Effect of Screw Configuration on the Rate of Correction for Guided Growth Using the Tension-band Plate.

BACKGROUND: This study investigated the effect of screw configuration on the rate of correction of coronal angular deformity of the knee joint in children who underwent guided growth using the tension-band plate. METHODS: Consecutive patients (76 patients with 154 physes; mean age: 11.8±2.2 y) who underwent guided growth using the tension-band plate for coronal angular deformity (genu varum or genu valgum) were included. The mechanical lateral distal femoral angle, mechanical medial proximal tibial angle, and screw angle were measured from the teleroentgenograms of preoperative and postoperative periodic follow-up visits. RESULTS: The mean initial screw angle and the mean rate of correction were 16.7±10.5 degrees and 6.5±5.3 degrees per year, respectively. The rate of correction was significantly affected by age at surgery, sex, physis treated, severity of deformity, and rate of change in screw angle (all P<0.001). However, the initial screw angle and type of deformity did not affect the rate of correction. The rate of correction per year was 3.6 degrees higher in boys than in girls and 2.8 degrees higher in the distal femur than in the proximal tibia. A 1 degree increase in the rate of change in screw angle was associated with a 0.5 degree increase in the correction rate. Screw angle significantly increased with follow-up duration (P<0.001) and the change in screw angle was significantly affected by age, sex, and physis treated (all P<0.001). CONCLUSIONS: This study demonstrated that screw configuration did not affect the correction rate of coronal angular deformity for guided growth using the tension-band plate. Therefore, surgeons only need to insert the screws according to anatomic restriction, not considering the screw configuration when using the tension-band plate for guided growth in children. LEVEL OF EVIDENCE: Prognostic level III.

Monocyte Chemoattractant Protein (MCP)-1 in Rotavirus-Associated White Matter Injury in Newborns.

Recent reports have suggested an association between rotavirus infection and a distinctive pattern of white matter injury (WMI) in neonates with seizures; however, the connection between the two is not fully understood. To evaluate the underlying mechanism, we profiled and compared eight cytokines (IL [interleukin]-1ß, IL-6, IL-8, IL-10, IFN-γ [interferon-γ ], MCP-1 [monocyte chemoattractant protein-1], MIP-1ß [macrophage inflammatory protein-1ß], and TNF-α [tumor necrosis factor-α]) in the cerebrospinal fluid (CSF) of 33 neonates with seizures who had no other well-known causes of seizures and 13 control patients (rotavirus-induced gastroenteritis but without seizures). Among the 33 neonates with seizures, 9 showed WMI and all were infected with rotavirus (R + W + ). Among the 24 patients without WMI, 11 were infected with rotavirus (R + W - ) and 13 were not (R - W - ).Only MCP-1 and MIP-1ß were different between the groups. MCP-1 was increased in R+ W+ compared with R + W- (p < 0.01), R - W- (p < 0.01), and control (p = 0.03) patients. MIP-1ß was decreased in R + W+ compared with R - W- (p < 0.01) and control (p < 0.01), but not R + W- (p = 0.23) patients. MCP-1 and MIP-1ß are C-C chemokines that recruit immune cells to the site of inflammation. Our pilot study suggests MCP-1-mediated monocyte recruitment may be linked with this complication caused by rotavirus.

Nationwide Survey for Application of ROME IV Criteria and Clinical Practice for Functional Constipation in Children.

BACKGROUND: This study aimed to investigate the awareness and application of ROME IV criteria for functional constipation (FC) in real-world practices and assessed differences between pediatric gastroenterologists (PGs) and general pediatricians. METHODS: A total of 239 (47.8%) out of 500 nationwide pediatricians answered a questionnaire for diagnosis and management of pediatric FC; 60 were PGs (75% of total PGs in Korea). RESULTS: A total of 16.6% of pediatricians were aware of the exact ROME IV criteria. Perianal examination and digital rectal examination were practiced less, with a higher tendency among PGs (P < 0.001). Treatment duration was longer among PGs for > 6 months (63.8%) than < 3 months among general pediatricians (59.2%, P < 0.001). Fecal disimpaction and rectal enema were practiced among 78.8% and 58.5% of pediatricians, respectively. High dose medication for initial treatment phase was prescribed by 70.7% of pediatricians, primarily within the first 2 weeks (48.3%). The most commonly prescribed medications in children aged > 1-year were lactulose (59.1%), followed by polyethylene glycol (PEG) 4000 (17.7%), and probiotics (11.8%). Prescription priority significantly differed between PGs and general pediatricians; lactulose or PEG 4000 were most commonly prescribed by PGs (89.7%), and lactulose or probiotics (75.7%) were prescribed by general pediatricians (P < 0.001). For patients aged < 1-year, lactulose (41.6%) and changing formula (31.7%) were commonly prescribed. Most participants recommended diet modification, and PGs more frequently used defecation diary (P = 0.002). CONCLUSION: Discrepancies between actual practice and Rome IV criteria and between PGs and general pediatricians were observed. This survey may help construct practice guidelines and educational programs for pediatric FC.

