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Quantification of infectious Human mastadenovirus in environmental matrices using PMAxx-qPCR. Braz J Microbiol 2022; 53:1465-1471. [PMID: 35666431 PMCID: PMC9168632 DOI: 10.1007/s42770-022-00775-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 05/27/2022] [Indexed: 11/02/2022] Open
Abstract
Molecular methodologies providing data on viral concentration and infectivity have been successfully used in environmental virology, supporting quantitative risk assessment studies. The present study aimed to assess human mastadenovirus (HAdV) intact particles using a derivative of propidium monoazide associated with qPCR (PMAxx-qPCR) in aquatic matrices. Initially, different concentrations of PMAxx were evaluated to establish an optimal protocol for treating different naturally contaminated matrices, using 10 min incubation in the dark at 200 rpm at room temperature and 15 min of photoactivation in the PMA-Lite™ LED photolysis device. There was no significant reduction in the quantification of infectious HAdV with increasing concentration of PMAxx used (20 μM, 50 μM, and 100 μM), except for sewage samples. In this matrix, a reduction of 5.01 log of genomic copies (GC)/L was observed from the concentration of 50 μM and revealed 100% HAdV particles with damaged capsids. On the other hand, the mean reduction of 0.51 log in stool samples using the same concentration mentioned above demonstrated 83% of damaged particles eliminated in the stool. Following, 50 μM PMAxx-qPCR protocol revealed a log reduction of 0.91, 0.67, and 1.05 in other samples of raw sewage, brackish, and seawater where HAdV concentration reached 1.47 × 104, 6.81 × 102, and 2.33 × 102 GC/L, respectively. Fifty micrometers of PMAxx protocol helped screen intact viruses from different matrices, including sea and brackish water.
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Paruch L. Molecular Diagnostic Tools Applied for Assessing Microbial Water Quality. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:5128. [PMID: 35564522 PMCID: PMC9105083 DOI: 10.3390/ijerph19095128] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/20/2022] [Accepted: 04/21/2022] [Indexed: 11/16/2022]
Abstract
Microbial water quality is of vital importance for human, animal, and environmental health. Notably, pathogenically contaminated water can result in serious health problems, such as waterborne outbreaks, which have caused huge economic and social losses. In this context, the prompt detection of microbial contamination becomes essential to enable early warning and timely reaction with proper interventions. Recently, molecular diagnostics have been increasingly employed for the rapid and robust assessment of microbial water quality implicated by various microbial pollutants, e.g., waterborne pathogens and antibiotic-resistance genes (ARGs), imposing the most critical health threats to humans and the environment. Continuous technological advances have led to constant improvements and expansions of molecular methods, such as conventional end-point PCR, DNA microarray, real-time quantitative PCR (qPCR), multiplex qPCR (mqPCR), loop-mediated isothermal amplification (LAMP), digital droplet PCR (ddPCR), and high-throughput next-generation DNA sequencing (HT-NGS). These state-of-the-art molecular approaches largely facilitate the surveillance of microbial water quality in diverse aquatic systems and wastewater. This review provides an up-to-date overview of the advancement of the key molecular tools frequently employed for microbial water quality assessment, with future perspectives on their applications.
