Viral respiratory infections in hospitalized and community control children in Alaska

Respiratory syncytial virus (RSV) in Alaska Native children from the Yukon Kuskokwim (YK) Delta is associated with a hospitalization rate five times higher than that reported for the general US child population. The role of other viral respiratory pathogens has not been studied in this population. YK Delta children <3 years of age hospitalized with respiratory infections and same aged community control children were prospectively enrolled between October 2005 and September 2007. Polymerase chain reaction detection of viruses was performed on nasopharyngeal samples. Characteristics of hospitalized and asymptomatic control children were analyzed. From October 2005 to September 2007, 440 hospitalized and 425 control children were analyzed. Respiratory viruses were detected in 90% (395) of hospitalized children: 194 (44%) rhinovirus, 131 (30%) adenovirus, 102 (23%) RSV, 77 (18%) para influenza viruses (PIV), 66 (15%) human metapneumovirus (hMPV), 23 (5%) influenza, and 25 (6%) coronavirus. Fifty‐two percent (221) of control children had a virus detected, most commonly rhinovirus (33%), and adenovirus (16%). RSV, PIV, hMPV, and influenza were significantly more common in hospitalized cases than control children, but rhinovirus, adenovirus, and coronavirus were not. RSV and hMPV were associated with higher severity of illness. In this study, RSV remains the most important virus associated with respiratory hospitalization, although hMPV and PIV were also common. RSV and hMPV were associated with more severe illness. Rhinovirus and adenovirus were detected in two‐thirds of hospitalized children, but their frequent detection in control children made their role in respiratory hospitalization uncertain. J. Med. Virol. 82:1282–1290, 2010. © 2010 Wiley‐Liss, Inc.     

Detection of human coronavirus NL63, human metapneumovirus and respiratory syncytial virus in children with respiratory tract infections in south-west Sweden

Two recently detected viruses, human metapneumovirus (hMPV) and coronavirus NL63 (HCoV-NL63), have been associated with acute respiratory tract infections, particularly in young children. This study investigated the frequency of hMPV and HCoV-NL63 infections in Swedish children by screening 221 nasopharyngeal aspirates, collected between November 2003 and May 2005, from 212 children attending the paediatric department of a county hospital in Sweden or submitted from local general practitioners. The samples were originally submitted to be tested for respiratory syncytial virus (RSV), and were examined retrospectively for hMPV and HCoV-NL63 by RT-PCR. Of the 212 patients, 101 were positive for RSV (48%), 22 (10%) were positive for hMPV, and 12 (6%) were positive for HCoV-NL63. The frequency of HCoV-NL63 infection increased from 1% in 2003-2004 to 10% in 2004-2005. Sequence analysis of parts of the coronavirus genomes showed considerable similarity to the HCoV-NL63 prototype sequence. The study demonstrated that HCoV-NL63 and hMPV occur in south-west Sweden with essentially the same frequency, seasonal distribution and clinical characteristics as have been reported in other countries.     

Etiology,seasonality, and clinical characterization of viral respiratory infections among hospitalized children in Beirut,Lebanon

Acute respiratory tract viral infections occur worldwide and are one of the major global burdens of diseases in children. The aim of this study was to determine the viral etiology of respiratory infections in hospitalized children, to understand the viral seasonality in a major Lebanese hospital, and to correlate disease severity and the presence of virus. Over a 1‐year period, nasal and throat swabs were collected from 236 pediatric patients, aged 16‐year old or less and hospitalized for acute respiratory illness. Samples collected were tested for the presence of 17 respiratory viruses using multiplex real‐time RT‐PCR. Pathogens were identified in 165 children (70%) and were frequently observed during fall and winter seasons. Co‐infection was found in 37% of positive samples. The most frequently detected pathogens were human Rhinovirus (hRV, 23%), Respiratory Syncytial Virus (RSV, 19%), human Bocavirus (hBov, 15%), human Metapneumovirus (hMPV, 10%), and human Adenovirus (hAdV, 10%). A total of 48% of children were diagnosed with bronchiolitis and 25% with pneumonia. While bronchiolitis was often caused by RSV single virus infection and hAdV/hBoV coinfection, pneumonia was significantly associated with hBoV and HP1V1 infections. No significant correlation was observed between a single viral etiology infection and a specific clinical symptom. This study provides relevant facts on the circulatory pattern of respiratory viruses in Lebanon and the importance of using PCR as a useful tool for virus detection. Early diagnosis at the initial time of hospitalization may reduce the spread of the viruses in pediatric units. J. Med. Virol. 88:1874–1881, 2016 . © 2016 Wiley Periodicals, Inc.

