• Clinical and Experimental Pediatrics
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• v.61 no.6
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• pp.180-186
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• 2018

Purpose: Despite the availability of molecular methods, identification of the causative virus in children with acute respiratory infections (ARIs) has proven difficult as the same viruses are often detected in asymptomatic children. Methods: Multiplex reverse transcription polymerase chain reaction assays were performed to detect 15 common respiratory viruses in children under 15 years of age who were hospitalized with ARI between January 2013 and December 2015. Viral epidemiology and clinical profiles of single virus infections were evaluated. Results: Of 3,505 patients, viruses were identified in 2,424 (69.1%), with the assay revealing a single virus in 1,747 cases (49.8%). While major pathogens in single virus-positive cases differed according to age, human rhinovirus (hRV) was common in patients of all ages. Respiratory syncytial virus (RSV), influenza virus (IF), and human metapneumovirus (hMPV) were found to be seasonal pathogens, appearing from fall through winter and spring, whereas hRV and adenovirus (AdV) were detected in every season. Patients with ARIs caused by RSV and hRV were frequently afebrile and more commonly had wheezing compared with patients with other viral ARIs. Neutrophil-dominant inflammation was observed in ARIs caused by IF, AdV, and hRV, whereas lymphocyte-dominant inflammation was observed with RSV A, parainfluenza virus, and hMPV. Monocytosis was common with RSV and AdV, whereas eosinophilia was observed with hRV. Conclusion: In combination with viral identification, recognition of virus-specific clinical and laboratory patterns will expand our understanding of the epidemiology of viral ARIs and help us to establish more efficient therapeutic and preventive strategies.

• The Journal of Korean Society of Virology
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• v.26 no.1
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• pp.9-22
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• 1996

Respiratory Syncytial virus (RSV) is an important cause of acute lower respiratory tract infections in human, with infants and young children being particularly susceptible. In the temperate zones, sharp annual outbreaks of RSV occur during the colder months, in both the northern and the southern hemisphere. RSV is unusual in that it can repeatedly reinfect individuals throughout life and infect babies in the presence of maternal antibody. RSV isolates can be divided into two subgroups, A and B, on the basis of their reactions with monoclonal antibodies, and the two subgroups are also distinct at the nucleotide sequence level. The specific diagnosis of RSV infection was best made by isolation of virus in tissue culture, identification of viral antigen, or by specific serologic procedures. Recently, rapid detection of RSV and analysis of RSV strain variation became possible by development of methods of reverse transcription and polymerase chain reaction amplification. In this study, to determine the genetic diversity of RSV found in Korea, 173 bp and 164 bp spanning selected regions of the RSV F and SH genes were enzymatically amplified and sequenced, respectively. Eight for F gene and three for SH gene were detected in 66 nasopharyngeal swap samples tested. Two major antigenic subgroups, A and B were confirmed from Korean samples (seven for subgroup A and one for subgroup B). At the nucleotide level of the F gene region, Korean subgroup A strains showed 95-99% homologies compared to the prototype A2 strain of subgroup A and 93-100% homologies among Korean subgroup A themselves. For the SH gene region, Korean subgroup A strain showed 97.5% homology compared to the prototype A2 strain of subgroup A, and Korean subgroup B strain showed 97% homology compared to the prototype 18537 strain of subgroup B. Most of base changes were transition and occured in codon position 3, which resulted in amino acid conservation. Using the maximum parsimony method, phylogenetic analysis indicated that Korean RSV strains formed a group with other RSV strains isolated from the United States, Canada, the Great Britain and Australia.

• Korean Journal of Veterinary Pathology
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• v.1 no.2
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• pp.125-134
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• 1997

Porcine Reproductive and Respiratory Syndrome Virus infection (PRRSV) was confirmed by serology histopathology immunohistochemistry and bacteriologic examination in young pigs. Four suckling and six weaned piglets submitted from three different farms showed coughing sneezing labored rapid abdominal respiration lethargy and anorexia. Grossly apical and cardiac lung lobes appeared mottled with pale to dark tan discoloration. Submandibular and bronchial lymph nodes were tan and enlarged. All piglets were seropositive for PRRSV antibodies by the indirect immunofluorescent antibody(IFA) test. Microscopically lung lesions were characterized by hyperplasia and hypertrophy of type 2 pneumocytes infiltration of mononuclear cells in alveolar intersitium accumulation of necrotic debris in alveolar spaces accompanied by proliferation of alveolar multinucleated syncytial cells. Using immunohistochemical technique PRRSV antigens were demonstrated in alveolar macrophages and type 2 pneumocytes in histologic lung tissue sections. Also PRRSV antigens were detected in brain lymph nodes spleen and heart. Additionally piglets showed nonsuppurative meningoencephalitis mandibular necrotic lymphadenopathy splenic atrophy and myocardial necrosis.

