Infectious diarrhea is a gastrointestinal infectious disease caused by a wide range of pathogens and found throughout the world. It is one of the most important public health problems in the world and the second leading cause of death among children under five years of age. The pathogens of infectious diarrhea include viral diarrhea pathogens, bacterial diarrhea pathogens, and parasites. Viruses are the most frequent pathogens, mainly including norovirus, rotavirus, astrovirus and sapovirus. The most frequently identified organisms causing bacterial diarrhea are diarrheagenic Escherichia coli, Salmonella, Shigella, Vibrio parahaemolyticus and Campylobacter. This paper provides an overview of the epidemiological trends and changes in the pathogen spectrum of infectious diarrhea for better understanding the distribution and epidemiological features of infectious diarrhea in China, and hopes to provide reference for developing prevention and control strategies and reducing the disease burden.

Objective:To clarify the pathogen types, genotypes and molecular biological characteristics of an outbreak in a high school in Yantai city in 2019, and to provide evidence for epidemic prevention and control.Methods:Eleven samples were collected from a high school in Yantai city in 2019. Quantitative PCR was used for primary type identification. RT-PCR and specific primers were used to amplify the target genes, and the sequences of norovirus were compared and analyzed for phylogenetic analysis.Results:The pathogen of this cluster outbreak was norovirus. Five GII-positive samples of norovirus were detected, 4 of which were GII.13 and 1 was GII.17. Sequence analysis of polymerase-capsid region showed that the amino acid sequence of this cluster outbreak was highly conserved.Conclusions:This outbreak is a cluster of diarrhea caused by GII.13 and GII.17 norovirus infection. The analysis of this outbreak is helpful to our general understanding of the evolution, genetic diversity and distribution of norovirus, and the surveillance of norovirus in the jurisdiction should be further strengthened.

Objective:To investigate the pathogenic spectrum of enteroviruses associated with hand, foot and mouth disease (HFMD) in the Yantai region of Shandong province in 2016, and analyze the evolution of epidemic strains of coxsackie virus group A type 6 (CV-A6) in the pathogenic spectrum of HFMD enteroviruses and the variations of important amino acid sites in the VP1 region.Methods:A total of 738 samples were collected from the patients with HFMD in Yantai region in 2016 to conduct DNA and serotype tests of enterovirus (EV) by real-time RT-PCR and further count the number and proportion of each type of enterovirus positive specimens. Based on the predominant serotype of enteroviruses, eight serotypes of the CV-A6 strains were selected to carry out VP1 regions amplification for the determination and analysis of nucleotide sequencing and phylogenetic analysis.Results:A total of 460 enteroviruses strains were isolated from 738 samples, including pathogens strains: 258 CV-A16 (56.09%), 62 EV-A71 (13.48%), 49 CV-A10 (10.65%), 44 CV-A6 (9.57%) and 9 CV-A4 (1.96%). Eight CV-A6 positive specimens were isolated from the viruses and the nucleotide-sequence analysis of the whole VP1 region was conducted. The sequence analysis of eight CV-A6 strains demonstrated that the homologies of nucleotide and amino acid were 96.12% - 100% and 97.78% - 100% respectively. The phylogenetic analysis indicated that the eight CV-A6 strains were subdivided into the genotype D subtype D3. Compared with the reference strain, CVA6-Gdula-AY421764, amino acids of CV-A6 strains in Yantai city observed at sites 10, 14, 174, 194, 279, 283 and 305 in VP1 region appeared mutant.Conclusions:CV-A16, EV-A71, CV-A10 and CV-A6 were the main common pathogens of HFMD in Yantai region in 2016. All the CV-A6 strains isolated in this study belonged to subtype D3 in genotype D.

