Spatial relationship between COVID-19 and previous infectious disease outbreaks: Evidence from South Korea.

As the novel coronavirus disease (COVID-19) has been rapidly spreading across the world, scholars have started paying attention to risk factors that affect the occurrence of the infectious disease. While various urban characteristics have been shown to influence the outbreak, less is known about whether COVID-19 is more likely to be transmitted in areas with a greater number of incidents of previous infectious diseases. This study examines a spatial relationship between COVID-19 and previous infectious diseases from a spatial perspective. Using the confirmed cases of COVID-19 and other types of infectious diseases across South Korea, we identified spatial clusters through regression and spatial econometric models. We found that COVID-19-confirmed case rates tended to be clustered despite no similarity with the spatial patterns of previous infectious diseases. Existing infectious diseases from abroad were associated with the occurrence of COVID-19, while the effect diminished after controlling for the spatial effect. Our findings highlight the importance of regional-level infectious disease surveillance for the effective prevention and control of COVID-19.

Early immune response of neuronal cells (U87) to heavy metal Cd or Pb exposure.

Heavy metals such as lead (Pb) and cadmium (Cd) exist as particulate matter (PM) in the air and can cause biological damage to cells, animals, and humans. However, the mechanism underlying the toxic effects of heavy metals on nerve cells has not yet been completely identified. Glioma is the most common and fatal tumor in the central nervous system; the U87 human glioblastoma cell line is commonly used when researching brain cancer, including aggressive malignant gliomas. Therefore, in this study, cell viability, cytotoxicity, and interleukin-6 (IL-6) levels were analyzed to confirm the effect of Cd and Pb exposure on U87 cells. On confirming the absence of significant effects on cell viability at low concentrations of heavy metals, Cd and Pb exposure had no effect on lactic acid dehydrogenase (LDH) activity at the concentrations (1 µg/L, 30 µg/L, and 1 mg/L) used in this study, and there was a remarkable effect of Cd and Pb exposure on the inflammatory response of these cells. Our findings provide a basis for future research elucidating the effects of heavy metal exposure on cellular pathology. Systematic studies with higher heavy metal concentrations and precision are warranted to deepen our understanding of the relationship between heavy metal exposure and neuronal responses.

Distribution Analysis of Candida albicans according to Sex and Age in Clinical Specimen Testing for Sexually Transmitted Diseases.

The prevalence of candidiasis, a contagious disease with high morbidity and mortality, has sharply increased globally over the last two decades. Candida albicans can cause serious infections in patients with weak immunity and in recipients of prolonged antibiotic treatment. Consequently, rapid and accurate identification of species can play an important role in the treatment of candidiasis. Here, we investigated the positive rate and infection trend of Candida albicans according to age, specimen type, and sex using multiplex real-time polymerase chain reactionbased testing of samples collected for the diagnosis of sexually transmitted diseases in Korea between 2018 and 2020. When the type of specimen collected was a swab, the positive rate of Candida albicans was higher among younger women, and tended to decrease with age. Analysis of swab samples revealed higher positive rates than urinalysis. The reduction trend in positive rates by age was comparable between the overall samples and urine specimens. Among male patients, the positive rate did not differ substantially across the various types of specimens collected. Previous studies have shown a higher prevalence of non-albicans Candida species than Candida albicans in clinical specimens, and exclusion of the former from our analysis may be a limitation of this study. However, our findings contribute significantly to the literature because globally, there is a paucity of epidemiological studies using molecular techniques to detect Candida albicans in sexually transmitted disease test samples.

Coinfections with multiple sexually transmitted pathogens in Republic of Korea, 2018-2020.

BACKGROUND: Sexually transmitted infections (STIs) can have serious consequences, and the global STI incidence remains high. However, there is little information on the frequency of STIs with multiple pathogens according to age. Accordingly, we conducted a study to determine the trends of coinfection with sexually transmitted pathogens according to age in the Republic of Korea from 2018 to 2020. METHODS: From January 2018 to December 2020, 65,191 samples of swab, urine, and other types submitted for STI screening were obtained from U2Bio Co. Ltd. (Seoul, Republic of Korea). Multiplex polymerase chain reaction, a sensitive and rapid method for simultaneous detection of STIs caused by multiple different pathogens, was performed using an AccuPower STI4C-Plex Real-Time PCR kit, AccuPower STI8A-Plex Real-Time PCR kit, and AccuPower STI8B-Plex Real-Time PCR kit with an Exicycler 96 Real-Time Quantitative Thermal Block. RESULTS: Of the 65,191 samples tested, 35,366 (54.3%) tested positive for one or more sexually transmitted pathogens. The prevalence of coinfections with two or more sexually transmitted pathogens was inversely proportional to age. Furthermore, the rates of coinfection with sexually transmitted pathogens and age distribution differed according to sex and the sexually transmitted pathogen type. CONCLUSION: This study confirmed that a significant proportion of patients with STIs are coinfected with multiple pathogens. Public health managers could use these results to recognize and prevent STIs according to age.

