Hospitalization for respiratory syncytial virus in the paediatric population in Spain

The aim of this population-based retrospective study was to determine the incidence of hospitalization for community-acquired, laboratory-confirmed respiratory syncytial virus (RSV) infection in an unselected paediatric population from southern Europe. The study was performed in an area with 15,700 children aged less than 5 years attended by a single hospital. The presence of RSV in nasopharyngeal aspirates from children with acute respiratory infection treated in the hospital was investigated in four seasons (July 1996-June 2000). A total of 390 episodes of hospitalization for RSV infection were detected and 83.3% of the children were aged less than 1 year old. The annual hospitalization rate was 37/1000 for infants aged less than 6 months and 25/1000 for those aged less than 1 year. During the study period, 2.5% of the infants younger than 1 year and approximately 5% of those younger than 3 months were hospitalized for RSV infection. The mean length of hospital stay was 5.9 days. Seven per cent of the patients required admission to the intensive care unit and more than half of these children were aged less than 1 month. In Spain, community-acquired RSV infection is a highly frequent cause of hospitalization in young children, especially in those aged less than 1 year. Prevention of RSV infection, through the development of vaccines and/or other strategies, should be a public health priority.     

Risk factors for hospitalization due to respiratory syncytial virus infection among infants in the Basque Country, Spain

This study analysed the role of several risk factors for hospitalization due to community-acquired, respiratory syncytial virus (RSV) infection. The risk factors detected in infants hospitalized for RSV infection in the first 24 months of life were compared with those in the general infant population in our region. There were 361 episodes of hospitalization in 357 infants. Eighty per cent of the infants did not present underlying conditions for severe RSV infection and only 10 (3%) were candidates for palivizumab prophylaxis. In multivariate analysis, birthweight of <2500 g was independently associated with hospitalization for RSV infection and was the most commonly detected medical risk factor. Other risk factors were maternal age at delivery <25 years, birth in the second half of the year, prematurity, suburban residence and congenital heart disease. In conclusion, together with well-known risk factors, we found that low birthweight was an independent factor for severe RSV infection.     

Coronavirus-related nosocomial viral respiratory infections in a neonatal and paediatric intensive care unit: a prospective study

The incidence of nosocomial viral respiratory infections (NVRI) in neonates and children hospitalized in paediatric and neonatal intensive care units (PNICU) is unknown. Human coronaviruses (HCoV) have been implicated in NVRI in hospitalized preterm neonates. The objectives of this study were to determine the incidence of HCoV-related NVRI in neonates and children hospitalized in a PNICU and the prevalence of viral respiratory tract infections in staff. All neonates (age< or =28 days) and children (age>28 days) hospitalized between November 1997 and April 1998 were included. Nasal samples were obtained by cytological brush at admission and weekly thereafter. Nasal samples were taken monthly from staff. Virological studies were performed, using indirect immunofluorescence, for HCoV strains 229E and OC43, respiratory syncytial virus (RSV), influenza virus types A and B, paramyxoviruses types 1, 2 and 3 and adenovirus. A total of 120 patients were enrolled (64 neonates and 56 children). Twenty-two samples from 20 patients were positive (incidence 16.7%). In neonates, seven positive samples, all for HCoV, were detected (incidence 11%). Risk factors for NVRI in neonates were: duration of hospitalization, antibiotic treatment and duration of parenteral nutrition (P<0.01). Monthly prevalence of viral infections in staff was between 0% and 10.5%, mainly with HCoV. In children, 15 samples were positive in 13 children at admission (seven RSV, five influenza and three adenovirus) but no NVRI were observed. In spite of a high rate of community-acquired infection in hospitalized children, the incidence of NVRI with common respiratory viruses appears low in neonates, HCoV being the most important pathogen of NRVI in neonates during this study period. Further research is needed to evaluate the long-term impact on pulmonary function.     