Ten-year Nationwide Population-based Survey on the Characteristics of Children with Henoch-SchÓ§nlein Purpura in Korea.

BACKGROUND: Henoch-SchÓ§nlein purpura (HSP) is a common vasculitis of childhood. Though HSP is usually self-limiting, severe complications can occur. The management for this condition has not been established yet. Thus, this nationwide study aimed at investigating epidemiological characteristics of children with HSP in Korea. The patterns of clinical practice with regard to the complications of the condition were also investigated. METHODS: This is a national population-based study that used the National Health Insurance Database. Children below 18 years who were diagnosed with HSP in Korea between 2006 and 2015 were enrolled. Data, such as age, sex, yearly and monthly distribution of HSP, hospitalization, re-hospitalization, comorbidities, and interventions were obtained. The use of steroids was also analyzed. RESULTS: A total of 56,841 children were enrolled. The annual incidence of HSP was 55.9 per 100,000 children. The peak age was 5 years. Spring was the most prevalent season. Sex (male) and young age (< 9 years) were risk factors of hospitalization. Younger children were more likely to be re-hospitalized and suspected with intussusception, arthritis, and nephritis. Only 4 children received laparotomy. In total, 57% were managed with steroids, and mean durations of medication were 4-5 days. Children who were hospitalized and those with comorbidities used steroids more frequently (P < 0.001). CONCLUSION: The annual incidence of HSP is 55.9 per 100,000 children which is higher in Korea than that in other countries. Younger children can have a more severe clinical course. This nationwide survey provides valuable information to understand HSP in children and to inspire further research on HSP.

Epidemiological Correlation between Fecal Adenovirus Subgroups and Pediatric Intussusception in Korea.

We investigated the adenoviral etiology and seasonal epidemic trends in intussusception and each adenoviral subgroup. Also we confirmed whether we can use the adenovirus data of Acute Infectious Agents Laboratory Surveillance Report (AIALSR) as an epidemic predictor of intussusception. Patients with intussusception (n = 126), < 5 years old, were enrolled and matched by age and sex with controls suffering acute gastroenteritis without intussusception (n = 106), all recruited at 8 centers. All fecal specimens were assayed for adenovirus, including subgroups A, B, C, E, and F, with reverse transcriptase-polymerase chain reaction (RT-PCR). Adenovirus was detected in 53 cases and 13 controls (P < 0.001). Nonenteric adenoviruses (NEAds) were detected in 51 cases and four controls (P < 0.001). We used Spearman's correlation analysis to analyze the incidence of intussusception and adenoviral epidemic trends, and compared them with fecal and respiratory adenoviral epidemic trends in the AIALSR. The trend of intussusception correlated with total NEAds (r = 0.635; P = 0.011), as did the fecal AIALSR adenovirus trends (r = 0.572; P = 0.026). Among the NEAd subgroups, subgroup C was dominant (P < 0.001), but subgroups B (P = 0.007) and E (P = 0.013) were also significant to intussusception. However, only subgroup C showed a significant epidemic correlation (r = 0.776; P = 0.001) with intussusception. Not respiratory but fecal AIALSR adenovirus trends correlated with the incidence of NEAds and intussusception. We suggest the possibility of using fecal AIALSR adenovirus data as an approximate epidemic predictor of intussusception.

Detection of Rotavirus Genotypes in Korea 5 Years after the Introduction of Rotavirus Vaccines.

