Burden of interpandemic influenza in children younger than 5 years: a 25-year prospective study.

Many respiratory viruses cause morbidity in young children, but a licensed vaccine and effective oral therapy are available only for influenzavirus. To determine the incidence of laboratory-confirmed influenza illness, we prospectively followed up 1665 healthy children aged <5 years who were enrolled in the Vanderbilt Vaccine Clinic at some point from 1974 through 1999. Viral cultures were obtained when the children presented with clinical illness. The isolation of influenzavirus was associated with an estimated 95 health care visits for children with symptoms of influenza, 46 episodes of acute otitis media, and 8 episodes of lower respiratory tract disease per 1000 children yearly. Rates of acute otitis media and lower respiratory tract disease were highest among children aged <2 years. Hospitalizations associated with culture-positive influenza occurred at an annual rate of 3-4 per 1000 children aged <2 years. Influenza is associated with substantial morbidity in otherwise healthy children aged <5 years.     

Human metapneumovirus and respiratory syncytial virus infections in older children with cystic fibrosis

BACKGROUND: Human metapneumovirus (hMPV) has been isolated from children with acute respiratory infection worldwide. Its epidemiology remains to be defined in children with cystic fibrosis (CF). We describe the epidemiology and clinical impact of hMPV in CF children and compared it to respiratory syncytial virus (RSV). METHODS: CF children ages 7-18 years were studied prospectively during the 1998 -1999 RSV season. Nasopharyngeal specimens were collected during acute respiratory illnesses and tested for respiratory viruses. Blood specimens were drawn early, mid, and end of the RSV season, and tested for serological evidence of hMPV and RSV infections. Rates of lower respiratory tract illnesses (LRTI) and hospitalizations for pulmonary exacerbations were compared during the time intervals they developed serological evidence of infection to their non-infection intervals. RESULTS: Six of 44 CF children had a virus positive respiratory illness in 56 LTRI events and 18 hospitalizations. Serological evidence of hMPV and RSV infections occurred in 16 and 20 CF children, respectively; 8 had infections with both viruses. A greater proportion of CF children had >or=1 LRTI during their infection intervals compared to their non-infection intervals (13/25 vs. 5/25; P=0.03). A trend for higher rates of LRTI was observed in the infection intervals compared to non-infection intervals (9.5 +/- 11.0 vs. 4.2 +/- 9.9 per 1,000 child-days; P=0.06), and it was significantly greater with a more conservative estimate (one event per child per interval; 7.4 +/- 7.7 vs. 2.6 +/- 5.4 per 1,000 child-days; P 相似文献   

Etiology of acute lower respiratory tract infection in children at Srinagarind Hospital, Khon Kaen, Thailand

We investigated the etiology of acute lower respiratory infection (ALRI) in children under 5 admitted to Srinagarind Hospital. The causative bacteria and viruses were determined by hemoculture and viral isolation from blood and nasopharyngeal aspirate samples. Antigens of respiratory syncytial virus (RSV) and Chlamydia trachomatis were detected using EIA. The 74 children less than 5 years of age with ALRI enrolled in our study were diagnosed with pneumonia (75.7%), croup (16.2%), and bronchiolitis (8.1%), respectively. Examination of blood or nasopharyngeal aspirate revealed viral or bacterial infections in 26 and 22 cases, respectively, whereas 5 of the children aged under 1 year (10%) were diagnosed with pneumonia caused by Chlamydia trachomatis. RSV was the most common virus detected (24.3%) and was associated with pneumonia and bronchiolitis, while the parainfluenza virus was the primary cause of croup. In cases of pneumonia, bacterial infections were identified in almost all of the cases: and Streptococcus pneumoniae and Haemophilus influenzae were the most commonly isolated (at 8.9% each). Mixed infections were detected in 8 cases (10.8%). The incidence of RSV infection peaked during the especially warm and cool seasons, whereas the bacterial infections were primarily associated with the relatively cool season. Our study indicates that a combined pneumococcal and Hib vaccine and a RSV vaccine would reduce the high rate of pneumonia in children under 5 years of age in Northeast Thailand.     

