BACKGROUND Respiratory syncytial virus(RSV) is a leading cause of lower respiratory infections among children.AIM To investigate the proportion of RSV and non-RSV respiratory viral infections among hospitalized childr...BACKGROUND Respiratory syncytial virus(RSV) is a leading cause of lower respiratory infections among children.AIM To investigate the proportion of RSV and non-RSV respiratory viral infections among hospitalized children ≤ 5 years.METHODS Hospitalized children aged < 5 years, with a diagnosis of acute lower respiratory infections(ALRI), admitted between August 2011-August 2013, were included.Cases were defined as laboratory-confirmed RSV and non-RSV respiratory viruses by direct fluorescence assay from the nasopharyngeal wash.RESULTS Of 383 1-59 mo old children hospitalized with an acute lower respiratory infection, 33.9%(130/383) had evidence of viral infection, and RSV was detected in 24.5%(94/383). Co-infections with RSV and other respiratory viruses(influenza A or B, adenovirus, para influenza 1, 2 or 3) were seen in children 5.5%(21/383). Over 90% of the RSV-positive children were under 2 years of age. RSV was detected throughout the year with peaks seen after the monsoon season.Children hospitalized with RSV infection were more likely to have been exposed to a shorter duration of breastfeeding of less than 3 mo. RSV positive children had a shorter hospital stay, although there were significant complications requiring intensive care. Use of antibiotics was high among those with RSV and non-RSV viral infections.CONCLUSION Our study provides evidence of a high proportion of RSV and other virusassociated ALRI among hospitalized children in India. RSV infection was associated with fewer days of hospital stay compared to other causes of lower respiratory infections. A high level of antibiotic use was seen among all respiratory virus-associated hospitalizations. These results suggest the need for implementing routine diagnostics for respiratory pathogens in order to minimize the use of unnecessary antibiotics and plan prevention strategies among pediatric populations.展开更多
Objective:To examine the effects of human bocavirus type 1(HBoV1)on the course of lower respiratory tract infections in cases of monoinfection and coinfection,and the effects of HBoV1 viral load on the disease in chil...Objective:To examine the effects of human bocavirus type 1(HBoV1)on the course of lower respiratory tract infections in cases of monoinfection and coinfection,and the effects of HBoV1 viral load on the disease in children under six years old hospitalized with a diagnosis of HBoV1-associated lower respiratory tract infections.Methods:Children under six years of age,who were hospitalized with the diagnosis of lower respiratory tract infection due to HBoV1 between 1 January 2021 and 1 January 2022 were included in the study.Laboratory confirmation of the respiratory pathogens was performed using polymerase chain reaction(PCR).Results:Fifty-four(16.4%)children with HBoV1 among 329 children whose PCR was positive with bacterial/viral agent in nasopharyngeal swab samples were included in the study.There were 28(51.9%)males and 26(48.1%)females with a median age 23.4 months[interquartile range(IQR):13.2,30.0 months](min-max:1 month-68 months).HBoV1 was detected as a monoinfecton in 26(48.1%)children,and as a coinfection with other respiratory agents in 28 children(51.9%).In multiple regression analysis,coinfection(P=0.032)was associated with the length of hospitalization(P<0.001;R^(2)=0.166).There was a negative correlation(r=−0.281,P=0.040)between cough and cycle threshold.Fever was found to be positively correlated with C-reactive protein(r=0.568,P<0.001)and procalcitonin(r=0.472;P=0.001).Conclusions:Although we found a higher HBoV1 viral load in children with more cough symptoms in our study,it had no effect on the severity of the disease,such as length of hospital stay and need for intensive care.Coinfection was found to affect the length of hospitalization.展开更多