Rotavirus (RV) is one of the most important viral etiologic agents of acute gastroenteritis (AGE) in children. Although effective RV vaccines (RVVs) are now used worldwide, novel genotypes and outbreaks resulting from rare genotype combinations have emerged. This study documented RV genotypes in a Korean population of children with AGE 5 yr after the introduction of RVV and assessed potential genotype differences based on vaccination status or vaccine type. Children less than 5-yr-old diagnosed with AGE between October 2012 and September 2013 admitted to 9 medical institutions from 8 provinces in Korea were prospectively enrolled. Stool samples were tested for RV by enzyme immunoassay and genotyped by multiplex reverse-transcription polymerase chain reaction. In 346 patients, 114 (32.9%) were RV-positive. Among them, 87 (76.3%) patients were infected with RV alone. Eighty-six of 114 RV-positive stool samples were successfully genotyped, and their combinations of genotypes were G1P[8] (36, 41.9%), G2P[4] (12, 14.0%), and G3P[8] (6, 7.0%). RV was detected in 27.8% of patients in the vaccinated group and 39.8% in the unvaccinated group (P=0.035). Vaccination history was available for 67 of 86 cases with successfully genotyped RV-positive stool samples; RotaTeq (20, 29.9%), Rotarix (7, 10.4%), unvaccinated (40, 59.7%). The incidence of RV AGE is lower in the RV-vaccinated group compared to the unvaccinated group with no evidence of substitution with unusual genotype combinations.

Detection of Aichi virus in South Korea.

Aichi virus (AiV) is considered to be a possible etiologic agent of acute gastroenteritis (GE). We analyzed 1,568 stool samples collected by the Seoul Metropolitan Health Research Center from patients with GE during outbreaks in Seoul, together with 378 archived common-enteric-virus-negative stool samples from children with GE hospitalized at a tertiary hospital in Seoul. AiV was detected in 1.7 % (27/1,568) of the first group but not found in the second group (0 %, 0/378). Genotypes A and B of AiV were both detected in this study. This is the first study confirming the circulation of AiV in Korea.

Detection of norovirus genogroup IV, klassevirus, and pepper mild mottle virus in sewage samples in South Korea.

Norovirus (NoV) genogroup (G) IV has been infrequently isolated from patients suffering from acute gastroenteritis (AGE), although this virus has not been detected in Korea. Klassevirus, a novel virus belonging to the family Picornaviridae and a possible etiologic agent of AGE, and pepper mild mottle virus (PMMoV), which originates from processed pepper products and is shed in human feces, are suggested to be new indicators of fecal pollution. We aimed to investigate the presence of NoV-GIV, klassevirus, and PMMoV in sewage samples collected in Korea. Between December 2010 and February 2012, influent sewage samples were collected every month from a wastewater treatment plant located in the eastern part of Seoul in Korea. The sewage samples were concentrated by the adsorption elution method using an HA (pore size of 0.45 µm with mixed cellulose ester) electronegative filter with an acid-rinse procedure. RT-PCR was performed using specific primers for the capsid gene of NoV-GII and NoV-GIV, the coat gene of PMMoV, and the VP0/VP1 gene of klassevirus. Among the 14 sewage samples tested, klassevirus was detected in eight (57.1 %), PMMoV in eight (57.1 %), NoV-GII in five (35.7 %), and NoV-GIV in three (21.4 %). NoV-GIV was detected in December 2010 and January and March 2011. PMMoV and klassevirus were frequently detected in winter. Phylogenetic analysis revealed that the NoV-GIV detected in this study belonged to G-IV1 lineage. This is the first study to confirm the presence of NoV-GIV, klassevirus, and PMMoV in sewage samples in Korea.

Risk factors for neurologic complications of hand, foot and mouth disease in the Republic of Korea, 2009.

In 2009, the first outbreak of hand, foot and mouth disease (HFMD) or herpangina (HP) caused by enterovirus 71 occurred in the Republic of Korea. This study inquired into risk factors associated with complications of HFMD or HP. A retrospective medical records review was conducted on HFMD or HP patients for whom etiologic viruses had been verified in 2009. One hundred sixty-eight patients were examined for this investigation. Eighty patients were without complications while 88 were accompanied by complications, and 2 had expired. Enterovirus 71 subgenotype C4a was the most prevalent in number with 67 cases (54.9%). In the univariate analysis, the disease patterns of HFMD rather than HP, fever longer than 4 days, peak body temperature over 39℃, vomiting, headache, neurologic signs, serum glucose over 100 mg/dL, and having an enterovirus 71 as a causative virus were significant risk factors of the complications. After multiple logistic analysis, headache (Odds ratio [OR], 10.75; P < 0.001) and neurologic signs (OR, 42.76; P < 0.001) were found to be the most significant factors. Early detection and proper management of patients with aforementioned risk factors would be necessary in order to attain a better clinical outcome.

Bioactive Scaffold With Spatially Embedded Growth Factors Promotes Bone-to-Tendon Interface Healing of Chronic Rotator Cuff Tear in Rabbit Model.

