PURPOSE: Acute respiratory tract infections are the most common illnesses in children. The great majority of these infections involving lower respiratory tracts infections(LRTIs) are caused by respiratory viruses such as respiratory syncytial virus(RSV), parainfluenza virus(PIV), influenza virus (Flu), and adenovirus(ADV), etc. Our purpose was to determine seasonal epidemiology and clinical characteristic features of each viral infection. METHODS: Nasopharyngeal aspirate(NPA)s were collected from 4,554 hospitalized children diagnosed as LRTIs on the first day of admission. The study period was from September 1998(Autumn) through May 2003(Spring). Respiratory viruses were detected in 881(19 percent) cases by isolation of the virus or by antigen detection method using indirect immunofluorescent staining. We reviewed the medical records of 837 cases retrospectively. RESULTS: The identified pathogens were RSV in 485 cases(55 percent), PIV in 152 cases(17 percent), FluA in 114 cases(13 percent), ADV in 79 cases(9 percent) and FluB in 51 cases(6 percent). Outbreaks of RSV occurred every year, mostly in the November through December period and of PIV in the April through June period. LRTIs by FluA reached the highest level in January, 2002. FluB infection showed an outbreak in April, 2002. The clinical diagnoses of viral LRTIs were bronchiolitis in 395 cases(47 percent), pneumonia in 305 cases(36 percent), croup in 73 cases(9 percent) and tracheobronchitis in 64 cases(8 percent). CONCLUSION: Viruses are one of the major etiologic agents of acute LRTIs in chidren. Therefore, we must continue to study their seasonal occurrence and clinical features to focus on management, and also for reasons of prevention.
Adenoviridae ; Bronchiolitis ; Child ; Child, Hospitalized ; Croup ; Diagnosis ; Disease Outbreaks ; Epidemiology* ; Humans ; Medical Records ; Orthomyxoviridae ; Paramyxoviridae Infections ; Pneumonia ; Respiratory Syncytial Viruses ; Respiratory System* ; Respiratory Tract Infections* ; Retrospective Studies ; Seasons

BACKGROUND: The information on the incidence, seasonal variation and clinical pattern of respiratory virus infections is very important for clinicians in managing their patients. This study was aimed to define the epidemiology of respiratory viral pathogens in Seoul and the neighboring areas from March 2004 to February 2006. METHODS: A total of 6,533 specimens were cultured for respiratory viruses during the study period. Madin-Darby canine kidney (MDCK), LLC-MK2, and HEp-2 cells, or R-mix cells (Diagnostic Hybrids Inc., Athens, Ohio, USA) were used for culture. Influenza virus types A & B (Inf A & B), parainfluenza virus (PIV), respiratory syncytial virus (RSV), and adenovirus (ADV) were identified by indirect immuno-fluorescent staining. Medical records of the patients with positive virus cultures were reviewed retrospectively. RESULTS: One or more viral agents were isolated from 1682 specimens (25.7%). The pathogens identified were RSV 37.2%, ADV 19.9%, Inf A 18.9%, PIV 17.5% and Inf B 6.4%. The most frequent pathogen of pneumonia and acute bronchiolitis was RSV and that of croup was PIV. Upper respiratory tract infections were more prevalent in adults and the most frequently caused by influenza virus. Influenza virus itself was more frequently isolated in children less than six years old, which was different from previous reports. Influenza virus was mostly isolated in the winter and spring, while RSV was usually isolated from early fall with a peak incidence in the winter. Inf A and RSV showed a dampening effect on the occurrence of other viruses during their major epidemic. PIV was mostly detected in the spring and summer. ADV was isolated throughout the whole year. CONCLUSIONS: The epidemiological characteristics of respiratory virus infections in Seoul and the neighboring areas in 2004-2006, were similar to the findings of previous reports except for some minor changes. These findings could be useful to clinicians in managing their patients.
Adenoviridae ; Adult ; Bronchiolitis ; Child ; Croup ; Epidemiology* ; Humans ; Incidence ; Kidney ; Medical Records ; Ohio ; Orthomyxoviridae ; Paramyxoviridae Infections ; Pneumonia ; Respiratory Syncytial Viruses ; Respiratory Tract Infections ; Retrospective Studies ; Seasons ; Seoul