Multiplex RT-PCR assays have been widely used tools for detection and differentiation of a panel of respiratory viral pathogens. In this study, we evaluated the Qiagen ResPlex lI V2.0 kit and explored factors influenc...Multiplex RT-PCR assays have been widely used tools for detection and differentiation of a panel of respiratory viral pathogens. In this study, we evaluated the Qiagen ResPlex lI V2.0 kit and explored factors influencing its sensitivity. Nasopharyngeal swab （NPS） specimens were prospectively collected from pediatric inpatients with lower respiratory tract infections at the time of admission in the Shenzhen Children＇s Hospital from May 2009 to April 2010. Total nucleic acids were extracted using the EZ1 system （Qiagen, Germany） and 17 respiratory viruses and genotypes including influenza A virus （FluA）, FluB, parainfluenza virus 1 （PIV1）, PIV2, PIV3, PIV4, respiratory syncytial virus （RSV）, human metapneumovirus （hMPV）, rhinoviruses （RhV）, enteroviruses （EnV）, human bocaviruses （hBoV）, adenoviruses （AdV）, four coronaviruses （229E, OC43, NL63 and HKU1）, and FluA 2009 pandemic H1NI（H1NI-p） were detected and identified by the ResPlex II kit. In parallel, 16 real-time TaqMan quantitative RT-PCR assays were used to quantitatively detect each virus except for RhV. Influenza and parainfluenza viral cultures were also performed. Among the total 438 NPS specimens collected during the study period, one or more viral pathogens were detected in 274 （62.6%） and 201（45.9%） specimens by monoplex TaqMan RT-PCR and multiplex ResPlex, respectively. When results from monoplex PCR or cell culture were used as the reference standard, the multiplex PCR possessed specificities of 92.9-100.0%. The sensitivity of multiplex PCR for PIV3, hMPV, PIV1 and BoV were 73.1%, 70%, 66.7% and 55.6%, respectively, while low sensitivities （11.1%-40.0%） were observed for FluA, EnV, OC43, RSV and H1N1. Among the seven viruses/genotypes detected with higher frequencies, multiplex PCR sensitivities were correlated significantly with viral loads determined by the TaqMan RT-PCR in FluA, H 1N 1-p and RSV （p=0.011-0.000） The Qiagen ResPlex II multiplex RT-PCR kit possesses excellent specificity for simultaneous detection of 17 viral pathogens in NPS specimens in pediatric inpatients at the time of admission. The sensitivity of multiplex RT-PCR was influenced by viral loads, specimen process methods, primer and probe design and amplification condition.展开更多
Human metapneumovirus(HMPV) infection is one of the leading causes of hospitalization in young children with acute respiratory illness. In this study, we prospectively collected respiratory tract samples from children...Human metapneumovirus(HMPV) infection is one of the leading causes of hospitalization in young children with acute respiratory illness. In this study, we prospectively collected respiratory tract samples from children who were hospitalized with acute lower respiratory tract infection in six hospitals in China from 2017 to 2019. HMPV was detected in 145 out of 2733 samples(5.3%) from the hospitalized children. The majority of HMPV-positive children were under the age of two(67.6%), with a median age of one year. HMPV can independently cause acute lower respiratory tract infection in young children, while all patients showed mild clinical symptoms. Of all the co-infected patients, HMPV was most commonly detected with enterovirus(EV) or rhinovirus(RhV)(38.0%),followed by respiratory syncytial virus(RSV)(32.0%). The highest detection rate occurred from March to May in both northern and southern China. Out of 145 HMPV positive samples, 48 were successfully typed, of which 36strains were subgrouped into subtypes A2c(75%), eight strains were included in subtype B1(16.7%), and four strains were included in subtype B2(8.3%). Moreover, 16 A2c strains contained 111-nucleotide duplications in the G gene. Twenty-seven complete HMPV genomes were successfully obtained, and 25(92.6%) strains belonged to subtype A2c, whereas one strain was included in subgroup B1 and another was included in subgroup B2. A total of 277 mutations were observed in the complete genomes of 25 A2c strains. All results presented here improve our understanding of clinical characteristics and molecular epidemiology of HMPV infection in children.展开更多
