Effects of social and family factors on viral respiratory infection and illness in the first year of life

Preschool-age children maintain a distinct memory CD4+ T cell and memory B cell response after SARS-CoV-2 infection

The development of the human immune system lasts for several years after birth. The impact of this maturation phase on the quality of adaptive immunity and the acquisition of immunological memory after infection at a young age remains incompletely defined. Here, using an antigen-reactive T cell (ARTE) assay and multidimensional flow cytometry, we profiled circulating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-reactive CD3+CD4+CD154+ T cells in children and adults before infection, during infection, and 11 months after infection, stratifying children into separate age groups and adults according to disease severity. During SARS-CoV-2 infection, children younger than 5 years old displayed a lower antiviral CD4+ T cell response, whereas children older than 5 years and adults with mild disease had, quantitatively and phenotypically, comparable virus-reactive CD4+ T cell responses. Adults with severe disease mounted a response characterized by higher frequencies of virus-reactive proinflammatory and cytotoxic T cells. After SARS-CoV-2 infection, preschool-age children not only maintained neutralizing SARS-CoV-2-reactive antibodies postinfection comparable to adults but also had phenotypically distinct memory T cells displaying high inflammatory features and properties associated with migration toward inflamed sites. Moreover, preschool-age children had markedly fewer circulating virus-reactive memory B cells compared with the other cohorts. Collectively, our results reveal unique facets of antiviral immunity in humans at a young age and indicate that the maturation of adaptive responses against SARS-CoV-2 toward an adult-like profile occurs in a progressive manner.

Number of children in the household influences respiratory morbidities in children with bronchopulmonary dysplasia in the outpatient setting

BACKGROUND

Bronchopulmonary dysplasia (BPD), a common complication of prematurity, is associated with outpatient morbidities, including respiratory exacerbations. Daycare attendance is associated with increased rates of acute and chronic morbidities in children with BPD. We sought to determine if additional children in the household conferred similar risks for children with BPD.

METHODS

The number of children in the household and clinical outcomes were obtained via validated instruments for 933 subjects recruited from 13 BPD specialty clinics in the United States. Clustered logistic regression models were used to test for associations.

RESULTS

The mean gestational age of the study population was 26.5 ± 2.2 weeks and most subjects (69.1%) had severe BPD. The mean number of children in households (including the subject) was 2.1 ± 1.3 children. Each additional child in the household was associated with a 13% increased risk for hospital admission, 13% increased risk for antibiotic use for respiratory illnesses, 10% increased risk for coughing/wheezing/shortness of breath, 14% increased risk for nighttime symptoms, and 18% increased risk for rescue medication use. Additional analyses found that the increased risks were most prominent when there were three or more other children in the household.

CONCLUSIONS

We observed that additional children in the household were a risk factor for adverse respiratory outcomes. We speculate that secondary person-to-person transmission of respiratory viral infections drives this finding. While this risk factor is not easily modified, measures do exist to mitigate this disease burden. Further studies are needed to define best practices for mitigating this risk associated with household viral transmission.

Influence of indoor volatile organic compounds and its relative respiratory effects among children living in rural biomass cooking households of Tamil Nadu and Andhra Pradesh

PURPOSE

Exposures to volatile organic compounds (VOCs) cause respiratory symptoms among children, a known vulnerable group. Reports on exposures to VOCs and respiratory symptoms among South Indian children living in biomass-using households are not available thus far.

METHODS

A cross-sectional study was conducted among 313 rural children to assess the influence of emitted VOCs on their respiratory health. Standard analytical procedures for VOCs and Pulmonary Function Test (PFT), allied questionnaires, and all ethical considerations were fulfilled in the study.

RESULTS

The increase in VOC concentrations was observed proportional to the amount of burnt biomass fuel in two selected sites in Tamil Nadu (TN) and Andhra Pradesh (AP). Houses cooked for more than 60 min showed a remarkable increase in VOC concentrations and was observed as statistically significant (p < 0.01) in AP households. Among the younger children, the peak expiratory flow rate (PEFR) values were found significantly higher than comparatively older children in both the sites, TN and AP. However, the trend with respect to FEV1 is statistically significant (p < 0.01) among AP children.

CONCLUSIONS

This study reports reduced lung function for a considerable proportion of the VOC-exposed selected children. Based on PFT, the children who were interpreted to be normal were found to be exposed to lesser indoor TVOC concentrations in comparison with the children of the households having restrictive or obstructive impairments. Diagnostic ratios with Benzene/Toluene (B/T) and Xylene/Ethyl benzene (X/E) confirmed the presence of VOCs-emissions from adjacent cooking fuels only. The observed results of this study recommends cleaner cooking fuel-use for better respiratory health among the citizens across the country, which in turn, in line with the Pradhan Mantri Ujjwala Yojana (PMUY), Government of India.

Does social distancing impact pediatric upper airway infections? An observational controlled study and a brief literature review

PURPOSE

SARS-CoV-2 pandemic has reduced social interaction even among children. The objective of the study was to assess the role of social distancing in the course of common pediatric upper airway recurrent diseases.

MATERIALS AND METHODS

Patients aged ≤14 years with at least one ENT-related clinical condition were retrospectively recruited. All patients had two outpatient evaluations in the same period (April - September): the control group had the first evaluation in 2018 and second in 2019, whereas the case group had the first evaluation in 2019 and second in 2020. Patients of each group were individually compared between their two visits and deemed improved/unchanged/worsened for each specific ENT condition. The percentage of children improved/unchanged/worsened were then collectively compared between the two groups for each condition.

RESULTS

Patients who experienced social distancing presented a significantly higher improvement rate than controls for recurrent acute otitis media episodes (35.1 % vs. 10.8 %; Fisher's exact test p = 0.033) and for tympanogram type (54.5 % vs. 11.1 %, Fisher's exact test p = 0.009).

CONCLUSIONS

The anti-contagion social restrictions decreased the prevalence of middle ear infections and effusion in children. Further studies on larger cohorts are required to better elucidate these findings.