Association between climatic factors and respiratory syncytial virus detection rates in Cheonan, Korea.

The use of big data may facilitate the recognition and interpretation of causal relationships between disease occurrence and climatic variables. This study examined the effects of various climatic variables on the seasonal epidemiology of respiratory syncytial virus (RSV) infections in the temperate climate of Korea. Trends in RSV detection were analyzed using 9010 samples tested between January 1, 2012, and December 31, 2018, at Dankook University Hospital in Cheonan, Korea. Seasonal patterns in RSV detection frequency were compared with local climatic variables during the same period. RSV detection rate of 12.8% (n = 1150/9010) was observed, which was higher for RSV-A (7.1%) than RSV-B (5.8%) and RSV-A and RSV-B alternated each year. Children < 1 year exhibited high infection rates with RSV-A (68.5%) and RSV-B (58.7%). RSV-A and RSV-B infection rates in children under 9 years old were 96.2% and 92.1%, respectively. RSV had a significant relationship with several climatic factors. Air temperature, wind chill temperature, and particulate matter concentration were lower on days with a higher frequency of RSV detection. In contrast, atmospheric pressure was higher on days with lower RSV detection. Although the detection rates for RSV-A and RSV-B increased on days with lower air temperatures, those for RSV-B also increased on days with lower wind chill temperatures. Our findings suggest that climatic variables affect the RSV detection rate among children under 10 years of age. The present data may help predict the time when prevention strategies may be the most effective.

Effects of climatic factors and particulate matter on Rotavirus A infections in Cheonan, Korea, in 2010-2019.

Rotavirus A is the most common cause of infectious diarrhea worldwide. This study aimed to retrospectively study and analyze 4009 stool samples that were tested for viruses causing diarrhea, using multiplex reverse transcription PCR at Dankook University Hospital between 2010 and 2019. Furthermore, we determined the correlation between these factors and various climatic factors, including wind-chill temperature, relative humidity, rate of sunshine, and particulate matter. Rotavirus A infections occurred frequently in February, March, and April on an annual basis. Furthermore, during the study, the detection rate was highest at 17.0% (n=61/359) in 2011. Based on an analysis of weather big data, patient age, and period-specific infection during the summer, when the wind-chill temperature and relative humidity were high, the Rotavirus A infection rate was very low. Relative humidity (p=0.020) and particulate matter (p=0.049) were associated with the average number of monthly cases of Rotavirus A infection. However, wind chill temperature (p=0.074) and rate of sunshine (p=0.993) were not associated with the average monthly distribution of Rotavirus A cases. These results indicate that Rotavirus A infection was correlated with relative humidity and particulate matter during the study period and further the current understanding of the distribution of Rotavirus A infections resulting from climatic factors and particulate matter. This could help establish climate-related health policies to reduce the incidence of diarrhea and guide the development of vaccines against Rotavirus A.

Climate and Human coronaviruses 229E and Human coronaviruses OC43 Infections: Respiratory Viral Infections Prevalence in Hospitalized Children in Cheonan, Korea.

The study of climate and respiratory viral infections using big data may enable the recognition and interpretation of relationships between disease occurrence and climatic variables. In this study, realtime reverse transcription quantitative PCR (qPCR) methods were used to identify Human respiratory coronaviruses (HCoV). infections in patients below 10 years of age with respiratory infections who visited Dankook University Hospital in Cheonan, South Korea, from January 1, 2012, to December 31, 2018. Out of the 9010 patients who underwent respiratory virus real-time reverse transcription qPCR test, 364 tested positive for HCoV infections. Among these 364 patients, 72.8% (n = 265) were below 10 years of age. Data regarding the frequency of infections was used to uncover the seasonal pattern of the two viral strains, which was then compared with local meteorological data for the same time period. HCoV-229E and HCoV-OC43 showed high infection rates in patients below 10 years of age. There was a negative relationship between HCoV-229E and HCoV-OC43 infections with air temperature and wind-chill temperatures. Both HCoV-229E and HCoV-OC43 rates of infection were positively related to atmospheric pressure, while HCoV-229E was also positively associated with particulate matter concentrations. Our results suggest that climatic variables affect the rate in which children below 10 years of age are infected with HCoV. These findings may help to predict when prevention strategies may be most effective.