Adenovirus infections and respiratory illnesses in children in group day care

Adenovirus infections and respiratory illnesses among 123 children attending a research day care center were analyzed from data collected prospectively from 1967 through 1981. During the 15-year study period, 298 adenovirus isolates were recovered from respiratory secretions of the study children, and five different serotypes were identified, with types 1, 2, and 5 accounting for 92% of the typed isolates. Annual incidence of each serotype varied greatly, with types 2 and 5 predominating before 1975 and type 1 thereafter. Exposure to adenovirus in the day care center correlated with acquisition of infection. Through two years of age, children were exposed to 3.4 +/- 0.9 (mean +/- SD) different serotypes and became infected by 2.1 +/- 0.8 different types. Most infections occurred before the child's second birthday, and incidence was highest from six to 12 months of age (1.4 primary infections/child-year). Mild and febrile illness accompanied 75% of primary isolations. Otitis media occurred in 37% of illnesses over all ages and in greater than 50% of illnesses among infants.     

A study of infections and illnesses in a day nursery based on inclusion-bearing cells in the urine and infectious agent in faeces, urine and nasal secretion.

During an epidemic-free period of nearly 2 years infections and illnesses were followed in a group of small children (2-3 1/2 years) in a day nursery. The incidence of illness was fairly low, 6.3 per child and year. The viral infections were followed by means of the inclusion reaction in the urine and isolation of virus, and the bacterial by culture of nasal secretion. In 60% of the cases the viral infection was accompanied by illness. In 57 cases of illness there were 27 (47%) with merely virus and/or inclusion reaction, 8 (14%) in which bacteria alone were discovered, and 22 (39%) with both. The viral infections were the decisive ones in about 80% of the illnesses. Enteric respiratory viruses of 10 types were detected. 16 (73%) of the 22 children had such an infection on at least one occasion, and spread within the group occurred on infection with echovirus 9, coxsackievirus B4 and reovirus. Enteric viruses accounted for 29% of the viral infections. Streptococci and Mycoplasma pneumoniae played no part in the bacterial infections, which were entirely dominated by pneumococci. Cytomegaloviruria was found in 13 (72%) of 18 children examined. No spread was detected within the group. Rotavirus was on no occasion found in faeces.     

Community incidences of respiratory infections in an actively followed cohort of children <1 year of age in Manhiça, a rural area of southern Mozambique

Objective To estimate the community incidence‐rates of respiratory infections among infants in Manhiça, southern Mozambique, and to determine risk factors associated with these infections. Methods A cohort of children <1 year of age were visited at home every week until they turned one. During the visits, field workers recorded signs/symptoms of respiratory infections and tested the children for malaria parasites when they had fever. Results Between 1 July 1998 and 30 June 1999, 1044 children contributed with 23 726 weeks at risk. Children met the criteria for acute respiratory infection in 19.2% of the visits, for lower respiratory infection in 0.9% and for severe lower respiratory infection in 0.2%. The crude incidence rate measured for acute respiratory infections was 23.0, that for lower respiratory infection was 0.9 and that for severe lower respiratory infection was 0.2 per 100‐person‐week‐at‐risk. The risk of acute and lower respiratory infection was inversely related to age. Females were at significantly lower risk for all three conditions than males. A trend of increased risk of severe lower respiratory infection was noted among children born during the rainy season (adjusted rate ratio = 1.95, P = 0.122 in only 47 episodes). Malaria was strongly associated with an increased risk of all three respiratory infections [rate ratio of 2.35, 10.90 and 13.82 (P < 0.001) in the adjusted analysis, respectively]. Thirty‐five children died during the follow‐up period; 20% of them from lower respiratory infection. Conclusions Respiratory infections are a major cause of morbidity and mortality among infants in rural Mozambique. Our study provides a better understanding of the associated determinants.     

Longitudinal study of acute respiratory diseases in Rio de Janeiro: occurrence of respiratory viruses during four consecutive years.