Protection against severe infectious disease in the past

Before the 20th century many deaths in England, and most likely a majority, were caused by infectious diseases. The focus here is on the biggest killers, plague, typhus, smallpox, tuberculosis, cholera, typhoid, dysentery, childhood infections, pneumonia, and influenza. Many other infectious diseases including puerperal fever, relapsing fever, malaria, syphilis, meningitis, tetanus and gangrene caused thousands of deaths. This review of preventive measures, public health interventions and changes in behavior that reduced the risk of severe infections puts the response to recent epidemic challenges in historical perspective. Two new respiratory viruses have recently caused pandemics: an H1N1 influenza virus genetically related to pig viruses, and a bat-derived coronavirus causing COVID-19. Studies of infectious diseases emerging in human populations in recent decades indicate that the majority were zoonotic, and many of the causal pathogens had a wildlife origin. As hunter-gatherers, humans contracted pathogens from other species, and then from domesticated animals and rodents when they began to live in settled communities based on agriculture. In the modern world of large inter-connected urban populations and rapid transport, the risk of global transmission of new infectious diseases is high. Past and recent experience indicates that surveillance, prevention and control of infectious diseases are critical for global health. Effective interventions are required to control activities that risk dangerous pathogens transferring to humans from wild animals and those reared for food.

Acute Respiratory Infections among Under-Five Age Group Children at Urban Slums of Gulbarga City: A Longitudinal Study

INTRODUCTION

Among all illness, Acute Respiratory Infections (ARI) account for 30-60% of paediatric outpatient attendance and 20-30% of hospital admissions.

AIM

To study the morbidity pattern of ARI among under-five-age group children and to assess the determinants.

MATERIALS AND METHODS

A longitudinal cohort study was conducted for a one year period, comprising a cumulative sample of 400 children from 3 urban slums of Gulbarga city. History of nasal discharge, cough, fever, sore throat, breathing difficulty, any discharge from ear alone or in combination, was used in the recognition of an ARI episode. Respiratory rate >60/minute (<2 month infants), >50(2-11 months) and >40(1-5 years) in a child with cough, cold or fever singly or in combination was considered the criteria for recognition of pneumonia.

RESULTS

Out of the 400 surveyed, ARI was detected among 109 children giving an incidence of 27.25%. Among these, Upper Respiratory Tract Infection (URTI) was found among 19.25% and Lower Respiratory Tract Infection (LRTI) among 8%. ARI was observed among 38.04% of infants, 37.84% of 2-3-year-old children, 36.87% of boys, 40.43% of children born to illiterate father's, 35.77% of SES class IV & 40.79% of SES class V, and 41.89% of children with family history of respiratory illness. All these data were found to be statistically significant. High rates of ARI were also observed among 41.36% of children living in households with firewood fuel usage, 35.04% of children with pets in the household, 34.82% of children with delayed milestones, 53.85% of children with grade IV and 66.67% of children with grade V malnutrition. More episodes occurred during winter months of the year (Oct - Jan). During the follow-up phase of study done on a cohort of 112 children for a period of one year, an attack rate of 3.27 episodes/child/year was observed.

CONCLUSION

Community education programs should focus on addressing specific issues viz. identification of respiratory illness, simple case management, proper immunization practices, breast feeding of infants & nutrition of child and reduction of domestic air pollution.

SmokeHaz: Systematic Reviews and Meta-analyses of the Effects of Smoking on Respiratory Health

BACKGROUND

Smoking tobacco increases the risk of respiratory disease in adults and children, but communicating the magnitude of these effects in a scientific manner that is accessible and usable by the public and policymakers presents a challenge. We have therefore summarized scientific data on the impact of smoking on respiratory diseases to provide the content for a unique resource, SmokeHaz.

METHODS

We conducted systematic reviews and meta-analyses of longitudinal studies (published to 2013) identified from electronic databases, gray literature, and experts. Random effect meta-analyses were used to pool the findings.

RESULTS

We included 216 articles. Among adult smokers, we confirmed substantially increased risks of lung cancer (risk ratio (RR), 10.92; 95% CI, 8.28-14.40; 34 studies), COPD (RR, 4.01; 95% CI, 3.18-5.05; 22 studies), and asthma (RR, 1.61; 95% CI, 1.07-2.42; eight studies). Exposure to passive smoke significantly increased the risk of lung cancer in adult nonsmokers and increased the risks of asthma, wheeze, lower respiratory infections, and reduced lung function in children. Smoking significantly increased the risk of sleep apnea and asthma exacerbations in adult and pregnant populations, and active and passive smoking increased the risk of tuberculosis.

CONCLUSIONS

These findings have been translated into easily digestible content and published on the SmokeHaz website.

Pneumonia and wheezing in the first year: An international perspective

BACKGROUND

The relationship between pneumonia and recurrent wheezing (RW) and the factors associated to pneumonia in wheezing and non-wheezing infants have not been compared between affluent and non-affluent populations.

METHODS

The International Study of Wheezing in Infants (EISL) is a large population-based cross-sectional study carried out in Latin America (LA) and Europe (EU). We used a validated questionnaire for identifying wheeze in the first year of life. The questionnaire also inquired about pneumonia diagnosis, together with other potentially related factors. Associations between both conditions and between potential risk/protective factors for pneumonia were tested by random-effects logit model and adjusting for all factors found previously associated to RW in this cohort.

RESULTS

Pneumonia and RW were strongly associated to each other in LA and EU (aOR 5.42; 95%CI: 4.87-6.04 and aOR 13.99; 95%CI: 9.61-20.36, respectively). Infant eczema was the most consistent risk factor of pneumonia in both continents, in the whole population and also among wheezers and non-wheezers (aOR ranging from 1.30; 95%CI: 1.11-1.52 to 2.65; 95%CI: 1.68-4.18); while breast feeding for at least 3 months was the most consistent protective factor (aOR ranging from 0.60; 95%CI: 0.51-0.71 to 0.76; 95%CI: 0.69-0.84). Factors associated to pneumonia were similar between continents among wheezers, but differed considerably among non-wheezers.

CONCLUSION

Pneumonia and RW are associated conditions sharing many risk/protective factors in EU and LA among wheezing infants, but not among non-wheezing infants. The association between pneumonia and RW could be due to shared pathophysiology or by diagnostic confusion between the two conditions.

