Airway infections in infancy and the presence of allergy and asthma in school age children

Anthropometry: A clue for Otorhinolaryngology surgical indications in children

BACKGROUND

There are reports in literature concerning the relation between some maternal and neonatal factors and future risk of disease, including atopy, recurrent infections and obstructive sleep disturbances, three common pathologies eliciting surgery in children.

OBJECTIVE

To evaluate if maternal and neonatal factors can relate to Otorhinolaryngology surgical indications in a cohort of children treated in a tertiary referral center.

MATERIAL AND METHODS

A retrospective analysis of data from children submitted to primary Otorhinolaryngology surgery in the pediatric ambulatory unit of Centro Hospitalar Universitário do Porto between March 2016 and March 2020 was performed. Children with orofacial congenital anomalies were excluded and 1256 children met the eligibility criteria. The associations between maternal and neonatal factors and the development of atopy, recurrent infections and obstructive sleep apnea were analyzed.

RESULTS

Atopic children showed higher birth weight percentile (p < 0,001) and birth weight-for-length index (p < 0,001) compared with non-atopic. Weight-at-surgery was also higher in atopic patients (p = 0,002). Maternal atopy significantly increased the risk of children atopic disease (p < 0,001; Odds Ratio 4,359). Children indicated for surgery for recurrent infections showed lower birth weight-for-length index (p = 0,038) and lower probability of atopic disease (p < 0,001). Recurrent acute otitis media related to both lower birth weight-for-length index (p = 0,002) and birth body mass index (p = 0,023). There was not a significant higher incidence of sleep apnea in preterm infants (p = 0,488). Obstructive sleep apnea patients showed lower weight-at-surgery percentile (p = 0,045).

CONCLUSION

This work suggests an association between birth anthropometric measurements and atopic and infectious diseases later in life, irrespective of gestational age. There was no consistent association between perinatal parameters and obstructive sleep apnea, but the impact of disordered breathing in childhood anthropometry was significative.

Prevalence of infant sneezing without colds and prediction of childhood allergy diseases in a prospective cohort study

Background

Allergy sensitization may begin during the perinatal period, but predicting allergic diseases in infancy remains difficult. This study attempted to identify early predictors of childhood allergy diseases in a prospective cohort study.

Materials and Methods

In a prospective birth cohort study at southern Taiwan locating in a subtropical region, questionnaire surveys of sneezing or cough without colds at 6 and 18 months of age were recorded, and the correlation with allergy diseases was assessed at 3 and 6 years of age.

Results

A total of 1812 pregnant women and 1848 newborn infants were prenatally enrolled, and 1543, 1344, 1236, and 756 children completed the follow-up at ages 6 months, 18 months, 3 years and 6 years, respectively. The prevalence of infant sneezing without colds at 6 and 18 months of age was 30.3% and 19.2%, respectively. The prevalence of infant cough without colds at 6 and 18 months of age was 10.6% and 5.7%, respectively. Infant sneezing without colds at 18 months of age was significantly correlated with atopic dermatitis, allergic rhinitis and asthma at 6 years of age. Infant cough without colds at 18 months of age significantly predicted asthma but not atopic dermatitis or allergic rhinitis at 6 years of age.

Conclusions

Infant sneezing without colds predicted all allergy diseases at 6 years of age in a subtropical country. This highlights a potential non-invasive clue in a subtropical region for the early prediction, treatment and prevention of childhood allergy diseases in infancy.

A prospective birth cohort study of different risk factors for development of allergic diseases in offspring of non-atopic parents

Background: Allergic diseases are thought to be inherited. Prevalence of allergic diseases has, however, increased dramatically in last decades, suggesting environmental causes for the development of allergic diseases.

Objective: We studied risk factors associated with the development of atopic dermatitis (AD), allergic rhinitis (AR) and asthma (AS) in children of non-atopic parents in a subtropical country.

Methods: In a birth cohort of 1,497 newborns, parents were prenatally enrolled and validated for allergic diseases by questionnaire, physician-verified and total or specific Immunoglobulin E (IgE) levels; 1,236 and 756 children, respectively, completed their 3-year and 6-year follow-up. Clinical examination, questionnaire, and blood samples for total and specific IgE of the children were collected at each follow-up visit.

