Epidemiological profile and clinical associations of human bocavirus and other human parvoviruses

BACKGROUND: Human bocavirus (HBoV) and PARV4 are newly discovered human parvoviruses. HBoV, which was first detected in respiratory samples, has a potential role in the development of human respiratory disease. The present study compared the frequencies, epidemiological profiles, and clinical backgrounds of HBoV and PARV4 infections with those of other respiratory virus infections, by evaluating diagnostic samples referred to the Specialist Virology Laboratory (SVL) at the Royal Infirmary of Edinburgh (Edinburgh, United Kingdom). METHODS: Anonymized samples and study subject information were obtained from the respiratory sample archive of the SVL. Samples were screened for HBoV, PARV4, B19, respiratory syncytial virus (RSV), adenoviruses, influenza viruses, and parainfluenza viruses by use of nested polymerase chain reaction. RESULTS: HBoV infection was detected in 47 (8.2%) of 574 study subjects, ranking third in prevalence behind RSV infection (15.7%) and adenovirus infection (10.3%). Peak incidences of HBoV were noted among infants and young children (age, 6-24 months) during the midwinter months (December and January) and were specifically associated with lower respiratory tract infections. HBoV infections were frequently accompanied by other respiratory viruses (frequency, 43%), and they were more prevalent among individuals infected with other respiratory viruses (17%), frequently adenovirus or RSV. All respiratory samples were negative for PARV4. CONCLUSIONS: In the present study, HBoV was a frequently detected, potential respiratory pathogen, with a prevalence and an epidemiological profile comparable to those of RSV. Identification of HBoV infections may be clinically important in the future.     

Human bocavirus infection in young children in the United States: molecular epidemiological profile and clinical characteristics of a newly emerging respiratory virus

BACKGROUND: Human bocavirus (HBoV) is a newly identified human parvovirus that was originally identified in the respiratory secretions of children with respiratory tract disease. To further investigate the epidemiological profile and clinical characteristics of HBoV infection, we screened infants and children <2 years of age (hereafter referred to as "children") for HBoV. METHODS: Children for whom respiratory specimens submitted to a diagnostic laboratory tested negative for respiratory syncytial virus, parainfluenza viruses (types 1-3), influenza A and B viruses, and adenovirus, as well as asymptomatic children, underwent screening for HBoV by use of polymerase chain reaction (PCR). Respiratory specimens were obtained from the children from 1 January 2004 through 31 December 2004. RESULTS: Twenty-two (5.2%) of the 425 children who had a respiratory specimen submitted to the diagnostic laboratory and 0 of the 96 asymptomatic children were found to be positive for HBoV by PCR (P=.02). Fever, rhinorrhea, cough, and wheezing were observed in > or =50% of the HBoV-positive children. Of the 17 children who had chest radiography performed, 12 (70.6%) had abnormal findings. HBoV appeared to have a seasonal distribution. Nucleotide polymorphisms were detected in the viral capsid protein (VP) 1/VP2 genes. Two distinct HBoV genotypes circulated during the study period. CONCLUSIONS: HBoV is circulating in the United States and is associated with both upper and lower respiratory tract disease in infants and young children.     

CD4+ T helper cell responses against human bocavirus viral protein 2 viruslike particles in healthy adults

BACKGROUND: Human bocavirus (HBoV) was recently described as a new member of the Parvoviridae family, and its possible association with respiratory illness in infants has been discussed. To date, HBoV genomes have been detected worldwide in respiratory tract samples obtained from children with pulmonary diseases, whereas only limited data on virus-specific immunity are available, mainly because of the lack of recombinant viral antigens. METHODS: HBoV viruslike particles (VLPs) were produced in insect cells and characterized by electron microscopy and cesium chloride gradient centrifugation. HBoV viral protein 2 (VP2)-specific antibodies and CD4+ T helper cell responses were analyzed by enzyme-linked immunosorbent assay and enzyme-linked immunospot assay. RESULTS: VP2 capsid proteins of HBoV were produced in insect cells infected with a recombinant baculovirus, and the formation of icosahedral VLPs (diameter, 21-25 nm; sedimentation density, 1.33 g/cm(3)) was demonstrated. A significant increase in secretion of VP2-specific interferon-gamma was detected in cultures of peripheral blood mononuclear cells obtained from 69 healthy adults found to be positive for HBoV-specific immunoglobulin G antibodies, compared with control stimulations. In parallel, T cell responses against identically expressed parvovirus B19 VP2 VLPs were frequently observed in the individuals studied, without there being obvious cross-reactions between HBoV and parvovirus B19. CONCLUSIONS: Data suggest the presence of HBoV-specific immune responses in adults and strongly support a high prevalence of HBoV among humans.     