Is population structure sufficient to generate area-level inequalities in influenza rates? An examination using agent-based models

Background

In New Haven County, CT (NHC), influenza hospitalization rates have been shown to increase with census tract poverty in multiple influenza seasons. Though multiple factors have been hypothesized to cause these inequalities, including population structure, differential vaccine uptake, and differential access to healthcare, the impact of each in generating observed inequalities remains unknown. We can design interventions targeting factors with the greatest explanatory power if we quantify the proportion of observed inequalities that hypothesized factors are able to generate. Here, we ask if population structure is sufficient to generate the observed area-level inequalities in NHC. To our knowledge, this is the first use of simulation models to examine the causes of differential poverty-related influenza rates.

Methods

Using agent-based models with a census-informed, realistic representation of household size, age-structure, population density in NHC census tracts, and contact rates in workplaces, schools, households, and neighborhoods, we measured poverty-related differential influenza attack rates over the course of an epidemic with a 23 % overall clinical attack rate. We examined the role of asthma prevalence rates as well as individual contact rates and infection susceptibility in generating observed area-level influenza inequalities.

Results

Simulated attack rates (AR) among adults increased with census tract poverty level (F = 30.5; P < 0.001) in an epidemic caused by a virus similar to A (H1N1) pdm09. We detected a steeper, earlier influenza rate increase in high-poverty census tracts—a finding that we corroborate with a temporal analysis of NHC surveillance data during the 2009 H1N1 pandemic. The ratio of the simulated adult AR in the highest- to lowest-poverty tracts was 33 % of the ratio observed in surveillance data. Increasing individual contact rates in the neighborhood did not increase simulated area-level inequalities. When we modified individual susceptibility such that it was inversely proportional to household income, inequalities in AR between high- and low-poverty census tracts were comparable to those observed in reality.

Discussion

To our knowledge, this is the first study to use simulations to probe the causes of observed inequalities in influenza disease patterns. Knowledge of the causes and their relative explanatory power will allow us to design interventions that have the greatest impact on reducing inequalities.

Conclusion

Differential exposure due to population structure in our realistic simulation model explains a third of the observed inequality. Differential susceptibility to disease due to prevailing chronic conditions, vaccine uptake, and smoking should be considered in future models in order to quantify the role of additional factors in generating influenza inequalities.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-015-2284-2) contains supplementary material, which is available to authorized users.

Long-term trends in cardiovascular disease mortality and association with respiratory disease

The recent decline in cardiovascular disease mortality in Western countries has been linked with changes in life style and treatment. This study considers periods of decline before effective medical interventions or knowledge about risk factors. Trends in annual age-standardized death rates from cerebrovascular disease, heart disease and circulatory disease, and all cardiovascular disease are reviewed for three phases, 1881–1916, 1920–1939, and 1940–2000. There was a consistent decline in the cerebrovascular disease death rate between 1891 and 2000, apart from brief increases after the two world wars. The heart disease and circulatory disease death rate was declining between 1891 and 1910 before cigarette smoking became prevalent. The early peak in cardiovascular mortality in 1891 coincided with an influenza pandemic and a peak in the death rate from bronchitis, pneumonia and influenza. There is also correspondence between short-term fluctuations in the death rates from these respiratory diseases and cardiovascular disease. This evidence of ecological association is consistent with the findings of many studies that seasonal influenza can trigger acute myocardial infarction and episodes of respiratory infection are followed by increased risk of cardiovascular events. Vaccination studies could provide more definitive evidence of the role in cardiovascular disease and mortality of influenza, other viruses, and common bacterial agents of respiratory infection.

Secondhand tobacco smoke exposure and severity of influenza in hospitalized children

OBJECTIVE

To assess whether children with influenza who are exposed to secondhand tobacco smoke (SHS) would have more severe illness than those not exposed.

STUDY DESIGN

We abstracted charts from pediatric inpatients with confirmed influenza from 2002-2009 for demographics, medical history, and smoke exposure. Severity indicators included intensive care, intubation, and length of stay (LOS) in the hospital; potential confounding factors included demographics and the presence of asthma or chronic conditions. All χ(2), t tests, and regression analyses were run using SPSS v. 18.0.

RESULTS

Of 117 children, 40% were exposed to SHS, who had increased need for intensive care (30% vs 10%, P < .01) and intubation (13% vs 1%, P < .05), and had longer LOS (4.0 vs 2.4 days, P < .01). Children with chronic conditions and SHS exposure required more intensive care (53% vs 18%, P < .05) and had longer LOS (10.0 vs 3.5 days, P < .01) than children not exposed to SHS with chronic conditions. In multivariate analyses controlling for potential confounding factors, children with SHS exposure were 4.7 times more likely to be admitted to intensive care (95% CI 1.4-18.5) and had a 70% longer LOS (95% CI 12%-230%).

CONCLUSIONS

Children with SHS exposure who are hospitalized with influenza have more severe illness. Efforts are needed to immunize this population against influenza, and eliminate children's exposure to SHS.

Parental and household smoking and the increased risk of bronchitis, bronchiolitis and other lower respiratory infections in infancy: systematic review and meta-analysis

BACKGROUND

Passive smoke exposure increases the risk of lower respiratory infection (LRI) in infants, but the extensive literature on this association has not been systematically reviewed for nearly ten years. The aim of this paper is to provide an updated systematic review and meta-analysis of studies of the association between passive smoking and LRI, and with diagnostic subcategories including bronchiolitis, in infants aged two years and under.

METHODS

We searched MEDLINE and EMBASE (to November 2010), reference lists from publications and abstracts from major conference proceedings to identify all relevant publications. Random effect pooled odds ratios (OR) with 95% confidence intervals (CI) were estimated.