Results: Prevalence of AD, AR and AS was, respectively, 8.2%, 30.8% and 12.4% in children of non-atopic parents. Prevalence of AR (p<.001) and AS (p=.018) was significantly higher in children of parents who were both atopic. A combination of Cesarean section (C/S) and breastfeeding for more than 1 month showed the highest risk for AD (OR=3.111, p=.006). Infants living in homes with curtains and no air filters had the highest risk for AR (OR=2.647, p<.001), and male infants of non-atopic parents living in homes without air filters had the highest risk for AS (OR=1.930, p=.039).

Conclusions: Breastfeeding and C/S affect development of AD. Gender, use of curtains and/or air filters affect AR and AS, suggesting that control of the perinatal environment is necessary for the prevention of atopic diseases in children of non-atopic parents.

Hay fever, asthma, and eczema and early infectious diseases among children in Kilimanjaro, Tanzania

OBJECTIVES

To investigate the hygiene (or "old friends") hypothesis in a high-infectious disease (ID) environment, rural Kilimanjaro, Tanzania.

METHODS

Among a cross-sectional sample of 2- to 7-year-old children, we collected physician-diagnosed hay fever, asthma, and eczema, history of hospitalization, family size, and household environment information via questionnaire; performed active and passive surveillance for ID; and, evaluated total immunoglobulin E (IgE) and biomarkers of inflammation in dried blood spot specimens. We used regression models to describe patterns in allergic diseases.

RESULTS

Complete information was available for 280 children: 12.5% had been diagnosed with hay fever; 18.9% with eczema; 2.1% with asthma. There was a positive association between hay fever and eczema diagnoses (π² : 4.07; P = 0.044); total IgE was positively associated with eczema (β: 0.24; P = 0.100) and allergic diseases together (β: 0.26; P = 0.042). ID were common: the incidence of any ID diagnosis was 28 per 100 children per month. Hay fever was inversely associated with household animals (OR: 0.27; P = 0.006), and positively associated with earth housing materials (OR: 1.93; P = 0.079) and hospitalization in infancy with an ID (3.16; P = 0.066); patterns were similar when allergic disease outcomes were considered together. Few associations between these predictors and eczema or asthma alone were apparent.

CONCLUSIONS

Allergic diseases were common among children in Kilimanjaro. The inverse association between household animals and allergy is consistent with the hygiene/old friends hypothesis; however, positive associations between allergic diseases and earth housing materials and early hospitalization with ID bear further explanation.

Lung function changes from childhood to adolescence: a seven-year follow-up study

BACKGROUND

As part of an investigation into the respiratory health in children conducted in Torino, northwestern Italy, our aim was to assess development in lung function from childhood to adolescence, and to assess changes or persistence of asthma symptoms on the change of lung function parameters. Furthermore, the observed lung function data were compared with the Global Lung Function Initiative (GLI) reference values.

METHODS

We conducted a longitudinal study, which lasted 7 years, composed by first survey of 4-5 year-old children in 2003 and a follow-up in 2010. Both surveys consisted in collecting information on health by standardized SIDRIA questionnaire and spirometry testing with FVC, FEV1, FEV1/FVC% and FEF25-75 measurements.

RESULTS

242 subjects successfully completed both surveys. In terms of asthma symptoms (AS = asthma attacks or wheezing in the previous 12 months), 191/242 were asymptomatic, 13 reported AS only in the first survey (early transient), 23 had AS only in the second survey (late onset), and 15 had AS in both surveys (persistent). Comparing the lung function parameters observed with the predicted by GLI only small differences were detected, except for FVC and FEF25-75, for which more than 5% of subjects had Z-score values beyond the Z-score normal limits. Furthermore, as well as did not significantly affect developmental changes in FVC and FEV1, the decrease in FEV1/FVC ratio was significantly higher in subjects with AS at the time of follow-up (late onset and persistent phenotypes) while the increase in FEF25-75 was significantly smaller in subjects with persistent AS (p < 0.05).

CONCLUSIONS

The GLI equations are valid in evaluating lung function during development, at least in terms of lung volume measurements. Findings also suggest that the FEF25-75 may be a useful tool for clinical and epidemiological studies of childhood asthma.