Serum Hepcidin to Prohepcidin Ratio in Children with Iron Deficiency Anemia.

BACKGROUND: Hepcidin is produced in hepatocytes as a precursor form that needs to be converted to a mature hepcidin to be active. In iron deficiency anemia (IDA), the synthesis of hepcidin is inhibited; however, it is not clear how the maturation of hepcidin precursor is affected. To assess the relative maturity of serum hepcidin in the setting of IDA, we compared the ratio of mature hepcidin to prohepcidin in children with different iron statuses. METHODS: A total of 51 children (age: 0.6~18.2 yr) with normal renal function and C-reactive protein levels were enrolled. Based on hemoglobin levels and iron status, the subjects were classified as control (n=29), iron deficiency without anemia (n=6), and IDA (n=16). Serum concentrations of hepcidin and prohepcidin were measured by enzyme-linked immunosorbent assays. RESULTS: Hepcidin was positively correlated with hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, iron, transferrin saturation, and ferritin, and negatively correlated with total iron binding capacity and transferrin. IDA patients had lower levels of prohepcidin [4.7(1.9~21.7) vs 34.6(11.0~140.4) ng/mL, p<0.001] and hepcidin [9.6(3.3~39.5) vs 75.2(19.9~256.4) ng/mL, p<0.001] than control subjects. Hepcidin was strongly correlated with prohepcidin (r=0.991, p<0.001). As compared with control subjects, the hepcidin to prohepcidin ratio was lower in those with IDA (1.89±0.24 vs 2.11±0.18, p=0.009) or low serum ferritin. CONCLUSION: These findings suggest that inhibited maturation, as well as inhibited synthesis, may contribute to low hepcidin level in IDA.

Laboratory Investigation of Trends in Bacterial Pneumonia in Cheonan, Korea, from January 2008 to September 2017.

Bacterial pneumonia is one of the most common causes of mortality in Korea. In 2016, the mortality rate from pneumonia was 16,476 deaths per 100,000, which was an 11% increase from the previous year. The aim of our study was to determine the distribution of the bacterial pathogens causing respiratory symptoms in different age groups over a 10-year period. Between January 2008 and September 2017, 1,861 specimens from 1,664 patients admitted to Dankook University Hospital with respiratory symptoms were examined. We used multiplex polymerase chain reaction (PCR) to detect six bacterial pneumonia pathogens: Bordetella pertussis, Chlamydophila pneumoniae, Haemophilus influenzae, Legionella pneumophila, Mycoplasma pneumoniae, and Streptococcus pneumoniae. We detected bacterial pneumonia pathogens in 1,281 (68.83%) specimens. Of the 1,709 pathogens detected, S. pneumoniae was the most common (48.57%; n = 830) followed by H. influenzae (40.08%; n = 685). Most infections were found among children younger than 10 years (92.69%; n = 1,584). Although S. pneumoniae was the most common pathogen detected in all age groups, M. pneumoniae infection increased in prevalence with age (p ＜ 0.05). The rate of co-infection was also high among these patients (31.1%; n = 399), which peaked in 2015 (54.55%; n = 42/77). The prevalence of bacterial pneumonia in Cheonan, along with the proportion of co-infections among patients increased over the 10-year study period. The findings will aid the development of treatment and prevention guidelines.

Genetic and phenotypic characterizations of drug-resistant Mycobacterium tuberculosis isolates in Cheonan, Korea.