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Affiliation(s)
- Lisa Paruch
- Division of Environment and Natural Resources, Norwegian Institute of Bioeconomy Research-NIBIO Oluf Thesens vei 43, 1433 Aas, Norway
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Pouillot R, Smith M, Van Doren JM, Catford A, Holtzman J, Calci KR, Edwards R, Goblick G, Roberts C, Stobo J, White J, Woods J, DePaola A, Buenaventura E, Burkhardt W. Risk Assessment of Norovirus Illness from Consumption of Raw Oysters in the United States and in Canada. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2022; 42:344-369. [PMID: 34121216 PMCID: PMC9291475 DOI: 10.1111/risa.13755] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 04/20/2021] [Accepted: 04/23/2021] [Indexed: 05/30/2023]
Abstract
Human norovirus (NoV) is the leading cause of foodborne illness in the United States and Canada. Bivalve molluscan shellfish is one commodity commonly identified as being a vector of NoV. Bivalve molluscan shellfish are grown in waters that may be affected by contamination events, tend to bioaccumulate viruses, and are frequently eaten raw. In an effort to better assess the elements that contribute to potential risk of NoV infection and illness from consumption of bivalve molluscan shellfish, the U.S. Department of Health and Human Services/Food and Drug Administration (FDA), Health Canada (HC), the Canadian Food Inspection Agency (CFIA), and Environment and Climate Change Canada (ECCC) collaborated to conduct a quantitative risk assessment for NoV in bivalve molluscan shellfish, notably oysters. This study describes the model and scenarios developed and results obtained to assess the risk of NoV infection and illness from consumption of raw oysters harvested from a quasi-steady-state situation. Among the many factors that influence the risk of NoV illness for raw oyster consumers, the concentrations of NoV in the influent (raw, untreated) and effluent (treated) of wastewater treatment plants (WWTP) were identified to be the most important. Thus, mitigation and control strategies that limit the influence from human waste (WWTP outfalls) in oyster growing areas have a major influence on the risk of illness from consumption of those oysters.
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Affiliation(s)
- Régis Pouillot
- U.S. Food and Drug Administration5001 Campus DriveCollege ParkMD20740USA
| | - Mark Smith
- Health Canada251 Sir Frederick Banting Driveway Tunney's Pasture, Mail Stop 2204EOttawaONK1A 0K9Canada
| | - Jane M. Van Doren
- U.S. Food and Drug Administration5001 Campus DriveCollege ParkMD20740USA
| | - Angela Catford
- Health Canada251 Sir Frederick Banting Driveway Tunney's Pasture, Mail Stop 2204EOttawaONK1A 0K9Canada
| | - Jennifer Holtzman
- Health Canada251 Sir Frederick Banting Driveway Tunney's Pasture, Mail Stop 2204EOttawaONK1A 0K9Canada
| | - Kevin R. Calci
- U.S. Food and Drug AdministrationGulf Coast Seafood LaboratoryDauphin IslandAL36528USA
| | - Robyn Edwards
- Canadian Food Inspection Agency1400 Merivale RoadOttawaONK1A 0Y9Canada
| | - Gregory Goblick
- U.S. Food and Drug AdministrationGulf Coast Seafood LaboratoryDauphin IslandAL36528USA
| | - Christopher Roberts
- Environment and Climate Change Canada45 Alderney Dr, 7th FloorDartmouthNSB2Y 2N6Canada
| | - Jeffrey Stobo
- Environment and Climate Change Canada45 Alderney Dr, 7th FloorDartmouthNSB2Y 2N6Canada
| | - John White
- Canadian Food Inspection Agency57 Central St., Suite 204SummersidePEC1N 3K9Canada
| | - Jacquelina Woods
- U.S. Food and Drug AdministrationGulf Coast Seafood LaboratoryDauphin IslandAL36528USA
| | - Angelo DePaola
- U.S. Food and Drug AdministrationGulf Coast Seafood LaboratoryDauphin IslandAL36528USA
| | - Enrico Buenaventura
- Health Canada251 Sir Frederick Banting Driveway Tunney's Pasture, Mail Stop 2204EOttawaONK1A 0K9Canada
| | - William Burkhardt
- U.S. Food and Drug AdministrationGulf Coast Seafood LaboratoryDauphin IslandAL36528USA
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Xu Y, Zhu Y, Lei Z, Rui J, Zhao Z, Lin S, Wang Y, Xu J, Liu X, Yang M, Chen H, Pan X, Lu W, Du Y, Li H, Fang L, Zhang M, Zhou L, Yang F, Chen T. Investigation and analysis on an outbreak of norovirus infection in a health school in Guangdong Province, China. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2021; 96:105135. [PMID: 34781036 DOI: 10.1016/j.meegid.2021.105135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 10/14/2021] [Accepted: 11/08/2021] [Indexed: 06/13/2023]