     

Newly identified respiratory viruses associated with acute lower respiratory tract infections in children in Lanzou,China, from 2006 to 2009

Nasopharyngeal aspirates were collected from 813 children <14 years old with acute lower respiratory tract infections in Lanzhou, China, from December 2006 to November 2009. PCR or RT-PCR was used to screen for the presence of 10 respiratory viruses. Viral agents were identified in 73.92% (601/813) of specimens, including RSV in 40.71%, hMPV in 6.15%, IFVA in 7.13%, IFVB in 0.98%, PIV1-3 in 7.87%, HCoV-HKU1 in 2.21%, HCoV-NL63 in 3.81%, HRV in 19.93%, AdV in 7.50% and HBoV in 11.56%. Two or more viruses were detected in 34.44% (280/813) of cases. The newly identified respiratory viruses, HBoV, hMPV, HCoV-HKU1 and HCoV-NL63, accounted for 22.01% of the detected viral pathogens. RSV and HRV were frequently detected in patients with bronchiolitis, and hMPV was frequently associated with pneumonia. HCoV-NL63 was found to be one of the causative agents of acute respiratory wheezing in young children. No seasonal variation was found in the incidence of detection of HCoV-HKU1, HCoV-NL63 or HBoV. This 3-year study demonstrated that viral pathogens play an important role in children with ALRTIs, and more attention should be paid to these newly identified viral agents.     

Human Metapneumovirus as a causative agent of acute bronchiolitis in infants.

BACKGROUND: Human Metapneumovirus (hMPV), has been recently isolated from children with acute respiratory tract infections (RTIs), including bronchiolitis, and classified in the Pneumovirinae subfamily within the Paramyxoviridae family. OBJECTIVES: Since most bronchiolitis studies fail to detect any viral pathogen in part of the samples, we sought for the presence of hMPV in a well characterized bronchiolitis cohort. STUDY DESIGN: Nasal washes were obtained from 56 children admitted to the hospital for acute bronchiolitis. RNA extraction and subsequent RT-PCR were used to detect hMPV, and correlated the presence of the virus with clinical characteristics of the disease. RESULTS AND CONCLUSIONS: PCR revealed the presence of hMPV in 16% of bronchiolitis cases, whereas respiratory syncytial virus (RSV; 67.9%) was the most frequently encountered viral pathogen. hMPV was identified either as a unique viral pathogen or co-existed with RSV, with whom they shared a similar seasonal distribution. There were no differences in disease characteristics, either clinical or laboratory, between bronchiolitis cases where hMPV was present and those caused by RSV or other viral pathogens. These findings suggest that hMPV is a common and important causative agent in infants with bronchiolitis, with clinical characteristics similar to that of RSV.     

