Follow-Up of Norovirus Contamination in an Oyster Production Area Linked to Repeated Outbreaks

A production area repeatedly implicated in oyster-related gastroenteritis in France was studied for several months over 2 years. Outbreaks and field samples were analyzed by undertaking triplicate extractions, followed by norovirus (NoV) detection using triplicate wells for genomic amplification. This approach allowed us to demonstrate that some variabilities can be observed for samples with a low level of contamination, but most samples analyzed gave reproducible results. At the first outbreak, implicated oysters were collected at the beginning of the contamination event, which was reflected by the higher NoV levels during the first month of the study. During the second year, NoV concentrations in samples implicated in outbreaks and collected from the production area were similar, confirming the failure of the shellfish depuration process. Contamination was detected mainly during winter-spring months, and a high prevalence of NoV GI contamination was observed. A half-life of 18 days was calculated from NoV concentrations detected in oysters during this study, showing a very slow decrease of the contamination in the production area. Preventing the contamination of coastal waters should be a priority.     

Detection and Typing of Norovirus from Frozen Strawberries Involved in a Large-Scale Gastroenteritis Outbreak in Germany

During September/October 2012, a norovirus gastroenteritis outbreak affecting about 11,000 people occurred in Germany. Epidemiological studies suggested that frozen strawberries represented the vehicle of infection. We describe here the analysis of frozen strawberries for the presence of norovirus. Samples were taken by applying a stratified subsampling scheme. Two different methods for virus extraction from strawberries were compared. First, viruses were eluted from strawberries under alkaline conditions and concentrated using a polyethylene glycol precipitation. Second, ultrafiltration was applied for concentration of viruses rinsed off of the berries. In both cases, RNA was extracted and analyzed by real-time RT-PCR. Application of the ultrafiltration method generally resulted in a lower detection rate. Noroviruses were detected in 7/11 samples derived from the lot of strawberries implicated in the outbreak using the precipitation method. Typing of norovirus revealed three different genotypes including a combination of norovirus genotype II.16 (viral polymerase) and II.13 (viral capsid). This genotype combination was also found in some of the patients that were involved in the outbreak, but that had not been reported in Germany so far. In conclusion, heterogeneously distributed noroviruses in frozen strawberries can be detected by applying an optimized combination of sampling procedures, virus extraction methods, and real-time RT-PCR protocols. The detection of several different genotypes in the strawberries may suggest contamination from sewage rather than from a single infected food handler.     

Simple and Rapid Detection of Human Norovirus from Produce Using SYBR Green I-based Real-time RT-PCR

Several foodborne norovirus gastroenteritis outbreaks have been linked to fresh produce. Rapid and sensitive detection can help prevent the release of contaminated produce items in the market. The objectives of this study were to apply a relatively inexpensive SYBR Green I-based real-time RT-PCR assay for the rapid detection of human norovirus (NoV) GI and GII on the surfaces of lettuce, cherry tomatoes, and green onions. Each washed produce commodity (25 g) was spiked with serial dilutions of NoV GI and GII stool samples. RNA was eluted from the produce surface and extracted using the TRIzol^? method. This was followed by detection using SYBR Green I real-time RT-PCR with primers specific for NoV GI (COG1F-COG1R) and GII (COG2F-COG2R) along with an internal RNA amplification control. End-point detection limits from lettuce and tomatoes were found to be 10 RT-PCR units/25 g for GI and GII and 1 RT-PCR unit/25 g for GI and 10 RT-PCR units/25 g for GII from green onions. These results were confirmed by Tm analysis (showing peaks at 81.5 and 84°C for GI and GII, respectively; and 83°C for the IAC) as well as agarose gel electrophoresis that confirmed products of ~95 bp for GI and GII and ~155 bp for the RNA IAC. Results could be obtained within one working day, showing potential for routine use in diagnostics and monitoring of NoV contamination by the produce industry.     