BACKGROUND: Although influenza has been a leading cause of global morbidity and mortality, we have few data regarding the epidemiological and clinical characteristics of influenza activity in Korea. Since an outbreak of influenza was recognized during winter of 1996-1997, we analyzed the epidemiological and clinical features of influenza activity in the hospital setting. METHODS: All clinical specimens requested for isolation of influenza virus at Samsung Medical Center from October 1996 to April 1997 were included. Mardin- Darby canine kidney (MDCK) cell line was used for virus culture. Isolated viruses were confirmed with immunostain followed by subtyping. The demographic and clinical characteristics of the patients were reviewed retrospectively. RESULTS: Ninety-eight influenza viruses were isolated from 461 patients (21.3%). Influenza A and B virus was isolated from 58 (54 children and 4 adults) and 40 pediatric patients, respectively. One of 31 influenza A viruses were confirmed as A/Wuhan/359/95-like strain and 5 of 12 influenza B viruses were confirmed as B/Guangdong/8/97-like strains. Two distinctive peaks of influenza activity were recognized and the most common age of patients was less than 1 year for influenza A, and 3 to 5 years for influenza B. Common lower respiratory infections were pneumonia followed by croup, bronchiolitis and laryngitis. CONCLUSION: We analyzed the epidemiological and clinical features of influenza activity during winter of 1996-1997. Although this study was performed not in the community but in the hospital setting, the morbidity caused by influenza may not be low in Korea. Therefore, nationwide surveillance for influenza activity is warranted.
Bronchiolitis ; Cell Line ; Child ; Croup ; Epidemiology ; Herpesvirus 1, Cercopithecine ; Humans ; Influenza A virus ; Influenza B virus ; Influenza, Human* ; Kidney ; Korea ; Laryngitis ; Mortality ; Orthomyxoviridae ; Pneumonia ; Respiratory Tract Infections ; Retrospective Studies

PURPOSE: Croup, a common childhood respiratory illness with various severities, has many unanswered questions. Laryngotracheobronchopneumonitis (LTBP) is a disease entity considered to be an extension of croup to the lower respiratory tract. The object of this study was to compare epidemiology, clinical characteristics, and viral etiologic spectrum between croup and LTBP. METHODS: Patients hospitalized with croup at Gachon University Gil Hospital from January 2010 to April 2016 were recruited. LTBP was defined as pneumonia confirmed on radiographs of patients with croup. Clinical findings and demographic data were reviewed of patients whose nasopharyngeal swabs were done for viral analysis. RESULTS: A total of 371 patients with only croup and 63 patients with LTBP were included. Croup was found to be significantly associated with parainfluenza virus type 1 (P=0.006). LTBP was related to parainfluenza virus type 3, respiratory syncytial virus, and human bocavirus (P=0.001, P=0.030, and P=0.019, respectively). The duration of fever was longer in patients with LTBP than in those with croup (3.87±1.85 days vs. 2.86±1.80 days, P<0.001). CONCLUSION: Specific etiologic viruses might be associated with the progression from croup to LTBP. Pronged fever is also associated with progression from croup to LTBP.
Child* ; Croup* ; Epidemiology ; Fever ; Human bocavirus ; Humans ; Parainfluenza Virus 1, Human ; Parainfluenza Virus 3, Human ; Pneumonia ; Respiratory Syncytial Viruses ; Respiratory System