BACKGROUND: Functional restoration of the bone-to-tendon interface (BTI) after rotator cuff repair is a challenge. Therefore, numerous biocompatible biomaterials for promoting BTI healing have been investigated. PURPOSE: To determine the efficacy of scaffolds with spatiotemporal delivery of growth factors (GFs) to accelerate BTI healing after rotator cuff repair. STUDY DESIGN: Controlled laboratory study. METHODS: An advanced 3-dimensional printing technique was used to fabricate bioactive scaffolds with spatiotemporal delivery of multiple GFs targeting the tendon, fibrocartilage, and bone regions. In total, 50 rabbits were used: 2 nonoperated controls and 48 rabbits with induced chronic rotator cuff tears (RCTs). The animals with RCTs were divided into 3 groups: (A) saline injection, (B) scaffold without GF, and (C) scaffold with GF. To induce chronic models, RCTs were left unrepaired for 6 weeks; then, surgical repairs with or without bioactive scaffolds were performed. For groups B and C, each scaffold was implanted between the bony footprint and the supraspinatus tendon. Four weeks after repair, quantitative real-time polymerase chain reaction and immunofluorescence analyses were performed to evaluate early signs of regenerative healing. Histological, biomechanical, and micro-computed tomography analyses were performed 12 weeks after repair. RESULTS: Group C had the highest mRNA expression of collagen type I alpha 1, collagen type III alpha 1, and aggrecan. Immunofluorescence analysis showed the formation of an aggrecan+/collagen II+ fibrocartilaginous matrix at the BTI when repaired with scaffold with GFs. Histologic analysis revealed greater collagen fiber continuity, denser collagen fibers, and a more mature tendon-to-bone junction in GF-embedded scaffolds than those in the other groups. Group C demonstrated the highest load-to-failure ratio, and modulus mapping showed that the distribution of the micromechanical properties of the BTI repaired with GF-embedded scaffolds was comparable with that of the native BTI. Micro-computed tomography analysis identified the highest bone mineral density and bone volume/total volume ratio in group C. CONCLUSION: Bioactive scaffolds with spatially embedded GFs have significant potential to promote the BTI healing of chronic RCTs in a rabbit model. CLINICAL RELEVANCE: The scaffolds with spatiotemporal delivery of GF may serve as an off-the-shelf biomaterial graft to promote the healing of RCTs.

Detection and molecular characterization of adenoviruses in Korean children hospitalized with acute gastroenteritis.

Human adenoviruses (HAdVs) are an important cause of acute gastroenteritis in children. However, few studies on the epidemiology or types of HAdVs associated with acute gastroenteritis have been conducted in Korea. Therefore, in the present study, the incidence of HAdV in 2064 stool samples from Korean children hospitalized with acute gastroenteritis (2004-2006) was assessed and the types of viruses present determined. Polymerase chain reaction, sequencing, and phylogenic analyses revealed that 113 samples (5.5%) were HAdV-positive. While HAdVs were mainly detected during July to October, no seasonal difference between the enteric and non-enteric viruses in the incidence of HAdV was observed. HAdV-41 and HAdV-40 were found in 54 (47.8%) and 3 (2.6%) HAdV-positive samples, respectively. HAdV-3, HAdV-7, HAdV-2, HAdV-31, HAdV-4, and HAdV-37 were detected in 11 (9.7%), 5 (4.4%), 2 (1.7%), 2 (1.7%), 1 (0.8%), and 1 (0.8%) of sample(s), respectively. Thus, not only enteric, but also non-enteric, HAdVs may play an important role in acute gastroenteritis in Korean children.

Saccharomyces boulardii and Lactulose for Childhood Functional Constipation: A Multicenter Randomized Controlled Trial.

Background/Aims: The effects of probiotics in children vary based on diseases and probiotic strains. We aim to investigate the effectiveness of Saccharomyces boulardii and lactulose for treating childhood functional constipation. Methods: This open-label randomized controlled trial was conducted at 10 university hospitals in Korea. Children who were diagnosed with functional constipation were allocated to 3 groups (lactulose monotherapy, combination therapy, and S. boulardii monotherapy). The primary outcome was treatment success rate that was accordingly defined as ≥ 3 bowel movements without incontinence at week 12. The cumulative successful maintenance and drug maintenance rates without drug changes were calculated throughout the study period. We compared stool frequency, incontinence, consistency, and painful defecation at week 2 among the 3 groups. Results: Overall, 187 children were assigned to the lactulose monotherapy (n = 69), combination therapy (n = 68), or S. boulardii monotherapy (n = 50) groups. The primary outcome was significantly higher in the lactulose monotherapy group (26.1%) or combination therapy group (41.2%) than in the S. boulardii monotherapy group (8.0%). The S. boulardii monotherapy group showed a significantly lower cumulative successful maintenance and drug maintenance rate than the other 2 groups. There were no significant intergroup differences in the frequency of defecation, incontinence, painful defecation, or stool consistency during the follow-up at week 2. Conclusion: S. boulardii monotherapy was not superior to lactulose monotherapy or combination therapy and showed a higher drug change rate, supporting the current recommendation of probiotics in the treatment of childhood functional constipation.