Human bocavirus amongst an all‐ages population hospitalised with acute lower respiratory infections in Cambodia

Please cite this paper as: Arnott et al. (2013) Human bocavirus amongst an all‐ages population hospitalised with acute lower respiratory infections in Cambodia. Influenza and Other Respiratory Viruses 7(2) 201–210. Background Human bocavirus (HBoV) is a novel parvovirus that is associated with respiratory and gastrointestinal tract disease. Objectives To investigate the prevalence and genetic diversity of HBoV amongst hospitalized patients with acute lower respiratory infection (ALRI) in Cambodia. Study Design Samples were collected from 2773 patients of all ages hospitalised with symptoms of ALRI between 2007 and 2009. All samples were screened by multiplex RT‐PCR/PCR for 18 respiratory viruses. All samples positive for HBoV were sequenced and included in this study. Results Of the samples tested, 43 (1·5%) were positive for HBoV. The incidence of HBoV did not vary between the consecutive seasons investigated, and HBoV infections were detected year‐round. The incidence of HBoV infection was highest in patients aged <2 years, with pneumonia or bronchopneumonia the most common clinical diagnosis, regardless of age. A total of 19 patients (44%) were co‐infected with HBoV and an additional respiratory pathogen. All isolates were classified as HBoV type 1 (HBoV‐1). High conservation between Cambodian NP1 and V1V2 gene sequences was observed. Conclusions Human bocavirus infection can result in serious illness, however is frequently detected in the context of viral co‐infection. Specific studies are required to further understand the true pathogenesis of HBoV in the context of severe respiratory illness.     

广东地区急性呼吸道感染儿童人类博卡病毒的流行状况

目的 了解广东地区急性呼吸道感染患儿人类博卡病毒(HBoV)的感染情况.方法 收集广东地区2007年6月至2008年5月期间呼吸道感染患儿的鼻咽分泌物447份,采用PCR法检测HBoV衣壳蛋白(VP)基因片段,阳性标本作核酸序列测定,并与基冈库中的已知序列进行序列比对和系统进化树分析.结果 447例呼吸道感染患儿标本中HBoV阳件率为5.1%.其中10例患儿与其他病毒混合感染,占阳性标本的43.5%.阳件患儿的主要临床诊断为喘息性肺炎、毛细支气管炎和支气管肺炎,年龄分布从42 d到6岁,主要集中在1岁以内,HBoV感染的季节分布偏向夏、秋及晚春.经序列比对和进化树分析.阳性株的VP基因片段与瑞典株ST1的核酸及氨基酸序列同源性分别为97.8%～98.8%及99.3%～100.0%.结论 HBoV是广东地区儿童下呼吸道感染的重要病原之一,且在1岁以内患儿中高发.该地区HBoV流行株的VP基因片段较为保守,但也存在导致氨基酸改变的突变株.     

广东地区首例人博卡病毒的检出及鉴定

目的 建立人博卡病毒(HBoV)筛查检测平台,了解广东地区支气管肺炎患儿HBoV感染情况.方法 采用PCR技术筛查HBoV核蛋白(NP)基因片段,阳性标本作HBoV衣壳蛋白(VP)基因片段鉴定,并进行核酸序列和进化树分析.结果 从50例住院支气管肺炎患儿鼻咽分泌物中检测出1例HBoV,为广东地区首例,命名为GD-1株.HBoV VP基因部分序列分析与基因库中HBov VP基因序列同源性比对,除与韩国KNIH-2K6GJ2713株同源性为36%、与美国NH4549株同源性为77%外,与其他所有VP基因序列同源性均>95%,与法国株、北京株、加拿大株的同源性>98%.GD-1株HBoV部分VP基因片段与北京CZ株、加拿大株、西班牙株、意大利株等在同一基因进化簇主分枝中,与法国175/03/2002FRA株同在一个侧枝中.结论 广东地区存在HBoV感染,有进一步研究的必要性.     