Implementation of real-time RT-PCR for detection of human metapneumovirus and its comparison with enzyme immunoassay

Human metapneumovirus (hMPV) is responsible for outbreaks of bronchiolitis in winter and early spring in young children. Due to the relatively recent discovery of hMPV, the diagnostic opportunities are limited, while differential diagnosis with respiratory syncytial virus (RSV) remains important. We validated the RT-PCR by comparing various methods of RNA extraction, one-step RT-PCR kits and primer-probe combinations. The optimized RT-PCR was evaluated using 47 nasopharyngeal aspirates (NPAs) collected from children younger than 5 years, with clinically suspected RSV infection. The evaluated RT-PCRs were also compared to a commercially available hMPV enzyme immunoassay (EIA). We found 8.5% hMPV positivity with both RT-PCRs, in agreement with published literature. hMPV EIA showed positive and indeterminate results in 17% and 8.5%, respectively, of the tested NPAs. Positive RT-PCR samples were positive or indeterminate by hMPV EIA. Samples that were positive for RSV and influenza A virus interfered with the hMPV EIA. In conclusion, although RT-PCR is already a valuable tool for diagnosing hMPV infections, further optimization of the RT-PCR method is recommended. The hMPV EIA kit shows poor specificity and therefore needs further improvement.     

Epidemiological and clinical features of hMPV, RSV and RVs infections in young children.

BACKGROUND: Human metapneumovirus (hMPV) has recently been isolated from children with acute respiratory tract infections (RTIs). The epidemiological and clinical characteristics of hMPV infection need further investigation. OBJECTIVES: The purpose of this study was to compare the clinical features of hMPV, respiratory syncytial virus (RSV) and rhinoviruses (RV) infections in children less than 3 years of age presenting to an emergency department with acute respiratory illness. STUDY DESIGN: From December 2002 to April 2004, all children under age three (n=931) admitted for acute respiratory illness to Dijon Hospital, France, were investigated for respiratory viruses in nasal washes. RESULTS: hMPV was detected in 6% of children (in 10.1% (n=38) the first winter and in 3.3% (n=17) the second winter); RSV was detected in 28.5% of the children, while rhinoviruses were found in 18.3%. Five hMPV-infected children had evidence of dual infection, two with RSV and three others with RV. The median age of the patients with hMPV infection was 6 months, and the main clinical symptoms were rhinorrhea (74.5%) and cough (67%). A lower tract disease occurred in 66% of hMPV-positive patients. Gene sequencing of hMPV isolates revealed co-circulation of the two major groups of hMPV during the study period; no difference in pathogenicity was found. There was no difference in the prevalence of bronchiolitis where hMPV, RSV or rhinoviruses were present. Asthma was found more often in hospitalized children with hMPV and rhinoviruses than among those with RSV (p<0.001). CONCLUSIONS: These results provide further evidence of the importance of hMPV as a pathogen associated with respiratory tract infection in children.     

Usefulness of two new methods for diagnosing metapneumovirus infections in children

Human metapneumovirus (hMPV) is associated with acute respiratory tract infections, mainly in paediatric patients. The aim of this study was to evaluate the usefulness of two new commercial techniques available for the detection of hMPV in clinical samples from children: an enzyme immunoassay, hMPV EIA (Biotrin International Ltd), and a molecular assay, real-time RT-PCR (Pro hMPV Real Time Assay Kit; Prodesse). A total of 184 nasopharyngeal aspirate specimens from 173 children aged less than 5 years who were hospitalized with acute wheezing were analysed. Respiratory syncytial virus was detected in 27% of the samples, followed by influenza A virus (6%), parainfluenza virus (PIV)3 (2.2%), adenovirus (2%), PIV1 (1.1%), PIV2 (1.1%), and influenza B virus (0.5%). The presence of hMPV was tested in all samples, using the real-time RT-PCR and EIA. Real-time RT-PCR detected 13 hMPV-positive samples (8%), and EIA detected 17 (9.3%). When the EIA results were compared with those of real-time RT-PCR for the detection of hMPV, a good correlation was found (94%). A relatively low co-infection rate (15%) was observed in our patients. RT-PCR and EIA provide robust methods for the diagnosis of hMPV infection in children.     