Human respiratory syncytial virus(RSV) is a major pathogen of acute lower respiratory tract infection among young children. To investigate the prevalence and genetic characteristics of RSV in China, we performed a mol...Human respiratory syncytial virus(RSV) is a major pathogen of acute lower respiratory tract infection among young children. To investigate the prevalence and genetic characteristics of RSV in China, we performed a molecular epidemiological study during 2015–2019. A total of 964 RSV-positive specimens were identified from 5529 enrolled patients during a multi-center study. RSV subgroup A(RSV-A) was the predominant subgroup during this research period except in2016. Totally, 535 sequences of the second hypervariable region(HVR-2) of the G gene were obtained. Combined with182 Chinese sequences from GenBank, phylogenetic trees showed that 521 RSV-A sequences fell in genotypes ON1(512),NA1(6) and GA5(3), respectively;while 196 RSV-B sequences fell in BA9(193) and SAB4(3). ON1 and BA9 were the only genotypes after December 2015. Genotypes ON1 and BA9 can be separated into 10 and 7 lineages, respectively. The HVR-2 of genotype ON1 had six amino acid changes with a frequency more than 10%, while two substitutions H258 Q and H266 L were co-occurrences. The HVR-2 of genotype BA9 had nine amino acid substitutions with a frequency more than10%, while the sequences with T290 I and T312 I were all from 2018 to 2019. One N-glycosylation site at 237 was identified among ON1 sequences, while two N-glycosylation sites(296 and 310) were identified in the 60-nucleotide duplication region of BA9. To conclusion, ON1 and BA9 were the predominant genotypes in China during 2015–2019. For the genotypes ON1 and BA9, the G gene exhibited relatively high diversity and evolved continuously.展开更多
Background： Wheezing is common in early childhood and remains an important health concern. The aim of this study was to assess the lung function of wheezing infants and to investigate the relationship between lung fu...Background： Wheezing is common in early childhood and remains an important health concern. The aim of this study was to assess the lung function of wheezing infants and to investigate the relationship between lung function and respiratory outcome. Methods： Infants 〈2 years of age with acute lower respiratory tract infection （ALRTI） who had undergone lung function tests were included in the study. They were assigned to wheeze or no wheeze group based on physical examination. Infants without any respiratory diseases were enrolled as controls. Lung function was measured during the acute phase and 3 months after ALRTI. One-year follow-up for infants with ALRTI was achieved. Results： A total of 252 infants with ALRTI who had acceptable data regarding tidal breathing were included in the final analysis. Compared with the control and the no wheeze groups, infants in the wheeze group had significantly decreased time to peak tidal expiratory flow as a percentage of total expiratory time （TPTEF/TE） （20.1 1 6.4% vs. 34.4 ± 6.2% and 26.4 ±8.3%, respectively, P 〈 0.0001） and significantly increased peak tidal expiratory flow （PTEF） （90.7 ± 26.3 ml/s vs. 79.3 ± 18.4 ml/s and 86.1 ± 28.0 ml/s, respectively, P 〈 0.01）, sReff and Reff. The infants in the wheeze group still had lower TPTEF/TE and volume to peak tidal expiratory flow as a percentage of total expiratory volume （VPTEF/VE） than the no wheeze infants 3 months after the ALRT1. Moreover, there was a significant inverse relationship between TPTEF/TE, VPTEF/VE, and the recurrence of wheezing and pneumonia. Conclusions： Impaired lung function was present in wheezing infants with ALRTI and the deficits persisted. In addition, the lower level of TPTEF/TE and VPTEF/VE was a risk factor for poor respiratory outcome.展开更多
Background The role of human bocavirus (HBoV) as a respiratory pathogen has not been fulfilled yet.We aimed to describe clinical and serological characteristics of children with HBoV hospitalized for acute respiratory...Background The role of human bocavirus (HBoV) as a respiratory pathogen has not been fulfilled yet.We aimed to describe clinical and serological characteristics of children with HBoV hospitalized for acute respiratory tract infection and to evaluate whether differences occur between HBoV alone and in co-infection.Methods We retrospectively reviewed data from 60 children (median age of 6.2 months,range 0.6-70.9) hospitalized for acute respiratory symptoms,with HBoV detected from a respiratory sample,using a reverse transcriptase-PCR for 14 respiratory viruses (including respiratory syncytial virus (RSV),influenza virus A and B,human coronavirus OC43,229E,NL-63 and HUK1,adenovirus,rhinovirus,parainfluenza virus 1-3,and human metapneumovirus).Results HBoV was detected alone in 29 (48.3%) patients,while in co-infection with other viruses in 31 patients (51.7%),with a peak between December and January.Among the 60 patients,34 were bronchiolitis,19 wheezing,3 