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Background Severe acute respiratory illness (SARI) is recognized as an important cause of morbidity, mortality, and hospitalization among children in developing countries. Little is known, however, in tropical countries like Cameroon about the cause and seasonality of respiratory infections, especially in hospitalized settings. Objectives: Our study investigates the viral etiology and seasonality of SARI in hospitalized children in Yaounde, Cameroon. Methods Prospective clinic surveillance was conducted to identify hospitalized children aged ≤15 years presenting with respiratory symptoms ≤5‐day duration. Demographic and clinical data, and respiratory specimens were collected. Nasopharyngeal samples were tested for 17 respiratory viruses using a multiplex polymerase chain reaction. The viral distribution and demographic data were statistically analyzed. Results From September 2011 through September 2013, 347 children aged ≤15 years were enrolled. At least one virus was identified in each of 65·4% children, of which 29·5% were coinfections; 27·3% were positive for human adenovirus (hAdV), 13·2% for human respiratory syncytial virus (hRSV), 11·5% for rhinovirus/enterovirus (RV/EV), 10·6% for human bocavirus (hBoV), 9·8% for influenza virus (Inf), 6·6% for human parainfluenza virus (hPIV), 5·7% for human coronavirus (hCoV), and 2·3% for human metapneumovirus (hMPV). While hRSV showed seasonal patterns, hAdV and RV/EV were detected throughout the year and no evident temporal patterns were observed for the remaining viruses. Conclusion Respiratory viruses were associated with a high burden of hospitalizations among children in Cameroon. Nevertheless, additional studies evaluating asymptomatic Cameroonian children will be important in understanding the relationship between viral carriage and disease.

Objective Human Bocavirus (HBoV) was first identified in 2005 and has been shown to be a common cause of respiratory infections and gastroenteritis in children. In a recent study, we found that 10.7% of children with acute respiratory infections (ARI) were infected by HBoV. Genetic characterization of this virus remains unknown in Central Africa, particularly in Cameroon Leeding us to evaluate the molecular characteristics of HBoV strains in Cameroonian children with ARI. Results Phylogenetic analysis of partial HBoV VP1/2 sequences showed a low level of nucleotide variation and the circulation of HBoV genotype 1 (HBoV-1) only. Three clades were obtained, two clustering with each of the reference strains ST1 and ST2, and a third group consisting of only Cameroon strains. By comparing with the Swedish reference sequences, ST1 and ST2, Cameroon sequences showed nucleotide and amino acid similarities of respectively 97.36–100% and 98.35–100%. These results could help improve strategies for monitoring and control of respiratory infections in Cameroon.

Objectives The genotypic analysis of human metapneumo‐(HMPV) and boca‐(HBoV) viruses circulating in Greece and their comparison to reference and other clinical strains. Design Genetic analysis of representative strains over three consecutive winter seasons of the years 2005–2008. Setting Representative positive specimens for HMPV and HBoV from paediatric patients of healthcare units and hospitals in Southern Greece with influenza‐like illness or other respiratory tract infections. Sample Seven to ten positive specimens for either HMPV or HBoV from each winter period. In total, 24 specimens positive for HMPV and 26 for HBoV, respectively. Main outcome measures Sequence diversity of HMPV and HBoV strains by sequencing the complete G and VP1/VP2 genes, respectively. Results In total, 24 HMPV strains were found to have a 92–100% nucleotide and a 85.9–100% amino acid identity. Phylogenetic analysis based on the number of amino acid differences, revealed circulation of 4 different subclusters belonging to genetic lineage B2. Similarly, analysis of 26 HBoV strains indicated that 22 clustered within genotype St2, 2 into genotype St1 and the remaining 2 formed a third cluster derived from potential recombination between different St1 genotype strains. St2 HBoV genotype was observed throughout the whole observation period whereas St1 only during the second and the third winter period. Higher levels of heterogeneity were observed between HMPV compared to HBoV strains. Conclusions Phylogenetic analysis revealed circulation of one single lineage (B2) for HMPV viruses and predominance of St2 genotype for HBoV viruses. A possible recombination between St1 genotype strains of HBoV was observed.