Human metapneumovirus infections in hospitalized children

We evaluated the percentage of hospitalizations for acute respiratory tract infections in children < or =3 years of age attributable to human metapneumovirus (HMPV) and other respiratory viruses in a prospective study during winter and spring 2002. We used real-time polymerase chain assays and other conventional diagnostic methods to detect HMPV, human respiratory syncytial virus (HRSV), and influenza viruses in nasopharyngeal aspirates of children. HMPV was detected in 12 (6%) of the 208 children hospitalized for acute respiratory tract infections, HRSV in 118 (57%), and influenza A in 49 (24%). Bronchiolitis was diagnosed in 8 (68%) and pneumonitis in 2 (17%) of HMPV-infected children; of those with HRSV infection, bronchiolitiss was diagnosed in 99 (84%) and pneumonitis in 30 (25%). None of the HMPV-infected children was admitted to an intensive-care unit, whereas 15% of those with HRSV or influenza A infections were admitted. HMPV is an important cause of illness in young children with a similar, although less severe, clinical presentation to that of HRSV.     

Genetic variability of human metapneumovirus amongst an all ages population in Cambodia between 2007 and 2009

First identified in 2001, human metapneumovirus (HMPV) is a novel pathogen and causative agent of acute respiratory tract infection. Re-infection with HMPV is common, and currently there is no available vaccine against HMPV infection. Two genotypes of HMPV have been identified, A and B, both of which can be divided further into at least two distinct sub-genotypes. Here we report the results of the first study to investigate the genetic variability of HMPV strains circulating within Cambodia. The overall incidence of HMPV infection amongst an all-ages population of patients hospitalised with ALRI in Cambodia during 3 consecutive years, between 2007 and 2009, was 1.7%. The incidence of HMPV infection was highest amongst children less than 5 years of age, with pneumonia or bronchopneumonia the most frequent clinical diagnoses across all age groups. The incidence of HMPV infection varied annually. As anticipated, genetic diversity was low amongst the conserved F gene sequences but very high amongst G gene sequences, some strains sharing as little as 56.3% and 34.2% homology at the nucleotide and amino acid levels, respectively. Simultaneous co-circulation of strains belonging to the HMPV sub-genotypes B1, B2 and lineage A2b, amongst patients recruited at 2 geographically distinct provincial hospitals, was detected. Sub-genotype B2 strains were responsible for the majority of the infections detected, and a significant (p  =  0.013) association between infection with lineage A2b strains and disease severity was observed.     

Incidence and risk factors for community-acquired hepatitis C infection from birth to 5 years of age in rural Egyptian children

A prospective study in three Egyptian villages (A, B and C) having a high prevalence of hepatitis C virus (HCV) infection examined incidence of community-acquired HCV infection in children; 2852 uninfected infants were prospectively followed from birth for up to 5.5 years. Fifteen seroconverted for either HCV antibodies and/or HCV-RNA (incidence of 0.53%). Ten had both anti-HCV and HCV-RNA; four had only anti-HCV; and one had HCV-RNA in the absence of antibody. The incidence rate at all ages was 2.7/1000 person-years (PY). It was 3.8/1000 PY during infancy and 2.0/1000 PY for the 1-5-years age group. Hospitalization and low birth weight increased the risk of infection; while living in village B, the family having a higher socioeconomic status, and advanced maternal education were protective. Six of eight HCV-infected infants reported iatrogenic exposures (e.g. hospitalization, therapeutic injections, ear piercing) prior to infection whereas only 2/7 children older than 1 year reported these exposures. Having an HCV-positive mother was the only other reported risk in two of these older children. The virus cleared in six (40%) children by the end of follow-up. Health education targeting iatrogenic exposures and focusing on risk factors could reduce HCV infection in children in high-risk populations.     