pneumonia,2 upper respiratory tract infection,and 2 whooping cough.Seven children (11.6%) required admission to the paediatric intensive care unit (PICU) for respiratory failure.No differences was observed in age,family history for atopy and/or asthma,clinical presentations,chest X-ray,or laboratory findings in children with HBoV alone vs.multiple viral detection.RSV was the most frequently co-detected virus (61.3%).When compared with HBoV detection alone,the co-detection of RSV and HBoV was associated with male sex (P=0.013),younger age (P=0.01),and lower blood neutrophil count (P=0.032).Conclusions HBoV can be detected alone and in co-infection respiratory samples of children with an acute respiratory tract infection.A cause-effect relationship between HBoV and respiratory infection is not clear,so further studies are needed to clarify this point.展开更多
文摘BACKGROUND Respiratory syncytial virus(RSV) is a leading cause of lower respiratory infections among children.AIM To investigate the proportion of RSV and non-RSV respiratory viral infections among hospitalized children ≤ 5 years.METHODS Hospitalized children aged < 5 years, with a diagnosis of acute lower respiratory infections(ALRI), admitted between August 2011-August 2013, were included.Cases were defined as laboratory-confirmed RSV and non-RSV respiratory viruses by direct fluorescence assay from the nasopharyngeal wash.RESULTS Of 383 1-59 mo old children hospitalized with an acute lower respiratory infection, 33.9%(130/383) had evidence of viral infection, and RSV was detected in 24.5%(94/383). Co-infections with RSV and other respiratory viruses(influenza A or B, adenovirus, para influenza 1, 2 or 3) were seen in children 5.5%(21/383). Over 90% of the RSV-positive children were under 2 years of age. RSV was detected throughout the year with peaks seen after the monsoon season.Children hospitalized with RSV infection were more likely to have been exposed to a shorter duration of breastfeeding of less than 3 mo. RSV positive children had a shorter hospital stay, although there were significant complications requiring intensive care. Use of antibiotics was high among those with RSV and non-RSV viral infections.CONCLUSION Our study provides evidence of a high proportion of RSV and other virusassociated ALRI among hospitalized children in India. RSV infection was associated with fewer days of hospital stay compared to other causes of lower respiratory infections. A high level of antibiotic use was seen among all respiratory virus-associated hospitalizations. These results suggest the need for implementing routine diagnostics for respiratory pathogens in order to minimize the use of unnecessary antibiotics and plan prevention strategies among pediatric populations.
文摘Objective:To examine the effects of human bocavirus type 1(HBoV1)on the course of lower respiratory tract infections in cases of monoinfection and coinfection,and the effects of HBoV1 viral load on the disease in children under six years old hospitalized with a diagnosis of HBoV1-associated lower respiratory tract infections.Methods:Children under six years of age,who were hospitalized with the diagnosis of lower respiratory tract infection due to HBoV1 between 1 January 2021 and 1 January 2022 were included in the study.Laboratory confirmation of the respiratory pathogens was performed using polymerase chain reaction(PCR).Results:Fifty-four(16.4%)children with HBoV1 among 329 children whose PCR was positive with bacterial/viral agent in nasopharyngeal swab samples were included in the study.There were 28(51.9%)males and 26(48.1%)females with a median age 23.4 months[interquartile range(IQR):13.2,30.0 months](min-max:1 month-68 months).HBoV1 was detected as a monoinfecton in 26(48.1%)children,and as a coinfection with other respiratory agents in 28 children(51.9%).In multiple regression analysis,coinfection(P=0.032)was associated with the length of hospitalization(P<0.001;R^(2)=0.166).There was a negative correlation(r=−0.281,P=0.040)between cough and cycle threshold.Fever was found to be positively correlated with C-reactive protein(r=0.568,P<0.001)and procalcitonin(r=0.472;P=0.001).Conclusions:Although we found a higher HBoV1 viral load in children with more cough symptoms in our study,it had no effect on the severity of the disease,such as length of hospital stay and need for intensive care.Coinfection was found to affect the length of hospitalization.