RESULTS

We identified 60 studies suitable for inclusion in the meta-analysis. Smoking by either parent or other household members significantly increased the risk of LRI; odds ratios (OR) were 1.22 (95% CI 1.10 to 1.35) for paternal smoking, 1.62 (95% CI 1.38 to 1.89) if both parents smoked, and 1.54 (95% CI 1.40 to 1.69) for any household member smoking. Pre-natal maternal smoking (OR 1.24, 95% CI 1.11 to 1.38) had a weaker effect than post-natal smoking (OR 1.58, 95% CI 1.45 to 1.73). The strongest effect was on bronchiolitis, where the risk of any household smoking was increased by an OR of 2.51 (95% CI 1.96 to 3.21).

CONCLUSIONS

Passive smoking in the family home is a major influence on the risk of LRI in infants, and especially on bronchiolitis. Risk is particularly strong in relation to post-natal maternal smoking. Strategies to prevent passive smoke exposure in young children are an urgent public and child health priority.

Day care increases the risk of respiratory morbidity in chronic lung disease of prematurity

OBJECTIVES

Infants and children with chronic lung disease of prematurity (CLDP) are at increased risk for morbidity and mortality from respiratory viral infections. Exposure to respiratory viruses may be increased in the day care environment. The risk of respiratory morbidity from day care attendance in the CLDP population is unknown. We therefore sought to determine if day care attendance is a significant risk factor for increased respiratory morbidity and symptoms in infants and children with CLDP.

METHODS

Between January 2008 and October 2009, parents of infants and children with CLDP were surveyed. Information on perinatal history, sociodemographic information, day care attendance, and indicators of respiratory morbidity, including emergency department (ED) visits, hospitalizations, systemic corticosteroid use, antibiotic use, and respiratory symptoms, was collected on children<3 years of age. Logistic regression models were constructed to examine associations between exposure to day care and respiratory morbidities.

RESULTS

Data were collected from 111 patients with CLDP. The average gestational age was 26.2±2.0 weeks. Day care attendance was associated with significantly higher adjusted odds for ED visits (odds ratio [OR]: 3.74 [95% confidence interval (CI): 1.41-9.91]; P<.008), systemic corticosteroid use (OR: 2.22 [CI: 1.10-4.49]; P<.026), antibiotic use (OR: 2.40 [CI: 1.08-5.30]; P<.031), and days with trouble breathing (OR: 2.72 [CI: 1.30-5.69]; P<.008). Although there was an increased OR for hospitalization (OR: 3.22 [CI: 0.97-10.72]; P<.057), this did not reach statistical significance.

CONCLUSIONS

We found that day care attendance is associated with increased respiratory morbidities in young children with CLDP. Physicians should consider screening for and educating caregivers about the risks of day care attendance by young children with CLDP.

Factors associated with increased risk of progression to respiratory syncytial virus-associated pneumonia in young Kenyan children

Objectives

To identify factors associated with developing severe respiratory syncytial virus (RSV) pneumonia and their commonality with all-cause lower respiratory tract infection (LRTI), in order to isolate those risk factors specifically associated with RSV-LRTI and identify targets for control.

Methods

A birth cohort of rural Kenyan children was intensively monitored for acute respiratory infection (ARI) over three RSV epidemics. RSV was diagnosed by immunofluorescence of nasal washings collected at each ARI episode. Cox regression was used to determine the relative risk of disease for a range of co-factors.

Results

A total of 469 children provided 937 years of follow-up, and experienced 857 all-cause LRTI, 362 RSV-ARI and 92 RSV-LRTI episodes. Factors associated with RSV-LRTI, but not RSV-ARI, were severe stunting (z-score ≤−2, RR 1.7 95%CI 1.1–2.8), crowding (increased number of children, RR 2.6, 1.0–6.5) and number of siblings under 6 years (RR 2.0, 1.2–3.4). Moderate and severe stunting (z-score ≤−1), crowding and a sibling aged over 5 years sleeping in the same room as the index child were associated with increased risk of all-cause LRTI, whereas higher educational level of the primary caretaker was associated with protection.

Conclusion

We identify factors related to host nutritional status (stunting) and contact intensity (crowding, siblings) which are distinguishable in their association with RSV severe disease in infant and young child. These factors are broadly in common with those associated with all-cause LRTI. The results support targeted strategies for prevention.

Risk factors for X-ray pneumonia in the first year of life and its relation to wheezing: a longitudinal study in a socioeconomic disadvantaged population

BACKGROUND

Although thousands of infants under the age of 12 months die each year from pneumonia in Latin America, little is known regarding the true occurrence of pneumonia, wheezing and other related respiratory illnesses in this age group.

METHODS AND RESULTS

In order to describe the prevalence and risk factors for radiologically confirmed pneumonia during the first year of life, a birth-cohort (n = 188) of infants born in a low-income area in Santiago, Chile was followed up monthly.

RESULTS

The prevalence of pneumonia during the first year of life was 13.3 % and there were no fatal events. Exclusive breastfeeding during the first 4 months of life was more prevalent in the non pneumonia group; conversely, wheezing episodes during 0-3 and 3-6 months of age, and hospitalization due to lower respiratory infection during 3-6 and 9-12 months of age were more prevalent in the pneumonia group. After a logistic multivariate analysis, the only risk factor that remained related with pneumonia was wheezing during the first 3 months of life (adjusted OR: 7.7, 95 CI: 1.32-44.92, p = 0.024); while breastfeeding during the first 4 months was an independent protective factor for pneumonia (adjusted OR: 0.11, 95 CI: 0.03-0.44, p = 0.002).

CONCLUSION

The significant protective effect of exclusive breast feeding against pneumonia in this cohort and the evident role of recurrent wheezing as risk factor for pneumonia during the first year of life support the implementation or reinforcement of public policies encouraging exclusive breastfeeding and an adequate management of wheezing since the first months of life.

Child Care Center Policies and Practices for Management of Ill Children

OBJECTIVES

The objectives of this study were to 1) describe child care staff knowledge and beliefs regarding upper respiratory tract infections and antibiotic indications and 2) evaluate child care staff reported reasons for a) exclusion from child care, b) referral to a health care provider, and c) recommending antibiotics for an ill child.

METHODS

A longitudinal study based in randomly selected child care centers in Massachusetts. Staff completed a survey to assess knowledge regarding common infections. For six weeks, staff completed a record of absences each day, describing the reason for an absence, and advice given to the parents regarding exclusion, referral to a health care provider, and obtaining antibiotics. Exclusions for the specific illness/symptom were defined as appropriate or inappropriate based on national guidelines.

