Unmasking bocavirus: is it a co-infectious agent or an actual respiratory pathogen?

OBJECTIVES: Although human bocavirus (HBoV) is primarily linked to respiratory tract infections, its exact role as a respiratory pathogen remains unclear. This study aims to investigate HBoV detection rates, as well as clinical, laboratory, microbiological, and radiological characteristics, length of stay in the emergency department (ED), rate of hospitalization, and severity of illness in cases where HBoV is detected in respiratory secretions. METHODS: We conducted a retrospective analysis of all consecutive patients under 18 years who visited a large-volume tertiary pediatric ED from January to December 2023 and tested positive for HBoV in their respiratory viral panel (RVP). RESULTS: Among the 14,315 patients who underwent RVP testing during the study period, 591 (4%) tested positive for HBoV. After excluding those with incomplete data, 528 patients (57% male) were included in the analyses. The median age was 2.8 [1.2 - 4.9] years. The most common symptoms were cough (67%), fever (58%), runny nose/nasal congestion/sore throat (34%), and respiratory distress (24%). Thirty percent of the patients had a history of antibiotic use before admission. Thirteen percent of the patients had at least one chronic illness. Co-infection with HBoV occurred in 37% of the patients, with Respiratory syncytial virus (RSV) being the most frequently co-detected virus (45%). Lymphopenia was documented in 12% of patients, and 36% had elevated C-reactive protein levels (median 21 [12- 38] g/dl). Abnormal chest X-rays were noted in 85% of patients. The management approach included outpatient care for more than half of the patients (69%). Clinical severity was classified as high in 11% of patients (n = 60), necessitating ICU admission. CONCLUSION: Although typically mild, HBoV infections can escalate to severe respiratory illnesses, requiring respiratory support and intensive care.

Uncovering the Presentation and Diagnosis of Human Bocavirus in a Patient at a Tertiary Care Center: A Case Report.

A toddler, thriving well, developmentally normal, and fully immunized, presented with fever, cough, and cold for a day, followed by breathing difficulty. Although the child was not ill upon admission, he had a fever and was breathing rapidly. On examination, visible sub-costal retractions and wheezing in both lungs were noted. He required Intensive Care Unit (ICU) management for a brief period, with oxygen supplementation, round-the-clock nebulization, and other supportive care. Initially, he was diagnosed with a wheeze-associated lower respiratory tract infection, as his chest X-ray showed bilateral hyperinflated lung fields. Blood investigations revealed microcytic hypochromic anemia, and his renal function tests, electrolytes, and liver function tests were within normal limits. C-reactive protein (CRP) was positive at 15.1 mg/L (≥10 mg/L considered positive), and the blood culture was sterile. A nasopharyngeal swab on day 2 of admission tested positive for reverse transcription-polymerase chain reaction (RT-PCR) of Human Bocavirus (HBoV). Gradually, the child's condition improved, and he was able to be taken off oxygen support two days after admission. Upon discharge, the child was managed symptomatically with oral medications.

Surveillance of norovirus, SARS-CoV-2, and bocavirus in air samples collected from a tertiary care hospital in Thailand.

This study aims to determine the presence of norovirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and bocavirus in air samples from a tertiary care hospital in Bangkok, Thailand. Air samples were collected in water using the BioSampler and concentrated using speedVac centrifugation. Based on RT-qPCR, norovirus RNA and SARS-CoV-2 RNA were detected in 13/60 (21.7%) and 3/60 (5.0%) of samples, respectively. One air sample had a weak positivity for both norovirus and SARS-CoV-2 RNAs. Detection rate of norovirus genogroup (G) II (13.3%) was higher than norovirus GI (6.7%). One air sample (1.7%) tested positive for GI and GII. The norovirus GI RNA concentration was 6.0 × 102 genome copies/m3. The norovirus GII RNA concentrations ranged from 3.4 × 101 to 5.0 × 103 genome copies/m3. Based on RT-nested PCR, norovirus GII was detected in two (3.3%) samples. All samples tested negative for GI RNA and bocavirus DNA. By phylogenetic analysis, GII.17, which is closely related to the outbreak Kawasaki308/JPN/2015 strain, was found in the RT-nested PCR-positive samples. This study highlights the potential of aerosols for norovirus and SARS-CoV-2 transmission and probably cause gastrointestinal and respiratory illnesses, respectively.