Real-Time PCR Detection of Norovirus in Mussels Collected from the Bosphorus in Istanbul,Turkey

Norovirus (NoV) is recognised as one of the most common causes of foodborne infections, and shellfish are a well-documented source of this virus. The presence of NoV in shellfish has not previously been investigated in Turkey, and hence the aim of this study was to determine the frequency of human NoV genogroups I and II in mussels collected from the Bosphorus, Istanbul, Turkey. A total of 320 mussels representing 110 samples originating along the Bosphorus coast were collected from fish distributors. RNA was extracted using the RNeasy Mini Kit and real-time RT–PCR performed using primers specific for NoV genogroup I and II. Amongst the 110 samples, 5 (4.5%) were found to be positive for NoV genogroup II by SYBR Green assay; no genogroup I was detected. A positive signal was obtained by SYBR Green for NoV Genogroup II in mussels collected in October, November and December 2008, and February and July 2009. Only four out of five SYBR Green positive samples could be confirmed by the use of a NoV GII probe-based real-time RT–PCR. The average count and SD of Enterobactericaeae, E. coli and sulphide reductase anaerobic bacteria in PCR positive mussels were 3.56 log ± 0.96 log, 2.32 log ± 0.77 log and 1.70 log ± 0.56 log, respectively. This study shows that NoV Genogroup II is present in mussels collected from the Bosphorus, Istanbul, and may constitute a risk to human health.     

Genetic Analysis of Norovirus Strains that Caused Gastroenteritis Outbreaks Among River Rafters in the Grand Canyon,Arizona

Toilet solid waste samples collected from five outbreaks among rafters in the Grand Canyon were subjected to sequencing analysis of norovirus partial capsid gene. The results revealed that a GI.3 strain was associated with one outbreak, whereas the other outbreaks were caused by GII.5 whose sequences shared >98.9% homology.     

A 2019 Outbreak Investigation of Hepatitis A Virus Infections in the United States Linked to Imported Fresh Blackberries

Globally, hepatitis A virus (HAV) is one of the most common agents of acute viral hepatitis and causes approximately 1.4 million cases and 90,000 deaths annually despite the existence of an effective vaccine. In 2019, federal, state, and local partners investigated a multi-state outbreak of HAV infections linked to fresh blackberries sourced from multiple suppliers in Michoacán, Mexico. A total of 20 individuals with outbreak-related HAV infection were reported in seven states, including 11 hospitalizations, and no deaths. The Food and Drug Administration (FDA), the Centers for Disease Control and Prevention (CDC), and Nebraska State and Douglas County Health Departments conducted a traceback investigation for fresh blackberries reportedly purchased by 16 ill persons. These individuals reported purchasing fresh blackberries from 11 points of service from September 16 through 29, 2019 and their clinical isolates assessed through next-generation sequencing and phylogenetic analysis were genetically similar. The traceback investigation did not reveal convergence on a common grower or packing house within Mexico, but all of the blackberries were harvested from growers in Michoacán, Mexico. FDA did not detect the pathogen after analyzing fresh blackberry samples from four distributors, one consumer, and from nine importers at the port of entry as a result of increased screening. Challenges included gaps in traceability practices and the inability to recover the pathogen from sample testing, which prohibited investigators from determining the source of the implicated blackberries. This multi-state outbreak illustrated the importance of food safety practices for fresh produce that may contribute to foodborne illness outbreaks.

     

1981~2017年四川省大气自净能力变化特征分析

利用四川省1981~2017年逐日地面气象观测资料和2017年1月环境监测资料,计算分析了四川省大气自净能力指数的时空变化特征及其影响因子,并初步探讨了2017年1月成都市大气自净能力指数与空气质量的关系.结果表明：四川省大气自净能力指数的分布形势以川西高原北部、川西高原南部、攀西地区、盆地西南部大气自净能力为较好到好,省内其余大部地区大气自净能力较差到差.近37a来,四川省、川西高原、攀西地区多年变化呈减弱趋势,四川盆地多年变化趋势不显著.影响因子中,四川省降水日平均大气自净能力指数小于非降水日.四川省以及各区域平均风速、通风量、风速较大日数和小风日数与大气自净能力指数呈显著正和负相关关系;混合层厚度与大气自净能力指数呈显著的正相关关系.     

Detection and Characterization of Hepatitis A Virus and Norovirus in Mussels from Galicia (NW Spain)

Shellfish are recognized as a potential vehicle of viral disease and despite the control measures for shellfish safety there is periodic emergence of viral outbreaks associated with shellfish consumption. In this study a total of 81 mussel samples from Ría do Burgo, A Coruña (NW Spain) were analysed. Samples were collected in seven different harvesting areas with the aim to establish a correlation between the prevalence of norovirus (NoV) and hepatitis A virus (HAV) in mussel samples and the water quality. In addition, the genogroup of the detected HAV and NoV strains was also determined. The HAV presence was detected in 18.5 % of the samples. Contamination levels for this virus ranged from 1.1 × 10² to 4.1 × 10⁶ RNA copies/g digestive tissue. NoV were detected in 49.4 % of the cases reaching contamination levels from 5.9 × 10³ to 1.6 × 10⁹ RNA copies/g digestive tissue for NoV GI and from 6.1 × 10³ to 5.4 × 10⁶ RNA copies/g digestive tissue for NoV GII. The χ²-test showed no statistical correlation between the number of positive samples and the classification of molluscan harvesting area based on the E. coli number. All the detected HAV strains belong to genogroup IB. NoV strains were assigned to genotype I.4, II.4 and II.6.     