RESULTS

A large proportion of child care staff incorrectly believed that antibiotics are indicated for bronchitis (80.5%) and green rhinorrhea (80.5%) in children. For 82.2% of absences, the circumstances or reasons for the absence were discussed with a child care staff member. Of 538 absences due to illness that child care staff discussed with parents, there were 45 inappropriate exclusions (8.4% of illnesses discussed), 91 appropriate exclusions (16.9% of illnesses discussed), and 402 cases (74.7%) in which no recommendation for exclusion was made.

CONCLUSIONS

Misconceptions regarding the need for antibiotics for URIs are common among child care staff. However, day care staff do not pressure parents to seek medical attention or antibiotics.

Parental factors affecting respiratory function during the first year of life

In a prospective, longitudinal, population-based cohort study of familial and environmental influences on the development of wheezing respiratory illness in early childhood, we identified infant length, weight, gender, and exposure to maternal cigarette smoking as significant determinants of lung function during the first year of life. A cohort of 237 infants (106 females: 131 males) was evaluated, and 496 lung function measurements were made between the ages of 1-12 months. Respiratory function was assessed using the rapid thoracic compression technique to obtain maximum expiratory flow at functional residual capacity (V'maxFRC). Parental history of asthma and smoking habits during pregnancy were obtained by questionnaire. Data were analyzed using a longitudinal random effects model. Infants with a parental history of asthma and/or in utero passive smoke exposure were compared to a reference group of infants who had no parental history of asthma and in whom neither parent smoked pre- or postnatally. Boys were found to have a consistently lower V'maxFRC (-21.05 mL.s(-1)) throughout the first year of life in comparison to girls (P < 0.05). Maternal smoking during pregnancy was associated with a lower V'maxFRC in both genders in comparison to unexposed infants (P < 0.05). V'maxFRC was unaffected by parental history of asthma. Gender-specific normative equations for V'maxFRC throughout the first year of life were derived for the infant cohort as a whole and also for subgroups of infants, based on parental asthma and smoking history. We conclude that lung function during the first year of life differs between genders and is adversely affected by in utero passive tobacco smoke exposure. Gender-specific predictive equations for V'maxFRC should be used during infancy.

Lower respiratory tract infections in an ethnic and social context

Family size and smoking during pregnancy were studied as mediating factors for social and ethnic variation of lower respiratory tract infection (LRI) in hospital discharge data. The study population consisted of all children aged 0-4 years in the three largest metropolitan areas of Sweden during 1990-94. Maternal smoking during pregnancy increased the risk of children being admitted to hospital for LRI during their first 3 years of life, with an adjusted odds ratio (OR) of 1.3 for the age-group 0-1 years. The risk attributed to smoking during pregnancy was the same in children of mothers in ethnic groups in which smoking during pregnancy was related to social adversity as in those in which it was not. Having at least one sibling increased the risk of being admitted to hospital for LRI in the age group 0-1 years (adjusted OR 2.2). This risk was lower in children in families in which the mother was born in southern Europe, Africa, Asia or Latin America, suggesting a contextual relation to ethnicity for this risk factor. It is concluded that family size and smoking during pregnancy are important mediators of the risk for LRI related to social adversity and ethnicity in Swedish children below 2 years of age.

Child-care attendance and common morbidity: evidence of association in the literature and questions of design

Papers on child-care attendance as a risk factor for acute respiratory infections and diarrhea were reviewed. There was great variety among the studies with regard to the design, definition of exposure and definition of outcomes. All the traditional epidemiological study designs have been used. The studies varied in terms of how child-care attendance in general was defined, and for different settings. These definitions differed especially in relation to the minimum time of attendance required. The outcomes were also defined and measured in several different ways. The analyses performed were not always appropriate, leading to sets of results of uneven quality, and composed of different measures of association relating different exposures and outcomes, that made summarizing difficult. Despite that, the results reported were remarkably consistent. Only two of the papers reviewed failed to show some association between child-care attendance and increased acute respiratory infections, or diarrhea. On the other hand, the magnitude of the associations reported varied widely, especially for lower respiratory infections. Taken together, the studies so far published provide evidence that children attending child-care centers, especially those under three years of age, are at a higher risk of upper respiratory infections, lower respiratory infections, and diarrhea. The studies were not consistent, however, in relation to attendance at child-care homes. Children in such settings were sometimes similar to those in child-care centers, sometimes similar to those cared for at home, and sometimes presented an intermediate risk.

Recurrent wheezing in very preterm infants

AIMS

To document the prevalence of, and identify risk factors for, recurrent wheezing treated with bronchodilators in the first year of life.

METHODS

Parental history and neonatal data were collected prospectively in a regional cohort of very preterm infants (< 33 weeks). Data on maternal smoking, siblings at home, breast feeding, respiratory symptoms, and hospital re-admissions were documented at 12 months.

RESULTS

Outcome data were available for 525/560 (95%) of survivors. The incidence of recurrent wheeze was 76/525 (14.5%) in very preterm infants and 20/657 (3%) in a cohort of term newborns. Significant risk factors for recurrent wheeze in very preterm infants were parental history of asthma, maternal smoking, siblings at home, neonatal oxygen supplementation at 28 days, 36, and 40 weeks of gestation.

CONCLUSIONS

Wheezing respiratory illnesses are common in very preterm infants. The factors involved are similar to those in more mature infants, with the addition of immaturity and neonatal lung injury.

Attendance at day care centers increases the risk of childhood pneumonia among the urban poor in Fortaleza, Brazil

We carried out a case-control study to investigate risk factors for childhood pneumonia in two groups of 650 children aged under two years in the city of Fortaleza, Ceará, Brazil. The cases were children recruited at the main pediatric hospital with a radiological diagnosis of pneumonia, and controls were children of the same age group recruited from the neighbourhood of the cases. In this paper we focus on variables related to childcare practices. Working mothers, proportion of time the mother had worked since the child was born, and use of day care centers emerged as important risk factors with estimated relative risks of 1.58, 1.76 and 5.22, respectively. Also important were the number of children living in the house and presence of grandparents. However, the presence of siblings under two years and the birth order were not associated with pneumonia. All analysis included adjustment for confounding by income, parents' education, and other risk factors as appropriate. This is the first study from a developing country to identify attendance at day care centers as a risk factor for increased childhood morbidity, in this case pneumonia. This finding is of significant public health importance for countries such as Brazil with growing urban populations and an increasing need by mothers to find work outside the home.