Co-circulation of genetically distinct human metapneumovirus and human bocavirus strains in young children with respiratory tract infections in Italy

The discovery of human Metapneumovirus (hMPV) and human Bocavirus (hBoV) identified the etiological causes of several cases of acute respiratory tract infections in children. This report describes the molecular epidemiology of hMPV and hBoV infections observed following viral surveillance of children hospitalized for acute respiratory tract infections in Milan, Italy. Pharyngeal swabs were collected from 240 children ≤3 years of age (130 males, 110 females; median age, 5.0 months; IQR, 2.0-12.5 months) and tested for respiratory viruses, including hMPV and hBoV, by molecular methods. hMPV-RNA and hBoV-DNA positive samples were characterized molecularly and a phylogenetical analysis was performed. PCR analysis identified 131/240 (54.6%) samples positive for at least one virus. The frequency of hMPV and hBoV infections was similar (8.3% and 12.1%, respectively). Both infections were associated with lower respiratory tract infections: hMPV was present as a single infectious agent in 7.2% of children with bronchiolitis, hBoV was associated with 18.5% of pediatric pneumonias and identified frequently as a single etiological agent. Genetically distinct hMPV and hBoV strains were identified in children examined with respiratory tract infections. Phylogenetic analysis showed an increased prevalence of hMPV genotype A (A2b sublineage) compared to genotype B (80% vs. 20%, respectively) and of the hBoV genotype St2 compared to genotype St1 (71.4% vs. 28.6%, respectively). Interestingly, a shift in hMPV infections resulting from A2 strains has been observed in recent years. In addition, the occurrence of recombination events between two hBoV strains with a breakpoint located in the VP1/VP2 region was identified.     

Human metapneumovirus infection in hospital referred South African children

Human metapneumovirus (hMPV) was first described in Dutch children with acute respiratory symptoms. A prospective analysis of the epidemiology, clinical manifestation, and seroprevalence of hMPV and other respiratory viruses in South African children referred to hospital for upper or lower respiratory tract infection were carried out during a single winter season, by using RT-PCR, viral culture, and enzyme-linked immunosorbent assays. In nasopharyngeal aspirates from 137 children, hMPV was detected by RT-PCR in 8 (5.8%) children (2-43 months of age) as a sole viral pathogen, respiratory syncytial virus (RSV) in 21 (15%), influenza A virus in 18 (13%) and influenza B virus in 20 (15%). Pneumonia was diagnosed in seven children and upper respiratory tract infection in one of the hMPV-infected children. One hMPV-infected child was admitted to the intensive care unit in need of mechanical ventilation and one child was infected with human immunodeficiency virus (HIV). No statistically significant differences were found between hMPV, RSV, and influenza virus infected groups with regard to clinical signs and symptoms and chest radiograph findings. The seropositive rate of hMPV specific IgG antibodies was 92% in children aged 24-36 months, the oldest seronegative child in our study was 7 years and 6 months of age. In conclusion, hMPV contributes to upper and lower respiratory tract morbidity in South African children.     

Detection of human metapneumovirus and respiratory syncytial virus by duplex real-time RT-PCR assay in comparison with direct fluorescent assay

Human respiratory syncytial virus (hRSV) and human metapneumovirus (hMPV) are important respiratory pathogens of small children and adults. The present study aimed to design a sensitive real-time RT-PCR assay for the detection of hRSV and hMPV in comparison with direct fluorescent assay (DFA) and to determine the incidence of hMPV and hRSV as causative agents of respiratory infections in a Finnish population. For DFA detection of hMPV antigen, four commercial antibodies were evaluated. The duplex real-time RT-PCR assay achieved a sensitivity of 10³ copies/mL of specimen for hRSV and hMPV type A viruses and 10⁴ copies/mL for type B hMPV. The detection rate of the RT-PCR assay was compared with those for DFA detection of hMPV and hRSV in analyses of 350 nasopharyngeal aspirates sent to HUSLAB, Helsinki University Hospital, for routine virus diagnostics during November 2007 to June 2008. Of the samples analyzed, 43 (12.3%) were positive for hRSV by DFA and an additional 13 specimens (3.7%) were positive for hRSV by RT-PCR. Only four samples (1.1 %) were found to be positive for hMPV RNA by RT-PCR, with two of them also positive by DFA. The duplex real-time RT-PCR assay described in the present study can therefore be applied for efficient identification of hMPV and hRSV in clinical specimens and collection of information on the epidemiology and clinical outcome of these viruses.     