2013～2017年江苏省人为源氨排放清单的建立及特征

根据江苏省各类氨排放源活动水平数据,采用合理的清单测算方法和排放因子,建立了2013～2017年江苏省人为源氨排放清单,对其历年来人为源氨排放量的变化趋势进行分析.利用Arc GIS软件对江苏省人为源氨排放量及排放强度的分布特征进行分析.结果表明,江苏省的氨排放量由2013年的624. 84 kt减少至2017年的562. 47 kt,年均下降率约为2. 6%.农业源一直是江苏省最主要的氨排放源,2017年时占江苏省氨排放总量的82. 4%;蛋鸡是畜禽养殖源中最大的氨排放源,占畜禽源氨排放量的49. 3%. 2017年江苏省氨平均排放强度为5. 3 t·km~(-2),其中盐城市和徐州市是江苏省人为源氨排放量和排放强度最大的两个城市,镇江市的氨排放量和排放强度最小.     

Modeling the Transport of Human Rotavirus and Norovirus in Standardized and in Natural Soil Matrix-Water Systems

Food and Environmental Virology - We modeled Group A Rotavirus (RVA) and Norovirus genogroup II (GII NoV) transport experiments in standardized (crystal quartz sand and deionized water with...     

Prevalence of Human Noroviruses in Frozen Marketed Shellfish,Red Fruits and Fresh Vegetables

Noroviruses (NoVs), currently recognised as the most common human food-borne pathogens, are ubiquitous in the environment and can be transmitted to humans through multiple foodstuffs. In this study, we evaluated the prevalence of human NoV genogroups I (GI) and II (GII) in 493 food samples including soft red fruits (n = 200), salad vegetables (n = 210) and bivalve mollusc shellfish (n = 83), using the Bovine Enterovirus type 1 as process extraction control for the first time. Viral extractions were performed by elution concentration and genome detection by TaqMan Real-Time RT-PCR (RT-qPCR). Experimental contamination using hepatitis A virus (HAV) was used to determine the limit of detection (LOD) of the extraction methods. Positive detections were obtained from 2 g of digestive tissues of oysters or mussels kept for 16 h in seawater containing 2.0–2.7 log₁₀ plaque-forming units (PFU)/L of HAV. For lettuces and raspberries, the LOD was, respectively, estimated at 2.2 and 2.9 log₁₀ PFU per 25 g. Of the molluscs tested, 8.4 and 14.4 % were, respectively, positive for the presence of GI NoV and GII NoV RNA. Prevalence in GI NoVs varied from 11.9 % for the salad vegetables samples to 15.5 % for the red soft fruits. Only 0.5 % of the salad and red soft fruits samples were positive for GII NoVs. These results highlight the high occurrence of human NoVs in foodstuffs that can be eaten raw or after a moderate technological processing or treatment. The determination of the risk of infection associated with an RT-qPCR positive sample remains an important challenge for the future.     

Hepatitis A Outbreak in Europe: Imported Frozen Berry Mix Suspected to be the Source of At least One Infection in Austria in 2013

We tested 19 sera from Austrian patients with acute hepatitis A. A serum from a 48-year-old female patient yielded HAV-nucleic acid that showed 99.7 % homology to the HAV-sequence obtained from samples taken during the current outbreak in several European countries, which is associated with consumption of frozen berries. So far, Austria was considered not to be affected by this hepatitis A outbreak.     