Abstract
Our objective was to describe the epidemiological features of an outbreak of norovirus infection in a health school in Guangdong province, China, to identify the cause of such a large scale outbreak of norovirus among older students, to simulate the transmission dynamics, and to evaluate the effect of intervention measures of GII.17 [P17] genotype norovirus infection. We identified all cases during the outbreak. Descriptive epidemiological, analytical epidemiological and hygiene survey methods were used to described the outbreak epidemic course and identify the cause of the outbreak of norovirus infection. We also used dynamical model to simulate the transmission dynamics of norovirus infection and evaluate the effect of intervention measures. Norovirus genotyping was assigned to the newly obtained strains, with a maximum likelihood phylogenetic analysis conducted. There were 360 cases of 42 classes in five grades with a 12.99% attack rate. Proportionally, more students were in contact with sick students and vomit in the suspected case group than the control group (χ2 = 5.535, P = 0.019 and χ2 = 5.549, P = 0.019, respectively). The basic reproduction number was 8.32 before and 0.49 after the intervention. Dynamical modeling showed that if the isolation rate was higher or case isolation began earlier, the total attack rate would decrease. Molecular characterization identified the GII.17 [P17] genotype in all stains obtained from the health school, which were clustered with high support in the phylogenetic tree. This was an outbreak of norovirus infection caused by contact transmission. The main reasons for the spread of the epidemic were the later control time, irregular treatment of vomit and no case isolation. The transmission dynamics of contact transmission was high, more efficient control measures should be employed.
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Affiliation(s)
- Yucheng Xu
- Futian District Center for Disease Control and Prevention, Shenzhen, People's Republic of China; Guangdong Field Epidemiology Training Program, Guangzhou, People's Republic of China
| | - Yuanzhao Zhu
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen City 361102, Fujian Province, People's Republic of China
| | - Zhao Lei
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen City 361102, Fujian Province, People's Republic of China
| | - Jia Rui
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen City 361102, Fujian Province, People's Republic of China
| | - Zeyu Zhao
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen City 361102, Fujian Province, People's Republic of China
| | - Shengnan Lin
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen City 361102, Fujian Province, People's Republic of China
| | - Yao Wang
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen City 361102, Fujian Province, People's Republic of China
| | - Jingwen Xu
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen City 361102, Fujian Province, People's Republic of China
| | - Xingchun Liu
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen City 361102, Fujian Province, People's Republic of China
| | - Meng Yang
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen City 361102, Fujian Province, People's Republic of China
| | - Hongsheng Chen
- Guangdong Provincial Center for Disease Control and Prevention, Guangzhou, People's Republic of China
| | - Xuemei Pan
- Lianzhou District Center for Disease Control and Prevention, Qingyuan, People's Republic of China
| | - Wentao Lu
- Qingyuan City Center for Disease Control and Prevention, Qingyuan, People's Republic of China
| | - Yuzhong Du
- Qingyuan City Center for Disease Control and Prevention, Qingyuan, People's Republic of China
| | - Hui Li
- Guangdong Provincial Center for Disease Control and Prevention, Guangzhou, People's Republic of China
| | - Ling Fang
- Guangdong Provincial Center for Disease Control and Prevention, Guangzhou, People's Republic of China
| | - Meng Zhang
- Guangdong Provincial Center for Disease Control and Prevention, Guangzhou, People's Republic of China
| | - Lina Zhou
- Department of Nephrology, The second Hospital of Xiamen Medical college, Xiamen 361021, China
| | - Fen Yang
- Guangdong Provincial Center for Disease Control and Prevention, Guangzhou, People's Republic of China.
| | - Tianmu Chen
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen City 361102, Fujian Province, People's Republic of China.