Life-Threatening Conditions in Children with Bocavirus Infection-Case Series and Mini Review of the Literature.

In this study, we present four cases of Human Bocavirus (HBoV) infection in children aged between 1 month and 4 years. Among these cases, two siblings were hospitalized with similar symptoms. Among the four pediatric cases of patients with HBoV infection, three were associated with acute respiratory failure and spontaneous pneumothorax, and two of these presented with subcutaneous emphysema. The presented patients were young children, aged between 1 month and 4 years, two of whom were siblings, suggesting a possible intrafamilial transmission of HBoV1 infection. These cases highlight the importance of considering HBoV as a differential diagnosis in pediatric patients with respiratory and gastrointestinal symptoms. Early recognition and appropriate medical care are important in treating HBoV infection in young children.

Diverse Head-to-Tail Sequences in the Circular Genome of Human Bocavirus Genotype 1 among Children with Acute Respiratory Infections Implied the Switch of Template Chain in the Rolling-Circle Replication Model.

Head-to-tail sequences have been reported in human bocavirus (HBoV) 1-4. To reveal their features and functions, HBoV DNA was screened among respiratory specimens from pediatric patients with an acute respiratory infection (ARI) between April 2020 and December 2022, followed by HBoV genotyping. Head-to-tail sequences were detected using nested PCR, TA cloning, and Sanger sequencing, and these findings were confirmed by mNGS and amplicon sequencing. The secondary structure was predicted using the Mfold web server. The results indicated that head-to-tail sequences were detected in 42 specimens through TA cloning from 351 specimens positive for HBoV1 DNA, yielding 92 sequences into 32 types and 2 categories. Additionally, head-to-tail sequences were detected in 16 specimens by amplicon sequencing, yielding 60 sequences categorized into 23 types. The 374nt type, detected in 13 specimens, contains variants 374a and 374b, which differ in the unpaired loop regions of the palindrome or complementary reverse sequences, implying a switch of template chains during the replication process. The mNGS results in three specimens confirmed the presence of circular genome in copies below 1%. In conclusion, head-to-tail sequences of HBoV1 were common in children with ARI and were highly diverse in length and sequences. The variants may be generated by the switch of the template chain in the rolling-circle replication model.

Prevalence and significance of a canine bocavirus-2 outbreak in a cohort of military dogs in Austria.

Introduction: Bocaviruses are single-stranded DNA viruses from the Parvoviridae family, which have been minimally discussed in veterinary literature and are considered potentially pathogenic. Due to the recurring illness among young dogs in a closed cohort of military dogs in Austria, we assessed the prevalence, possible disease manifestation and outcome of CBoV-2 infection in this cohort. Materials and methods: This led to a comprehensive study that not only analyzed past cases but also performed prospective screening PCR tests to identify CBoV-2 positive dogs within this specific dog population. Pharyngeal and rectal swabs were taken. In addition, a control group (n = 20) of clinically healthy client-owned dogs was sampled. A total of 190 samples were taken and tested for the presence of CBoV-2 specific nucleic acid using screening PCR. In addition to the primers used for routine diagnostics, two other primer pairs were used to verify questionable results. The retrospective part of the study includes a total of 13 military dogs that had previously shown suspected clinical signs. Results: At the time of the first examination within the prospective part of the study, CBoV-2 was detected in 31% (12/39) of the dogs. During the second examination, 2% (1/47) tested positive, while all PCR testing in the control group (n = 20) was negative in all cases. The retrospective evaluation of the 13 cases revealed a total of six animals tested positive for CBoV-2 via screening PCR. All puppies suffered from skin lesions (papules, vesicles, or pustules). Other clinical signs included diarrhea (83%), vomiting (77%), respiratory (15%), and neurological (8%) signs. Discussion: According to the study there are certain indications that CBoV-2 shares similarities with CPV-2 infection but also exhibits critical differences, making their differentiation essential for patient management, outcomes, and prevention strategies.