Impact of human metapneumovirus and human cytomegalovirus versus other respiratory viruses on the lower respiratory tract infections of lung transplant recipients

Viral respiratory tract infections in lung transplant recipients may be severe. During three consecutive winter-spring seasons, 49 symptomatic lung transplant recipients with suspected respiratory viral infection, and 26 asymptomatic patients were investigated for presence of respiratory viruses either in 56 nasopharyngeal aspirate or 72 bronchoalveolar lavage samples taken at different times after transplantation. On the whole, 1 asymptomatic (3.4%) and 28 symptomatic (57.1%) patients were positive for human metapneumovirus (hMPV, 4 patients), influenza virus A (3 patients), and B (2 patients), respiratory syncytial virus (2 patients), human coronavirus (2 patients), human parainfluenza virus (2 patients), rhinovirus (5 patients), while 4 patients were coinfected by 2 respiratory viruses, and 5 were infected sequentially by 2 or more respiratory viruses. In bronchoalveolar lavage samples, hMPV predominated by far over the other viruses, being responsible for 60% of positive specimens, whereas other viruses were present in nasopharyngeal aspirates at a comparable rate. RT-PCR (detecting 43 positive samples/128 examined) was largely superior to monoclonal antibodies (detecting 17 positive samples only). In addition, HCMV was detected in association with a respiratory virus in 4/18 HCMV-positive patients, and was found at a high concentration (>10(5) DNA copies/ml) in 3/16 (18.7%) patients with HCMV-positive bronchoalveolar lavage samples and pneumonia. Coinfections and sequential infections by HCMV and respiratory viruses were significantly more frequent in patients with acute rejection and steroid treatment. In conclusion: (i) about 50% of respiratory tract infections of lung transplant recipients were associated with one or more respiratory viruses; (ii) hMPV largely predominates in bronchoalveolar lavage of symptomatic lung transplant recipients, thus suggesting a causative role in lower respiratory tract infections; (iii) RT-PCR appears to be the method of choice for detection of respiratory viruses in lung transplant recipients, (iv) a high HCMV load in bronchoalveolar lavage is a risk factor for viral pneumonia, suggesting some measure of intervention for the control of viral infection.     

Multicentered study of viral acute lower respiratory infections in children from four cities of Argentina, 1993-1994

This study describes the first multicentered study of acute lower respiratory infection viral etiology in young children from four different geographical areas of Argentina. A total of 1,278 children under 5 years of age, hospitalized in primary care centers from Buenos Aires, Córdoba, Santa Fé and Mar del Plata cities during a 2-year period were studied (1993-1994). Nasopharyngeal aspirates were investigated for respiratory syncytial virus (RSV), adenovirus, parainfluenza, and influenza A and B viruses by indirect immunofluorescence. Out of the patients studied, 946 (74%) were under 1 year of age. Viruses were detected in 399 patients (32%). RSV was observed in 25.3% of the samples, representing 78.2% of all viral positive cases. Adenoviruses were detected in 2.5% of the cases, parainfluenza in 2.2%, influenza A in 2.1%, and influenza B in 0.2%. Compared with other viruses, the higher RSV frequency was statistically significant (P < 0.000). Most RSV cases were detected between May and September with a significant peak in July (P < 0.000). Pneumonia was observed in 46% of the patients, bronchiolitis in 41% and other entities in 13%. The case fatality rate observed during the 2 year study was 0.73%. Most of the above respiratory viruses were detected in the four cities, however, the frequency of RSV and influenza were different in the southern city.