Expanding the hygiene hypothesis: early exposure to infectious agents predicts delayed-type hypersensitivity to Candida among children in Kilimanjaro

Background

Multiple lines of evidence suggest that infections in early life prevent the development of pathological immune responses to allergens and autoantigens (the hygiene hypothesis). Early infections may also affect later immune responses to pathogen antigen.

Methods

To evaluate an association between early infections and immune responses to pathogen antigen, delayed-type hypersensitivity (DTH) to Candida albicans was evaluated among 283 2- to 7-year-old children in Kilimanjaro, Tanzania. A questionnaire and physical examination were used to characterize variables reflecting early exposure to infectious agents (family size, house construction materials, BCG vaccination, hospitalization history). Logistic regression was used to evaluate the association between early exposure to infectious agents and DTH to C. albicans.

Results

Triceps skinfold thickness (OR: 1.11; 95% CI: 1.01, 1.22) and age (OR: 1.27; 95% CI: 1.04, 1.55) were positively associated with DTH to C. albicans. Adjusted for age and sex, large family size (OR: 2.81; 95% CI: 1.04, 7.61), BCG vaccination scar (OR: 3.10; 95% CI: 1.10, 8.71), and hospitalization during infancy with an infectious disease (OR: 4.67; 95% CI: 1.00, 21.74) were positively associated with DTH to C. albicans.

Conclusions

Early life infections were positively associated with later DTH to C. albicans. This result supports an expansion of the hygiene hypothesis to explain not only pathological immune responses to allergens, but also appropriate immune responses to pathogens. Immune system development may be responsive to early infections as an adaptive means to tailor reactivity to the local infectious disease ecology.

Early-life otitis media and incident atopic disease at school age in a birth cohort

BACKGROUND

Otitis media is a common and costly disease that peaks in early childhood. Recent reviews concluded that the relationship between otitis media and atopy is not well understood, and that further research is warranted.

METHODS

Logistic regression was used to analyze data from a German Birth Cohort (n = 1690; born 1997–1999). Parental questionnaires were used to assess children for physician-diagnosed otitis media throughout the first 2 years of life and for incident atopic disease (asthma, allergic rhinitis, and eczema) during the sixth year of life. Odds ratios were adjusted for gender, older siblings, city, parental education, breast-feeding, and daycare. Parallel analyses were completed for the full birth cohort and for a population subset with atopic mothers.

RESULTS

The adjusted odds of asthma were elevated for children with early-life otitis media, but were statistically significant only for those children with at least 3 episodes (adjusted odds ratio: 4.26 [95% confidence interval: 1.34–13.6]). Associations between early-life otitis media and allergic rhinitis were largely inconsistent. There was a positive association between early-life otitis media and late-onset allergic eczema (≥2 episodes: 2.68 [1.35–5.33], ≥3 episodes: 3.84 [1.80–8.18]). Similar results were found for the maternal atopy subgroup but with greater effect estimates.

CONCLUSIONS

Children diagnosed with otitis media during infancy were at greater risk for developing late-onset allergic eczema and asthma during school age, and associations were stronger for frequent otitis. These results indicate that frequent otitis media during infancy may predispose children to atopic disease in later life.

Risk factors associated with allergic and non-allergic asthma in adolescents

INTRODUCTION

Risk factors for asthma have been investigated in a large number of studies in adults and children, with little progress in the primary and secondary prevention of asthma. The aim of this investigation was to investigate risk factors associated with allergic and non-allergic asthma in adolescents.

METHODS

In this study, 959 schoolchildren (13-14 years old) answered a questionnaire and performed exhaled nitric oxide (NO) measurements. All children (n = 238) with reported asthma, asthma-related symptoms and/or increased NO levels were invited to a clinical follow-up which included a physician evaluation and skin-prick testing.

