8) and rhinitis (OR: 2.9, CI: 1.1-7.4). Formula feeding before 3 months of age predisposed to asthma at age 4 years (OR: 1.8, CI: 1.2-2.6). The effect of maternal smoking on childhood wheeze seen at 1 and 2 years was lost by age 4, except for a subgroup with negative skin test responses (nonatopic asthma). Less than half (46%) of the infantile wheezers were still wheezing at 4 years of age.

CONCLUSION

Family history of atopy remains the most important risk factor for atopy in children, but other markers can be identified with a potential for intervention at an early age.