Epidemiology and genetic diversity of bocavirus in wild rodents in urban areas of Guangzhou, Southern China.

Members of the genus Bocaparvovirus have a significant impact on human health and can infect a wide range of hosts, increasing the likelihood of crossing species barriers. Among the various mammalian hosts, rodents are widely recognized as important reservoirs for emerging and zoonotic viruses. However, despite recent reports of bocavirus infections in rodents, our current understanding of rat bocavirus (RBoV) genetic diversity and evolution is limited. In this study, rodent samples were collected from the urban areas of Guangzhou city, Southern China, to investigate the presence and genetic diversity of RBoV. Through PCR-based screening of 296 rodent spleens, 54 samples were determined to be positive for RBoV infection, and 12 nearly complete genome sequences of RBoV were recovered. Phylogenetic analysis revealed distinct lineages and sub-lineages of RBoV, and six recombination events with strong statistical support were identified, with five of these events involving sequences obtained from this study. These results highlight the genetic diversity of RBoV circulating in rodents in Guangzhou city and emphasize the importance of extensive surveillance to gain a better understanding of RBoV epidemiology, evolutionary characteristics, and potential for cross-species transmission.

Distinct clinical characteristics of bocavirus and Mycoplasma pneumoniae infection in children plastic bronchitis.

BACKGROUND: This study investigated clinical and laboratory characteristics of human bocavirus type 1 (HBoV1)-plastic bronchiolitis (PB), Mycoplasma pneumoniae (MP)-associated plastic bronchitis (PB) and MP-NPB in children, highlighting inflammation, coagulation, and bronchoscopic needs. METHODS: Data on preschool children with PB during HBoV1 or MP infection were collected, comparing MP-PB to severe Mycoplasma pneumoniae pneumonia. RESULT: Compared with the MP-PB group, the HBoV1-PB group, with younger children, had significantly milder clinical symptoms but higher WBC counts (p = .028). The MP-PB group exhibited notably elevated Fibrinogen (p = .045) and d-dimer levels (p < .001). When contrasting the MP-PB with the MP-NPB group, children in MP-PB group still had higher levels of d-dimer and increased inflammatory indicators such as C-reactive protein, procalcitonin, lactate dehydrogenase, and interleukin-6, which were significantly elevated compared with the MP-NPB group. MP-PB showed a higher prevalence of plastic bronchial casts in lower lobes (p = .016) and a dominance of neutrophils in BALF cytology. Additionally, children in the MP-PB group tended to undergo a greater number of bronchoscopies. CONCLUSION: This study identifies key differences in plastic bronchitis in children due to HBoV1 and MP, highlighting HBoV1's milder inflammation in younger kids and MP's link to severe inflammatory and coagulation responses, guiding clinical diagnosis and treatment.

Epidemiology and genotypic diversity of feline bocavirus identified from cats in Harbin, China.

Feline bocavirus (FBoV) is a globally distributed linear, single-stranded DNA virus infect cats, currently classified into three distinct genotypes. Although FBoV can lead to systemic infections, its complete pathogenic potential remains unclear. In this study, 289 blood samples were collected from healthy cats in Harbin, revealing an overall FBoV prevalence of 12.1%. Notably, genotypes 1 and 3 of FBoV were found co-circulating among the cat population in Harbin. Additionally, recombination events were detected, particularly in the newly discovered NG/104 and DL/102 strains. Furthermore, negative selection sites were predominantly observed across the protein coding genes of FBoV. These findings suggest a co-circulation of genetically diverse FBoV strains among cats in Harbin, indicate that purifying selection is the primary driving force shaping the genomic evolution of FBoV, and also underscore the importance of comprehensive surveillance efforts to enhance our understanding of the epidemiology and evolutionary characteristics of FBoV.