RESULTS

Asthma was diagnosed in 96 adolescents, whereof half had allergic and half non-allergic asthma. Children with both allergic and non-allergic asthma had a significantly higher body mass index (BMI) (20.8 and 20.7 vs. 19.8 kg/m(2)) (p < 0.05) and a higher prevalence of parental asthma (30% and 32% vs. 16%) (p < 0.05). Early-life infection (otitis and croup) [adjusted odds ratio (OR) (95% confidence interval (CI)): 1.99 (1.02-3.88) and 2.80 (1.44-5.42), respectively], pets during the first year of life [2.17 (1.16-4.04)], window pane condensation [2.45 (1.11-5.40)] and unsatisfactory school cleaning [(2.50 (1.28-4.89)] was associated with non-allergic but not with allergic asthma.

CONCLUSION

This study indicates the importance of distinguishing between subtypes of asthma when assessing the effect of different risk factors. While the risk of both allergic and non-allergic asthma increased with increasing BMI, associations between early-life and current environmental exposure were primarily found in relation to non-allergic asthma.

Frequent ear infections in infancy and the risk of asthma in Mexican American children

OBJECTIVES

This study examined the associations of history of ear infections in infancy with doctor-diagnosed asthma in a large sample of Mexican American children.

METHODS

In this population-based cross-sectional study, parents of 2023 children completed a questionnaire that collected data on doctor-diagnosed asthma, doctor-diagnosed ear infections, as well as antibiotics use in infancy, and other potential confounding variables.

RESULTS

Children with a history of ear infections in infancy were more likely to have asthma compared with those who had no history of ear infections in infancy; the adjusted odds ratios (ORs) were 2.52 (95% confidence interval [CI]: 1.35-4.69) and 1.27 (95% CI: 0.79-2.04) in children who had >or=3 and 1-2 (versus none) ear infections in infancy, respectively, p for trend = .0074. These associations were independent of antibiotics use, acetaminophen consumption, and history of various infections (other than ear infections) in the first year of life. In stratified analyses, the increased risk of asthma in children with recurrent ear infections in infancy persisted among children whose parents reported no lifetime history of rhinitis but not in children who had a history of rhinitis.

CONCLUSIONS

This study demonstrated significant associations of asthma with history of ear infections in infancy, with a significant dose-response effect of repeated ear infections on the odds of asthma. These findings add to the growing body of literature linking early childhood infections with the risk of asthma and highlight the need for more research to identify the mechanisms through which ear infections may be associated with asthma.

Dental caries and allergic disorders in Japanese children: the Ryukyus Child Health Study

BACKGROUND

Dental caries is an infectious disease and is highly prevalent among children. In the etiology of allergic diseases, the hygiene hypothesis contends that infections might confer protection against the development of allergic diseases. The aim of this cross-sectional study was to investigate the association between dental caries and the prevalence of allergic disorders.

METHODS

Study subjects were 21,792 children 6 to 15 years of age in Okinawa, Japan. Outcomes were based on diagnostic criteria from the International Study of Asthma and Allergies in Childhood. Data on dental caries were obtained from school records. Children were classified as having dental caries if one or more teeth had decayed and/or had been filled. Adjustment was made for sex, age, region of residence, number of siblings, smoking in the household, paternal and maternal history of asthma, atopic eczema, or allergic rhinitis, and paternal and maternal educational level.

RESULTS

The prevalence of wheeze, asthma, atopic eczema, and allergic rhinoconjunctivitis in the previous 12 months was 10.8%, 7.6%, 6.8%, and 7.6%, respectively. In an overall analysis, no measurable relationship was found between dental caries and the prevalence of wheeze, asthma, atopic eczema, or allergic rhinoconjunctivitis. However, dental caries was significantly inversely associated with the prevalence of allergic rhinoconjunctivitis only among children with a positive parental allergic history: The adjusted odds ratio was 0.84 (95% confidence interval: 0.72, 0.99).

CONCLUSIONS

The present findings do not support the hypothesis that dental caries was protective against allergic diseases. However, a parental allergic history may affect the association between dental caries and allergic rhinoconjunctivitis.

The potential biases in studying the relationship between asthma and microbial infection

OBJECTIVE

To assess bias in parent reports of asthma status of children and detection bias of medical records-based asthma ascertainment and to examine effects of such bias on the association between asthma status and infections.