In this study, the swabs were collected among patients with an influenza-like illness (ILI) admitted to 2 sentinel surveillance hospitals of Yantai from April 2014 to August 2017. All specimen were cultured and identified by hemagglutination inhibition assay. Complete sequences of Hemagglutinin (HA) of influenza A were amplified, sequenced and analyzed using molecular and phylogenetic methods. The potential vaccine efficacy were calculated using Pepitope model. The results showed that the antigenicity of A (H3N2) had changed greatly. 8 strains of influenza A (H1N1) pdm09 belonged to subclade 6B.1 and 14 strains clustered in 6B.2. 12 strains of influenza A (H3N2) fell into subgroup 3C.3a and 33 strains clustered in 3C.2a. Several residues at antigen sites and potential glycosylation sites had changed in influenza A strains. Vaccine efficacy of influenza A (H1N1) pdm09 in 2015/2016 and 2016/2017 seasons were 77.29% and 79.11% of that of a perfect match with vaccine strain, meanwhile vaccine efficacy of influenza A (H3N2) in 2014/2015, 2015/2016 and 2016/2017 were-5.18%, 16.97% and 42.05% separately. In conclusion, the influenza A virus circulated in Yantai from 2014 to 2017 presented continual genetic variation. The recommended vaccine strains still afforded protection against influenza A (H1N1) pdm09 strains and provided suboptimal protection against influenza A (H3N2) strains.

Objective: To detect norovirus (NoV) GⅠ.1- and GⅡ.4-specific IgG, IgA and histo-blood group antigen (HBGA)-blocking antibodies in healthy populations of all age groups in China for better understanding the epidemiological features of norovirus in China from a serological point of view and providing basic data for vaccine development and clinical trial design. Methods: Indirect ELISA and HBGA-blocking assay were used to detect NoV-specific IgG, IgA and HBGA-blocking antibodies in serum samples collected from healthy natural populations (n=839, aged from six months to 88 years old) in Guangzhou, Fuyang and Yantai. The results were statistically analyzed. Results: The total positive rates of NoV GⅠ.1- and GⅡ.4-specific IgG antibodies were 91.9% and 93.0%. The positive rates of GⅠ.1- and GⅡ.4-specific IgA antibodies were 48.6% and 75.6%, and the titers of HBGA-blocking antibodies to GⅠ.1 and GⅡ.4 norovirus were 5.04 (95%CI: 4.63-5.49) and 18.15 (95%CI: 16.11-20.44). The positive rates of IgG and IgA antibodies generally showed an increasing trend with age. The positive rates of GⅠ.1- and GⅡ.4-specific IgG antibodies ranged from 79.2% to 100.0% and 76.7% to 100.0% in different age groups. They were 81.7% and 85.0% in the age group of 0.5-<1 year, 79.2% and 76.7% in the age group of 1-<2 years, and 98.1% and 96.3% in the age group of 12-<18 years, and maintained at 96% and 98% in the older age groups. The positive rates of GⅠ.1-specific IgA antibody ranged from 11.7% to 93.8% in different age groups and rapidly increased with age. It was 11.7% in the age group of 0.5-<1 year, and reached 93.3% in people aged 45-<60 years and 93.8% in people aged ≥60 years. The positive rates of GⅡ.4-specific IgA antibody ranged from 50.8% to 88.8% in different age groups with 50.8% in people aged 0.5-<1 year, and 86.7%-90.7% in people aged 12-<18 years and older. The titer of GⅠ.1 HBGA-blocking antibody generally increased with age. The antibody titer in populations aged 0.5-<12 years old was lower than that in those aged 18 years and above (GMT: 2.98-4.07 vs 8.21-11.62, P<0.001), and the titer in people of 12-<18 years old was lower than that in those of 45 years old and above (GMT: 5.21 vs 11.03-11.62, P<0.05). No obvious change with age was observed in the titer of GⅡ.4 HBGA-blocking antibody excepting the significant difference between populations of 2-<5 and 22-<45 years old (GMT: 26.73 vs 11.87, P<0.01). Conclusions This study revealed the characteristics of serum NoV GⅠ.1- and GⅡ.4-specific IgG, IgA and HBGA blocking antibodies in populations of different age groups in central and eastern China through analyzing their positive rates and titers and provided preliminary seroepidemiological data for the development of NoV vaccines in China.