Prevalence and Molecular Characterization of Human Bocavirus Detected in Croatian Children with Respiratory Infection

Human bocavirus (HBoV) 1 is considered an important respiratory pathogen, while the role of HBoV2-4 in clinical disease remains somewhat controversial. Since, they are characterized by a rapid evolution, worldwide surveillance of HBoVs’ genetics is necessary. This study explored the prevalence of HBoV genotypes in pediatric patients with respiratory tract infection in Croatia and studied their phylogeny. Using multiplex PCR for 15 respiratory viruses, we investigated 957 respiratory samples of children up to 18 years of age with respiratory tract infection obtained from May 2017 to March 2021 at two different hospitals in Croatia. Amplification of HBoV near-complete genome or three overlapping fragments was performed, sequenced, and their phylogenetic inferences constructed. HBoV was detected in 7.6% children with a median age of 1.36 years. Co-infection was observed in 82.2% samples. Sequencing was successfully performed on 29 HBoV positive samples, and all belonged to HBoV1. Croatian HBoV1 sequences are closely related to strains isolated worldwide, and no phylogenetic grouping based on mono- or co-infection cases or year of isolation was observed. Calculated rates of evolution for HBoV1 were 10⁻⁴ and 10⁻⁵ substitutions per site and year. Recombination was not detected among sequences from this study.     

Serologically diagnosed acute human bocavirus 1 infection in childhood community‐acquired pneumonia

Aim

To assess the role of human bocavirus 1 (HBoV1) as a causative agent of non‐severe community‐acquired pneumonia (CAP) in children.

Methods

Patients aged 2‐59 months with non‐severe CAP (respiratory complaints and radiographic pulmonary infiltrate/consolidation) attending a University Hospital in Salvador, Brazil were enrolled in a prospective cohort. From 820 recruited children in a clinical trial ( ClinicalTrials.gov NCT01200706), nasopharyngeal aspirate (NPA), and acute and convalescent serum samples were obtained from 759 (92.6%) patients. NPAs were tested for 16 respiratory viruses by PCR. Acute HBoV1 infection was confirmed by measuring specific IgM and IgG responses in paired serum samples.

Results

Respiratory viruses were detected in 693 (91.3%; 95%CI: 89.1‐93.2) CAP cases by PCR. HBoV1‐DNA was detected in 159 (20.9%; 95%CI: 18.2‐24.0) cases. Of these 159 PCR positive cases, acute HBoV1 infection was confirmed serologically in 38 cases (23.9%; 95%CI: 17.8‐31.0). Overall, acute HBoV1 infection was confirmed in 5.0% (38/759) of non‐severe CAP patients. HBoV1 was detected in 151 cases with at least one other virus making 31.7% of all multiple virus (n = 477) detections. Among all 759 cases, 216 had one respiratory virus detected, and sole HBoV1 was detected in only 8 (3.7%). Acute HBoV1 infection was serologically diagnosed in 34 (22.5%) HBoV1‐DNA‐positive cases with another virus, compared to 4 (50.0%) cases with sole virus detection (p = 0.09).

Conclusion

HBoV1 was detected by PCR in one fifth of the children with non‐severe CAP and acute HBoV1 infection was serologically confirmed in one quarter of these cases.

     

Detection and Molecular Characterization of Enteric Viruses in Bivalve Mollusks Collected in Arraial do Cabo,Rio de Janeiro,Brazil

Viral bivalve contamination is a recognized food safety hazard. Therefore, this study investigated the detection rates, seasonality, quantification, and genetic diversity of enteric viruses in bivalve samples (mussels and oysters). We collected 97 shellfish samples between March 2018 and February 2020. The screening of samples by qPCR or RT-qPCR revealed the detection of norovirus (42.3%), rotavirus A (RVA; 16.5%), human adenovirus (HAdV; 24.7%), and human bocavirus (HBoV; 13.4%). There was no detection of hepatitis A virus. In total, 58.8% of shellfish samples tested positive for one or more viruses, with 42.1% of positive samples contaminated with two or more viruses. Norovirus showed the highest median viral load (3.3 × 10⁶ GC/g), followed by HAdV (median of 3.5 × 10⁴ GC/g), RVA (median of 1.5 × 10³ GC/g), and HBoV (median of 1.3 × 10³ GC/g). Phylogenetic analysis revealed that norovirus strains belonged to genotype GII.12[P16], RVA to genotype I2, HAdV to types -C2, -C5, and -F40, and HBoV to genotypes -1 and -2. Our results demonstrate the viral contamination of bivalves, emphasizing the need for virological monitoring programs to ensure the quality and safety of shellfish for human consumption and as a valuable surveillance tool to monitor emerging viruses and novel variants.     