PURPOSE: We aimed to identify the epidemiology and the clinical characteristics of human parainfluenza virus type 4 (HPIV-4) infection compared to HPIVs 1–3 infections in Korean children. METHODS: We reviewed medical records of children with HPIV infection who visited Seoul National University Children's Hospital from 2015 to 2017. Detection of respiratory viruses was performed using real time-polymerase chain reaction (rt-PCR), which could differentiate HPIVs 1–4. Diagnosis was classified as a febrile illness, upper respiratory tract infection (URI), croup, bronchiolitis, or pneumonia. The epidemiology, demographic features, and clinical characteristics among HPIV types were compared. The clinical data were analyzed only for the previously healthy children. RESULTS: Of the 472 children diagnosed with HPIV infection, 108 (22.9%) were previously healthy: 24 (22.2%), 19 (17.6%), 39 (36.1%), and 26 (24.1%) in HPIV types 1, 2, 3, and 4, respectively. The median age of children with HPIV-4 infection was 11 (0–195) months: the proportion of children aged < 2 years and 2 to < 5 years were 65.4% and 19.2%, respectively. Clinical diagnoses of HPIV-4 infection were bronchiolitis (38.5%), pneumonia (30.8%), and URI (30.8%). Croup was the most prevalent in HPIV-2 (21.1%) and none in HPIV-4 infection (P=0.026). Hospital admission rates among HPIV types were not significantly different (P> 0.05). CONCLUSIONS: We observed seasonal peak of HPIV-4 infection in 2015 and 2017. HPIV-4 was a common respiratory pathogen causing lower respiratory tract infection in hospitalized children.
Bronchiolitis ; Child ; Child, Hospitalized ; Croup ; Diagnosis ; Epidemiology ; Humans ; Medical Records ; Parainfluenza Virus 4, Human ; Paramyxoviridae Infections ; Pneumonia ; Respiratory Tract Infections ; Seasons ; Seoul

PURPOSE: Croup is a common respiratory disease in children. The aim of this study was to analyze the epidemiology, etiology, and seasonal variations of respiratory virus infections in children with croup. METHODS: From October 2009 to September 2017, children admitted with croup to Gachon University Gil Medical Center under the age of 18 years were enrolled in this study. We retrospectively reviewed patients' medical records. RESULTS: A total of 1,053 of 27,330 patients (3.9%) infected with lower respiratory infections were diagnosed as having croup. In the age distribution, croup was most common (50.0%) in children aged 1 to <2 years. There were 2 peaks, the major in summer (July to August) and the minor in spring (March to May). Parainfluenza virus type 1 (15.8%) was most prevalent and coincided with the summer peaks of croup. Influenza virus type B and parainfluenza virus type 3 were the most frequent etiologic agents in a spring peak of croup. Although parainfluenza virus type 1 was predominant of all ages, human coronavirus was a significant cause of croup in children younger than 1 year, whereas influenza virus played an important role in children above the age of 3 years. CONCLUSION: Seasonality and epidemiology of croup varied with age and regions. Two peaks of seasonal fluctuation were in summer and spring, which were related to the seasonality of respiratory viruses in croup. These results may be helpful in planning clinical and research needs.
Age Distribution ; Child ; Coronavirus ; Croup* ; Epidemiology ; Humans ; Medical Records ; Orthomyxoviridae ; Parainfluenza Virus 1, Human ; Parainfluenza Virus 3, Human ; Respiratory System* ; Respiratory Tract Infections* ; Retrospective Studies ; Seasons*