Whole-genome characterization and genotyping of global WU polyomavirus strains.

Exploration of the genetic diversity of WU polyomavirus (WUV) has been limited in terms of the specimen numbers and particularly the sizes of the genomic fragments analyzed. Using whole-genome sequencing of 48 WUV strains collected in four continents over a 5-year period and 16 publicly available whole-genome sequences, we identified three main WUV clades and five subtypes, provisionally termed Ia, Ib, Ic, II, IIIa, and IIIb. Overall nucleotide variation was low (0 to 1.2%). The discriminatory power of the previous VP2 fragment typing method was found to be limited, and a new, larger genotyping region within the VP2/1 interface was proposed.

Emergence of norovirus GII-4/2008 variant and recombinant strains in Seoul, Korea.

Recently, the emergence of a new NoV GII-4 variant strain every 2 or 3 years has been reported. One hundred seventeen NoV GII strains were detected by RT-PCR in children with AGE between August 2008 and February 2010. In phylogenetic analyses, GII-4 and GII-3 were the most frequently detected strains. The detection rate of the 2008 variant was similar to that of the 2006b variant in the winter seasons of 2009 and 2010. This study shows a changing pattern of a predominant GII-4/2006b variant to the 2008 variant, as well as a novel NoV recombinant strain, GII-6/GII-14, in Korea.

Detection of human parechoviruses in children with gastroenteritis in South Korea.

Human parechoviruses (HPeVs) are associated with gastroenteritis (GE), although their etiologic role is uncertain. The purpose of this study was to detect HPeVs in children with GE in Korea. A total of 348 stool samples that were negative for common enteric viruses were screened for HPeV using RT-PCR. Of the 348 stool samples, seven (2.0%) were positive for HPeV. Five Korean strains belonged to HPeV-1, and two strains belonged to HPeV-4. Four Korean HPeV-1 strains clustered with strain 7555312 and the other HPeV-1 strain clustered with the BNI-788St strain. Two HPeV-4 strains showed discordant phylogenic relationships in the 3D gene, suggesting that recombination had occurred. This is the first study reporting the detection of HPeVs in children with GE in Korea.

Nationwide "Pediatric Nutrition Day" survey on the nutritional status of hospitalized children in South Korea.

BACKGROUND/OBJECTIVES: To evaluate the nutritional status and prevalence of malnutrition in hospitalized children at admission and during hospitalization in South Korea. SUBJECTS/METHODS: This first cross-sectional nationwide "Pediatric Nutrition Day (pNday)" survey was conducted among 872 hospitalized children (504 boys, 368 girls; 686 medical, 186 surgical) from 23 hospitals in South Korea. Malnutrition risk was screened using the Pediatric Yorkhill Malnutrition Score (PYMS) and the Screening Tool Risk on Nutritional status and Growth. Nutritional status was assessed by z-scores of weight-for-age for underweight, weight-for-height for wasting, and height-for-age for stunting as well as laboratory tests. RESULTS: At admission, of the 872 hospitalized children, 17.2% were underweight, and the prevalence of wasting and stunting was 20.2% and 17.3%, respectively. During hospitalization till pNday, 10.8% and 19.6% experienced weight loss and decreased oral intake, respectively. During the aforementioned period, fasting was more prevalent in surgical patients (7.5%) than in medical patients (1.6%) (P < 0.001). According to the PYMS, 34.3% and 30% of the children at admission and on pNday, respectively, had a high-risk of malnutrition, requiring consultation with the nutritional support team (NST). However, only 4% were actually referred to the NST during hospitalization. CONCLUSIONS: Malnutrition was prevalent at admission and during hospitalization in pediatric patients, with many children experiencing weight loss and poor oral intake. To improve the nutritional status of hospitalized children, it is important to screen and identify all children at risk of malnutrition and refer malnourished patients to the multidisciplinary NST for proper nutritional interventions.

