湖北省某中学因面条引起诺如病毒感染性腹泻暴发

目的分析湖北省某中学一起诺如病毒感染性腹泻暴发疫情的流行病学因素,为制定防控措施提供依据。方法采用现场流行病学的方法,对病例进行调查,运用描述性流行病学方法、病例对照方法对暴发疫情数据和各种因素进行分析。结果疫情涉及91例疑似病例和2名隐性感染者,罹患率为33.8%(91/269)。4名厨工中,2名为隐性感染者。首发病例为八(2)班学生,发病日期为2017年2月15日7∶30。69.2%(63/91)的病例在2月15日8∶00～24∶00发病,发病时间中位数为2月15日16∶00。病例对照研究结果提示,进食2月14日早餐热干面发病风险增加[比值比(OR)=9.93,95%置信区间(95%CI)为1.17～84.04]。结论此次事件为一起由诺如病毒引起的感染性腹泻暴发疫情,在诺如病毒感染性腹泻高发季节,应继续加强对学校诺如病毒感染性腹泻疫情监测,积极开展健康教育,有效预防诺如病毒感染性腹泻暴发疫情的发生。     

Broad range RT-PCR assays targeting human noroviruses also detect swine noroviruses

Conventional broad range RT-PCR and real time RT-PCR assays designed to detect human noroviruses (NoVs) also efficiently detect swine NoVs. Investigation of the primers and probe binding sites revealed strong homologies between swine NoVs genomic sequences and human primer sequences. These findings have a serious impact on food diagnostic methods and laboratories.     

Bacteria isolated from shellfish digestive gland with antipathogenic activity as candidates to increase the efficiency of shellfish depuration process

The aim of the work, as part of the FP7 Beads project, was to isolate potentially probiotic bacteria targeted to shellfish, which could facilitate depuration of commercial molluscs. A total of 365 bacteria were isolated from shellfish digestive gland and screened for activity against different pathogens. One bacterial isolate obtained from Mytilus galloprovincialis, designated as 3M21 and identified as Enterococcus hirae, presented antibacterial activity against Listeria monocytogenes, Listeria innocua, Enterococcus faecalis, and antiviral activity against Hepatitis A ATCC VR-1402 and murine Norovirus (MNV-1), culturable in vitro. This strain was sensitive to chloramphenicol, fusidic acid, ampicillin, vancomycin and gentamicin. The active substance produced by 3M21 was partially characterized and shown to be proteic, with a molecular weight of 6.95 kDa determined by Tris–Tricine electrophoresis, high thermostability (30 min at 100 °C), resistant to a wide pH range (2–9) and to treatment with certain surfactants (Tween 20, 80 and EDTA at 2 mM). After its partial purification, the bacteriocin was encapsulated in 3% of alginate and an alternative using BaCl₂ instead of CaCl₂ in the hardening bath significantly improved its encapsulation. Although the use of probiotic bacteria is gaining in popularity in the aquaculture industry, its application in shellfish depuration has seldom been studied. The isolation, characterization and microencapsulation of a bacterium with antipathogen activity already acclimatized to seafood environment, as the isolate 3M21, could increase the efficiency of shellfish depuration process.     

Norovirus, hepatitis A virus and enterovirus presence in shellfish from high quality harvesting areas in Portugal

This is the first report on the screening of shellfish from Portugal for the presence of human enteropathogenic viruses. Approximately 2000 shellfish (Curbicula fluminea, Ruditapes decussatus, Tellina crassa, Spisula solida, Dosinia exoleta, Ensis spp., Mytilus spp., Ostrea edulis and Cerastoderma edule), organized in 49 batches, were collected between March 2008 and February 2009. They were tested for norovirus (NoV), hepatitis A virus (HAV) and enterovirus (EV) by RT-PCR followed by nucleotide sequencing. Bacterial contamination was also evaluated by Escherichia coli counts. Viral contamination was detected throughout the year in all shellfish species and in all collection areas, independently of their harvesting areas classification. Overall, 67% of all analyzed batches were contaminated by at least one of the studied viruses while the simultaneous presence of two and three viruses was detected in 22% and 6% batches, respectively. Of the three viruses, NoV was detected in 37% of the batches, followed by EV in 35%, and HAV in 33%. Nucleotide sequencing of the NoV and HAV RT-PCR products demonstrated that all strains belonged to NoV genotype GII.4 and HAV subgenotype 1B. The presence of NoV and HAV in shellfish from “A class” harvesting areas of Portugal can represent a potential health risk.     

2019年连云港市农贸市场双壳贝类中诺如病毒污染状况调查

目的了解连云港市农贸市场双壳贝类中诺如病毒污染状况。方法于2019年6、8和11月在连云港三县三区各采集10份双壳贝类食物,共180份,及时分离消化腺于-75℃保存,采用实时荧光定量PCR检测诺如病毒基因型。结果 5种双壳贝类中诺如病毒基因总检出率为26.67%(48/180),基因型分型中GⅠ型检出率为5.00%(9/180)、GⅡ型检出率为17.78%(32/180)、GⅠ+GⅡ型检出率为3.89%(7/180);诺如病毒基因检出率在采样月份、地区分布无差异;帘蛤科诺如病毒检出率最高。结论连云港市农贸市场双壳贝类诺如病毒携带形势严峻,分布特征具有特殊性,亟需明确本地的诺如病毒传播模式并采取相应防控措施。     

High occurrence of hepatitis E virus in samples from wastewater treatment plants in Switzerland and comparison with other enteric viruses

Hepatitis E virus (HEV) is responsible for many enterically transmitted viral hepatitides around the world. It is currently one of the waterborne diseases of global concern. In industrialized countries, HEV appears to be more common than previously thought, even if it is rarely virulent. In Switzerland, seroprevalence studies revealed that HEV is endemic, but no information was available on its environmental spread. The aim of this study was to investigate –using qPCR– the occurrence and concentration of HEV and three other viruses (norovirus genogroup II, human adenovirus-40 and porcine adenovirus) in influents and effluents of 31 wastewater treatment plants (WWTPs) in Switzerland. Low concentrations of HEV were detected in 40 out of 124 WWTP influent samples, showing that HEV is commonly present in this region. The frequency of HEV occurrence was higher in summer than in winter. No HEV was detected in WWTP effluent samples, which indicates a low risk of environmental contamination. HEV occurrence and concentrations were lower than those of norovirus and adenovirus. The autochthonous HEV genotype 3 was found in all positive samples, but a strain of the non-endemic and highly pathogenic HEV genotype I was isolated in one sample, highlighting the possibility of environmental circulation of this genotype. A porcine fecal marker (porcine adenovirus) was not detected in HEV positive samples, indicating that swine are not the direct source of HEV present in wastewater. Further investigations will be necessary to determine the reservoirs and the routes of dissemination of HEV.