Interaction of Poliovirus Capsid Proteins with the Cellular Autophagy Pathway

The capsid precursor P1 constitutes the N-terminal part of the enterovirus polyprotein. It is processed into VP0, VP3, and VP1 by the viral proteases, and VP0 is cleaved autocatalytically into VP4 and VP2. We observed that poliovirus VP0 is recognized by an antibody against a cellular autophagy protein, LC3A. The LC3A-like epitope overlapped the VP4/VP2 cleavage site. Individually expressed VP0-EGFP and P1 strongly colocalized with a marker of selective autophagy, p62/SQSTM1. To assess the role of capsid proteins in autophagy development we infected different cells with poliovirus or encapsidated polio replicon coding for only the replication proteins. We analyzed the processing of LC3B and p62/SQSTM1, markers of the initiation and completion of the autophagy pathway and investigated the association of the viral antigens with these autophagy proteins in infected cells. We observed cell-type-specific development of autophagy upon infection and found that only the virion signal strongly colocalized with p62/SQSTM1 early in infection. Collectively, our data suggest that activation of autophagy is not required for replication, and that capsid proteins contain determinants targeting them to p62/SQSTM1-dependent sequestration. Such a strategy may control the level of capsid proteins so that viral RNAs are not removed from the replication/translation pool prematurely.     

Human bocavirus: a novel parvovirus epidemiologically associated with pneumonia requiring hospitalization in Thailand

BACKGROUND: We detected human bocavirus (HBoV) infection in 4.5% of hospitalized patients with pneumonia in rural Thailand. However, the role of HBoV as a pathogen is unclear. METHODS: We compared HBoV infection in patients with pneumonia with that in asymptomatic control patients enrolled between 1 September 2004 and 31 August 2005 in the same hospitals in Thailand. We examined outpatients with influenza-like illness for HBoV infection and tested for 13 additional respiratory viruses. Epidemiologic and clinical characteristics of HBoV infection are described. RESULTS: HBoV infection was detected in 20 (3.9%) of 512 outpatients and 3 (1%) of 280 control patients. Coinfection with other viruses was detected in 83% of patients with pneumonia and in 90% of outpatients. Compared with control patients, HBoV infection was significantly associated with pneumonia requiring hospitalization (adjusted odds ratio, 3.56 [95% confidence interval, 1.06-11.91]; P=.04). Eighty-three percent of HBoV infections were detected in patients with pneumonia who were <5 years old. More patients with pneumonia associated with HBoV-respiratory syncytial virus (RSV) or human parainfluenza virus (HPIV) coinfections had wheezing than patients with RSV and HPIV infections alone (9 [53%] of 17 vs. 32 [23%] of 138]; P=.01). CONCLUSIONS: HBoV infection was epidemiologically associated with pneumonia among young children in rural Thailand, but infection and illness may be dependent on coinfection with other viruses.     

Evaluation of yield of currently available diagnostics by sample type to optimize detection of respiratory pathogens in patients with a community‐acquired pneumonia

Background

For the detection of respiratory pathogens, the sampling strategy may influence the diagnostic yield. Ideally, samples from the lower respiratory tract are collected, but they are difficult to obtain.

Objectives

In this study, we compared the diagnostic yield in sputum and oropharyngeal samples (OPS) for the detection of respiratory pathogens in patients with community-acquired pneumonia (CAP), with the objective to optimize our diagnostic testing algorithm.

Methods

Matched sputum samples, OPS, blood cultures, serum, and urine samples were taken from patients (>18 years) with CAP and tested for the presence of possible respiratory pathogens using bacterial cultures, PCR for 17 viruses and five bacteria and urinary antigen testing.

Results

When using only conventional methods, that is, blood cultures, sputum culture, urinary antigen tests, a pathogen was detected in 49·6% of patients (n = 57). Adding molecular detection assays increased the yield to 80%. A pathogen was detected in 77 of the 115 patients in OPS or sputum samples by PCR. The sensitivity of the OPS was lower than that of the sputum samples (57% versus 74%). In particular, bacterial pathogens were more often detected in sputum samples. The sensitivity of OPS for the detection of most viruses was higher than in sputum samples (72% versus 66%), except for human rhinovirus and respiratory syncytial virus.