• Pediatric Infection and Vaccine
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• v.22 no.3
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• pp.172-177
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• 2015

Purpose: This study aimed to analyze the epidemic period of RSV infection and evaluate the appropriate time of palivizumab immunoprophylaxis. Methods: From January 1991 to July 2012, nasopharyngeal (NP) aspirates were obtained from patients who visited Seoul National University Children's Hospital for respiratory symptoms. NP samples were used to detect respiratory viruses. Among them, we analyzed the positive number and detection rate of RSV infection in two-week interval. The beginning of RSV season was defined when RSV positive number was more than 4 and RSV detection rate was over 10%. From January 2007 to March 2014, we analyzed the starting time of palivizumab immunoprophylaxis for the infants at high risk. Results: The RSV detection rate was 2,013/21,698 (9.69%) over 22 years. The median RSV season was from $2^{nd}-3^{rd}$ week of October to $1^{st}-2^{nd}$ week of February. The earliest starting week was the 3rd week of July in year 2001, and the latest end week was the 3rd week of May in year 1990. Palivizumab immunoprophylaxis was initiated most frequently at the 3rd week of October (18.7%). However, the percentage of starting palivizumab on the 1st week of September has increased from 3.8% in the year 2007 to 14.1% in 2013. Conclusions: The year to year variability of RSV season exists. The starting time of palivizumab immunoprophylaxis should be adjusted based on the season of RSV epidemic.

• Tuberculosis and Respiratory Diseases
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• v.80 no.4
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• pp.358-367
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• 2017

Background: Bacterial pneumonia occurring after respiratory viral infection is common. However, the predominant bacterial species causing pneumonia secondary to respiratory viral infections other than influenza remain unknown. The purpose of this study was to know whether the pathogens causing post-viral bacterial pneumonia vary according to the type of respiratory virus. Methods: Study subjects were 5,298 patients, who underwent multiplex real-time polymerase chain reaction for simultaneous detection of respiratory viruses, among who visited the emergency department or outpatient clinic with respiratory symptoms at Ulsan University Hospital between April 2013 and March 2016. The patients' medical records were retrospectively reviewed. Results: A total of 251 clinically significant bacteria were identified in 233 patients with post-viral bacterial pneumonia. Mycoplasma pneumoniae was the most frequent bacterium in patients aged <16 years, regardless of the preceding virus type (p=0.630). In patients aged ${\geq}16years$, the isolated bacteria varied according to the preceding virus type. The major results were as follows (p<0.001): pneumonia in patients with influenza virus (type A/B), rhinovirus, and human metapneumovirus infections was caused by similar bacteria, and the findings indicated that Staphylococcus aureus pneumonia was very common in these patients. In contrast, coronavirus, parainfluenza virus, and respiratory syncytial virus infections were associated with pneumonia caused by gram-negative bacteria. Conclusion: The pathogens causing post-viral bacterial pneumonia vary according to the type of preceding respiratory virus. This information could help in selecting empirical antibiotics in patients with post-viral pneumonia.

• Pediatric Infection and Vaccine
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• v.14 no.2
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• pp.179-187
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• 2007

Purpose : Acute viral respiratory tract infection is the most common illness among children. Involved organisms are respiratory syncytial virus (RSV), influenza virus, adenovirus, parainfluenza virus, etc. The objective of the present study is to determine epidemiology of each viral infection in Busan, South Korea between January 2004 and December 2006. Methods : We retrospectively analyzed the results of clinical samples of throat and nasal swab collected from Busan city, South Korea between January 2004 and December 2006. We collected these samples from the children with acute respiratory illness. Viruses were detected by virus culture Results : The identified pathogens were influenza A in 131 cases (46.6 percent), RSV in 40 cases (14.2 percent), influenza B in 37 cases (13.2 percent), adenovirus in 23 cases (8.2 percent), enterovirus in 37 cases (13.2%) [coxsackie virus in 20 cases (7.1 percent), atypical enterovirus in 9 cases (3.2 percent), poliovirus in 4 cases (1.4 percent), echovirus in 4 cases (1.4 percent)], rhinovirus in 9 cases (3.2 percent), parainfluenza virus in 2 cases (0.7 percent), coronavirus and bocavirus in each 1 case (0.4 percent). Influenza A were detected every year, mostly in December through April and RSV in October through February. Adenovirus were detected through out the year. Bocavirus occurred in December, 2006. Conclusion : We analyzed epidemiologic characteristics of viruses to cause the respiratory disease that prevailed at Busan area for recent three years, and from now on, a further continuous study will be necessary.

• Pediatric Infection and Vaccine
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• v.30 no.2
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• pp.62-72
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• 2023

Purpose: A change is expected in the pattern of respiratory viruses including human coronavirus (HCoV) after the coronavirus disease 2019 (COVID-19) outbreak. Accordingly, identifying the distribution of respiratory viruses before the COVID-19 outbreak is necessary. Methods: We retrospectively analyzed the results of samples of nasal swabs collected from children under aged ≤18 years who were hospitalized at Myongji Hospital, Gyeonggi-do due to acute respiratory infections from 2017 to 2019. Viruses were detected by real-time reverse transcription polymerase chain reaction (RT-PCR). Results: Out of 3,557 total patients, 3,686 viruses were detected with RT-PCR including coinfections. Of the 3,557 patients, 2,797 (78.6%) were confirmed as PCR-positive. Adenovirus and human rhinovirus (hRV) were detected throughout the year, and human enterovirus was most detected during summer. Respiratory syncytial virus, influenza virus, and HCoV were prevalent in winter. In patients with croup, parainfluenza virus was most frequently detected, followed by hRV and HCoV. The PCR positive rate in summer and winter differed significantly. Conclusions: Respiratory virus patterns in northwestern Gyeonggi-do were not much different from previously reported data. The data reported herein regarding respiratory virus epidemiological information before the COVID-19 outbreak can be used for use in comparative studies of respiratory virus patterns after the COVID-19 outbreak.