Sequencing and characterization of human bocavirus genomes from patients diagnosed in Southern France between 2017 and 2022.

The diversity and evolution of the genomes of human bocavirus (HBoV), which causes respiratory diseases, have been scarcely studied. Here, we aimed to obtain and characterize HBoV genomes from patients's nasopharyngeal samples collected between 2017 and 2022 period (5 years and 7 months). Next-generation sequencing (NGS) used Illumina technology after having implemented using GEMI an in-house multiplex PCR amplification strategy. Genomes were assembled and analyzed with CLC Genomics, Mafft, BioEdit, MeV, Nextclade, MEGA, and iTol. A total of 213 genomes were obtained. Phylogeny classified them all as of Bocavirus 1 (HBoV1) species. Five HBoV1 genotypic clusters determined by hierarchical clustering analysis of 27 variable genome positions were scattered over the study period although with differences in yearly prevalence. A total of 167 amino acid substitutions were detected. Besides, coinfection was observed for 52% of the samples, rhinoviruses then adenoviruses (HAdVs) being the most common viruses. Principal component analysis showed that HBoV1 genotypic cluster α tended to be correlated with HAdV co-infection. Subsequent HAdV typing for HBoV1-positive samples and negative controls demonstrated that HAdVC species predominated but HAdVB was that significantly HBoV1-associated. Overall, we described here the first HBoV1 genomes sequenced for France. HBoV1 and HAdVB association deserves further investigation.

Plastic bronchitis associated with human bocavirus 1 infection in children.

BACKGROUND: Plastic bronchitis (PB) is a clinical-pathological syndrome characterized by the abnormal accumulation of endogenous substances in the bronchial airways, causing partial or complete obstruction and resulting in impaired lung ventilation. METHODS: In this retrospective analysis, we aim to summarize the clinical manifestations, imaging characteristics, diagnostic methods, and treatment approaches to enhance clinicians' ability to detect children who are infected with human bocavirus 1 (hBoV 1) and develop PB. RESULTS: In the period from January 2021 to January 2024, a total of six hBoV 1 infection children were diagnosed with PB through bronchoscopy. The onset of the condition was mainly concentrated between June and December. The detection methods used included metagenomic next-generation sequencing for pathogen identification (three cases) and respiratory pathogen nucleic acid 13-plex detection (oropharyngeal swab) (three cases), both of which confirmed the presence of hBoV 1. Out of the six children with PB, two were girls and four were boys. Their ages ranged from 10 months to 4 years old. Common symptoms reported by all patients included fever, cough, and wheezing. Chest high-resolution computed tomography scans revealed atelectasis in six cases, in addition to pneumonia. After the removal of the plastic bronchi via bronchoscopy, the airway obstruction symptoms in the children were relieved, and no recurrence was observed during the follow-up period. Pathological findings indicated cellulose exudation and inflammatory cell infiltration, consistent with nonlymphatic PB. CONCLUSION: When children infected with hBoV 1 exhibit persistent or worsening symptoms such as cough, fever, and wheezing despite treatment, clinicians should remain highly vigilant for the potential occurrence of PB. Bronchoscopy plays a crucial role not only in diagnosing the presence of a plastic bronchus but also in effectively treating PB.

Establishment and application of multiplex PCR for rapid detection of three mink diarrhea-associated viruses.