湖南省2012-2014年发热呼吸道症候群哨点监测结果及分析

目的 通过“发热呼吸道症候群监测”了解湖南省主要呼吸道病毒流行情况及病原谱分布,为发热呼吸道症候群防控及临床诊疗提供科学依据。 方法 2012年1月-2014年12月,从符合发热呼吸道症候群定义的患者身上采集鼻/咽拭子、肺泡灌洗液、痰液样本。采用基于毛细管凝胶电泳的“9+7呼吸道病毒多重PCR检测法”对标本中流感病毒(Flu)、呼吸道腺病毒(AdV)、呼吸道合胞病毒(RSV)、人鼻病毒(hRV)、副流感病毒(PIV)、偏肺病毒(HMPV)、人博卡病毒(hBoV)和人冠状病毒(hCoV)共8种病毒的16个亚型进行核酸检测。使用SPSS17.0统计学软件对个案信息及检测结果进行统计学分析。 结果 2012年1月-2014年12月,从哨点医院采集各类呼吸道标本共961份,其中男性病例标本595份,占61.91%;女性病例标本366份,占38.09%。在961份已检测的标本中,通过PCR检出阳性标本456份,阳性检出率为47.45%。男、女病例标本的阳性检出率差异无统计学意义(P>0.05)。按年龄将病例分为7个年龄组,各年龄组的阳性检出率分别为 1岁以下(52.80%)、1~2岁(66.53%)、2~5岁(49.86%)、6~15岁(25.56%)、16~49岁(11.11%)、50~64岁(17.39%)和65岁以上(19.40%)。在456份病毒阳性的标本中,检出混合感染48例,非混合感染408例。在检出的呼吸道病毒中,AdV、RSV和Flu所占的比例最大(病原谱构成比分别为25.90%、21.31%和17.73%),其次为hRV(14.14%)和PIV(11.75%);HMPV(4.78%)和hBoV(3.98%)检出较少,而hCoV只有两例阳性被检出。男性、女性的病原构成差异无统计学意义(P>0.05)。各年龄段的病原构成差异有统计学意义(P<0.05),其中2岁以下的儿童病例中检出的病毒以RSV(29.36%)和AdV(23.02%)为主,其次为PIV(13.10%)、hRV(11.90%)和Flu(11.11%);2~5岁的儿童病例中,AdV所占比例最大(34.02%),其次为hRV(18.56%)、Flu(18.04%)和RSV(15.46%);6~15岁少儿病例中以Flu(31.43%)和PIV(34.29%)为主,其次为AdV(17.14%)和hRV(14.29%);在16~49岁的病例中,只有Flu检出;在50岁以上老年病例中,病原构成以Flu(68.41%)为主,其余为PIV(10.53%)、HMPV(10.53%)和RSV(10.53%)。监测还发现,Flu、AdV有夏季和冬春季两个流行高峰;RSV有冬春季流行高峰;hRV有秋冬季流行高峰。 结论 所监测的8种呼吸道病毒是引发严重急性呼吸道住院病例的重要病原。5岁以下儿童及65岁以上的老人可能是主要的易感人群。其中,RSV、AdV、 Flu可能是引发儿童病毒性呼吸道感染的主要病原,而Flu则可能是引发成人病毒性呼吸道感染的主要原因。因此,应将这几种病毒作为呼吸道病毒防控的重点,进行更多的监测和更深入的研究。     

Epidemiologic patterns of acute diarrhea and endemic Shigella infections in children in a poor periurban setting in Santiago, Chile

To prepare a field site for evaluating preventive interventions against endemic shigellosis, the authors followed prospectively a cohort of 360 children (90 each of children aged 0-11, 12-23, 24-35, and 36-47 months) in Santa Julia, a low socioeconomic area in Santiago, Chile, from November 1986 through April 1989 with twice weekly household visits for diarrheal disease; infants replaced children who reached 60 months of age. Coprocultures on 2 consecutive days from children with diarrhea and from age-matched controls within the cohort were cultured for Shigella. Bacteriologic surveillance was also maintained in the health center and children's hospital serving Santa Julia. In this community, where all households had access to potable water (68% inside) and all but 3% had access to a toilet, but where there was marked crowding, the overall incidence of diarrheal disease in the cohort was low (2.26 episodes/12 child months of observation in children aged 0-11 months and 2.09 in those aged 12-23 months), yet Shigella infections were common. Shigella accounted for 10% of diarrheal episodes in the cohort (vs. 3.2% isolation rate in controls, p less than 0.0001). The incidence of shigellosis in children aged 12-47 months was 0.16 cases per 12 child months of observation; in the first 5 years of life, a child had a 67% chance of experiencing shigellosis. Shigella sonnei, Shigella flexneri 2a, and S. flexneri 6 caused greater than 79% of the infections. Shigella occurred more often in hospitalized cases of diarrhea than in age-matched cases detected in the health center or by household surveillance (p less than 0.0001). An initial episode of Shigella diarrhea did not diminish overall the risk of subsequent shigellosis but did confer 72% protection (p = 0.05) against illness due to the homologous serotype. The high rate of both S. sonnei and S. flexneri shigellosis in a population with a low background rate of diarrhea makes Santa Julia an appropriate site for assessing the efficacy and effectiveness of measures to reduce Shigella infections.     