Klassevirus infection in children, South Korea.

South Korea, we performed molecular screening in fecal and nasopharyngeal samples from hospitalized children with gastroenteritis. A total of 26 (8.8%) of 294 fecal samples were positive for klassevirus. Klassevirus may be a possible cause of gastroenteritis.

Detection of GII-4/2006b variant and recombinant noroviruses in children with acute gastroenteritis, South Korea.

Norovirus (NoV), a single-stranded, positive RNA virus, is an important etiologic agent of acute gastroenteritis in children worldwide. In this study, a total of 434 fecal samples collected from 434 children with acute gastroenteritis in Seoul, between September 2007 and July 2008 were tested to determine the molecular epidemiology of NoVs and characterize recombinant strains by using RT-PCR followed by sequencing. Of the 434 specimens, NoV, rotavirus, and adenovirus were detected in 155 (35.8%), 72 (16.6%), and 19 specimens (4.3%), respectively. NoV GI was detected in 7 specimens (1.6%) and GII in 148 (34.1%) specimens. Phylogenetic analysis of capsid sequences in the GII-positive specimens revealed the presence of the following strains: GII-4, 111 (75.0%); GII-3, 35 cases (23.6%); GII-6b, 1 case; and GII-16, 1 case. Most of the GII-4 strains were grouped with the GII-4/2006b variant with 98-100% nucleotide identity. Eleven strains were identified as recombinant (GII-4/GII-3 in 10 cases and GII-b polymerase/GII-16 capsid in 1 case) by sequencing based on the RdRP and capsid genes. The putative recombination point in the recombinant strains was the ORF-1/ORF2 overlap, located at nucleotide 5,046 with reference to Lordsdale. In conclusion, GII-4/2006b variants were detected predominantly and a new recombinant strain (GII-4/GII-3) was found in the Korean children with gastroenteritis. Continuous monitoring of the genetic diversity of NoVs is important to determine the trend of the predominant genotype and new recombinant strain.

Genetic characterization of rotavirus in children in South Korea from 2007 to 2009.

Rotavirus is the most important etiological agent in children with acute gastroenteritis (AGE). The recent implementation of a rotavirus vaccine in Korea requires the monitoring of prevailing rotavirus strains in order to control the infection. One hundred thirty-nine rotavirus strains were detected in children hospitalized with AGE in Seoul, Korea from 2007 to 2009. The most frequent combination of genotypes was G9P[8] (32.1%), followed by G1P[8] (20.7%) and G3P[8] (11.7%). Mixed G-types were detected in 14 samples (10.0%), and mixed P-types were found in six samples (4.3%). G9 genotypes were predominant from 2007 to 2008, whereas G1 and G3 genotypes were predominant from 2008 to 2009. G1 strains clustered mostly in the Id lineage, and some clustered in the Ic, IId, and Ia lineages. G2 strains clustered in the IV and V lineages. G3 and G9 strains clustered in the IIId and Id lineages, respectively. This study shows a rapid change of the prevalent genotype from G9 to G1 and G3 genotypes, suggesting that continuous surveillance of rotavirus strains is important for rotavirus vaccination.

Clinical and epidemiological comparison of human metapneumovirus and respiratory syncytial virus in seoul, Korea, 2003-2008.

Human metapneumovirus (HMPV) shares clinical and epidemiological characteristics with well-known respiratory syncytial virus (RSV). The aim of this study was to investigate the clinical and epidemiological differences between HMPV- and RSV-induced wheezing illnesses. A total of 1,008 nasopharyngeal aspirate specimens was collected from 1,008 pediatric patients hospitalized with acute respiratory tract infection at Inje University Sanggye Paik Hospital from December 2003 to April 2008, and tested for seven common respiratory viruses. Conditions classified as wheezing illness were bronchiolitis, reactive airways disease, and bronchial asthma. HMPV caused a significantly lower proportion of wheezing illness when compared to RSV (48.1% vs. 82.2%, P<0.05). HMPV-induced wheezing illness occurred predominantly in older patients when compared to RSV patients (P<0.001). RSV infections peaked in the fall and winter followed by peaks of HMPV infection in winter and spring. Eosinophil counts were significantly higher (P<0.01) in RSV patients when compared to HMPV patients. These results show that human metapneumovirus patients exhibit several different clinical and epidemiological characteristics, such as higher proportion of wheezing illness, age and seasonal incidence, and eosinophil counts, when compared to RSV patients.