In this report, a multiplex PCR method was developed for the detection of three diarrhea-associated viruses in mink, including circovirus (MCV), bocavirus (MBoV), and enteritis virus (MEV). Three compatible sets of primers specific for each virus were designed respectively based on their conserved sequences. After optimization of the crucial factors such as primer concentration and annealing temperature in single and multiple amplification, three specific fragments were simultaneously amplified with the highest sensitivity and specificity in one PCR reaction. The fragments amplified were 259 bp (MCV)，455 bp (MBoV) and 671 bp (MEV). The sensibility of this one-step multiplex PCR is about 10 times lower than that of regular singleplex PCR. There were no cross-reactions with some relevant pathogens like mink coronavirus, canine distemper virus, and aleutian mink disease virus. In our study we analyzed viral DNA in mink fecal samples by multiplex PCR assay from China, which revealed the occurrence of MCV, MBoV, and MEV as 3.1 %, 5.7 %, and 9.8 %, respectively. The testing results of multiplex PCR agreed with the singleplex PCR results with a coincidence rate of 100 %. These results indicated that the method could provide technical support for rapid detection of the three diarrhea-associated viruses, and epidemiological investigation of mink viral diarrhea.

An Investigation of the Relationship between Henoch-Schönlein Purpura and Viral Infection in Korea Using the Health Insurance Database.

(1) Background: This study investigated the epidemiology and viral connections of Henoch-Schönlein purpura (HSP) using information from the Korea Disease Control and Prevention Agency and the Health Insurance Review and Assessment database. (2) Method: Between 2016 and 2019, a total of 25,443 patients with HSP were identified, with 51.3% of patients under the age of 20 years and the highest incidence in March. (3) Results: The autoregressive integrated moving average model and Granger causality test were used to analyze the association between the virus positivity detection rate and HSP incidence. (4) Conclusions: The incidence of HSP was associated with rotavirus, bocavirus, parainfluenza virus, and respiratory syncytial virus in individuals under 20 years of age, whereas adenovirus, respiratory syncytial virus, and norovirus were associated with individuals above that age.

Human bocavirus in Saudi Arabia: Molecular epidemiology and Co-infections among children with acute respiratory tract infections during 2014-2016.

Respiratory tract infections due to a variety of viruses continue to threaten the human population worldwide, particularly in developing countries. Among the responsible viruses, Human Bocavirus (HBoV), a novel discovered virus, causes respiratory tract and gastroenteritis disorders in young children. In Saudi Arabia, data regarding virus molecular epidemiology and evolution and its implication in respiratory tract infection are scarce. In the current study, genetic diversity and circulation pattern of HBoV-1 among hospitalized children due to acute respiratory tract infection (ARTI) during two consecutive years were charted. We found that 3.44% (2014/2015) and 11.25% (2015/2016) of children hospitalized due to ARTI were infected by HBoV-1. We have shown that HBoV was detected year-round without a marked seasonal peak. HBoV-1 also was co-detected with one or multiple other respiratory viruses. The multisequence analysis showed high sequence identity (∼99%) (few point mutation sites) between strains of each genotype and high sequence variation (∼79%) between HBoV-1 and the other 3 genotypes. Phylogenetic analysis showed the clustering of the study's isolates in the HBoV-1 subclade. Our data reveal that genetically conserved HBoV-1 was circulating among admitted children during the course of the study. Further epidemiological and molecular characterization of multiple HBoV-1 strains for different years and from all regions of Saudi Arabia are required to understand and monitor the virus evolution.

Human Bocavirus 1 NP1 acts as an ssDNA-binding protein to help AAV2 DNA replication and cooperates with RPA to regulate AAV2 capsid expression.