BACKGROUND: Mycobacterium tuberculosis (MTB) causes tuberculosis (TB), which is a fatal disease. Cases of drug-resistant MTB have increased in recent years. In this study, we analyzed 7 sites of MTB DNA sequences, including the rpoB and inhA gene, to investigate the relationship between gene mutations and drug resistance in MTB. METHODS: Mycobacterium tuberculosis liquid culture samples (197 specimens from 74 cases) were collected between June 2015 and May 2016 and sequenced. The results were compared with those obtained from antibiotic susceptibility tests. RESULTS: In 65 (87.8%) cases, the antibiotic-resistant phenotype was consistent with genotyping results, whereas in 9 (12.2%) cases, there was no match. Eight mutations were detected in the rpoB gene, which showed the highest mutation rate. Sequencing results indicated that these mutations were present in 12 cases. CONCLUSION: Previously published data on antibiotic resistance genes are insufficient for effective prevention of multidrug- or extensive drug-resistant TB. Additional studies are needed to characterize the complement of antibiotic resistance genes in MTB.

Distribution of Mycobacterium tuberculosis in Korea in the preceding decade.

BACKGROUND: Tuberculosis (TB) is an infectious disease caused by the bacillus Mycobacterium tuberculosis (MTB); it is transmitted among people through air. The aim of this study was to assess the prevalence of TB and its clinical trends by collecting and analyzing data on specimens in Korea. METHODS: All clinical specimens referred to the Dankook University Hospital Laboratory in Cheonan, Korea, from September 2005 to June 2016 were tested to isolate MTB using solid and liquid cultures, acid-fast bacilli (AFB) smears, and polymerase chain reactions (PCR). RESULTS: In total, 146 150 specimens were collected; the mean TB positivity rate was 7.8%. The highest positivity rate was observed among patients 30-39 years of age (12.6%), followed by those 20-29 years of age (12.2%). The mean positivity rate was highest in 2010 and lowest in 2016 (10.7% and 6.7%, respectively). When comparing 2015-2011, we saw a decrease in the number of TB-positive patients of 3.4%; this represented an annual decrease in 0.9%. CONCLUSION: Our data revealed a trend for a decrease in TB prevalence over time. Moreover, TB positivity rates were highest among the younger age groups in our study. Therefore, rapid diagnosis and treatment of TB in younger individuals are crucial.

Detection of clarithromycin-resistant Helicobacter pylori by polymerase chain reaction using residual samples from rapid urease test.

BACKGROUND: Approximately 50% of the world population is infected with Helicobacter pylori, which corresponds to a high infection rate. Furthermore, the incidence of antibiotic-resistant H. pylori has increased with the recent rise in use of antibiotics for H. pylori elimination, suggesting growing treatment failures. AIM: The study was aimed to assess the use of residual samples from rapid urease test (RUT) for biomolecular testing as an effective and accurate method to detect antibiotic-resistant H. pylori. SETTINGS AND DESIGN: This study was a retrospective study performed using data obtained from medical records of previously isolated H. pylori strains. MATERIALS AND METHODS: RUT was conducted for 5440 biopsy samples from individuals who underwent health examination in South Korea. Subsequently, 469 RUT residual samples were randomly selected and subjected to polymerase chain reaction (PCR) to detect antibiotic-resistant H. pylori. STATISTICAL ANALYSIS USED: The Chi-square test was used to analyse categorical data. P < 0.05 was considered statistically significant. RESULTS: The results showed a concordance between the results of PCR and conventional RUT in 450 of 469 samples, suggesting that the H. pylori PCR test is a time- and cost-effective detection method. CONCLUSIONS: This study demonstrated that PCR test can aid physicians to prescribe the appropriate antibiotics at the time of diagnosis, thus preventing the reduction in H. pylori eradication due to antibiotic resistance, averting progression to serious diseases and increasing the treatment success rate.

Isolation Frequency Characteristics of Candida Species from Clinical Specimens.

Candida spp. is an invasive infectious fungus, a major risk factor that can increase morbidity and mortality in hospitalized patients. In this study, 2,508 Candida spp. were isolated from various clinical specimens collected from university hospitals from July 2011 to October 2014. They were identified in order to determine isolation frequencies and characteristics by specimen, gender, age group, year, season, and month. The strain-specific isolation rate of Candida spp. is in the order of Candida albicans (1,218 strains, 48.56%), Candida glabrata (416 strains, 16.59%), Candida utilis (305 strains, 12.16%), Candida tropicalis (304 strains, 12.12%), and Candida parapsilosis (116 strains, 4.63%) and these five species accounted for more than 94% of the total strains. Of the specimens, Candida spp. were most frequently isolated from urine-catheter, followed by urine-voided, blood, sputum, other, open pus, vaginal discharge, Tip, ear discharge, bronchial aspiration and bile, in that order. Looking at the age distribution, the detection rate of patients in their 60s and older was significantly higher at 75.8% (1,900/2,508). The detection rate of patients in their 20s and younger was shown to be very low at 2.55% (64/2,508). By year, the detection rate of non-albicans Candida spp. showed a tendency to gradually increase each year compared with C. albicans. As isolation of Candida spp. from clinical samples at the specie level can vary depending on characteristics of the patient, sample, season, etc., continual studies are required.