METHODS

A prospective cohort study was conducted to compare the correlations between the frequency of acute illnesses and that of medical evaluations between children with or without asthma according to parental report and medical record review by following a group of children who were enrolled in the Mayo Clinic Sick Child Care Program in Rochester, Minnesota. Parents completed a self-administered questionnaire to determine asthma status of their child. Also, comprehensive medical record reviews were conducted to determine asthma status of each subject by applying predetermined criteria for asthma.

RESULTS

A convenience sample of 115 parents and their children participated in this study. The mean age of the parents who participated in the study was 32.8 years (standard deviation: 5.4 years); 93% were female (mothers); and 90% were white. Of the 115 children who participated in this study, 84% were reported to be white and 49% were female. The mean age of the children was 2 years (standard deviation: 1.0 year). Parents whose children had asthma by report appeared to be less likely to seek medical evaluations (Spearman's rho: 0.42,p = 0.11) when their children had acute illnesses, compared to those of non-asthmatic children (rho: 0.64,p < 0.001). Concerns that asthmatic patients (rho: 0.62,p < 0.001) are more likely to see health care providers and undergo medical evaluations and laboratory tests when they have acute illnesses than non-asthmatic patients (rho: 0.64,p < 0.001) are not supported by our study.

CONCLUSION

Parental report bias needs to be considered carefully when studying the relationship between asthma and microbial infection.

Allergies, infections and the hygiene hypothesis--the epidemiological evidence

The 'hygiene hypothesis' was first proposed by Strachan in 1989 suggesting that infections and unhygienic contact with older siblings or through other exposures may confer protection from the development of allergic illnesses. This hypothesis has evolved in various ways exploring the role of overt viral and bacterial infections, the significance of environmental exposure to microbial compounds, and their effect on underlying responses of innate and adaptive immunity. So far a truly unifying concept is still lacking, but various pieces of a complex interplay between a host's immune response, characteristics of the invading microorganism, the level and variety of the environmental exposure, and the interactions between a genetic background and a range of exposures become apparent. All these pieces eventually assemble to the clinical presentation of a complex syndrome namely of asthma and allergic illnesses. Even if today practical implications cannot directly be deduced from these findings, there is great potential for the development of novel preventive and therapeutic strategies in the future based on the concepts of the 'hygiene hypothesis'.

Reference values of Forced Expiratory Volumes and pulmonary flows in 3-6 year children: a cross-sectional study

BACKGROUND

The aims of this study were to verify the feasibility of respiratory function tests and to assess their validity in the diagnosis of respiratory disorders in young children.

METHODS

We performed spirometry and collected information on health and parents' lifestyle on a sample of 960 children aged 3-6.

RESULTS

The cooperation rate was 95.3%. Among the valid tests, 3 or more acceptable curves were present in 93% of cases. The variability was 5% within subjects in 90.8% of cases in all the parameters. We propose regression equations for FVC (Forced Vital Capacity), FEV1, FEV0.5, FEV0.75 (Forced Expiratory Volume in one second, in half a second and in 3/4 of a second), and for Maximum Expiratory Flows at different lung volume levels (MEF75, 50, 25). All parameters are consistent with the main reference values reported in literature. The discriminating ability of respiratory parameters versus symptoms always shows a high specificity (>95%) and a low sensitivity (<20%) with the highest OR (10.55; CI 95% 4.42-25.19) for MEF75. The ability of FEV0.75 to predict FEV1 was higher than that of FEV0.50: FEV0.75 predicts FEV1 with a determination coefficient of 0.95.

CONCLUSION

Our study confirms the feasibility of spirometry in young children; however some of the current standards are not well suited to this age group. Moreover, in this restricted age group the various reference values have similar behaviour.

Respiratory illnesses in early life and asthma and atopy in childhood

BACKGROUND

The relation between respiratory illnesses in early life and the development of asthma and atopy in childhood is incompletely understood.

OBJECTIVE

We sought to examine the relationship between respiratory illnesses in early life and atopic diseases at school age.

METHODS

We performed a prospective birth cohort study of the relationship between respiratory illnesses in the first year of life and asthma, atopy (sensitization to >or=1 allergen), and allergic rhinitis at school age in 440 children with a parental history of atopy. Logistic regression was used to examine the relationship between respiratory illnesses and asthma, atopy, and allergic rhinitis. The relationship between respiratory illnesses in early life and repeated measures of wheezing between the ages of 1 and 7 years was investigated by using a proportional hazards models.