The occurrence of different viruses in nasopharyngeal secretions from children less than 5 years old with acute respiratory infections (ARI) was investigated over a period of 4 years (1982-1985) in Rio de Janeiro. Of the viruses known to be associated with ARI, all but influenza C and parainfluenza types 1, 2 and 4 were found. Viruses were found more frequently in children attending emergency or pediatric wards than in outpatients. This was clearly related to the high incidence of respiratory syncytial virus (RSV) in the more severe cases of ARI. RSV positive specimens appeared mainly during the fall, over four consecutive years, showing a clear seasonal occurrence of this virus. Emergency wards provide the best source of data for RSV surveillance, showing sharp increase in the number of positive cases coinciding with increased incidence of ARI cases. Adenovirus were the second most frequent viruses isolated and among these serotypes 1, 2 and 7 were predominant. Influenza virus and parainfluenza virus type 3 were next in frequency. Influenza A virus were isolated with equal frequency in outpatient departments, emergency and pediatric wards. Influenza B was more frequent among outpatients. Parainfluenza type 3 caused outbreaks in the shanty-town population annually during the late winter or spring and were isolated mainly from outpatients. Herpesvirus, enterovirus and rhinovirus were found less frequently. Other viruses than RSV and parainfluenza type 3 did not show a clear seasonal incidence.     

Association of viral and Mycoplasma pneumoniae infections with acute respiratory illness in patients with chronic obstructive pulmonary diseases

The relative importance of respiratory virus and M. pneumoniae infections as causes of acute respiratory illnesses was studied over an 8 yr period in 150 subjects who were normal or who had varying degrees of chronic obstructive pulmonary disease (COPD). Viral or M. pneumoniae infections were associated with 186 of 1,030 (18%) illnesses studied, whereas these infections were detected in only 86 of 1,398 (6%) illness-free periods (P less than 0.01). Rhinoviruses, influenza viruses, parainfluenza viruses and coronaviruses were each significantly associated with acute respiratory illnesses. The occurrence of acute respiratory illnesses and viral infections was the same in subjects with moderate to severe COPD as it was in subjects who were normal or who had mild disease.     

Viral infection related to the appearance of acute bacterial respiratory tract infections

To investigate what viruses are related to acute bacterial respiratory tract infections, we prospectively evaluated 113 cases with respiratory tract infections (always accompanying by purulent sputum) experienced between July 1998 and March 2000. Acute viral infections were detected in 25 cases (22%); 10 cases of influenza A virus and 6 cases of respiratory syncytial (RS) virus. The epidemiology of the influenza A virus and RS virus was mainly identified as from December to February in both winter seasons. A bacteriological examination of sputum cultures isolated 12 cases of Streptococcus pneumoniae and 10 cases of Haemophilus influenzae during the same periods and mixed infections of both viruses and bacteria were recognised in 16 cases (14%). These results suggest a significantly high percentage of mixed infections of both viruses and bacteria. However, it was unknown whether the patients with acute bacterial respiratory infections had been infected with viruses prior to the bacterial infections. The frequency of appearance of respiratory tract infections tended to increase with the seasonale epidemiology of viral infections.     

Conventional respiratory viruses recovered from immunocompromised patients: clinical considerations.

Lower respiratory tract infection is the most common complication in the immunocompromised patient. From January 1991 to December 1995, 785 consecutive patients with suspected respiratory tract infections were studied. One hundred ninety-nine viruses were isolated from 182 (23%) of 785 bronchoalveolar lavage fluid specimens. Cytomegalovirus was isolated from 131 patients, herpes simplex virus was recovered from 31, and conventional respiratory viruses (CRVs) were recovered from 36. There were 9 influenza A viruses, 2 influenza B viruses, 7 parainfluenza viruses, 5 respiratory syncytial viruses, 5 adenoviruses, 6 enteroviruses, and 3 rhinoviruses. We identified 22 patients from whom a CRV was the only microorganism recovered; 13 patients developed pneumonia, 10 had acute respiratory failure, 5 required support with mechanical ventilation, and 5 (23%) died. In conclusion, CRVs are frequent causes of respiratory illnesses and are associated with high rates of morbidity and mortality among immunocompromised patients.     