The clinical impact of human respiratory virus infections

Acute respiratory infections are the most frequent illnesses of the human host. Most infections are caused by viruses and bacteria; the proportion caused by viruses is much greater. The viruses most frequently involved are adenoviruses, influenza viruses, parainfluenza viruses, respiratory syncytial viruses, and rhinoviruses. Acute respiratory infections are more common in young children, have rather specific seasonal occurrences, and some agents are associated with specific respiratory syndromes. Risk factors associated with increased incidence or severity of respiratory infections are occurrence in the very young or the elderly; crowding; being male; inhaled pollutants; anatomic, metabolic, genetic or immunologic disorders; and malnutrition, including vitamin or micronutrient deficiency. Respiratory infections are a much greater problem in developing countries than in developed countries and are the leading causes of death in children under 5 yr of age. The same agents cause infections, and the incidence of total respiratory infections is the same as in the developed countries. The precise causes of increased morbidity and mortality in the developing world are unclear, but crowding, inhaled pollutants, and malnutrition are likely candidates. The interactive role of viruses and bacteria is not clear but may play a role in increased severity of respiratory infections.

Form of day care and respiratory infections among Finnish children

The relationship between respiratory infectious diseases and form of day care was assessed in a retrospective cohort study of 2568 randomly selected children aged 1 through 7 years in Espoo, Finland. Day-care center children had an increased risk for the common cold, acute otitis media, and pneumonia. The risk concentrated in 1-year-old children, for whom the adjusted relative risks (incidence density ratios) for the common cold, otitis media, and pneumonia were 1.69 (95% confidence interval [CI] = 1.43, 2.01), 1.99 (95% CI = 1.57, 2.52), and 9.69 (95% CI = 2.31, 40.55), respectively. Among 1-year-old children, the proportion of infections attributable to care at day-care centers were 41% (95% CI = 30, 50) for colds, 50% (95% CI = 36, 60) for otitis media, and 85% (95% CI = 57, 98) for pneumonia. The results provide evidence that care in day-care centers is a determinant of acute respiratory infections in children under 2, whereas family day care does not essentially increase risk.

Acute illnesses in children. A description and analysis of the cumulative incidence proportion

OBJECTIVES

To describe parent-reported morbidity in relation to the psycho-social conditions of the families and to characterize families whose children are frequently ill.

DESIGN

The parent-reported morbidity in a two-month prospective period, and the psychosocial conditions of the families were registered by means of a questionnaire. The conditioned probability of parents' reporting an episode of illness was estimated by means of logistic regression analysis, taking the psycho-social conditions into consideration.

SETTING

18,949 families with at least one child under the age of 8 years, resident in the County of Ringkjøbing in western Denmark at 1 March 1988.

SUBJECTS

An age-stratified random sample of 1982 families was entered in the study. 1588 (82%) families returned the questionnaire.

RESULTS

The parents reported considerable morbidity in their children. The cumulative incidence proportion (CIP) for the period was 48%. The multivariate analysis of the parent-reported morbidity led to the following main results: 1) the morbidity was greatest for children aged 6 to 18 months, after which it decreased with age, 2) there was interaction between the care conditions and the child's age--CIP for children up to two years was largest for the children who were cared for in daycare, while the CIP for the older children was largest for the children who were cared for at home, 3) if the parents reported that the child's siblings suffered from chronic or frequently recurring morbidity, the child's morbidity rate was significantly increased, 4) mothers with higher education reported more morbidity in their children than mothers without this education, and 5) parents with a high perception of the general health threat ("worried" parents) reported more morbidity than did parents with a low perception.

CONCLUSIONS

The results made it possible to characterize families whose children were frequently reported ill.

Effectiveness of thymostimulin and study of lymphocyte-dependent antibacterial activity in children with recurrent respiratory infections

Recurrent respiratory infections (RRI) consist of more relapsing acute respiratory infections than the ones expected for the age [> 6 acute respiratory tract infections (RTI) per year if age is > 3 years, and > 8 acute RTI per year if age is < 3 years]. Concerning the pathogenesis of RRI, several investigations report the important role of environmental factors, early socialization and immunological dysfunctions, such as lymphocyte subpopulations alterations, IgG subclass deficiency and phagocytosis and/or opsonization deficit during acute infections. In this framework, we have studied the lymphocyte-dependent antibacterial activity (ABA) among 121 children affected by RRI. Results show a statistically significant alteration of this function in 38 children (31.4%): 19 of them exhibited an absent ABA (group 1), while in the others same function was reduced (group 2). A bovine thymic extract, thymostimulin, was administered to both groups by intramuscular injections (1 mg/kg) for a 3 month cycle. At the end of therapy we observed a statistical significant rise of ABA only in group 1 and among children aged > 3 years. Among the same patients, 33 children (86.8%) improved in terms of reduction of clinical score and better results were seen among children aged > 3 years. These data emphasize the beneficial role of thymostimulin in RRI-affected children, suggesting a transient immaturity of the immune system as one of the possible pathogenetic factor.

Comparability of parent reports of respiratory illnesses with clinical diagnoses in infants

In a cohort study of respiratory illnesses from birth through age 18 months, the investigators assessed the occurrence of illness by telephone reports of respiratory symptoms. To assess the comparability of illness events based on symptom reports with usual clinical modalities, a nurse practitioner examined children during illnesses, and office and clinic records of outpatient visits were reviewed. Respiratory illnesses were defined as symptom episodes of at least 2 days; lower respiratory illnesses included at least 1 day of either wet cough or wheeze. This report is based on 10,771 illnesses in the 1,315 subjects enrolled. Runny or stuffy nose was reported for most (93%) illnesses, wet cough in 33%, and wheeze in 6%. In comparison with the diagnoses made by a nurse practitioner, parent report of wet cough or wheeze was sensitive (93.4%) for detecting lower respiratory illnesses, but nonspecific with specificity of only 24.2%. The majority of the false-positive lower respiratory illnesses had the symptom of wet cough. The comparison of parent reports with outpatient records provided similar findings. Standardized reporting of respiratory illnesses can be achieved with a telephone surveillance system but classification of specific illnesses from the surveillance information may differ from diagnoses made by clinicians.