Conclusion

Addition of PCR on both OPS and sputum samples significantly increased the diagnostic yield. For molecular detection of bacterial pathogens, a sputum sample is imperative, but for detection of most viral pathogens, an OPS is sufficient.     

Human bocavirus - insights into a newly identified respiratory virus

Human Bocavirus (HBoV) was discovered in 2005 using a molecular virus screening technique. It is often found in respiratory samples and is a likely cause for respiratory diseases in children. HBoV is distributed worldwide and has been found not only in respiratory samples, but also in feces, urine and serum. HBoV infections are mostly found in young children and coinfections with other respiratory viruses are often found, exacerbating the efforts to link HBoV to specific symptoms. The purpose of this review is to give an overview of recent HBoV research, highlighting some recent findings.     

Human bocavirus infection in hospitalized children in Italy

Background Human bocavirus (HBoV) was first discovered in Sweden in 2005 and has now been found worldwide; however its role in clinically relevant diseases has not yet been clearly defined. Objectives To gain new insight into HBoV infection among children hospitalized with acute respiratory infections in Rome. Methods Between November 2004 and May 2007, 415 nasal washings were tested for the presence of an extensive range of respiratory viruses using molecular methods. Results Viral pathogens were detected in 214 children (51·6%), 28·9% being respiratory syncytial virus (RSV) and 9·6% being rhinovirus positive. Of the 34 children (8·2%) who tested positive for HBoV, 21 (61·8%) were co‐infected with another respiratory virus, mainly RSV. Human bocavirus was the only pathogen identified in four pneumonia and six bronchiolitis cases in March 2005 and January 2007, respectively. Human bocavirus was also detected in one child hospitalized with gastroenteritis and in another with erythema. Conclusions In the examined population, HBoV was the third most common virus detected but with a high rate of co‐infection with other respiratory viruses. Human bocavirus appeared to be the etiological agent in some pneumonia and bronchiolitis cases in which tests for all likely respiratory pathogens were negative.     

粤东地区毛细支气管炎病毒病原谱的变迁探究

目的探讨近年来粤东地区毛细支气管炎病毒病原学的构成现状。方法收集粤东地区2007年7月至2010年6月3年间毛细支气管炎患儿的咽拭子共508份,采用多重PCR方法检测呼吸道合胞病毒、腺病毒、流感病毒A型、流感病毒B型、副流感病毒1型、副流感病毒3型、鼻病毒、人类博卡病毒、人类偏肺病毒、WU多瘤病毒,共8种lO型病毒。结果①508例患儿中男374例（73．6％）,女134例（26．4％）。②508例患儿中1岁以下年龄组393例（77．4％）,病毒检出率为77．2％;1岁以上年龄组115例（22．6％）,病毒检出率为22．8％。③2007年7至2008年6月病毒阳性率为47．5％（77／162）,病毒检出第1位为呼吸道合胞病毒（33．7％）,新发现呼吸道病毒（人类博卡病毒、人类偏肺病毒、wu多瘤病毒）占14．3％;2008年7月至2009年6月病毒阳性率为51．7％（124／240）,病毒检出第1位为流感病毒A型（38．4％）,新发现呼吸道病毒占6．4％;2009年7月至2010年6月病毒阳性率为45．3％（48／106）,病毒检出第1位为鼻病毒（22．4％）,新发现呼吸道病毒占20．9％。④3年间病毒混合感染率分别为20．8％、42．7％、27．1％。结论①毛细支气管炎患儿中男孩多见,1岁以下年龄组发病率及病毒检出率均高于1岁以上年龄组。②鼻病毒、流感病毒A型在不同年度是小儿毛细支气管炎首位病原体,既往研究中占首位的呼吸道合胞病毒有逐年下降趋势。③新发现呼吸道病毒在小儿毛细支气管炎病例中检出,并有逐年上升趋势。④毛细支气管炎病例中存在不同病毒混合感染的现象。     

High prevalence of human bocavirus 1 in infants with lower acute respiratory tract disease in Argentina, 2007-2009