• Pediatric Infection and Vaccine
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• v.9 no.2
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• pp.201-207
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• 2002

Purpose : We analyzed clinical features and causal viruses of acute lower respiratory tract infections(LRTIs) in order to improve the management of these infections. Methods : From end of April to early May 2001, amongst 30 children at a local institute for children's adoption and welfare, 13 were admitted to the hospital with the diagnostic impression of acute LRTIs. Nasopharyngeal aspirates were sent in Seoul National University Hospital for viral culture of respiratory syncytial virus(RSV), adenovirus, parainfluenza virus. Results : One or more viral agents were identified in 4 cases(30.7%) : were RSV(15.4%), adenovirus(7.7%), and a mix of these two viruses(7.7%). Initial symptoms were fever(69%), cough(100%), tachypnea(54%), chest retraction(69%), rale(85%) and wheezing(15%). Leukocytosis was noted in 23%, CRP increased more than 10 mg/L in 46%. Chest X-ray abnormalities were 69%. Conclusion : Although viruses were identified in 30.7%, further studies should be made for prevention and treatment of acute viral LRTIs.

• Clinical and Experimental Pediatrics
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• v.49 no.4
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• pp.394-400
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• 2006

Purpose : This study was design and performed for evaluations of resent clinical pattern of bronchiolitis caused by RSV infection with children under 2 year of age for 5 years, who were admitted to pediatric ward. Methods : The inclusion criteria of the patients were children under 24 month-of-age, clinical manifestations of lower respiratory tract infection, and RSV antigen that was detected by a direct immunofluorescence test from the nasal secretions. The additional laboratory and simple chest X-ray findings were reviewed from the medical records of children who were admitted Wonkwang university hospital from Jan. 1999 to Dec. 2003. Results : In the 5 year study duration, 127 patients were enrolled and outbreak of RSV bronchiolitis took place in 2001. The 80 cases(63 percent) of RSV infection were concentrated in later autumn and winter. Number of the cases show coughing were 120(94.5 percent), but rale was audible in 78 cases(61.4 percent). Dyspnea, wheezing, and intercostal retraction were noticed in 27(21.3 percent), 21(16.5 percent), and 4(3 percent) cases respectively. The most common chest X-ray finding was hyperinflation of the lung that was noticed in 110 cases(86.6 percent). Care with mechanical ventilator for more than 2 days required in 5 cases. Conclusion : Lower respiratory tract infection by RSV was common in late autumn and winter season but year-round infection was noticed. The severity of RSV respiratory tract infectiontakes in some degree a grave course. So we suggest that population-based surveillance of acute respiratory infection due to RSV is necessary for assessment of prevalence and epidemiology of this disease.

• Pediatric Infection and Vaccine
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• v.20 no.3
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• pp.178-185
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• 2013

Objective: Cytopenia is a common hematologic complication of viral infections. However, information regarding hematologic effects of common respiratory virus infections is scarce. This study aimed to evaluate hematologic complications and the clinical course of patients infected with common respiratory viruses. Methods: We retrospectively analyzed 496 patients with respiratory tract infections admitted to the Department of Pediatrics, Wonkwang University Hospital from November 2011 to March 2012 using multiplex real-time polymerase chain reaction to detect the presence of respiratory viruses and hematologic abnormalities. Results: Respiratory viruses were identified in 379 patients. Respiratory syncytial virus (RSV) was most frequently detected (55.7%), followed by influenza A (Flu-A, 23.0%). Further, cytopenia was observed in 35.5% of RSV-infected patients, 25.0% of Flu-A-infected patients, and 34% of patients infected by other viruses. Each virus caused a decrease in 3 blood cell component values, which corresponded with cytopenia frequency. Of the 379 infected patients, 83 had anemia ($9.71{\pm}1.09g/dL$); 46 had neutropenia ($803.70{\pm}263.09cells/mm^3$); and 23 had transient thrombocytopenia ($142,434.78{\pm}86,835.18cells/mm^3$). However, no patient required treatment. A comparison of clinical characteristics between RSV- and Flu-A-positive patients with anemia revealed that RSV-infected patients had significantly longer duration of hospitalization. RSV was detected more commonly in young neutropenic patients, who had a shorter duration of fever. Conclusions: Our findings suggest that infections, particularly RSV and Flu-A, result in varying degrees of cytopenia, which usually improves without treatment and does not affect the clinical course of the infection.