***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The prevalence of  atopic dermatitis  increased markedly in the period 1960s to the 1990s . Earlier findings indicate that infections acquired in early life enhance or suppress the expression of atopic disease as a result of a change in immune reactivity . Our objectives were to examine the association between measles , mumps and rubella vaccination , measles infection and the risk of  atopic dermatitis . A r and om sample of 9,744 children were followed up from birth to 3 - 15 years . Their parents responded to a question naire including highly structured questions on atopic dermatitis , measles , mumps and rubella vaccination and measles infection . Information on parental educational level was obtained from Statistics Denmark . The cumulative incidence of atopic dermatitis at age 14 was 19.7 % . The confounder adjusted incidence ratio of atopic dermatitis among measles , mumps and rubella vaccinated children versus children not subjected to measles , mumps and rubella vaccination and measles infection was 1.86 ( 95 % CI 1.25 - 2.79 ) ; the incidence ratio for measles-infected children was similar . The incidence of atopic dermatitis increased after measles , mumps and rubella vaccination and measles infection , which is surprising in view of the hygiene hypothesis . We suggest further study of the possible short-term and long-term effects of virus and bacteria on the immune responses and expression of atopic disease BACKGROUND This study addresses the causes of the increases in  childhood asthma and allergic disease .  On the basis of an observed inverse relationship between family size and allergic disease or atopy , it has been proposed that a fall in common childhood infections may have been responsible for the rise in asthma . This study was undertaken to investigate the relationships between family size and reported allergic disease and to test the hypothesis that an inverse relationship between the two is a consequence of childhood infections . METHODS Data had been obtained in a 1964 cross sectional survey of a r and om sample of Aberdeen schoolchildren aged between 10 and 14 in that year . Records of the presence or absence of asthma , eczema , or hay fever at the time of the survey and a history of measles , pertussis , varicella , rubella , and mumps before and after the age of three years were available for 2111 subjects . RESULTS The risks of hay fever ( odds ratio 0.2 , 95 % CI 0.1 to 0.8 ) and eczema ( OR 0.3 , CI 0.1 to 0.7 ) were inversely related to having had three or more older siblings , whilst the risk of asthma ( OR 0.4 , CI 0.1 to 0.9 ) was inversely related to having had three or more younger siblings . Increasing total numbers of siblings showed a significant trend in protection against both eczema and hay fever . A weak protective effect against asthma was found for measles after the age of three ( OR 0.5 , CI 0.3 to 0.9 ) and slight increases in the risk of eczema were associated with having had rubella or pertussis and of asthma with having had varicella . The number of infections before the age of three was associated with a significant trend in the odds ratios towards increased risk of asthma ( p = 0.025 ) . There were significant trends in the odds ratios towards greater risk of eczema and hay fever with increasing exposure to rubella , mumps , and varicella . These relations between infection and atopic diseases were independent of the potential confounding factors age , sex , father 's social class , and total number of siblings . CONCLUSIONS These data add to the accumulating evidence that membership of a large sibship confers some protection against atopic disease . This does not appear to be explained by the common childhood infections which show conflicting relationships with atopic disease , in that measles may have some protective effect against asthma but the more infections a child has had , the more likely he or she is to have atopic disease . The explanation of the sibship effect is likely to lie elsewhere and the fall in common childhood infections is unlikely to explain the rise in atopic disease BACKGROUND An inverse association between domestic exposure to endotoxin and  atopy in childhood has been observed . The relevance of this aspect of the hygiene hypothesis to US inner-city communities that have disproportionately high asthma prevalence has not been determined . OBJECTIVES To measure endotoxin in the dust from inner-city homes , evaluate associations between endotoxin and housing/lifestyle characteristics , and determine whether endotoxin exposure predicted wheeze , allergic rhinitis , and eczema  over the first 3 years of life . METHODS As part of an ongoing prospect i ve birth cohort study , children of Dominican and African-American mothers living in New York City underwent repeated question naire measures . Dust sample s collected from bedroom floors at age 12 or 36 months were assayed for endotoxin . RESULTS Among the sample s collected from 301 participants ' homes , the geometric mean endotoxin concentration ( 95 % CI ) was 75.9 EU/mg ( 66 - 87 ) , and load was 3892 EU/m2 ( 3351 - 4522 ) . Lower endotoxin concentrations were associated with wet mop cleaning and certain neighborhoods . Endotoxin concentration correlated weakly with cockroach ( Bla g 2 : r = 0.22 , P < .001 ) and mouse ( mouse urinary protein : r = 0.28 ; P < .001 ) allergens in the dust . Children in homes with higher endotoxin concentration were less likely to have eczema at age 1 year ( odds ratio , 0.70 [ 0.53 - 0.93 ] ) and more likely to wheeze at age 2 years ( odds ratio , 1.34 [ 1.01 - 1.78 ] ) . These associations were stronger among children with a maternal history of asthma . CONCLUSION Endotoxin levels in this inner-city community are similar to those in nonfarm homes elsewhere . In this community , domestic endotoxin exposure was inversely associated with eczema at age 1 year , but positively associated with wheeze at age 2 years . CLINICAL IMPLICATION S Endotoxin exposure in the inner-city community may be related to wheeze in the early life ; however , given the inverse association seen with eczema , the long-term development of allergic disease is still in question BACKGROUND Bacille Calmette-Guérin ( BCG ) is a strong T helper 1 incentive and , thus , may contribute to a decreased risk of T helper 2-dependent atopic disease . OBJECTIVE To investigate the natural course of specific immunoglobulin E ( IgE ) responses and atopic disease in  BCG-vaccinated and nonvaccinated children . PARTICIPANTS Seven hundred seventy-four children from a prospect ively followed birth