Human bocavirus (HBoV) is a parvovirus whose association with respiratory disease is currently under investigation.ObjectiveTo determine HBoV prevalence in children with lower acute respiratory infection.MethodsWe investigated HBoV in 433 nasopharyngeal aspirates collected in 2007–2009 from children 0 to 5 years old hospitalized with bronchiolitis or pneumonia in Córdoba, Argentina.ResultsThe general prevalence of HBoV was 21.5% and the positive cases (HBoV+) were more frequent during winter and spring. The mean age of HBoV+ patients was 6.9 months, with 87.1% of the detections corresponding to infants less than 1 year old (among which the prevalence of HBoV was 26.3% in patients < 3 months of age, 22.1% in 3 to 6 months, 25.3% in 6 to 9 months, and 18.8% in 9 to 12 months). The sequence analysis of the NP1 coding region of 15 isolates showed that all isolates from Cordoba were HBoV1 which exhibited a homology of nearly 100% both among themselves and with the originally discovered virus from 2005.ConclusionOverall, our results indicate that HBoV is a significant pathogen that contributes to acute respiratory infection both on its own and during coinfection with other viruses.     

Enterovirus replication in valvular tissue from patients with chronic rheumatic heart disease.

AIMS: To investigate the involvement of enterovirus infection in chronic, rheumatic heart disease. METHODS AND RESULTS: Formalin-fixed, paraffin-embedded, surgical samples of valve tissue were examined for the presence of enteroviral RNA and virus capsid protein VP1 by in situ hybridization and immunostaining. Of 53 cases, 33 were patients with chronic rheumatic heart disease and 20 had Marfan's syndrome or degenerative valve disease. Enterovirus RNA was detected in 8 (24.2%) of 33 patients with chronic rheumatic heart disease by in situ hybridization using strand-specific oligonucleotide probes, complementary to conserved sequences in enterovirus genomic (positive strand) RNA. The replication template (negative strand) RNA also was found in seven of these eight cases. The viral capsid protein VP1 was detected in 16 (48.5%) of 33 patients with chronic rheumatic heart disease by immunohistochemistry and correlated with viral RNA detection. Virus was localized generally to valvular tissue. Neither viral RNA nor capsid protein VP1 were found in valvular tissue from any of the 20 comparison cases. CONCLUSIONS: This is the first demonstration of detection and localization of both enterovirus RNA and capsid protein in chronic rheumatic heart disease. The presence of negative strand RNA and VP1 indicates enteroviral RNA replication and protein synthesis and suggests an aetiological role of enterovirus in the pathogenesis of chronic rheumatic heart disease.     

Human bocavirus infection in a neonatal intensive care unit

Human bocavirus (HBoV) plays a non-insignificant role as a pathogen in respiratory tract diseases in the pediatric population, especially in infants younger than 2 years of age. In this paper, we have described two cases of a possible nosocomial infection in a neonatal intensive care unit being HBoV the sole detected respiratory virus in clinical samples.     

Epidemiological study of influenza virus infections in young adult outpatients from Buenos Aires,Argentina

Background Influenza virus is the most common cause of influenza‐like illness (ILI) in adults. In Argentina, studies on influenza and other respiratory viruses were performed mostly in pediatric populations. Objectives To determine: (1) the frequency of influenza virus and other common respiratory viruses in adult outpatients with ILI, (2) whether the signs and symptoms predict viral etiology, (3) whether viral diagnosis changes clinical management or infection control measures and (4) to characterize the influenza strains circulating in the community. Population and methods Nasal and pharyngeal swabs from adult outpatients with ILI attending the emergency room during the winter seasons of 2004 and 2005 in Argentina were evaluated by immunofluorescence and RT‐PCR. Results Of 151 samples analyzed, 39 (26%) were influenza A positive, 5 (3·3%) influenza B positive and 4 (2·6%) respiratory syncytial virus positive by immunofluorescence. Two samples (1·3%) were human metapneumovirus positive by RT PCR. Cell culture detected six additional influenza viruses and one adenovirus positive sample. The sensitivity of immunofluorescence for influenza compared with culture was 70%. Symptoms did not predict etiology. Conclusions In this study, 40% of the patients with ILI had a specific viral infection and 83% were influenza viruses. Viral detection was necessary to determine the etiology as signs and symptoms were not different between patients with or without viral infection. Viral diagnosis was important to implement infectious control measures. Circulating influenza strains in this study were similar to the correspondent vaccine strains selected for the Southern hemisphere.