RESULTS

Physician-diagnosed croup (adjusted odds ratio [OR], 0.30; 95% CI, 0.12-0.72) and having 2 or more physician-diagnosed ear infections (adjusted OR, 0.58; 95% CI, 0.35-0.98) in the first year of life were inversely associated with atopy at school age. Physician-diagnosed bronchiolitis before age 1 year was significantly associated with asthma at age 7 years (adjusted OR, 2.77; 95% CI, 1.23-6.22). Recurrent nasal catarrh (>or=3 episodes of a runny nose) in the first year of life was associated with allergic rhinitis at age 7 years (adjusted OR, 2.99; 95% CI, 1.03-8.67).

CONCLUSION

The relationship between early-life respiratory illnesses and asthma and atopy is complex and likely dependent on the type of infection and immune response it initiates.

CLINICAL IMPLICATIONS

Certain respiratory illnesses in early life modify the risk of atopy and asthma at school age.

The many faces of the hygiene hypothesis

About 15 years have gone by since Strachan first proposed the idea that infections and unhygienic contact might confer protection against the development of allergic illnesses. The so-called hygiene hypothesis has ever since undergone numerous more or less subtle modifications by various researchers in the fields of epidemiology, clinical science, and immunology. Three major tracts have developed exploring the role of overt viral and bacterial infections, the significance of environmental exposure to microbial compounds, and the effect of both on underlying responses of the innate and adaptive immunity. To date, a truly unifying concept has not yet emerged, but various pieces of a complex interplay between immune responses of the host, characteristics of the invading microorganism, the level and variety of the environmental exposure, and the interactions between a genetic background and a range of exposures becomes apparent. These influences are discussed as determinants for a number of complex allergic illnesses in this review, while we attempt to pay attention to the importance of different phenotypes, namely of the asthma syndrome. Even if today practical implications cannot directly be deduced from these findings, there is great potential for the development of novel preventive and therapeutic strategies in the future.

Early respiratory infections, asthma, and allergy: 10-year follow-up of the Oslo Birth Cohort

OBJECTIVE

It has been hypothesized that early infections protect against the development of atopic disease, but there have been few long-term follow-up studies. We estimated the associations between early respiratory infections and doctor-diagnosed asthma, allergic rhinitis, and skin-prick sensitization in children at 10 years of age in the Oslo Birth Cohort, established in 1992-1993. We also considered birth order and attendance at a child care center as proxy measures of increased exposure to infections early in life.

METHODS

A total of 2540 children were followed from birth to the age of 10 years. Experiences of respiratory infections were recorded in follow-up surveys at 6 and 12 months. At age 10, questions were asked about current symptoms of asthma and allergic rhinitis and about having ever received a doctor diagnosis for these diseases. A subsample (n = 1740) of the cohort was tested for skin-prick test reactivity.

RESULTS

Current asthma was related to lower respiratory tract infection (adjusted odds ratio [OR]: 2.1; 95% confidence interval: 1.3-3.0) and croup (adjusted OR: 2.3; 95% confidence interval: 1.3-4.2) in the first year. ORs for allergic rhinitis and skin-prick sensitization were smaller but mainly positive. Birth order and child care attendance at age 1 year were not significantly associated with any of the studied outcomes.

CONCLUSIONS

Early respiratory infections did not protect against the development of asthma, allergic rhinitis, or sensitization to common allergens during the first 10 years of life but increased the risk for asthma symptoms at age 10 in this population.

Environment and development of atopy

PURPOSE OF REVIEW

Asthma and other atopic disorders are the result of complex interactions between genetic predisposition and multiple environmental influences. However, the marked increase in asthma prevalence over recent decades is unlikely to be due to genetic changes, highlighting the contribution of environmental factors to the process of allergic sensitization.

RECENT FINDINGS

This article reviews recent information on environmental influences on the development of atopy in children. Both observational and interventional studies continue to shed new light on the critical influence of early life events--such as events in pregnancy, exposure to allergens and endotoxin, pet ownership, infections, family size--and have highlighted important gene-environment interactions that modify the relationships between environmental exposures and atopic outcomes.