Effects of glutathione S-transferase P1, M1, and T1 on acute respiratory illness in school children

The relationships between glutathione S-transferase (GST) M1, GSTT1, and GSTP1 genotypes and acute respiratory illness were investigated in a cohort of fourth grade school children aged 9-11 years who resided in 12 southern California communities. We used respiratory illness-related absences as a measure of respiratory illness occurrence. We ascertained respiratory illness-related school absences using an active surveillance system from January 1996 through June 1996. Genotypes for GSTM1 (null versus present), GSTT1 (null versus present), and GSTP1 (Ile105Val) were determined using genomic DNA from buccal cell specimens. The effects of GST genotypes on respiratory illness were assessed using stratified absence incidence rates and Poisson regression models. GSTP1 genotype was associated with risk for respiratory illness severe enough to result in a school absence. Children who were homozygous for the Val105 variant allele had lower incidence rates of upper and lower respiratory illnesses than did children who were homozygous for the Val105 allele. Children inheriting at least one Val105 allele were protected from respiratory illnesses (relative risk, 0.80; 95% confidence interval, 0.65-0.99). GSTM1 and T1 genotypes were not associated with respiratory illness. We conclude that GSTP1 genotype influences the risk or severity of respiratory infections in school-aged children.     

Virological surveillance of acute respiratory tract illnesses of children in Morioka, Japan. II. Rhinovirus infection]

Rhinoviruses (HRVs) were isolated from 307 children (7.1%) in the virological surveillance of 4334 children with acute respiratory tract illnesses in Morioka, Japan (September 1973-December 1983). Although HRVs were isolated throughout the year, frequency of HRV infection was significantly higher (p less than 0.001) during the April-November (233/2853; 8.2%) than during the December-March (47/1481; 5.0%). There were two peaks of incidence in May (9.5%) and September (9.1%). During the May-September, the rate of HRV infection was higher in patients under the age of 11 months than the next higher group of 1-2 years old (p less than 0.001). The incidence decreased with increasing age. The illnesses of HRV infection were analysed in 294 patients, except one patient who had symptoms of measles, from whom HRV was isolated singly. Although HRV-associated illnesses were generally mild (57.5%). Upper respiratory tract illnesses (URTIs) with fever were found in 22.1% and lower respiratory tract illnesses (LRTIs) in 20.4% of these. The rate of LRTI was higher during the epidemic period (April-September) than other periods (p less than 0.02). Major symptoms of HRV-associated illnesses observed were sore throat (87.4%), cough (84.0%), and nasal obstruction and/or discharge (72.8%). Wheezing was observed in 21.8% of these. From 19 (21.8%) of 47 patients clinically diagnosed as asthmatic bronchitis in this survey, viruses were isolated. HRV was detected most frequently in 12.8% of these patients, followed by respiratory syncytial virus (RSV, 6.4%) and adenovirus (2.1%). HRV- and RSV-associated asthmatic bronchitis were observed during April-September and November-February, respectively. Viral dual infections were detected in total 20 cases included 12 HRV-associated cases. In no case was the illness of greater severity than might have been caused by either agent acting singly.     

Otitis media among children in day care: epidemiology and pathogenesis

Acute and persistent middle-ear effusions are the most common complications of upper respiratory illness in young children. Knowledge of the impact of day care attendance on the incidence and prevalence of these conditions is not as complete as is desirable. Several studies suggest that the incidence of acute otitis media may be higher in children who attend group and home day care, but from these studies it is difficult to assess the magnitude of the risk of otitis media related to day care attendance. Research by Danish investigators indicates that the point prevalence of middle-ear effusion may be two to four times higher in children younger than four years old attending group day care centers than in children cared for at home or in smaller home day care settings. Recent epidemiologic and laboratory investigations have begun to elucidate the role of viral infections and of virus-bacteria interaction in the pathogenesis of acute middle-ear effusion. A thorough understanding of the relationship between day care attendance and the occurrence of otitis media with effusion would require studies that quantify the differential risk of disease in different care settings and that relate illness risk to the epidemiology of both viral and bacterial infections of the upper respiratory tract in the different environments. This type of research has not yet been conducted.     