Epidemic Trends of Enterovirus Infections From Pediatric Patients in Cheonan, Korea.

BACKGROUND: This study was performed to investigate the epidemiology of enterovirus (EV) infections in children at a single hospital during recent 5 years. This study was preformed from December 2008 to November 2013. METHODS: We subjected 1,067 cerebrospinal fluid (CSF) specimens from 1,053 patients and 678 stool specimens from 665 patients using real-time reverse-transcription polymerase chain reaction tests that could detect EV. The data were analyzed according to seasonality and patient age and sex. RESULTS: During this period, 176 of the total 1,053 patients (16.81%) were positive for EV in CSF. The highest rate of EV-positive samples occurred in children less than 1 year of age (114/176, 64.77%), and the most prevalent month was June. The results for CSF and stool specimens were concordant in 545 (80.38%) of 678 cases. CONCLUSION: We described the epidemiological analytic data of the EV in the population of Cheonan, South Korea. The combination of the CSF and stool specimen enhances the diagnostic yield. There is a need for continuous study of EV infections and its clinical manifestations.

Correlation Between Abnormal Platelet Count and Respiratory Viral Infection in Patients From Cheonan, Korea.

BACKGROUND: In this study, the effects of viral infections on platelet (PLT) count have been reported. This study examined the correlation between PLT count and respiratory virus (RV) infections. METHODS: Patients who visited Dankook University Hospital between December 2006 and February 2014 with symptoms of suspected RV infection were recruited. Multiplex reverse transcriptase polymerase chain reactions identified the causative virus(es). PLT counts were analyzed with respect to virus, age and sex of the patient, and length of hospital stay. RESULTS: Of the 8,147 patients, 62.8% were RV-positive, and 18.6% of RV-positive patients had abnormal PLT counts. There were no differences in the rates of abnormal PLT counts between single-infection and virus co-infection cases. In RV infection patients, the incidence of abnormal PLT count increased with age and varied depending on the RV infection type. Patients with abnormal PLT count stayed in hospital longer than those with normal PLT count. CONCLUSIONS: The incidence of thrombocytopenia was higher among the elderly; in younger patients, thrombocytosis was more prevalent than thrombocytopenia. Respiratory tract infections caused by different viruses resulted in varied PLT count changes. Further systematic research of PLT count changes related to viral infections is required.

IL-32θ gene expression in acute myeloid leukemia suppresses TNF-α production.

The proinflammatory cytokine TNF-α is highly expressed in patients with acute myeloid leukemia (AML) and has been demonstrated to induce rapid proliferation of leukemic blasts. Thus suppressing the production of TNF-α is important because TNF-α can auto-regulate own expression through activation of NF-κB and p38 mitogen-activated protein kinase (MAPK). In this study, we focused on the inhibitory effect of IL-32θ on TNF-α production in acute myeloid leukemia. Approximately 38% of patients with AML express endogenous IL-32θ, which is not expressed in healthy individuals. Furthermore, plasma samples were classified into groups with or without IL-32θ; then, we measured proinflammatory cytokine TNF-α, IL-1ß, and IL-6 levels. TNF-α production was not increased in patients with IL-32θ expression than that in the no-IL-32θ group. Using an IL-32θ stable expression system in leukemia cell lines, we found that IL-32θ attenuated phorbol 12-myristate 13-acetate (PMA)-induced TNF-α production. IL-32θ inhibited phosphorylation of p38 MAPK, inhibitor of κB (IκB), and nuclear factor κB (NF-κB), which are key positive regulators of TNF-α expression, and inhibited nuclear translocation of NF-κB. Moreover, the presence of IL-32θ attenuated TNF-α promoter activity and the binding of NF-κB with the TNF-α promoter. In addition, IL-32γ-induced TNF-α production has no correlation with inhibition of TNF-α via IL-32θ expression. Thus, IL-32θ may serve as a potent inhibitor of TNF-α in patients with AML.