Adeno-associated virus (AAV) requires co-infection with helper virus for efficient replication. We previously reported that Human Bocavirus 1 (HBoV1) genes, including NP1, NS2, and BocaSR, were critical for AAV2 replication. Here, we first demonstrate the essential roles of the NP1 protein in AAV2 DNA replication and protein expression. We show that NP1 binds to single-strand DNA (ssDNA) at least 30 nucleotides (nt) in length in a sequence-independent manner. Furthermore, NP1 colocalized with the BrdU-labeled AAV2 DNA replication center, and the loss of the ssDNA-binding ability of NP1 by site-directed mutation completely abolished AAV2 DNA replication. We used affinity-tagged NP1 protein to identify host cellular proteins associated with NP1 in cells cotransfected with the HBoV1 helper genes and AAV2 duplex genome. Of the identified proteins, we demonstrate that NP1 directly binds to the DBD-F domain of the RPA70 subunit with a high affinity through the residues 101-121. By reconstituting the heterotrimer protein RPA in vitro using gel filtration, we demonstrate that NP1 physically associates with RPA to form a heterologous complex characterized by typical fast-on/fast-off kinetics. Following a dominant-negative strategy, we found that NP1-RPA complex mainly plays a role in expressing AAV2 capsid protein by enhancing the transcriptional activity of the p40 promoter. Our study revealed a novel mechanism by which HBoV1 NP1 protein supports AAV2 DNA replication and capsid protein expression through its ssDNA-binding ability and direct interaction with RPA, respectively.IMPORTANCERecombinant adeno-associated virus (rAAV) vectors have been extensively used in clinical gene therapy strategies. However, a limitation of these gene therapy strategies is the efficient production of the required vectors, as AAV alone is replication-deficient in the host cells. HBoV1 provides the simplest AAV2 helper genes consisting of NP1, NS2, and BocaSR. An important question regarding the helper function of HBoV1 is whether it provides any direct function that supports AAV2 DNA replication and protein expression. Also of interest is how HBoV1 interplays with potential host factors to constitute a permissive environment for AAV2 replication. Our studies revealed that the multifunctional protein NP1 plays important roles in AAV2 DNA replication via its sequence-independent ssDNA-binding ability and in regulating AAV2 capsid protein expression by physically interacting with host protein RPA. Our findings present theoretical guidance for the future application of the HBoV1 helper genes in the rAAV vector production.

Molecular characterization of human bocavirus in municipal wastewaters using amplicon target sequencing.

Human bocavirus (HBoV) is an emerging health concern worldwide, associated with range of clinical manifestations, including gastroenteritis and respiratory infections. Therefore, it is crucial to comprehend and minimize their prevalence in different systems. In this study, we conducted regular sampling throughout the year in two different sizes and work processes of wastewater treatment plants (WWTPs) in Tianjin, China. Our objective was to investigate the occurrence, prevalence, and endurance of HBoV in wastewater, while also evaluating the efficacy of amplicon target sequencing in directly detecting HBoV in wastewater. At two WWTPs, HBoV2 (45.51 %-45.67 %) and HBoV3 (38.30 %-40.25 %) were the most common genotypes identified, and the mean concentration range of HBoV was 2.54-7.40 log10 equivalent copies/l as determined by multiplex real-time quantitative PCR assay. A positive rate of HBoV was found in 96.6 % (29/30) samples of A-WWTP, and 96.6 % (26/27) samples of B-WWTP. The phylogenetic analysis indicated that the nucleotide similarity between the HBoV DNA sequences to the reference HBoV sequences published globally ranged from 90.14 %-100 %. A significant variation in the read abundance of HBoV2 and HBoV3 in two wastewater treatment plants (p < 0.05) was detected, specifically in the Winter and Summer seasons. The findings revealed a strong correlation between the genotypes detected in wastewater and the clinical data across various regions in China. In addition, it is worth mentioning that HBoV4 was exclusively detected in wastewater and not found in the clinical samples from patients. This study highlights the high prevalence of human bocavirus in municipal wastewater. This finding illustrates that amplicon target sequencing can amplify a wide variety of viruses, enabling the identification of newly discovered viruses.

Genotypic diversity and long-term impact of human bocavirus on diarrheal disease: Insights from historical fecal samples in Brazil.

