| PART ⅠIMPACT OF HUMAN RHINOVIRUS TYPES AND VIRAL LOAD ON THE SEVERITY OF ILLNESS IN HOSPITALIZED CHILDREN WITH ACUTE RESPIRATORY TRACT INFECTIONSBackground and object:Human rhinovirus (HRV) is not only responsible for at least one-half of all common colds but is also associated with bronchitis, bronchiolitis, pneumonia, and acute asthma exacerbation. The severe acute respiratory tract infection (ARTI) of HRV infection was associated with different subtypes and viral load. However, the impact of different HRV types and viral load on severe ARTI has not been thoroughly elucidated. This study is designed to determine the different clinical features, especially severe respiratory infection, of patients infected with different HRV types among hospitalized children with ARTI. We also aimed to investigate the relationship between the viral load of the three HRV types and severe respiratory infection.Methods:From January 2012 to September 2014,1876 nasopharyngeal aspirate (NPA) specimens from hospitalized children with ARTI were collected to detect respiratory viruses by polymerase chain reaction (PCR). The HRV positive specimens were analyzed viral loads by quantitative HRV-specific quantitative polymerase chain reaction (Q-PCR).Results:Among these 1876 NPA specimens,473 (25.2%) were positive for HRV. HRV-A, HRV-B, HRV-C, and HRV-untyped virus were detected in 254 (53.7%),28 (5.9%),122 (25.8%), and 69 (14.6%) specimens, respectively. Except children who experienced wheezing were more common in the HRV-C detection group than in the HRV-A detection group, there were no other significant differences between the two groups, including the percent of children diagnosed with severe pneumonia and severe asthma exacerbation. Logistic regression models demonstrated that there was no difference in disease severity including severe pneumonia and severe asthma exacerbation among HRV subtypes. A HRV load of 106copies/mL was used to divide high and low HRV viral loads. Of the HRV single detection occurrences, children diagnosed with severe pneumonia were more common in high viral load group than in low viral load group in HRV-A detection group (36.4% vs.12.7%, P=0.023), while there was no significant difference in severe pneumonia between a high viral load and a low viral load in the HRV-C detection group (25.0% vs.25.0%, P=0.559). Among children<2 years of age, in HRV-A detection group, the viral load was higher in the severe pneumonia group than in the non-severe pneumonia group (4.7×105copies/mL vs.8.1×104 copies/mL, P=0.042), but in HRV-C detection group, there was no difference (7.9×103 copies/mL vs.1×104 copies/mL, P=0.589).Conclusion:HRV was frequently present in hospitalized children with ARTI in Chongqing. HRV-C could cause more children with wheezing than HRV-A, but the severe pneumonia and severe asthma exacerbation for HRV-C and HRV-A was similar. A high load of HRV-A in the lower respiratory tract might be connected with severe pneumonia in children under 2 years of age.PART ⅡPREVALENCE AND MOLECULAR CHARACTERIZATIONS OF ENTERVIRUS D68 AMONG CHILDREN WITH ACUTE RESPIRATORY INFECTION IN CHINA BETWEEN 2012 AND 2014Background and object:Human enterovirus D68 (HEV-D68) that belongs to species Human enterovirus D is associated with respiratory illness. The US and Canada experienced widespread outbreaks of HEV-D68 infections associated with severe respiratory diseases that began in August 2014. In the viral surveillance of acute respiratory tract infection (ARTI) in Chongqing, China, the detection rate of HEV-D68 was significantly higher in September and October 2014 than before; this increase was consistent with the outbreak in North America. This study is designed to analyze the characteristics of clinical and genome structure of HEV-D68 in Chongqing.Methods:From January 2012 to November 2014,1876 nasopharyngeal aspirate (NPA) specimens from hospitalized children with ARTI were collected to detect respiratory viruses by PCR. Nearly whole-genome sequences of HEV-D68 were obtained by PCR. Phylogenetic trees were generated using the obtained sequences.Results:Among these 1876 NPA specimens,26 (1.4%) were positive for Human enterovirus (HEV). HEV-D68 was detected in 19 children (1.0%,19/1876). The frequency of HEV-D68 detection was 9.8%(13/132) in September and October 2014. A phylogenetic tree of VP1 gene nucleotide sequences showed that 19 HEV-D68 strains grouped into clade A and clade B. All 13 strains of the Chongqing 2014 detected were grouped into clade B and had high homology with the main strains of the 2014 US outbreak. Sequence analysis of 5’untranslated regions showed that clade B had two blocks of deletions (681-703 and 717-728). Among the 19 children with HEV-D68 infections,13 (68.4%) children had a history of recurrent wheezing,13 (68.4%) children were diagnosed with asthma including 11 acute asthma exacerbation (severe:5 cases, moderate:6 cases). HEV-D68 was detected as a sole pathogen in 8 children. Children diagnosed with asthma were more common in HEV-D68 single detection than in co-detection (100% vs 45.5%, P=0.018). HEV-D68 was the predominant pathogen that evoked asthma exacerbation in September and October of 2014.Conclusion:Clade A and B were the main epidemic subtypes of HEV-D68 in Chongqing, China. Clade B had an increase in September and October 2014. A past history of recurrent wheezing appeared to be a risk factor for the detection of HEV-D68 and inducing the acute asthma exacerbation was a clinical feature of HEV-D68 infection. |
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