不同年龄社区获得性肺炎住院儿童的病原学及临床特征研究

目的 了解盐城地区住院儿童社区获得性肺炎(CAP)感染的病原学及临床特征,为盐城地区儿童CAP的防治提供参考依据。方法 回顾性分析2014年10月-2015年9月在盐城市妇幼保健院住院的CAP患儿541例的临床资料。住院期间多病原检测包括:痰常见7种呼吸道病毒抗原、血肺炎支原体(MP)- IgM抗体、血EB四项抗体、痰培养或血培养。结果 病原体阳性检出率为62.8%。MP28.7%,病毒21.8%,细菌16.8%。从单一病原来看,以MP感染率最高(28.7%),其次为呼吸道合胞病毒、肺炎链球菌。>1~5岁龄组及>5~14岁龄组CAP患儿,MP检出阳性率均较高。病毒感染主要发生于1岁以内婴儿。年龄与发热的发生比及高低程度呈正相关,1岁以内年龄组发热比例低(41.6%)且以低热及中等度发热为主,1岁以上年龄组发热比例高(55.6%)以高热为主。CAP患儿5岁以下年龄组咳嗽、喘息气促的发生率明显高于5岁以上儿童;年龄越小肺部体征越明显。1月~1岁龄组CAP胸部影像学主要表现为小斑片影,多为单侧肺受累;>5~14岁龄组患儿则多为大叶受累阴影,多为单侧肺受累。结论 盐城地区住院儿童CAP病原依次为支原体、病毒、细菌。不同年龄段CAP患儿病原体检出率不同。不同年龄和不同病原学感染的儿童CAP的影像学表现各有特点。     

Epidemiology of hospital-acquired infections in veterans with spinal cord injury and disorder.

OBJECTIVE: To describe the epidemiology of hospital-acquired infections (HAIs) in veterans with spinal cord injury and disorder (SCI&D). DESIGN: Retrospective medical record review. SETTING: Midwestern Department of Veterans Affairs spinal cord injury center. PARTICIPANTS: A total of 226 patients with SCI&D hospitalized at least once during a 2-year period (October 1, 2001, through September 30, 2003). RESULTS: A total of 549 hospitalizations were included in the analysis (mean duration of hospitalization, 33.7 days); an HAI occurred during 182 (33.2%) of these hospitalizations. A total of 657 HAIs occurred during 18,517 patient-days in the hospital (incidence rate, 35.5 HAIs per 1,000 patient-days). Almost half of the 226 patients had at least 1 HAI; the mean number of HAIs among these patients was 6.0 HAIs per patient. The most common HAIs were urinary tract infection (164 [25.0%] of the 657 HAIs; incidence rate, 8.9 cases per 1,000 patient-days), bloodstream infection (111 [16.9%]; incidence rate, 6.0 cases per 1,000 patient-days), and bone and joint infection (103 [15.7%]; incidence rate, 5.6 cases per 1,000 patient-days). The most common culture isolates were gram-positive bacteria (1,082 [45.6%] of 2,307 isolates), including Staphylococcus aureus, and gram-negative bacteria (1,033 [43.6%] of isolates), including Pseudomonas aeruginosa. Multivariable regression demonstrated that predictors of HAI were longer length of hospital stay (P=.002), community-acquired infection (P=.007), and use of a urinary invasive device (P=.01) or respiratory invasive device (P=.04). CONCLUSIONS: The overall incidence of HAIs in persons with SCI&D was higher than that reported for other populations, confirming the increased risk of HAI in persons with spinal cord injury. The increased risk associated with longer length of stay and with community-acquired infection suggests that strategies are needed to reduce the duration of hospitalization and to effectively treat community-acquired infection, to decrease infection rates. There is significant room for improvement in reducing the incidence of HAIs in this population.     

Primary pneumocystis infection in infants hospitalized with acute respiratory tract infection

Acquisition of Pneumocystis jirovecii infection early in life has been confirmed by serologic studies. However, no evidence of clinical illness correlated with the primary infection has been found in immunocompetent children. We analyzed 458 nasopharyngeal aspirates from 422 patients hospitalized with 431 episodes of acute respiratory tract infection (RTI) by using a real-time PCR assay. In 68 episodes in 67 infants, P. jirovecii was identified. The odds ratio (95% confidence interval) of a positive signal compared with the first quartile of age (7-49 days) was 47.4 (11.0-203), 8.7 (1.9-39.7), and 0.6 (0.1-6.7) for infants in the second (50-112 days), third (113-265 days), and fourth (268-4,430 days) age quartiles, respectively. Infants with an episode of upper RTI (URTI) were 2.0 (1.05-3.82) times more likely to harbor P. jirovecii than infants with a lower RTI. P. jirovecii may manifest itself as a self-limiting URTI in infants, predominantly those 1.5-4 months of age.     