This study aimed to investigate the frequency and genotypic diversity of human bocavirus (HBoV) in historical fecal samples collected before 2005 in Brazil and understand its natural history in patients with diarrhea. Between 1998 and 2005, 3347 samples were tested for HBoV by RT-PCR, with a detection rate of 5.8% (195/3347). Coinfection with norovirus (NoV) and human adenovirus (HAdV) was found in 34.9% (68/195), indicating HBoV's potential role as a causative agent of diarrheal disease. The detection rate varied over the years (p < 0.05), suggesting natural oscillatory fluctuations. HBoV was more prevalent in fall and winter, with higher positivity in children ≤5 years (p < 0.05), reinforcing that HBoV is an important pathogen in childhood diarrhea. Genotyping (32.8%; 64/195) revealed the circulation of HBoV-1 (79.7%, 51/64), HBoV-3 (12.5%, 8/64), HBoV-2 (6.2%, 4/64), and the rare HBoV-4 (1.6%, 1/64). Difference in HBoV-1 and HBoV-2/-3 mono-infections prevalence (p < 0.05), suggests a potential role of HBoV-1 in the pathogenicity of diarrheal disease. The study highlights HBoV's lasting impact on viral gastroenteritis in Brazil and emphasizes its genotypic diversity. Recommending screening for HBoV in public health laboratories is crucial for understanding its role in gastrointestinal diseases. The data also contribute to understanding the molecular characterization of enteric viruses in historical fecal samples.

Clinical and molecular characterization of children and adults with respiratory bocavirus infection in Mexico: a cross-sectional nested study within the ILI002 prospective observational study.

Background: Human Bocaviruses (HBoV) can cause acute respiratory tract infections. High coinfection rates cloud its pathogenicity. This study sought to describe the clinical features of HBoV1 disease in children and adults with Influenza-like illness (ILI), exploring associations between viral load, clinical features, and seasonality. Methods: Patients who tested positive for HBoV1 by polymerase chain reaction, enrolled from April 2010 to March 2014 in the ILI002 prospective observational cohort study were included in this cross-sectional nested study. Participants were included in ILI002 if they presented with signs and/or symptoms suggestive of influenza-like illness. Samples were tested for viral load, and NP1 and VP1/VP2 phylogenetic analyses, except for the samples lacking suitable and viable clinical material for genotyping. Findings: We identified HBoV1 in 157 (2.8%) of participants. Prevalence was 4.5% in children and 1.8% in adults. Single HBoV1 detection occurred in 41.1% and 46.3% of children and adults, respectively. Children commonly experienced fever (83.3%), cough with sputum (74.4%), and shortness of breath (72.2%). In the multivariate analysis of children, significant positive associations were detected between viral loads and age (0.20 [95% CI: 0.07, 0.33]), and the presence of fever (2.64 [95% CI: 1.35, 3.94]), nasal congestion (1.03 [95% CI: 0.07, 1.99]), dry cough (1.32 [95% CI: 0.42, 2.22]), chest congestion (1.57 [95% CI: 0.33, 2.80]), red eyes (1.25 [95% CI: 0.35, 2.14]), cough with sputum (1.79 [95% CI: 0.80, 2.78]), and other signs and symptoms such as chills, dizziness, and diaphoresis (1.73 [95% CI: 0.19, 3.27]). In contrast, significant negative associations were found between viral loads and percent neutrophils on the blood count (-0.04 [95% CI: -0.06, -0.02]), fatigue (-1.60 [95% CI: -2.46, -0.74]) and the presence of other symptoms or signs, including adenopathy and rash (-1.26 [95% CI: -2.31, -0.21]). Adults commonly experienced sore throat (73.1%), fatigue (77.4%), and headache (73.1%). In the multivariate analysis of adults, significant positive associations were detected between viral load and body mass index (0.13 [95% CI: 0.04, 0.21]), and the presence of confusion (1.54 [95% CI: 0.55, 2.53]), and sore throat (1.03 [95% CI: 0.20, 1.85]), and significant negative associations were detected between viral load and chest congestion (-1.16 [95% CI: -2.07, -0.24]). HBoV1 was detected throughout the year irrespective of season, temperature, and humidity. Interpretation: This study demonstrated the importance of detecting HBoV1 in patients with influenza-like illness either as single infection or co-infection, in both adults and children, and improves the characterization of HBoV1 seasonality, clinical features, and viral load. Phylogenetic analyses show a high conservation. Funding: The Mexican Emerging Infectious Diseases Clinical Research Network (LaRed), CONACYT (Fondo Sectorial SSA/IMSS/ISSSTE, Projects No. 71260 and No. 127088), Fondos federales no. HIM/2015/006, NIAID, NIH through a contract with Westat, Inc. (HHSN2722009000031, HHSN27200002), NCI, NIH (75N91019D00024, 75N91019F00130). Additional information at the end of the manuscript.