cohort . OUTCOME MEASURES Physical examination and case history were performed at 3 , 6 , 12 , 18 , 24 , 36 , 48 , 60 , 72 , and 84 months of age . Total and specific serum IgE levels to 9 common inhalant and food allergens were determined ( CAP ; Pharmacia , Freiburg , Germany ) at 12 , 24 , 36 , 60 , 72 , and 84 months of age . Purified protein derivative ( PPD ) skin testing was performed at 84 months . RESULTS Period and lifetime prevalences of atopic dermatitis and recurrent wheezing tended to be lower in the BCG-vaccinated group early in life , whereas no such trend was found after the second birthday or for allergic rhinitis . The proportion of children remaining free of clinical manifestations tended to be higher in the BCG-vaccinated group but differences decreased over time . No statistically significant differences were found for total IgE levels ( median ) . Atopic sensitization tended to be lower among BCG-vaccinated children during the first 2 years of life . The diameter of the skin reaction to PPD did not correlate with total serum IgE. Clinical and serologic correlates of atopy were not significantly different between children with a skin test diameter of > /=5 mm and those with a smaller diameter . CONCLUSION These results do not support the hypothesis that BCG vaccination in early infancy is associated with a subsequently markedly decreased risk of atopic sensitization or allergy . In addition , PPD skin test reactivity was not impaired in atopic individuals The role of repeated infections early in life in the development of childhood asthma and allergies has not been clarified . The aim of this study was to investigate the effect of repeated episodes of fever and antibiotic treatments during the first years of life on the prevalence of asthma , bronchial hyperresponsiveness ( BHR ) , and atopy at school age in a representative population . R and om sample s of schoolchildren aged 5 - 7 yrs ( n=7,545 ) and 9 - 11 yrs ( n=7,498 ) were studied using the International Study of Asthma and Allergies in Childhood ( ISAAC ) phase II protocol . To assess the prevalence of disease and early childhood exposures , parental question naires were administered ( response rates 82.2 % and 85.3 % , respectively ) . In addition , children underwent skin prick tests , hypertonic saline challenge and blood sampling for the measurement of serum immunoglobulin (Ig)E. Repeated episodes of fever and antibiotic treatment in early life were strongly associated with the prevalence of asthma ( odds ratio (OR)=7.95 ; 95 % confidence interval ( CI ) 6.02 - 10.50 ) and current wheeze at school age . Within asthmatic children the number of fever episodes and antibiotic courses were strongly inversely related to the prevalence of atopy ( OR=0.25 ; 95 % CI 0.11 - 0.54 for skin test reactivity ) and BHR ( OR=0.31 ; 95 % CI 0.10 - 0.92 ) . Furthermore , asthmatic children with recurrent early childhood infections were at a lower risk of being symptomatic at school age . When considering atopic and nonatopic asthmatic children separately , the highest risk of asthma with repeated early childhood infections was found for nonatopic asthma ( OR=24.29 ; 95 % Cl 11.86 - 49.76 ) . These findings suggest that a subgroup of children with a triggering or inducing of asthmatic symptoms through repeated early childhood infections exists within the " asthma syndrome " which has a better prognosis and is less related to the atopic phenotype BACKGROUND The prevalence rates of asthma and other atopic disorders have increased steadily in many developed countries over the past few decades . Recent epidemiological and animal studies have suggested that BCG vaccination might be beneficial in reducing the subsequent development of atopy . This study investigates the relationship between asthma , allergic symptoms , atopy , and tuberculin response in Chinese schoolchildren who received BCG vaccination at birth . METHODS A total of 3110 schoolchildren aged 10 years were recruited for the Hong Kong arm of the phase II International Study of Asthma and Allergies in Childhood . Of the 2599 children born in Hong Kong and vaccinated with BCG after birth , 2201 had tuberculin testing performed at a mean ( SD ) age of 8.4 ( 1.4 ) years . A r and om sub sample of 980 children was also recruited for skin prick testing . RESULTS The prevalence rates of asthma ever , wheeze ever , current wheeze , current rhinoconjunctivitis , and current flexural eczema were not significantly different between tuberculin positive and negative subjects . The mean ( SE ) tuberculin response was 3.4 ( 0.2 ) mm in atopic subjects and 3.3 ( 0.2 ) mm in non-atopic subjects ( difference not significant ) . Logistic regression analyses did not reveal any significant relationship between asthma ever , current wheeze , atopy , and positive tuberculin responses . CONCLUSIONS This study did not find any relationship between asthma , allergic symptoms , atopy , and positive tuberculin reactivity in Chinese schoolchildren vaccinated with BCG at birth BACKGROUND The intestinal microflora is a likely source for the induction of immune deviation  in infancy . OBJECTIVE The purpose of this study was to prospect ively relate the intestinal microflora to allergy development in 2 countries differing with respect to the prevalence of atopic diseases . METHODS Newborn infants were followed prospect ively 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 sample s 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 st and ard 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 Stap 
    Output:
    
There is evidence to support an inverse relationship between AD and endotoxin , early day care , farm animal and dog exposure in early life .
Cat exposure in the presence of skin barrier impairment is positively associated with AD .
Helminth infection at least partially protects against AD .
This is not the case for viral and bacterial infections , but consumption of unpasteurized farm milk seems protective .
Routine childhood vaccinations have no effect on AD risk .
The positive association between viral infections and AD found in some studies appears confounded by antibiotic prescription , which has been consistently associated with an increase in AD risk .
There is convincing evidence for an inverse relationship between helminth infections and AD but no other pathogens .
The protective effect seen with early day care , endotoxin , unpasteurized farm milk and animal exposure is likely to be due to a general increase in exposure to non-pathogenic microbes .
This would also explain the risk increase associated with the use of broad-spectrum antibiotics .