In this study, the swabs were collected among patients with an influenza?like illness (ILI) admitted to 2 sentinel surveillance hospitals of Yantai from April 2014 to August 2017. All specimen were cultured and identified by hemagglutination inhibition assay. Complete sequences of Hemagglutinin (HA) of influenza A were amplified, sequenced and analyzed using molecular and phylogenetic methods. The potential vaccine efficacy were calculated using Pepitope model. The results showed that the antigenicity of A (H3N2) had changed greatly. 8 strains of influenza A (H1N1) pdm09 belonged to subclade 6B.1 and 14 strains clustered in 6B.2. 12 strains of influenza A (H3N2) fell into subgroup 3C.3a and 33 strains clustered in 3C.2a. Several residues at antigen sites and potential glycosylation sites had changed in influenza A strains. Vaccine efficacy of influenza A (H1N1) pdm09 in 2015/2016 and 2016/2017 seasons were 77.29% and 79.11% of that of a perfect match with vaccine strain, meanwhile vaccine efficacy of influenza A (H3N2) in 2014/2015, 2015/2016 and 2016/2017 were-5.18%, 16.97% and 42.05% separately. In conclusion, the influenza A virus circulated in Yantai from 2014 to 2017 presented continual genetic variation. The recommended vaccine strains still afforded protection against influenza A (H1N1) pdm09 strains and provided suboptimal protection against influenza A (H3N2) strains.

In this study, the swabs were collected among patients with an influenza?like illness (ILI) admitted to 2 sentinel surveillance hospitals of Yantai from April 2014 to August 2017. All specimen were cultured and identified by hemagglutination inhibition assay. Complete sequences of Hemagglutinin (HA) of influenza A were amplified, sequenced and analyzed using molecular and phylogenetic methods. The potential vaccine efficacy were calculated using Pepitope model. The results showed that the antigenicity of A (H3N2) had changed greatly. 8 strains of influenza A (H1N1) pdm09 belonged to subclade 6B.1 and 14 strains clustered in 6B.2. 12 strains of influenza A (H3N2) fell into subgroup 3C.3a and 33 strains clustered in 3C.2a. Several residues at antigen sites and potential glycosylation sites had changed in influenza A strains. Vaccine efficacy of influenza A (H1N1) pdm09 in 2015/2016 and 2016/2017 seasons were 77.29% and 79.11% of that of a perfect match with vaccine strain, meanwhile vaccine efficacy of influenza A (H3N2) in 2014/2015, 2015/2016 and 2016/2017 were-5.18%, 16.97% and 42.05% separately. In conclusion, the influenza A virus circulated in Yantai from 2014 to 2017 presented continual genetic variation. The recommended vaccine strains still afforded protection against influenza A (H1N1) pdm09 strains and provided suboptimal protection against influenza A (H3N2) strains.

OBJECTIVETo learn the prevalence of infection of human and animals severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) in Yantai, Shandong province, and to analyze the pathogenic features of SFTSV as well as its relationship between human and animal hosts.

METHODSFrom April to November in 2011, 3 576 serum samples were collected from domesticated animals, including sheep, cattle, pigs, dogs, chickens, in Laizhou and Penglai areas where fever with thrombocytopenia syndrome frequently occurred among local residents. Total SFTSV antibodies and virus-specific nucleic acids of the serum were tested by ELISA and Real time RT-PCR, respectively. SFTSV infection on each animal was observed in different months. 2 590 human serum samples were also collected in Laizhou and Penglai areas, with IgG antibodies tested by ELISA. Virus was isolated with Vero cells from the serum which SFTSV viral nucleic acids were positive. S fragments were amplified by RT-PCR and sequenced, with homology analysis conducted on these sequences.

RESULTSThe overall positive rate of serum samples from animals on the total SFTSV antibodies was 40.24% (1 439/3 576) while the positive rate for specific nucleic acids was 4.56% (163/3 576). The positive rates for SFTSV antibodies were 62.78%, 52.97%, 45.56%, 28.73%, 1.45% and the positive rates for specific nucleic acids were 5.72%, 4.63%, 3.02%, 5.25% and 3.73%, in sheep, cattle, chickens, dogs, pigs, respectively. The antigens/antibodies for SFTSV in animals changed seasonally. The overall positive rate for SFTSV IgG antibody from 2 590 human samples was 5.41%. Thirteen virus strains were isolated from these serum samples (10 strains from human and 3 strains from animals). The nucleotide homology of 13S fragments' sequences ranged from 95.23% to 100.00% and the nucleotide homology with the isolates from other provinces were between 94.72% and 99.13%. The homology was considered to be high.

CONCLUSIONHigh prevalence of SFTSV infections occurred both in human and domestic animals in Yantai city. The nucleotide sequences of SFTSV were highly homologous among human and domestic animals. The findings suggested that domesticated animals might serve as SFTSV proliferation and the hosts for transmission thus should be attached great importance.