[Prognostic factors of hospital mortality from diarrhea or pneumonia in infants younger than 1 year old. A case-control study]

Diarrhea and pneumonia are common diseases in children aged under one year, for which there are simple therapeutic measures. However, infant mortality due to these diseases is still very high, varying markedly according to socio-economic status. The characteristics of children who died (cases) and of those who were hospitalized with diarrhea or pneumonia, but survived (controls), were studied. The following groups of variables were studied: socio-economic, environmental and biological conditions, nutritional status and breast-feeding. Information on cases and controls was collected from hospital records and through home interviews. Important losses occurred in the latter: 40% of cases and 50% of controls were not interviewed. There were no significant differences between cases who were included and those who were not, in terms of age, sex or place of residence. To estimate relative risks of prognostic factors unconditional Logistic Regression was used to calculate the odds ratios and their 95% confidence intervals. Prematurity, low birth weight, weight/age deficit, presence of edema and poor general status at hospital admission were prognostic factors for hospital case-fatality. In relation to the anthropometric variables, it was not possible to conclude for certain whether the increased case-fatality was linearly or non-linearly (threshold) associated with nutritional deficit. The duration of breast-feeding was only associated with case-fatality for pneumonia. Socio-economic factors were not important for the prognosis of children admitted to hospital with diarrhea or pneumonia. Some of the expected risk factor associations were not detected, maybe due to the small sample size (resulting from the high losses) which was insufficient to show small differences. In this study the biological conditions of children with diarrhea or pneumonia appeared to be the important prognostic factors for hospital case-fatality.

Lower respiratory illness in infants and low socioeconomic status

OBJECTIVES

Infants from families of low socioeconomic status are said to suffer higher rates of lower respiratory illness, but this assertion has not been carefully examined.

METHODS

We studied the frequency and determinants of lower respiratory illness in infants of different socioeconomic status (n = 393) by analyzing data from a community-based cohort study of respiratory illness during the first year of life in central North Carolina.

RESULTS

The incidence of lower respiratory illness was 1.41 in the low socioeconomic group, 1.26 in the middle group, and 0.67 in the high group. The prevalence of persistent respiratory symptoms was 39% in infants in the low socioeconomic group, 24% in infants in the middle group, and 14% in infants in the high group. The odds of persistent respiratory symptoms in infants of low and middle socioeconomic status were reduced after controlling for environmental risk factors for lower respiratory illness. Enrollment in day care was associated with an increased risk of persistent symptoms among infants of high but not low socioeconomic status.

CONCLUSIONS

Infants of low socioeconomic status are at increased risk of persistent respiratory symptoms. This risk can be partly attributed to environmental exposures, most of which could be changed.

[Risk factors for death caused by pneumonia in children younger than 1 year old in a metropolitan region of southeastern Brazil. A case- control study]

In a case-control study, a sample of post-neonatal deaths from pneumonia occurring in the Metropolitan Area of Rio de Janeiro, Brazil (1986-1987) were compared with healthy controls who lived in the same neighborhood. Risk factors investigated were variables related to the mother's pregnancy history and the child's birth, to the family's social condition and to the use of health services. Using the univariate logistic regression model, the coefficients of each independent variable, the relative risk and its confidence limits were first estimated. Birth weight and age of weaning were strongly associated with the dependent variable. After adjustment by means of the multiple logistic regression model, only 4 variables remained statistically associated with mortality: age of weaning, birth weight, over crowding, and BCG vaccination. Based on the available data, it was concluded that mortality from pneumonia in children under 1 year of age is significantly related to the social condition of the family, particularly to that of the mother.

Children with recurrent respiratory tract infections tend to belong to families with health problems

Children (7-11 years of age) who had recurrent respiratory tract infections (RTI) treated with antibiotics as preschoolers (n = 41), and their families were compared with regard to medical and social factors to families with children of comparable age who had had no such infections as preschoolers, or only isolated episodes (controls; n = 29). All the children studied had attended day-care centres as preschoolers. The two groups of children did not differ with regard to socio-economic conditions or age at admission to day-care centres. There was a difference in the two groups with regard to signs noted at physical examination (p less than 0.05), eardrum changes being observed in 34% of the children with recurrent episodes of RTI as preschoolers and in none of the controls (p less than 0.001). Questionnaires answered by parents indicated diseases, particularly cardiovascular diseases, to be significantly more frequent in the families of the children with recurrent RTIs as preschoolers than in those of the controls (p less than 0.01). Parents of the controls were more often satisfied with their own health (p less than 0.05) and reported fewer symptoms of minor illness (p less than 0.05), as compared with parents of the children with recurrent RTIs as preschoolers. Thus, the results of the present study support the idea that children with recurrent bacterial RTIs as preschoolers tend to belong to families with health problems.

Respiratory tract infections in children with recurrent episodes as preschoolers

The occurrence of respiratory tract infections (RTI) in 41 school-age children, who had recurrent RTIs treated with antibiotics as preschoolers, was followed prospectively for two years through diary reports by parents and medical consultations, and compared with that in 29 children of the same age and socio-economic background, who had few or no such infections as preschoolers. During the two-year follow-up, a greater number of episodes of RTI and a longer mean duration of such episodes were reported in the diaries concerning the children with recurrent bacterial RTIs as preschoolers compared with the controls (p less than 0.01). The annual incidence of bacterial RTI from birth onwards decreased with age among the children with recurrent episodes as preschoolers, unlike in the control group, where the incidence remained consistently low, the difference in incidence being significant up to the age of eight years (p less than 0.01). Acute otitis media was the predominant bacterial RTI in preschoolers, and acute tonsillitis in school-age children. There was a tendency toward a greater incidence of other types of disease and complications/sequelae of infections among the RTI-afflicted group than among the controls, both as preschoolers and as school children. Our findings suggest that certain children constitute a group with high morbidity, susceptible to RTIs and other illnesses over a rather long period of years.