Detection of Norovirus GII.17 Kawasaki 2014 in Shellfish,Marine Water and Underwater Sewage Discharges in Italy

Norovirus (NoV) is a major cause of non-bacterial acute gastroenteritis worldwide, and the variants of genotype GII.4 are currently the predominant human strains. Recently, a novel variant of NoV GII.17 (GII.P17_GII.17 NoV), termed Kawasaki 2014, has been reported as the cause of gastroenteritis outbreaks in Asia, replacing the pandemic strain GII.4 Sydney 2012. The GII.17 Kawasaki 2014 variant has also been reported sporadically in patients with gastroenteritis outside of Asia, including Italy. In this study, 384 shellfish samples were subjected to screening for human NoVs using real-time PCR and 259 (67.4%) tested positive for Genogroup II (GII) NoV. Of these, 52 samples, selected as representative of different areas and sampling dates, were further amplified by conventional PCR targeting the capsid gene, using broad-range primers. Forty shellfish samples were characterized by amplicon sequencing as GII.4 (n = 29), GII.2 (n = 4), GII.6 (n = 2), GII.12 (n = 2), and GII.17 (n = 3). Sixty-eight water samples (39 seawater samples from the corresponding shellfish production areas and 29 water samples from nearby underwater sewage discharge points) were also tested using the above broad-range assay: eight NoV-positive samples were characterized as GII.1 (n = 3), GII.2 (n = 1), GII.4 (n = 2), and GII.6 (n = 2). Based on full genome sequences available in public databases, a novel RT-PCR nested assay specific for GII.17 NoVs was designed and used to re-test the characterized shellfish (40) and water (8) samples. In this second screening, the RNA of GII.17 NoV was identified in 17 additional shellfish samples and in one water sample. Upon phylogenetic analysis, these GII.17 NoV isolates were closely related to the novel GII.17 Kawasaki 2014. Interestingly, our findings chronologically matched the emergence of the Kawasaki 2014 variant in the Italian population (early 2015), as reported by hospital-based NoV surveillance. These results, showing GII.17 NoV strains to be widespread in shellfish samples collected in 2015 in Italy, provide indirect evidence that this strain has started circulating in the Italian population. Notably, using a specific assay, we were able to detect many more samples positive for GII.17 NoV, indicating that, in food and water matrices, broad-range assays for NoV may grossly underestimate the prevalence of some, less common, NoVs. The detection of the GII.17 strain Kawasaki 2014 in clinical, water and food samples in Italy highlights the need for more systematic surveillance for future disease control and prevention.     

Quantitative Detection and Characterization of Human Adenoviruses in the Buffalo River in the Eastern Cape Province of South Africa

Buffalo River is an important water resource in the Eastern Cape Province of South Africa. Over a 1-year period (August 2010?CJuly 2011), we assessed the prevalence of human adenoviruses (HAdVs) at a total of 6 sites on the river and three dams along its course. HAdVs were detected by real-time quantitative PCR in about 35?% of the samples with concentrations ranging from 1.2?×?10¹ genome copies (GC)/l to 4.71?×?10³ GC/l. HAdVs were detected at 5 of the 6 sampling sites with the detection rate ranging from 8.3?% at Rooikrantz Dam to 92?% at Parkside. The HAdV concentrations across the sampling sites were as follows: Parkside (3.25?×?10²?C4.71?×?10³?GC/); King William??s Town (1.02?×?10²?C4.56?×?10³?GC/l); and Eluxolzweni (1.17?×?10²?C3.97?×?10² GC/l). Significantly (P?<?0.05) higher concentrations were detected at the non-dam sites compared to the dam sites. A very low mean concentration of 1.86?×?10¹ HAdV GC/l was observed at Bridle Drift Dam. While HAdVs were detected only once at Rooikrantz Dam (1.74?×?10¹?GC/l), no HAdV was detected at Maden Dam. Epidemiologically important serotypes, Ad40/41, constituted 83.3?%, while Ad21 made up 16.7?% of the all HAdVs detected and were characterized by qualitative PCR. The Buffalo River presents a public health risk heightened by the presence of Ad 40/41 and Ad21. Our results make imperative the need for assessing water sources for viral contamination in the interest of public health. This work is a significant contribution to the molecular epidemiology of adenoviruses and to the best of our knowledge this is the first report on detection of enteric virus from surface waters in the Eastern Cape.     