Epidemiology, clinical characteristics and antimicrobial resistance patterns of community-acquired pneumonia in 1702 hospitalized children in Singapore

OBJECTIVE AND BACKGROUND: Childhood community-acquired pneumonia (CAP) remains a leading cause of morbidity and mortality worldwide. The features of childhood CAP vary between countries. The aim of this study was to delineate the clinical characteristics, complications, spectrum of pathogens and patterns of antimicrobial resistance associated with hospitalized cases of childhood CAP in Singapore. METHODS: A retrospective study was conducted of patients discharged from Singapore's only children's hospital over a 3-year period with a principal diagnosis of CAP. RESULTS: A total of 1702 children, with a median age of 4.2 years (range: 1 month-16.3 years) were enrolled. A pathogen was identifiable in 38.4% of cases, including Mycoplasma pneumoniae in 20.3%, typical respiratory bacteria in 10.3% (64.6%Streptococcus pneumoniae; 21.7% non-typeable Haemophilus influenzae), viruses in 5.5% and mixed bacterial/viral infections in 2%. The majority of M. pneumoniae infections were in school-aged children (>5 years). Severity of infection was greater in CAP caused by typical bacteria, as reflected by length of hospital stay, CRP level, white cell and absolute neutrophil counts. Mortality from typical bacterial infections (8.9%) exceeded that from M. pneumoniae (0.3%) and viral pneumonias (0%) (P < 0.001). Aminopenicillins were often prescribed empirically for suspected S. pneumoniae and H. influenzae infections; however, resistance to these agents was frequently documented among S. pneumoniae (58.5%) and H. influenzae isolates (51%). CONCLUSION: In Singaporean children hospitalized with CAP, M. pneumoniae is the most commonly identified causative organism, followed by common respiratory viruses, S. pneumoniae and H. influenzae. Streptococcus pneumoniae and H. influenzae are associated with greater severity of infection than other organisms, and have high levels of resistance to commonly prescribed antibiotics.     

Policies for the exclusion of ill children from group day care: an unresolved dilemma

Although the problem of how to manage children with mild infectious illnesses who attend group day care programs arises often, appropriate criteria for the exclusion of ill children have not been determined. Substantial variation in the policies of different programs for excluding ill children exists. Studies of the epidemiology of common infectious illnesses indicate that asymptomatic children may transmit infections and that symptomatic children often shed infectious particles both before the onset and after the resolution of symptoms. The little information that is available supports the contention that the exclusion of mildly ill children has little effect on the incidence of infections among children who attend group day care programs. Consequently, policies for exclusion should focus on the needs and behavior of the ill child rather than on easily measured but less germane factors such as the child's body temperature. If the facilities and staff available are adequate to meet the needs of both the ill child and other children in the group, it is appropriate to allow children with mild infectious illnesses to attend group day care programs.     

Virological surveillance of acute respiratory tract illnesses of children in Morioka, Japan. I. Epidemiological patterns of infection with respiratory viruses over a 10-year period]