基金supported in part by Grant Name awarded to the State Key Lab of Respiratory Diseases,Guangzhou Medical College (2007DA780154F0910)
文摘Multiplex RT-PCR assays have been widely used tools for detection and differentiation of a panel of respiratory viral pathogens. In this study, we evaluated the Qiagen ResPlex lI V2.0 kit and explored factors influencing its sensitivity. Nasopharyngeal swab （NPS） specimens were prospectively collected from pediatric inpatients with lower respiratory tract infections at the time of admission in the Shenzhen Children＇s Hospital from May 2009 to April 2010. Total nucleic acids were extracted using the EZ1 system （Qiagen, Germany） and 17 respiratory viruses and genotypes including influenza A virus （FluA）, FluB, parainfluenza virus 1 （PIV1）, PIV2, PIV3, PIV4, respiratory syncytial virus （RSV）, human metapneumovirus （hMPV）, rhinoviruses （RhV）, enteroviruses （EnV）, human bocaviruses （hBoV）, adenoviruses （AdV）, four coronaviruses （229E, OC43, NL63 and HKU1）, and FluA 2009 pandemic H1NI（H1NI-p） were detected and identified by the ResPlex II kit. In parallel, 16 real-time TaqMan quantitative RT-PCR assays were used to quantitatively detect each virus except for RhV. Influenza and parainfluenza viral cultures were also performed. Among the total 438 NPS specimens collected during the study period, one or more viral pathogens were detected in 274 （62.6%） and 201（45.9%） specimens by monoplex TaqMan RT-PCR and multiplex ResPlex, respectively. When results from monoplex PCR or cell culture were used as the reference standard, the multiplex PCR possessed specificities of 92.9-100.0%. The sensitivity of multiplex PCR for PIV3, hMPV, PIV1 and BoV were 73.1%, 70%, 66.7% and 55.6%, respectively, while low sensitivities （11.1%-40.0%） were observed for FluA, EnV, OC43, RSV and H1N1. Among the seven viruses/genotypes detected with higher frequencies, multiplex PCR sensitivities were correlated significantly with viral loads determined by the TaqMan RT-PCR in FluA, H 1N 1-p and RSV （p=0.011-0.000） The Qiagen ResPlex II multiplex RT-PCR kit possesses excellent specificity for simultaneous detection of 17 viral pathogens in NPS specimens in pediatric inpatients at the time of admission. The sensitivity of multiplex RT-PCR was influenced by viral loads, specimen process methods, primer and probe design and amplification condition.
基金funded by the National Natural Science Foundation of China(82172275)the CAMS Innovation Fund for Medical Sciences,China(CIFMS,2019-I2M-5-026)
文摘Human metapneumovirus(HMPV) infection is one of the leading causes of hospitalization in young children with acute respiratory illness. In this study, we prospectively collected respiratory tract samples from children who were hospitalized with acute lower respiratory tract infection in six hospitals in China from 2017 to 2019. HMPV was detected in 145 out of 2733 samples(5.3%) from the hospitalized children. The majority of HMPV-positive children were under the age of two(67.6%), with a median age of one year. HMPV can independently cause acute lower respiratory tract infection in young children, while all patients showed mild clinical symptoms. Of all the co-infected patients, HMPV was most commonly detected with enterovirus(EV) or rhinovirus(RhV)(38.0%),followed by respiratory syncytial virus(RSV)(32.0%). The highest detection rate occurred from March to May in both northern and southern China. Out of 145 HMPV positive samples, 48 were successfully typed, of which 36strains were subgrouped into subtypes A2c(75%), eight strains were included in subtype B1(16.7%), and four strains were included in subtype B2(8.3%). Moreover, 16 A2c strains contained 111-nucleotide duplications in the G gene. Twenty-seven complete HMPV genomes were successfully obtained, and 25(92.6%) strains belonged to subtype A2c, whereas one strain was included in subgroup B1 and another was included in subgroup B2. A total of 277 mutations were observed in the complete genomes of 25 A2c strains. All results presented here improve our understanding of clinical characteristics and molecular epidemiology of HMPV infection in children.
基金This work was supported by the National Science and Technology Major Projects(Grant Number 2017ZX10104001-005-010,2017ZX10103004-004)the CAMS Innovation Fund for Medical Sciences(CIFMS)(Grant Number 2019-I2M-5-026)。
文摘Human respiratory syncytial virus(RSV) is a major pathogen of acute lower respiratory tract infection among young children. To investigate the prevalence and genetic characteristics of RSV in China, we performed a molecular epidemiological study during 2015–2019. A total of 964 RSV-positive specimens were identified from 5529 enrolled patients during a multi-center study. RSV subgroup A(RSV-A) was the predominant subgroup during this research period except in2016. Totally, 535 sequences of the second hypervariable region(HVR-2) of the G gene were obtained. Combined with182 Chinese sequences from GenBank, phylogenetic trees showed that 521 RSV-A sequences fell in genotypes ON1(512),NA1(6) and GA5(3), respectively;while 196 RSV-B sequences fell in BA9(193) and SAB4(3). ON1 and BA9 were the only genotypes after December 2015. Genotypes ON1 and BA9 can be separated into 10 and 7 lineages, respectively. The HVR-2 of genotype ON1 had six amino acid changes with a frequency more than 10%, while two substitutions H258 Q and H266 L were co-occurrences. The HVR-2 of genotype BA9 had nine amino acid substitutions with a frequency more than10%, while the sequences with T290 I and T312 I were all from 2018 to 2019. One N-glycosylation site at 237 was identified among ON1 sequences, while two N-glycosylation sites(296 and 310) were identified in the 60-nucleotide duplication region of BA9. To conclusion, ON1 and BA9 were the predominant genotypes in China during 2015–2019. For the genotypes ON1 and BA9, the G gene exhibited relatively high diversity and evolved continuously.