福建省2005-2017年大气边界层SO2的时空变化特征

为研究近年来福建省SO₂污染的时空动态特征,利用臭氧观测仪（ozone monitoring instrument,OMI）卫星遥感反演的PBL（planetary boundary layer,大气边界层）SO₂柱含量数据,分析了2005-2017年福建省PBL SO₂柱含量的时空间分布特征.结果表明:①在长时间尺度上,PBL SO₂柱含量的变化趋势可分为2个时段,其中,2005-2011年PBL SO₂柱含量呈逐渐上升趋势,6 a增加了约0.027 DU,增长率约为6.12%;2011-2017年PBL SO₂柱含量呈下降趋势,7 a减少了约0.018 DU,下降率约为3.89%.②PBL SO₂柱含量呈明显的周期性变化特征,最小值和最大值分别出现在6月和12月,多年平均值分别约为0.383和0.555 DU.③PBL SO₂柱含量的3个高值区分别出现在沿海的福州市,厦门市、漳州市东部和泉州市西部,三明市和南平市部分地区,这3个高值区多年平均PBL SO₂柱含量分别约为0.505、0.495和0.485 DU.从城市尺度上来看,PBL SO₂柱含量最大值出现在厦门市,其多年平均值为（0.486±0.015）DU;其次为福州市,PBL SO₂柱含量多年平均值为（0.465±0.026）DU;最低值出现在漳州市,PBL SO₂柱含量多年平均值为（0.429±0.020）DU.④福建省PBL SO₂柱含量变化趋势在空间分布上存在明显的差异,不同时期、不同区域变化趋势不一致.2005-2011年PBL SO₂柱含量的变化范围为-0.13~0.18 DU,变化率范围为-25%~50%,PBL SO₂柱含量出现增长的区域主要是在高值区,如龙岩市西部、厦门市北部以及三明市东部等区域;2011-2017年PBL SO₂柱含量的变化范围为-0.13~0.15 DU,变化率范围为-29%~34%.2011-2017年福州市和厦门市PBL SO₂柱含量下降最为明显,减少了约0.10 DU,下降率约为25%.研究显示,卫星遥感估算的PBL SO₂柱含量具有一定的可靠性,可以用于区域SO₂污染的研究.      

Occurrence of Norovirus and Hepatitis A Virus in Wild Mussels Collected from the Baltic Sea

The aim of the study was to define the occurrence of human noroviruses of genogroup I and II (NoV GI and NoV GII) and hepatitis A virus (HAV) in the Baltic Sea mussels. The shellfish samples were taken at the sampling sites located on the Polish coast. In total, 120 shellfish were tested as pooled samples using RT-PCR and hybridisation with virus specific probes. NoV GI was detected in 22 (18.3 %), NoV GII in 28 (23.3 %), and HAV in 9 (7.5 %) of the shellfish. The nucleotide sequence analysis of the detected NoV GII strains showed a 97.3–99.3 % similarity to GII.4 virus strain. This is the first report describing the NoV and HAV occurrence in wild Baltic mussels and their possible role as bioindicators of seawater contamination with human enteric viruses.     

2000～2017年贵州省植被覆盖时空变化特征及其对气候变化的响应

利用MODIS/NDVI数据、近18年来贵州省气象站点数据，辅以时间序列、变化趋势和空间动态变化分析等方法，研究贵州省植被覆盖的时空变化特征；探讨植被覆盖变化对气象因子在地域、变化速率和变化方向方面的时空响应规律。研究结果显示：（1）2000~2017年贵州省植被覆盖呈现显著增加的趋势，增速为0.004/a，夏季NDVI值最高，冬季增加趋势最大；空间上，贵州省植被覆盖格局呈现"南高北低、东高西低"的空间分布特征。在变化趋势上，贵州省植被覆盖呈改善和退化趋势的面积分别占贵州省总面积的94.97%和5.03%。（2）2000~2017年，贵州省气候变化特征是降雨量在年内分布不均，且主要分布在5月至8月；温度在各个季节变化趋势不明显，但是总体呈上升的趋势。气温和降水变化趋势大于零的面积分别占贵州省总面积的98.4%和60.46%，说明在全球暖湿化的大背景下，贵州省大部分地区亦呈温度升高、降水增加的态势。（3）贵州省NDVI与气温的相关性大于降水，但其对降水的滞后性却高于气温。其中，秋季植被受降水影响滞后性最强，其次是夏季。（4）不同气候要素对贵州省植被生长影响具有空间差异性，98.4%的地区NDVI与同期温度均达到正相关水平；NDVI与同期降水并未表现出良好的相关性，但82.63%的地区植被与前一年降水呈正相关水平。植被与降水呈负相关的地区，建设用地、裸地占更大比率，且人类活动在植被变化中的作用不容忽视。     

Development of a Specific Anti-capsid Antibody- and Magnetic Bead-Based Immunoassay to Detect Human Norovirus Particles in Stool Samples and Spiked Mussels via Flow Cytometry

Food and Environmental Virology - Human noroviruses impose a considerable health burden globally. Here, a flow cytometry approach designed for their detection in biological waste and food samples...