A new species of parvovirus, tentatively named human bocavirus 4 (HBoV4), was genetically characterized. Among 641 feces samples obtained from children and adults, the most commonly detected bocavirus species were, in descending order, HBoV2, HBoV3, HBoV4, and HBoV1, with an HBoV2 prevalence of 21% and 26% in Nigerian and Tunisian children, respectively. HBoV3 or HBoV4 species were found in 12 of 192 patients with non-polio acute flaccid paralysis in Tunisia and Nigeria and 0 of 96 healthy Tunisian contacts (P= .01). Evidence of extensive recombination at the NP1 and VP1 gene boundary between and within bocavirus species was found. The high degree of genetic diversity seen among the human bocaviruses found in feces specimens, relative to the highly homogeneous HBoV1, suggest that this worldwide-distributed respiratory pathogen may have recently evolved from an enteric bocavirus after acquiring an expanded tropism favoring the respiratory tract. Elucidating the possible role of the newly identified enteric bocaviruses in human diseases, including acute flaccid paralysis and diarrhea, will require further epidemiological studies.

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 × 10 2 genome copies/m 3 . The norovirus GII RNA concentrations ranged from 3.4 × 10 1 to 5.0 × 10 3 genome copies/m 3 . 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.

Human bocaviruses (HBoVs), first identified in 2005 and composed of genotypes 1-4, have been increasingly detected worldwide in pediatric patients with acute gastroenteritis. HBoV-1 has been primarily associated with respiratory symptoms, while HBoV2-4 are mostly found in gastrointestinal (GI) samples. Results from case-control studies are still controversial; however, epidemiological evidence has shown a significant association between HBoV-2 and gastroenteritis. This review will primarily focus on this association, with a brief discussion of evidence related to other HBoV genotypes. Pathological and molecular studies on the pathogenesis of HBoV, particularly in GI cells, are very scarce, possibly due to the difficulties of in vitro HBoV culture. Nonetheless, some relevant findings from colorectal cancer samples have yielded valuable insights regarding the behavior of HBoV in the GI system. In the present review, we provide an updated overview of the epidemiological evidence for an association of HBoV infection with acute gastroenteritis and focus on the cellular and molecular perspectives of HBoV pathogenicity. Finally, we look at the knowledge gaps about how HBoV affects the GI system and explore future directions.

Background. Human bocavirus 1 (HBoV-1) is frequently detected in young children. The role of HBoV-1 in respiratory illness is unclear, owing to frequent detection in asymptomatic children. Methods. Weekly oral fluid samples from a longitudinal cohort of infants were tested by quantitative polymerase chain reaction for HBoV-1 DNA. Symptoms during HBoV-1 primary shedding events were compared to those during 14-day control periods occurring 1 month prior to and following the primary event. Eight single-nucleotide polymorphisms were analyzed to assess HBoV-1 variants. Results. Sixty-six of 87 children (76%), followed for at least 18 months from birth, had a primary HBoV-1 infection. HBoV-1 was consistently detected for >1 month (maximum duration, 402 days) following 42 of 66 primary shedding events. Children were more likely to experience new cough symptoms (odds ratio [OR], 2.7; 95% confidence interval [CI], 1.4-5.5) and to visit a healthcare provider (OR, 2.8; 95% CI, 1.02-7.7) during the 14 days surrounding the time of initial detection of HBoV-1. Recurrent HBoV-1 shedding events were found in 33 children (50%). Twelve of 48 children with HBoV-1 variant data had multiple viral allelic patterns over time. Conclusions. HBoV-1 primary shedding events are associated with mild respiratory illness with subsequent prolonged detection of HBoV-1 DNA for up to a year. HBoV-1 reinfection contributes to long-term shedding.