Emerging Human Metapneumovirus Gene Duplication Variants in Patients with Severe Acute Respiratory Infection,China, 2017–2019

We detected human metapneumovirus (HMPV) in 72 (7.1%) of 1,021 patients hospitalized with severe acute respiratory infection in Luohe, China, during 2017–2019. We detected HMPV most frequently in young children and less often in adults. HMPV genotype A2c variants 111 nt and 180 nt duplications predominated, demonstrating their continuing geographic spread.     

Association of diarrhoea and upper respiratory infections with weight and height gains in Bangladeshi children aged 5 to 11 years

INTRODUCTION: The association between infection and growth delay is not well documented in school-age children in developing countries. We conducted a prospective cohort study to examine the association between infectious disease and weight and height gains among Bangladeshi children. METHODS: A one-year follow-up study was performed to elucidate the determinants and consequences of physical growth of children under five years of age. The study included 135 households randomly selected from four villages in the Matlab area. RESULTS: The most frequent infections were upper respiratory infections (mean = 4 episodes or 27 days per year) followed by non-dysenteric diarrhoea (mean = 2.3 episodes or 15 days per year) and dysentery (mean = 0.2 episodes or 2 days per year). The number of episodes and their duration decreased significantly with age. Over a 12-month period the mean weight gain was 1.3 kg and the mean increase in height was 2.9 cm. The total number of days when diarrhoea occurred was negatively associated with annual weight gain (regression coefficient beta = -7 g per day, P = 0.02), with adjustment for age, sex, energy and protein intake, and household land ownership. The incidence of diarrhoeal disease was significantly associated with weight gain in intermediate models but only marginally associated with it in the final multivariate model (P = 0.08). Neither the incidence nor the duration of upper respiratory infections was associated with weight gain. Height gain was not significantly associated with the duration or incidence of either category of illness. Diarrhoea was a significant correlate of retarded weight gain among children above preschool age, whereas upper respiratory infections were not. DISCUSSION: Diarrhoeal morbidity slowed growth in children well beyond the weaning age, suggesting that increased attention should be given to the study of the continuous impact of diarrhoea in children aged over 5 years. An understanding of the determinants of growth in school-age children in developing countries would maximize the health and developmental outcomes that are the target of international child survival strategies at younger ages.     

河北省涿州市儿童社区获得性肺炎流行特征及病原菌分布

目的 分析涿州市儿童社区获得性肺炎病例流行特征及病原菌分布状况,为本地区儿童社区获得性肺炎的防治工作提供借鉴资料。方法 以2018年7月至2020年6月涿州某医院收治入院的社区获得性肺炎儿童病例为研究对象,收集儿童基本资料并进行病原菌检测,对常见细菌耐药性进行分析。结果 本研究共对涿州市儿童社区获得性肺炎病例829例进行分析,病例中男女性别比为1.03∶1,婴幼儿、学龄前和学龄期儿童分别占48.9%、35.8%、15.3%,发生季节主要为秋冬季,分别占27.9%、36.4%。检出病原菌阳性523例,检出率为63.1%。不同年龄、不同季节的儿童社区获得性肺炎病例病原菌检出率差异有统计学意义（P<0.05或P<0.01）,其中婴幼儿和秋冬季病原菌检出率较高。痰培养细菌检出326株,其中革兰阴性菌228株（占69.9%）。革兰阳性菌98株（占30.1%）,革兰阴性菌以大肠埃希菌为主,革兰阳性菌以肺炎链球菌为主。血清抗体检出支原体阳性53例,阳性率为6.4%,衣原体阳性64例,阳性率为7.7%。咽拭子检测呼吸道合胞病毒感染49例,阳性率为5.9%,流感病毒检出31例,阳性率为3.7%。主要革兰阴性菌大肠埃希菌、肺炎克雷伯杆菌对氨苄西林（59.5%）、头孢唑林（50.6%）的耐药率最高,对亚胺培南、头孢吡肟等敏感;主要革兰阳性菌肺炎链球菌、金黄色葡萄球菌对青霉素（97.2%、85.2%）、红霉素（86.1%、70.4%）的耐药率最高,对万古霉素、阿米卡星等敏感。结论 河北省涿州市儿童社区获得性肺炎以婴幼儿为主,该群体病原菌检出率较高,应根据患儿病原菌分布特点及药敏试验结果合理选择抗菌药物,提高治疗效果的同时预防、延缓耐药菌的产生。     