Airways and air pollution in childhood: state of the art

Correlations between ambient pollutants and health effects, such as observed in SIDS, may in reality be to a larger extent the result of indoor sources. These distinctions between indoor and outdoor sources, while important, do not detract from the overall conclusion that pollution affects the airway in children directly and indirectly. Much still needs to be learned about the permanence of these effects, the mechanism by which the effect is mediated, and the conditions under which some of these effects are maximal. Two approaches seem particularly suited to shed further light on these issues. First, identification of biological markers for exposure to pollutants will yield both more accurate measures of exposure to pollutants and information about health consequences. Second, newer modeling techniques promise to predict health outcomes under a variety of environmental conditions. Shumway et al., for instance, describe a promising model predicting an increase in mortality due to ambient pollutants in the Los Angeles Basin with higher levels under extremes of temperature, especially during cold spells. Time series and factor analyses may further our knowledge as well. In the near future, large cohort studies should begin to reveal the cumulative effects of air pollution on the respiratory system, especially in relation to active smoking. Finally, studies in Black children are virtually unavailable. Given their high risk for respiratory illnesses, such studies are sorely needed.

Acute respiratory illness in Adelaide children: breast feeding modifies the effect of passive smoking

STUDY OBJECTIVE

The aim was to investigate the relation between passive smoking and childhood acute respiratory illness.

DESIGN

The study involved an initial postal survey on a random sample of children followed by a case-control study based on the survey. A respiratory illness score was calculated from maternal reports of episodes of illness in the previous 12 months.

SETTING

The study was a population survey based on Adelaide metropolitan area in South Australia.

PARTICIPANTS

The reference population (n = 13,996) was all live born children registered in South Australia in 1983 whose parents lived in Adelaide metropolitan area. Of these, 4985 families were contacted by post and from 2125 respondents, 1218 (58%) gave consent for home interview. "Cases" were children with respiratory illness scores in the top 20%, controlling for age and time of year (n = 258); "controls" were taken in the bottom 20% (n = 231).

MEASUREMENTS AND MAIN RESULTS

Maternal smoking in the first year of life was associated with a doubling in relative odds of respiratory proneness in the child (odds ratio = 2.06, 95% CI 1.25-3.39) after adjustment for confounding by parental history of respiratory illness, other smokers in the home, use of group child care, parent's occupation, and levels of maternal stress and social support. There was no evidence that this association was attributable to differences in the way smoking and non-smoking parents perceived or managed childhood acute respiratory illness. Maternal smoking in the first year, without smoking in pregnancy, was also associated with increased risk of respiratory proneness (odds ratio 1.75, 95% CI 1.03-3.0), showing an effect of passive smoking independent of any in utero effect. There was a strong negative effect modification by breast feeding: relative odds of respiratory proneness with maternal smoking were seven times higher among children who were never breast fed than among those who were breast fed.

CONCLUSIONS

The results suggest a relatively small but real effect of passive smoking on childhood acute respiratory illness. Effect modification by breast feeding may be due to a combination of behavioural and biological mechanisms.

A retrospective study of respiratory tract infections among children in different forms of day care

This retrospective study investigated the records from July 1985 to June 1986 of all medical visits due to acute respiratory tract infections (RTIs) in infants aged 1-3 years. The study, in a municipal district, included all visits to the district health centre as well as visits to the paediatric and ear, nose and throat departments of the nearby hospital. The study population consisted on 489 children, of whom 140 were cared for in day-care centres (DCC), 146 in family day-care (FDC), while 203 did not receive any sort of municipally-supported day care (home care, HC). During the year studied, 223 children needed treatment by a doctor for acute RTI on altogether 499 occasions leading to the prescription of 325 courses of antibiotics. As regards RTIs as a whole and regarding those treated with antibiotics, the incidence density was greatest among the DCC children and lowest among the HC children, while the FDC children formed an intermediate group.

Factors affecting the occurrence of acute otitis media during the first year of life

A regional birth cohort of 5,356 infants was enrolled into a follow-up study in order to investigate the determinants of the development of infectious diseases in children. The infants were examined at three months, six months and twelve months of age by the physicians at the well-baby clinics. At these occasions the number of episodes of acute otitis media in the infants, the duration of breast-feeding, the number of siblings, the type of day care, parental smoking, the presence of animal pets at home and the number and type of other illnesses than otitis were registered. Two thirds of the infants had no episodes of acute otitis media. The median age for the first episode of acute otitis media was eight months. About 10% of the infants had experienced recurrent otitis media (three episodes or more) during their first year of life. Significant associations were found between the occurrence of acute otitis media and the number of siblings, the type of day care, the sex of the infant, the duration of breast feeding, maternal socioeconomic status and prematurity.

Trial of an intervention to reduce passive smoking in infancy

We tested a health education intervention program to reduce passive smoking in infancy. The aim was to develop an instrument for study of tobacco smoke exposure and childhood respiratory illness. One hundred and eighty-four women who had smoked during pregnancy were allocated by month of delivery to an intervention group, to a minimal contact group, or to a follow-up only comparison group. Exposure to smoke was assessed 3 months later by questionnaire and by measurement of cotinine in samples of maternal and infant urine. There was a reduction in maternal smoking associated with contact with research staff, but this was not statistically significant. There were no differences between the groups in the exposure of infants to tobacco smoke. Reasons for this finding may include the timing of the intervention, the heterogeneity of the target group, and the manner in which information was presented on health risks caused by parental smoking.

The common cold

The common cold continues to be the major cause of absences from school and work. A better understanding of the epidemiology and the natural history should lead to less anxiety about this disease. Although there is still much misinformation among the public, the time should soon come when better-informed patients with this disease will make fewer visits to the physician and will not expect unnecessary and worthless treatment.