We aimed to elucidate the epidemiological characteristics and co-infection status of HBoV in Guangzhou and to investigate the potential recombination events and alterations in antigenic properties among circulating HBoV strains. Utilizing respiratory specimens collected from patients at sentinel surveillance hospitals in Guangzhou between August 2023 and December 2025, multiplex pathogen detection was performed. We describe the temporal and demographic distribution of HBoV in Guangzhou and determine its co-infection patterns. Subsequent sequence analysis focused on identifying potential recombination events and characterizing antigenic properties. The epidemiological features of HBoV in Guangzhou exhibited a primary epidemic peak around the autumn season, followed closely by a secondary peak. HBoV infection was predominantly observed in children under three years of age. Co-infections with rhinovirus and parainfluenza virus were common. Whole-genome sequencing yielded 15 complete HBoV genome sequences. Recombination analysis and verification suggested potential recombination events in two of these sequences. A comparative analysis of the antigenic characteristics of one identified recombinant strain, GZ-2024-20891, against its putative parental strains and domestic prevalent strains revealed potential alterations in its antigenic characteristic. Bocavirus is highly prevalent among young children under 3 years of age, with a secondary peak following the main epidemic peaks around autumn in Guangzhou. Genetic recombination and potential antigenic alteration were detected in bocavirus.

Human bocavirus 1 (HBoV1) has been identified as one of the etiological agents of wheezing in young children with acute respiratory-tract infections. In this study, we have obtained the sequence of a full-length HBoV1 genome (including both termini) using viral DNA extracted from a nasopharyngeal aspirate of an infected patient, cloned the full-length HBoV1 genome, and demonstrated DNA replication, encapsidation of the ssDNA genome, and release of the HBoV1 virions from human embryonic kidney 293 cells. The HBoV1 virions generated from this cell line-based production system exhibits a typical icosahedral structure of approximately 26 nm in diameter, and is capable of productively infecting polarized primary human airway epithelia (HAE) from the apical surface. Infected HAE showed hallmarks of lung airway-tract injury, including disruption of the tight junction barrier, loss of cilia and epithelial cell hypertrophy. Notably, polarized HAE cultured from an immortalized airway epithelial cell line, CuFi-8 (originally derived from a cystic fibrosis patient), also supported productive infection of HBoV1. Thus, we have established a reverse genetics system and generated the first cell line-based culture system for the study of HBoV1 infection, which will significantly advance the study of HBoV1 replication and pathogenesis.

Objective This is a multicenter retrospective study aimed to evaluate the concordance between nucleic acid testing and targeted next-generation sequencing (tNGS) for etiologic detection, and to identify potential risk factors for severe community-acquired pneumonia (SCAP), thereby providing evidence for precision clinical management. Methods We retrospectively analyzed 191 pediatric Community-Acquired Pneumonia(CAP) cases positive for bocavirus by tNGS from April 2023 to June 2025. Etiologic concordance and coinfection patterns were evaluated. Univariate and multivariate logistic regression identified independent risk factors for SCAP. Results 191 children were included. Significant heterogeneity was observed among the four centers in age distribution, SCAP incidence, imaging findings, and treatment patterns ( P  < 0.05). Children’s Hospital, Zhejiang University School of Medicine (ZCH) reported the highest SCAP incidence (50.0%), with markedly higher rates of pulmonary consolidation (66.7%), atelectasis (100.0%), and pleural effusion (16.7%) compared with other centers, whereas DY had the lowest SCAP incidence (11.0%). All cases were bocavirus-positive by tNGS, while the positivity rate by nucleic acid testing was 51.3%. tNGS identified 44 cases of mixed detection (23.0%), including 35 bacterial (18.3%) and 7 viral co-detections (3.7%), whereas nucleic acid testing identified only 9 mixed detections (4.7%). tNGS demonstrated a clear advantage in detecting mixed and bacterial detections ( P  < 0.001). Multivariate logistic regression revealed that age < 3 years, plastic bronchitis, and increased prealbumin were independent risk factors for SCAP ( P  < 0.05). Conclusion Clinical profiles of bocavirus-associated CAP vary significantly across centers. tNGS offers a broader range of pathogen co-detection compared with conventional nucleic acid testing. Early recognition of high-risk children—particularly those < 3 years with potential plastic bronchitis and viral co-detection—is essential for timely SCAP management. Clinical trial registration This multicenter retrospective study was registered with the Chinese Clinical Trial Registry (ChiCTR), a primary registry within the WHO Registry Network. The registration was completed on January 19, 2025 (Registration number: ChiCTR2400080059), with a predefined target of enrolling at least 150 cases.