PURPOSE: Acute lower respiratory tract infections (LRI) are important causes of pediatric morbidity and mortality. Recently among the common pathogens causing acute LRI in children respiratory viruses are apparently increasing rather than bacteria and mycoplasma in Korea. This study was aimed to define the distribution of age, seasonal variation and clinical manifestation of respiratory virus in children. METHODS: All 328 children in Seoul, who had hospitalized at the Pediatric ward of Hanyang University (138 children), Hallym University (61 children) and Sungkunkwan University (129 children) for the treatment of respiratory diseases were studied from March, 1997 to February, 1998. In nasopharyngeal aspirates obtained from these patients viral agents were detected by virus isolation and/or antigen detection by indirect immunofluorescent staining. But the subjects who was not found respiratory virus were excluded, although respiratory symptoms were present. RESULTS: 1) One or more agents were identified in 328 subjects. 2) The pathogens identified were Respiratory syncytial virus (RSV : 44.7%), influenza A virus (25.6 %), parainfluenza virus (14.6%), influenza B virus (14.3%), adenovirus (4.3%) and two or more viruses (3%). 3) Infections with RSV, parainfluenza virus and influenza A and B virus occured in epidemics, while adenovirus was isolated sporadically throughout the study period. 4) Clinical patterns of viral LRI were pneumonia (39%), bronchiolitis (34%), croup (18%), acute pharyngitis (7%) and asthma (2%). CONCLUSIONS: RSV was the most important in viral respiratory tract infection in children. Clinical manifestation and epidemic characterics were variable according to the agent. Accordingly, we should acknowledge the importance of respiratory virus to cause the repiratory tract diseases in children.
Adenoviridae ; Asthma ; Bacteria ; Bronchiolitis ; Child ; Croup ; Epidemiology* ; Herpesvirus 1, Cercopithecine ; Humans ; Influenza A virus ; Influenza B virus ; Influenza, Human ; Korea ; Mortality ; Mycoplasma ; Paramyxoviridae Infections ; Pharyngitis ; Pneumonia ; Respiratory Syncytial Viruses ; Respiratory System* ; Respiratory Tract Infections* ; Seasons ; Seoul*

PURPOSE: Causes of acute lower respiratory tract infections (ALRI) in children are diverse. But virus is the most common cause of ALRI, so it is important to understand the etiology and epidemiology of ALRI. This study was performed to investigate the etiologic organisms, age distribution, clinical manifestations and seasonal occurrence of ALRI in hospitalized children. METHODS: We confirmed viral etiologies using nasopharyngeal aspirates in 377 patients of the ages of 15 years or younger who were hospitalized for ALRI from March, 1996 to February, 1999 at Samsung Seoul Hospital, Seoul, Korea. Viral agents were detected by virus isolation and antigen detection by indirect immunofluorescent staining. RESULTS: The viral pathogens identified were influenza A (22.2%), influenza B (9.0 %), adenovirus (21.2%), parainfluenza virus type 1 (8.8%), type 2 (3.4%), type 3 (15.1%) and respiratory syncytial virus (RSV) (20.2%). The occurrence of ALRIs was high under 2 year old. The clinical patterns of viral ALRI include pneumonia (49.9%), croup (20.2%), bronchiolitis (22.0%), tracheobronchitis (8.0%). The specific viruses are frequently associated with specific clinical syndrome of ALRI. The respiratory agents and associated syndromes frequently have characteristic seasonal patterns. CONCLUSION: This study will help us to estimate the etiologic agents of ALRI, and to avoid inappropriate antibiotic therapy. An annual nationwide survey is necessary to understand the viral epidemiology associated with respiratory illness.
Adenoviridae ; Age Distribution ; Bronchiolitis ; Child ; Child, Hospitalized* ; Child, Preschool ; Croup ; Epidemiology ; Humans ; Influenza, Human ; Korea ; Parainfluenza Virus 1, Human ; Pneumonia ; Respiratory Syncytial Viruses ; Respiratory System* ; Respiratory Tract Infections* ; Seasons ; Seoul