A virological surveillance of acute respiratory tract illnesses (RTI) of children in Morioka, Japan, was maintained from September 1973 to December 1983. Nasal and throat swabs were collected from 4,334 children with RTI. These patients consisted of 3,500 children (80.8%) with upper RTI (URTI) and 834 children (16.2%) with lower RTI. When these patients with URTI were classified by maximum temperature recorded into 4 groups (less than or equal to 37.0 degrees C, 37.1-37.9 degrees C, 38.0-38.4 degrees C, and greater than or equal to 38.5 degrees C), the number of patients in each group was 1,909 (44.0% of all patients), 702 (16.2%), 378 (8.7%), and 512 (11.8%), respectively. The viruses were recovered from 932 patients (21.5%). The most frequently recovered virus was rhinovirus (HRV; 31.7% of positive patients). The other common viruses were respiratory syncytial virus (RSV; 15.3% of positives), enteroviruses (13.9%), adenoviruses (13.6%), and influenza viruses (11.1%). Coronaviruses (HCV) were isolated from 2 patients and dual infections were detected in 20 patients (2.1% of positives). HRVs were isolated from 8.9% of afebrile URTI, in addition to 7.4% of bronchitis and 12.8% of asthmatic bronchitis. RSVs were mainly isolated in the winter, but some of them were isolated in the summer of 1974 and 1975. HCVs were isolated from 2 patients with afebrile URTI in the spring of 1979. Consistent patterns have been observed in clinical manifestation, seasonal occurrence, and age distribution of infections; we indicated that HRV was not only most important pathogen of URTI, but also it was important in bronchitis and asthmatic bronchitis of children.     

Pneumococcal isolations from patients with pneumonia and control subjects in a prepaid medical care group.

The incidence of pneumococcal infections and pneumonia among the 150,000 members of a prepaid medical care group in Seattle was assessed by an intensive study of outpatients for one year from June 1971 through May 1972. Respiratory specimens (sputum, pharyngeal, and nasal) from patients with pneumonia or febrile respiratory disease and from age- and sex-matched control subjects were cultured for pneumococci on media and in mice. Total rate of pneumonia was 11 per 1,000. Twenty-four per cent of patients with pneumonia and 12 per cent of control subjects carried pneumococci. The patients with pneumonia from whom the pneumococcus was isolated did not differ clinically on average from those without such isolates. Lobar and bacteremic pneumonia were extremely rare. The rate of pneumococcal infections and carriers was highest in the spring. Although young children had the highest rate of pneumonia from all causes there was no difference in the isolation rate between ill children and control children. The highest rate attributable to pneumococci was in those larger than 40 years of age. Pneumococcal carrier rates were much lower than those reported in the 1930s. Thirty-nine per cent of patients with pneumonia had evidence of viral or mycoplasmal infection, as determined primarily by serologic methods. Pneumococcal pneumonia was not a serious problem in this average, employed population in Seattle.     

Pathogenetic study on bronchopulmonary infections in 1,416 patients by transtracheal aspiration method]

We have performed transtracheal aspiration (TTA) in 1,416 patients, who were suspected to have bronchopulmonary infection, in order to collect non-contaminated specimens directly from the lower airway. The overall isolation rates in 1,416 TTA were 68.7% for any microorganisms. Aerobes had a high incidence but many kinds of microorganisms were associated with bronchopulmonary infections. Haemophilus influenzae was the major pathogen in patients with acute bronchitis. Streptococcus pneumoniae was the most important pathogen and mycoplasma was often isolated in patients with community-acquired pneumonia. Major pathogens of nosocomial pneumonia consisted of alpha-streptococcus spp., anaerobes and Pseudomonas aeruginosa. Anaerobes were isolated from transtracheal aspirates in 20 of 33 episodes of lung abscesses. H. influenzae and P. aeruginosa were the main persistent pathogens and H. influenzae, S. pneumoniae and anaerobes were important exacerbated pathogens in patients with chronic lower respiratory tract infection. S. pneumoniae was isolated more from TTA than expectorated sputa. Oropharyngeal flora bacteria were easily isolated in the culture of expectorated sputa. We assessed the final diagnosis or causative factor in 443 patients whom no microorganism was isolated from transtracheal aspirates. The final diagnosis was infectious diseases in 52 patients (11.7%) and non-infectious diseases in 80 patients (18.1%), respectively. The causative factor was unsuited TTA sample in 81 patients (18.3%), preceding antimicrobial chemotherapy in 95 patients (21.4%) and unknown in 135 patients (30.5%), respectively. The pathogenesis of bronchopulmonary infections is complex and various microorganisms are associated with pathogens of bronchopulmonary infections. Therefore, we should accurately diagnose the pathogens in patients with bronchopulmonary infections. TTA is one of the useful methods that we can accurately detect the respiratory pathogens.