SUMMARY

The future is likely to see a concerted effort to further define the role that these environmental exposures play in allergic sensitization and the expression of atopic diseases, in order to provide a rational platform on which to develop new methods of allergy prevention that can be targeted at high-risk children.

Cytokine response patterns, exposure to viruses, and respiratory infections in the first year of life

Daycare attendance and siblings are associated with viral-induced wheezing in children. Preexisting immunologic factors may influence the expression of viral infections in infancy, and in turn, recurrent infections may influence the development of immune responses. A total of 285 children were enrolled in the Childhood Origins of Asthma Project at birth and followed for at least 1 year. Cord blood and 1-year mononuclear cells were stimulated with phytohemagglutinin, and cytokine-response profiles were measured by enzyme-linked immunosorbent assay. Nasal lavage was performed for moderate to severe respiratory illnesses. Daycare attendance and/or siblings significantly increased the likelihood of contracting respiratory syncytial virus (1.5-1.6-fold increase) and rhinovirus (1.8-2.1-fold increase), and increased the risk of rhinovirus-induced wheezing (14-18% vs. 2%, p = 0.011). Cord blood IFN-gamma responses were inversely related to the frequency of viral respiratory infections (r(s) = -0.11, p = 0.05), and more significant for subjects with high exposure to other children (r(s) = -0.27, p = 0.028). The interval change in infantile IFN-gamma responses correlated positively with the frequency of viral infections in infancy (r(s) = 0.12, p = 0.047). These data suggest that neonatal IFN-gamma responses may influence antiviral activity, or may represent a marker of antiviral immunity maturation. Conversely, the frequency of viral infections in infancy can influence IFN-gamma responses.

The hygiene hypothesis of atopic disease--an extended version

The hygiene hypothesis of atopic disease suggests that environmental changes in the industrialized world have lead to reduced microbial contact at an early age and thus resulted in the growing epidemic of atopic eczema, allergic rhinoconjunctivitis, and asthma. The epidemiological findings have been combined with the Th1/Th2 paradigm of immune responsiveness to provide a coherent theory. Recent advances in epidemiology and immunology demonstrate, however, that the hygiene hypothesis may need to be extended in three respects. First, the importance of infections in causing immune deviance may be outweighed by other sources of microbial stimulation, perhaps most importantly by the indigenous intestinal microbiota. Second, immunomodulatory and suppressive immune responses complement the Th1/Th2 paradigm. Third, in addition to protection against atopy, protection against infectious, inflammatory, and autoimmune diseases may also depend upon healthy host-microbe interactions implicated in the hygiene hypothesis.

Current challenges in lower respiratory infections in children

PURPOSE OF REVIEW

Lower respiratory infections threaten the health of children worldwide. Streptococcus pneumoniae remains the most common bacterial cause of lower respiratory infection in children, whereas viral pathogens dominate as a more common cause of lower respiratory infection illness in infants and children overall. The diagnosis and clinical management of lower respiratory infections pose challenges to pediatric health providers as new technology is developed and new pathogens emerge in the spectrum of clinical disease.

RECENT FINDINGS

Human metapneumovirus is now recognized as a cause of lower respiratory infection disease in children, and coronavirus has been linked to epidemics of severe acute respiratory syndrome. Respiratory syncytial virus continues to be a major source of viral lower respiratory infection illness in children and can lead to childhood asthma. Treatment for respiratory syncytial virus bronchiolitis depends largely on the severity of disease and the course of clinical symptoms. The diagnosis of bacterial lower respiratory infection disease remains a clinical challenge, but new methods to detect S. pneumoniae, or Chlamydia pneumoniae and Mycoplasma pneumoniae may facilitate the clinical management of these illnesses. As immunization against S. pneumoniae becomes more widely used, the complications of bacterial lower respiratory infections will diminish markedly.

SUMMARY

Future progress in the clinical management of lower respiratory infection diseases will entail improved methods of early diagnosis, broader options for treatment, and better defined clinical parameters for triage and follow-up of children with lower respiratory infections.