Installation of platform screen doors and their impact on indoor air quality: Seoul subway trains.

In this study, variations of particulate matter (PM) concentrations in subway trains following installation of platform screen doors (PSDs) in the Seoul subway system were investigated. PM samples were collected in the trains on subway lines 1-8 before and after installation of PSDs. It was found that the mean PM10 concentration in the trains after PSDs installation increased significantly by 29.9% compared to that before installation. In particular, the increase of PM10 in line 6 was the highest at 103%. When the relationship between PM10 and PM2.5 was compared, coefficients of determination (r2) before and after PSDs installations were 0.696 and 0.169, respectively. This suggests that air mixing between the platform and the tunnel after PSDs installation was extremely restricted. In addition, the indoor/outdoor PM10 ratio following PSDs installation increased from 1.32 to 2.97 relative to the period with no installed PSDs. Furthermore, this study revealed that PM levels in subway trains increased significantly after all underground PSDs were put in use. Several potential factors were examined that could result in this PM increase, such as train ventilation systems, operational conditions, passenger volume, subway depth, and the length of underground segments. Implications: PM10 concentrations inside the subway trains increased after PSDs installation. This indicates that air quality in trains was very seriously impacted by PSDs. PM10 levels were also influenced by the tunnel depth and length of the underground segments. To prevent the adverse effect on human health by PM10 emitted from the tunnel, an applicable ventilation system to reduce PM10 is required inside trains and tunnels.

Prevalence and genotype distribution of human papillomavirus in Cheonan, Korea.

Human papillomavirus (HPV) infection is considered to play a critical role in the development of cervical carcinoma, which is the third most common cancer among Korean females. Here, we performed a baseline study of HPV infection and genotyping using an HPV DNA chip, which is a type of oligonucleotide microarray. A total of 6,855 cervical swab specimens from 5,494 women attending Dankook University Hospital Health Improvement Center in Cheonan, Korea between 2006 and 2012, originally collected for HPV infection screening, were genotyped for HPV. The extracted DNA from the cervical specimens was investigated by an HPV DNA chip designed to detect 41 different HPV types. HPV was identified as positive in 1,143 (16.7%) of the 6,855 samples. The most frequently detected HPV genotypes were HPV types 16, 53, 56, 58, 39, 52, 70, 84, 68, 62, 35, 54, 81, 18, and 30, in descending order of incidence. The proportions of single and multiple HPV infections in the HPV-positive specimens were 78.1% and 21.9%, respectively. The average age of HPV-positive patients was 39.9 years, with the positive rate of HPV being the highest in the 10-29 age group (20.6%). We report here on the prevalence and distribution of 41 different genotypes of HPV according to age among women in Cheonan, Korea. These data may be of use as baseline data for the assessment of public health-related issues and for the development of area-specific HPV vaccines.

Epidemiology of respiratory viral infection using multiplex rt-PCR in Cheonan, Korea (2006-2010).

Multiplex RT-PCR was used to detect respiratory viruses in 5,318 clinical samples referred to the laboratory of a tertiary teaching hospital from December 2006 to November 2010. The acquired data were analyzed with respect to types, ratio, and co-infection trends of infected respiratory viruses. Trends in respiratory viral infection according to sex, age, and period of infection were also analyzed. Of the 5,318 submitted clinical samples, 3,350 (63.0%) specimens were positive for at least one respiratory virus. The infection rates were 15.8% for human rhinovirus, 14.4% for human respiratory syncytial virus A, 9.7% for human respiratory syncytial virus B, 10.1% for human adenovirus, 5.4% for influenza A virus, 1.7% for influenza B virus, 4.7% for human metapneumovirus, 2.3% for human coronavirus OC43, 1.9% for human coronavirus 229E/NL63, 3.7% for human parainfluenza virus (HPIV)-1, 1.1% for HPIV-2, and 5.3% for HPIV-3. The co-infection analysis showed 17.1% of double infections and 1.8% of triple infections. The median age of virus-positive patients was 1.3 years, and 91.5% of virus-positive patients were under 10 years old. Human respiratory syncytial virus was the most common virus in children under 5 years of age, and the influenza A virus was the most prevalent virus in children over 5 years of age. These results help in elucidating the tendency of respiratory viral infections.