Animals ; Antibodies, Viral ; blood ; Bunyaviridae Infections ; epidemiology ; China ; epidemiology ; Humans ; Prevalence ; RNA, Viral ; blood ; Sequence Analysis, RNA

Objective To learn the prevalence of infection of human and animals severe fever with thrombocytopenia syndrome bunyavirus(SFTSV)in Yantai,Shandong province,and to analyze the pathogenic features of SFTSV as well as its relationship between human and animal hosts. Methods From April to November in 2011,3 576 serum samples were collected from domesticated animals,including sheep,cattle,pigs,dogs,chickens,in Laizhou and Penglai areas where fever with thrombocytopenia syndrome frequently occured among local residents. Total SFTSV antibodies and virus-specific nucleic acids of the serum were tested by ELISA and Real time RT-PCR,respectively. SFTSV infection on each animal was observed in different months. 2 590 human serum samples were also collected in Laizhou and Penglai areas,with IgG antibodies tested by ELISA. Virus was isolated with Vero cells from the serum which SFTSV viral nucleic acids were positive. S fragments were amplified by RT-PCR and sequenced,with homology analysis conducted on these sequences. Results The overall positive rate of serum samples from animals on the total SFTSV antibodies was 40.24%(1 439/3 576)while the positive rate for specific nucleic acids was 4.56%(163/3 576). The positive rates for SFTSV antibodies were 62.78%,52.97%,45.56%,28.73%,1.45%and the positive rates for specific nucleic acids were 5.72%,4.63%,3.02%,5.25%and 3.73%,in sheep,cattle,chickens,dogs, pigs,respectively. The antigens/antibodies for SFTSV in animals changed seasonally. The overall positive rate for SFTSV IgG antibody from 2 590 human samples was 5.41%. Thirteen virus strains were isolated from these serum samples(10 strains from human and 3 strains from animals). The nucleotide homology of 13S fragments’sequences ranged from 95.23%to 100.00%and the nucleotide homology with the isolates from other provinces were between 94.72%and 99.13%. The homology was considered to be high. Conclusion High prevalence of SFTSV infections occured both in human and domestic animals in Yantai city. The nucleotide sequences of SFTSV were highly homologous among human and domestic animals. The findings suggested that domesticated animals might serve as SFTSV proliferation and the hosts for transmission thus should be attached great importance.

Objective To evaluate the performance of Beckman Coulter Enhanced troponin Ⅰ immunoassay system (including the limit of detection and total imprecision) and establish the 99th percentile of Enhanced troponin Ⅰ in apparently healthy Chinese people in Kunming and Wuhan.Methods Evaluated the limit of detection and total imprecision of Beckman Enhanced troponin Ⅰ according to protocols EP of Clinical Laboratory Standards Institute; chose apparently healthy people from Wuhan (average altitude of 27 m) which represents plain regions,and Kunming (average altitude of 1895 m) which represents plateau regions.760 subjects from Wuhan were selected,aging from 30 to 91,included 400 males and 360 females.A total of 192 subjects from Kunming were selected,aging from 30 and 77,60 patients,which included 60 male and 132 female cases.To calculate the 99th percentile of Enhanced troponin Ⅰ by region,age,and gender.Results The limit of detection of Beckman Enhanced troponin Ⅰ is 0.013 μg/L,the cTnI concentration is 0.025 μg/L at 10％ CV.The 99th percentile of Enhanced troponin Ⅰ of the total population in Wuhan is 0.036 μg/L,the 99th percentile of men and women are 0.038 μg/L and 0.035 μg/L respectively,the 99th percentile in the 30-69 years group and over 70 years group are 0.038 μg/L and 0.035 μg/L respectively.The 99th percentile of Enhanced troponin Ⅰ of the total population in Kunming is 0.040 μg/L.To keep the 2nd digit after decimal point for results from Wuhan and Kunming,the 99th percentile of Enhanced troponin Ⅰ of the apparently healthy Chinese in 0.04 μg/L,where the CV is 8.23％.The percentage of positive samples detected below the 99th percentile in the normal reference population in Wuhan is 94％.Conclusions The 99th percentile of Beckman Enhanced troponin Ⅰ of the Chinese apparently healthy people is 0.04 μg/L,where the total imprecision is 8.23％,and the detection performance reach the acceptable levels per the guideline.