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Zweigart MR, Becker-Dreps S, Bucardo F, González F, Baric RS, Lindesmith LC. Serological Humoral Immunity Following Natural Infection of Children with High Burden Gastrointestinal Viruses. Viruses 2021; 13:2033. [PMID: 34696463 PMCID: PMC8538683 DOI: 10.3390/v13102033] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 10/01/2021] [Accepted: 10/03/2021] [Indexed: 12/14/2022] Open
Abstract
Acute gastroenteritis (AGE) is a major cause of morbidity and mortality worldwide, resulting in an estimated 440,571 deaths of children under age 5 annually. Rotavirus, norovirus, and sapovirus are leading causes of childhood AGE. A successful rotavirus vaccine has reduced rotavirus hospitalizations by more than 50%. Using rotavirus as a guide, elucidating the determinants, breath, and duration of serological antibody immunity to AGE viruses, as well as host genetic factors that define susceptibility is essential for informing development of future vaccines and improving current vaccine candidates. Here, we summarize the current knowledge of disease burden and serological antibody immunity following natural infection to inform further vaccine development for these three high-burden viruses.
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Affiliation(s)
- Mark R. Zweigart
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC 27599, USA; (M.R.Z.); (S.B.-D.)
| | - Sylvia Becker-Dreps
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC 27599, USA; (M.R.Z.); (S.B.-D.)
- Department of Family Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Filemón Bucardo
- Department of Microbiology, National Autonomous University of Nicaragua, León 21000, Nicaragua; (F.B.); (F.G.)
| | - Fredman González
- Department of Microbiology, National Autonomous University of Nicaragua, León 21000, Nicaragua; (F.B.); (F.G.)
| | - Ralph S. Baric
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC 27599, USA; (M.R.Z.); (S.B.-D.)
| | - Lisa C. Lindesmith
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC 27599, USA; (M.R.Z.); (S.B.-D.)
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Chan JC, Mohammad KN, Zhang LY, Wong SH, Chan MCW. Targeted Profiling of Immunological Genes during Norovirus Replication in Human Intestinal Enteroids. Viruses 2021; 13:v13020155. [PMID: 33494515 PMCID: PMC7910953 DOI: 10.3390/v13020155] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 01/14/2021] [Accepted: 01/18/2021] [Indexed: 12/18/2022] Open
Abstract
Norovirus is the leading cause of acute gastroenteritis worldwide. The pathogenesis of norovirus and the induced immune response remain poorly understood due to the lack of a robust virus culture system. The monolayers of two secretor-positive Chinese human intestinal enteroid (HIE) lines were challenged with two norovirus pandemic GII.4 Sydney strains. Norovirus RNA replication in supernatants and cell lysates were quantified by RT-qPCR. RNA expression levels of immune-related genes were profiled using PCR arrays. The secreted protein levels of shortlisted upregulated genes were measured in supernatants using analyte-specific enzyme-linked immunosorbent assay (ELISA). Productive norovirus replications were achieved in three (75%) out of four inoculations. The two most upregulated immune-related genes were CXCL10 (93-folds) and IFI44L (580-folds). Gene expressions of CXCL10 and IFI44L were positively correlated with the level of norovirus RNA replication (CXCL10: Spearman’s r = 0.779, p < 0.05; IFI44L: r = 0.881, p < 0.01). The higher level of secreted CXCL10 and IFI44L proteins confirmed their elevated gene expression. The two genes have been reported to be upregulated in norovirus volunteer challenges and natural human infections by other viruses. Our data suggested that HIE could mimic the innate immune response elicited in natural norovirus infection and, therefore, could serve as an experimental model for future virus-host interaction and antiviral studies.
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Affiliation(s)
- Jenny C.M. Chan
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China; (J.C.M.C.); (K.N.M.); (L.-Y.Z.)
| | - Kirran N. Mohammad
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China; (J.C.M.C.); (K.N.M.); (L.-Y.Z.)
| | - Lin-Yao Zhang
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China; (J.C.M.C.); (K.N.M.); (L.-Y.Z.)
| | - Sunny H. Wong
- Li Ka Shing Institute of Health Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China;
- Department of Medicine and Therapeutics, Institute of Digestive Disease, State Key Laboratory of Digestive Disease, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Martin Chi-Wai Chan
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China; (J.C.M.C.); (K.N.M.); (L.-Y.Z.)