Nosocomial rotavirus infections in a pediatric unit: surveillance during four successive winters

The incidence of rotavirus and RSV outbreaks during winter seasons leads to overcrowding of pediatric units in the Paris area, and increases the risk of viral nosocomial infections in hospitalized young infants. OBJECTIVE: The aim of this study was to measure the incidence of rotavirus nosocomial infections in children less than 2 years of age during 4 consecutive winters. METHODS: All infants admitted in the pediatric unit during the winter were prospectively screened for rotavirus with a stools exam. All children with negative stools examination on admission but developing diarrhea after 2 days of hospitalization underwent a new screening test for rotavirus in stools. RESULTS: During the 4 consecutive winters, the global incidence of nosocomial rotavirus infection was 13.9% (12.7 to 15.9%). Asymptomatic carriage of rotavirus was detected in 3% of admitted infants. The risk of nosocomial rotavirus infection increases with young age and the length of hospital stay. CONCLUSION: The incidence of nosocomial rotavirus infections was high in this unit. It is related to overcrowding due to coincidence of diarrhea and bronchiolitis outbreaks in the Paris area and to the young age of hospitalized patients.     

Incidence of nosocomial rotavirus infections, symptomatic and asymptomatic, in breast-fed and non-breast-fed infants

Rotavirus is one of the most important aetiological agents of nosocomial infections in childhood. We studied the incidence of nosocomial rotavirus infections in 420 patients (age range 1-18 months) consecutively admitted from 1 December 1999 to 31 May 2000 to the infant ward of the Department of Paediatrics, University of Turin. We also evaluated the protective effect of breast feeding. Faecal specimens were collected from every child (whether developing diarrhoeic symptoms or not) and tested for rotavirus during hospitalization and 72 h after discharge. The incidence of rotavirus nosocomial infections was 27.7%. The incidence of symptomatic nosocomial infections was 16.8%, and the incidence of asymptomatic infections was 10.9%. The attack rate of the infections that occurred during hospitalization was 11.8%, while for those occurring after discharge, it was 15.9%. Rotavirus infection, on average, prolonged hospital stay from 5.2 to 6.4 days. 10.6% of breast-fed infants and 32.4% of non-breast-fed infants contracted rotavirus infection (P<0.005). None of the breast-fed infants who contracted rotavirus infection developed diarrhoeic symptoms.     

Global estimate of the incidence of clinical pneumonia among children under five years of age

OBJECTIVE: Clinical pneumonia (defined as respiratory infections associated with clinical signs of pneumonia, principally pneumonia and bronchiolitis) in children under five years of age is still the leading cause of childhood mortality in the world. In this paper we aim to estimate the worldwide incidence of clinical pneumonia in young children. METHODS: Our estimate for the developing world is based on an analysis of published data on the incidence of clinical pneumonia from community based longitudinal studies. Among more than 2000 studies published since 1961, we identified 46 studies that reported the incidence of clinical pneumonia, and 28 of these met pre-defined quality criteria. FINDINGS: The estimate of the median incidence from those studies was 0.28 episodes per child-year (e/cy). The 25-75% interquartile range was 0.21-0.71. We assessed the plausibility of this estimate using estimates of global mortality from acute respiratory infections and reported case fatality rates for all episodes of clinical pneumonia reported in community-based studies or the case-fatality rate reported only for severe cases and estimates of the proportion of severe cases occurring in a defined population or community. CONCLUSION: The overlap between the ranges of the estimates implies that a plausible incidence estimate of clinical pneumonia for developing countries is 0.29 e/cy. This equates to an annual incidence of 150.7 million new cases, 11-20 million (7-13%) of which are severe enough to require hospital admission. In the developed world no comparable data are available. However, large population-based studies report that the incidence of community-acquired pneumonia among children less than five years old is approximately 0.026 e/cy, suggesting that more than 95% of all episodes of clinical pneumonia in young children worldwide occur in developing countries.