Analysis of a Cohort of 165 Pediatric Patients with Human Bocavirus Infection and Comparison between Mono-Infection and Respiratory Co-Infections: A Retrospective Study.

INTRODUCTION: Human Bocavirus (HBoV) is mainly associated with respiratory tract infections. However, its role as respiratory pathogen is not fully understood for a high co-infection rate in symptomatic patients and a significant HBoV detection rate in asymptomatic subjects. This study aimed to describe a large cohort of children with HBoV infection and to compare HBoV mono-infection and co-infections. METHODS: We retrospectively reviewed data from 165 children admitted to Meyer Children's Hospital IRCCS from March 2022 to March 2023 with the diagnosis of HBoV infection, detected using Reverse Transcription qPCR from nasal swabs. Thereafter, we compared patients with HBoV mono-infection (Group A) and those with HBoV co-infections (Group B) in terms of disease severity, established by the length of stay (LOS), the requirement of Pediatric Intensive Care Unit (PICU), and advanced respiratory support (ARS). RESULTS: The median age was 1.5 years; 80% of patients presented with respiratory symptoms. The discharge rate from the emergency department (ED) within 24 h was 42.4%. Most cases (57.6%) were hospitalized, and 7.3% were admitted to PICU due to respiratory failure. Group A comprised 69 patients, and Group B 96 children (95% viral co-infections, 2% bacterial, 3% viral and bacterial). Group A and Group B were similar in hospitalization rate but differed significantly in LOS (median 3 vs. 5 days) and requirement of PICU admission (0 vs. 12 patients, p < 0.001). Patients with a respiratory disease history (17.5%) showed significantly longer LOS and more necessity of inhaled bronchodilator therapy. CONCLUSIONS: HBoV should be considered a relevant respiratory pathogen especially in viral co-infections. Patients with HBoV co-infections have a higher risk of necessitating advanced respiratory support with more PICU admission and longer LOS; a previous respiratory disease puts them at a higher risk of longer hospitalization.

Antibiotic Utilization in Hospitalized Children with Bronchiolitis: A Prospective Study Investigating Clinical and Epidemiological Characteristics at a Secondary Hospital in Madrid (2004-2022).

Bronchiolitis is a viral respiratory infection, with respiratory syncytial virus (RSV) being the most frequent agent, requiring hospitalization in 1% of affected children. However, there continues to be a noteworthy incidence of antibiotic prescription in this setting, further exacerbating the global issue of antibiotic resistance. This study, conducted at Severo Ochoa Hospital in Madrid, Spain, focused on antibiotic usage in children under 2 years of age who were hospitalized for bronchiolitis between 2004 and 2022. In that time, 5438 children were admitted with acute respiratory infection, and 1715 infants (31.5%) with acute bronchiolitis were included. In total, 1470 (87%) had a positive viral identification (66% RSV, 32% HRV). Initially, antibiotics were prescribed to 13.4% of infants, but this percentage decreased to 7% during the COVID-19 pandemic thanks to adherence to guidelines and the implementation of rapid and precise viral diagnostic methods in the hospital. HBoV- and HAdV-infected children and those with viral coinfections were more likely to receive antibiotics in the univariate analysis. A multivariate logistic regression analysis revealed a statistically independent association between antibiotic prescription and fever > 38 °C (p < 0.001), abnormal chest-X ray (p < 0.001), ICU admission (p = 0.015), and serum CRP (p < 0.001). In conclusion, following guidelines and the availability of rapid and reliable viral diagnostic methods dramatically reduces the unnecessary use of antibiotics in infants with severe bronchiolitis.