PURPOSE: Acute respiratory tract infection is one of the most common illnesses in children. Causes of acute lower respiratory infections (ALRI) are known to be caused by bacteria, mycoplasma, and respiratory viruses. There is a wide geographic variation regarding the relative importance of each viral agent. This study was to examine the seasonal occurrences of respiratory viruses and the viral etiologic agents, and age, sex distribution, clinical manifestations of viral ALRI in children of the Choongchung Province area. METHODS: Nasopharyngeal aspirates were collected from 2, 209 hospitalized children on the first day of admission at Soonchunhyang University Hospital at Cheonan and examined by indirect immunofluorescent staining from May 2001 through April 2004. RESULTS: Viral agents were detected in 26.4% (583/2, 209). The pathogens identified were RSV 62.1% (366), parainfluenza virus 14.6% (85), adenovirus 13.7% (80), Influenza virus type A 59.3 percent (54), Influenza virus type B 0.1% (5). Outbreaks of RSV infections occurred every year but mostly in January 2003 and December 2003. Infections with influenza virus type A, B, parainfluenza virus and adenovirus occurred in epidemics. The occurrence of viral ALRI was highest in the 1st year of life. The clinical patterns of viral ALRI were pneumonia (48.9%), bronchiolitis (36.7%), tracheobronchitis (9.5%), and croup (4.0%). The most common cause of bronchiolitis was RSV. CONCLUSIONS: Viral agents were detected by indirect immunofluorescent staining in 26.4% (583 cases) from NPA of 2, 209 hospitalized pediatric patients with acute respiratory tract diseases in the Choongchung Province from May 2001 through Apr 2004. RSV, Influenza virus type A, B, parainfluenza virus and adenovirus in pediatric ALRI have had their own characteristic outbreak patterns and clinical features in this area.
Adenoviridae ; Bacteria ; Bronchiolitis ; Child ; Child, Hospitalized* ; Chungcheongnam-do ; Croup ; Disease Outbreaks ; Epidemiology* ; Humans ; Mycoplasma ; Orthomyxoviridae ; Paramyxoviridae Infections ; Pneumonia ; Respiratory System* ; Respiratory Tract Diseases ; Respiratory Tract Infections* ; Seasons ; Sex Distribution

BACKGROUND: This study was performed to investigate the epidemiologic and clinical features of acute respiratory viral infection in hospitalized children. METHODS: From 2010 to 2012, we tested nasopharyngeal swab specimen in 1,584 hospitalized children with multiple real-time polymerase chain reactions to identify 10 kinds of respiratory viruses (including influenza virus A, B (FluA, FluB), respiratory syncytial virus (RSV), human metapneumovirus (MPV), adenovirus (AdV), human coronavirus (CoronaV), human enterovirus (HEV), human bocavirus (HBoV), parainfluenza virus (PIV), and human rhinovirus (Rhinovirus)). We analyzed the positive rate, annual and seasonal variations, and clinical features (respiratory tract and non-respiratory tract) according to the retrospective review of medical records. RESULTS: Respiratory viruses were detected from 678 (42.8%) of 1,584 patients. The most common detected virus was RSV (35.0%), and then AdV (19.0%), HEV (18.1%). The critical period of the respiratory viral infection was during the first 12 months of a child's life. PIV increased by 8.4%, 12.1%, and 21.1% annually. Bronchiolitis was most frequently caused by RSV, and croup was frequently caused by PIV. The most common cause of meningitis was HEV. Hepatitis-associated respiratory virus was developed 111 in 678 cases. CONCLUSION: Although this study was confined to a single medical center for three years, we identified the epidemiology and clinical feature of respiratory viruses in Daegu from 2010 to 2012. Future surveillance will be necessary for annual and seasonal variations.
Adenoviridae ; Bronchiolitis ; Child ; Child, Hospitalized ; Coronavirus ; Critical Period (Psychology) ; Croup ; Daegu* ; Enterovirus ; Epidemiology* ; Human bocavirus ; Humans ; Inpatients* ; Medical Records ; Meningitis ; Metapneumovirus ; Orthomyxoviridae ; Paramyxoviridae Infections ; Polymerase Chain Reaction ; Respiratory Syncytial Viruses ; Respiratory Tract Infections ; Retrospective Studies ; Rhinovirus ; Seasons ; Viruses