文摘Background： Wheezing is common in early childhood and remains an important health concern. The aim of this study was to assess the lung function of wheezing infants and to investigate the relationship between lung function and respiratory outcome. Methods： Infants 〈2 years of age with acute lower respiratory tract infection （ALRTI） who had undergone lung function tests were included in the study. They were assigned to wheeze or no wheeze group based on physical examination. Infants without any respiratory diseases were enrolled as controls. Lung function was measured during the acute phase and 3 months after ALRTI. One-year follow-up for infants with ALRTI was achieved. Results： A total of 252 infants with ALRTI who had acceptable data regarding tidal breathing were included in the final analysis. Compared with the control and the no wheeze groups, infants in the wheeze group had significantly decreased time to peak tidal expiratory flow as a percentage of total expiratory time （TPTEF/TE） （20.1 1 6.4% vs. 34.4 ± 6.2% and 26.4 ±8.3%, respectively, P 〈 0.0001） and significantly increased peak tidal expiratory flow （PTEF） （90.7 ± 26.3 ml/s vs. 79.3 ± 18.4 ml/s and 86.1 ± 28.0 ml/s, respectively, P 〈 0.01）, sReff and Reff. The infants in the wheeze group still had lower TPTEF/TE and volume to peak tidal expiratory flow as a percentage of total expiratory volume （VPTEF/VE） than the no wheeze infants 3 months after the ALRT1. Moreover, there was a significant inverse relationship between TPTEF/TE, VPTEF/VE, and the recurrence of wheezing and pneumonia. Conclusions： Impaired lung function was present in wheezing infants with ALRTI and the deficits persisted. In addition, the lower level of TPTEF/TE and VPTEF/VE was a risk factor for poor respiratory outcome.
文摘Background The role of human bocavirus (HBoV) as a respiratory pathogen has not been fulfilled yet.We aimed to describe clinical and serological characteristics of children with HBoV hospitalized for acute respiratory tract infection and to evaluate whether differences occur between HBoV alone and in co-infection.Methods We retrospectively reviewed data from 60 children (median age of 6.2 months,range 0.6-70.9) hospitalized for acute respiratory symptoms,with HBoV detected from a respiratory sample,using a reverse transcriptase-PCR for 14 respiratory viruses (including respiratory syncytial virus (RSV),influenza virus A and B,human coronavirus OC43,229E,NL-63 and HUK1,adenovirus,rhinovirus,parainfluenza virus 1-3,and human metapneumovirus).Results HBoV was detected alone in 29 (48.3%) patients,while in co-infection with other viruses in 31 patients (51.7%),with a peak between December and January.Among the 60 patients,34 were bronchiolitis,19 wheezing,3 pneumonia,2 upper respiratory tract infection,and 2 whooping cough.Seven children (11.6%) required admission to the paediatric intensive care unit (PICU) for respiratory failure.No differences was observed in age,family history for atopy and/or asthma,clinical presentations,chest X-ray,or laboratory findings in children with HBoV alone vs.multiple viral detection.RSV was the most frequently co-detected virus (61.3%).When compared with HBoV detection alone,the co-detection of RSV and HBoV was associated with male sex (P=0.013),younger age (P=0.01),and lower blood neutrophil count (P=0.032).Conclusions HBoV can be detected alone and in co-infection respiratory samples of children with an acute respiratory tract infection.A cause-effect relationship between HBoV and respiratory infection is not clear,so further studies are needed to clarify this point.
