Objective: To analyze epidemiological and genetic characteristics of the fifth avian influenza A (H7N9) wave in Suzhou, and to provide scientific basis for prevention and control of H7N9 virus infection. Methods: Respectively, influenza A/B, H1N1 (pdm09), H3, H5N1, and H7N9 real-time PCR kits were used to detected pharyngeal swab samples which were collected from severe acute respiratory syndrome infection (SARI) cases in Suzhou. The H7N9-positive samples were further examined for virus isolation and gene sequencing. Results: The H7N9 virus was mainly prevalent in winter in Suzhou City. In the fifth H7N9 virus epidemic, the overall fatality rate of human infection with H7N9 virus in Suzhou city was 40% (22/55). Additionally, most were older people (median age was 58 years) and more than 80% of H7N9 patients had live poultry exposure history. The nucleic acid homology of HA gene was 98.7-100%. There were no mutations in the key sites of the HA gene sequence. Conclusions The H7N9 virus can not be effectively spread in the crowd currently, with no significant changes in receptor binding sites (RBS). In addition, exposure to live poultry or contaminated environment is still the main source of human infection with H7N9. At present, the viruses circulating in Suzhou city are low pathogenic to poultry.

Objective: To investigate the epidemical features, etiological and clinical characteristics of HFMD in Suzhou city, from 2011 to 2015, providing the scientific supports for HFMD prevention and control. Methods: In each district of Suzhou city, at least five specimens of mild cases were collected per month, while all of the severe cases were sampled. The RNA from each sample was examined using a commercially available real-time PCR kit. Statistical analysis was performed using SPSS version 11.5 software. Results: We retrospectively analyzed HFMD epidemiological data in Suzhou from 2011 to 2015, a total of 4 552 outpatients in Suzhou city were diagnosed with HFMD, including 2 818 positive specimen, the total positive rate was 61.90%, and there was a significant difference in the positive rates between the adjacent years (χ²=186.09, P<0.0001). From 2011 to 2015 in Suzhou, HFMD mainly affected children aged 1 to 5 years old, 66.17% of them were 1to 3 years old. Enterovirus 71(EV71) and coxsackievirus A16(CVA16) were the predominant viral genotypes in Suzhou from 2011 to 2012, and 2014. In 2013, other EVs were dominant, the severe cases mainly correlated with EV71 subtypes, and the proportion of patients with severe disease was significantly decreased in 2013. Conclusions EV71 and CVA16 are still the important pathogens of HFMD, other EVs also occupy a certain proportion, it is the time to select one or two advantage pathogens from the other EVs into the HFMD monitoring.

Objective:To investigate the viral molecular mutations of 2019 novel coronavirus (2019-nCoV) and host adaptability in Suzhou City.Methods:The throat swab specimens from nine local cases and six imported cases with 2019-nCoV viral nucleic acid test positive in Suzhou City were sequenced for the whole genome of the virus, and the Wuhan-Hu-1 strain was used as the reference sequence for alignment and analysis. The phylogenetic tree of the viral whole genome sequence was constructed by MEGA 7.0 software.Results:According to the Chinese typing method, Nextstrain typing method, Pangolin classification method and Global Initiative on Sharing All Influenza Data (GISAID) typing method, the 15 2019-nCoV genome sequences could be divided into seven types, six types, eight types and five subtypes, respectively. Compared with Wuhan-Hu-1 strain, the median number of amino acid sequence mutation sites based on nucleotide translation was three (ranging from 0 to 12). D614G mutation of spike protein was identified from all six imported viral strains, which could enhance the transmissibility. No Alpha, Beta, or Gamma mutants, which also could enhance the transmissibility, was found in the genomic sequences of the imported cases. The median number of nucleotide mutation sites in 15 sequences was eight (ranging from three to 23).Conclusions:2019-nCoV is constantly mutating, and a variety of evolutionary lineages/genotypes have been derived. All imported viruses in Suzhou City carry mutations that can increase infectivity.