- Li Ka Shing Institute of Health Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China;
- Correspondence:
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Parrón I, Barrabeig I, Alseda M, Cornejo-Sánchez T, Guix S, Jané M, Izquierdo C, Rius C, Domínguez À. Involvement of Workers in Closed and Semiclosed Institutions in Outbreaks of Acute Gastroenteritis Due to Norovirus. Viruses 2020; 12:E1392. [PMID: 33291823 PMCID: PMC7762007 DOI: 10.3390/v12121392] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 11/26/2020] [Accepted: 11/30/2020] [Indexed: 12/19/2022] Open
Abstract
Norovirus outbreaks frequently occur in closed or semiclosed institutions. Recent studies in Catalonia and various countries indicate that, during outbreaks in these institutions, norovirus is detected in between 23% and 60% of workers, and the prevalence of infection in asymptomatic workers involved in outbreaks ranges from 17% to 40%. In this work, we carried out a prospective study to investigate the involvement of workers in closed and semiclosed institutions during outbreaks. The attack rates (ARs) and the rate ratios (RRs) were calculated according to the type of transmission and occupational category. The RRs and 95% confidence intervals (CIs) between workers and users were calculated. The mean cycle of quantification (Cq) values were compared according to the genogroup and the presence of symptoms. ARs were higher in person-to-person transmission than in common vehicle outbreaks, and 38.8% of workers were symptomatic. The RR between workers and users was 0.46 (95% CI 0.41-0.52). The ARs in workers were high, particularly in workers with closer contact with users. The mean Cq was lower in patients than in asymptomatic infected persons, although the difference was only significant for genogroup I (GI). The frequency of asymptomatic infected persons suggests that personal hygiene measures should be followed by all workers in the centers affected.
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Affiliation(s)
- Ignacio Parrón
- Sub-Direcció Regional a Barcelona del Departament de Salut, 08005 Barcelona, Spain;
| | - Irene Barrabeig
- Sub-Direcció Regional a Barcelona del Departament de Salut, 08005 Barcelona, Spain;
- CIBER Epidemiologia y Salud Pública, Instituto de Salud Carlos III, 28029 Madrid, Spain; (M.J.); (C.R.); (À.D.)
| | - Miquel Alseda
- Sub-Direcció Regional a Lleida del Departament de Salut, 25006 Lleida, Spain;
| | | | - Susana Guix
- Enteric Virus Laboratory, Department of Genetics, Microbiology and Statistics, Section of Microbiology, Virology and Biotechnology, School of Biology, Institute of Nutrition and Food Safety, University of Barcelona, 08028 Barcelona, Spain;
| | - Mireia Jané
- CIBER Epidemiologia y Salud Pública, Instituto de Salud Carlos III, 28029 Madrid, Spain; (M.J.); (C.R.); (À.D.)
- Sub-Direcció General de Vigilància i Resposta a Emergències de Salut Pública, 08005 Barcelona, Spain;
- Departament de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
| | - Conchita Izquierdo
- Sub-Direcció General de Vigilància i Resposta a Emergències de Salut Pública, 08005 Barcelona, Spain;
| | - Cristina Rius
- CIBER Epidemiologia y Salud Pública, Instituto de Salud Carlos III, 28029 Madrid, Spain; (M.J.); (C.R.); (À.D.)
- Agència de Salut Pública de Barcelona, 08023 Barcelona, Spain
| | - Àngela Domínguez
- CIBER Epidemiologia y Salud Pública, Instituto de Salud Carlos III, 28029 Madrid, Spain; (M.J.); (C.R.); (À.D.)
- Departament de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
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Detection of Norovirus in Saliva Samples from Acute Gastroenteritis Cases and Asymptomatic Subjects: Association with Age and Higher Shedding in Stool. Viruses 2020; 12:v12121369. [PMID: 33266188 PMCID: PMC7761458 DOI: 10.3390/v12121369] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 11/26/2020] [Accepted: 11/28/2020] [Indexed: 12/11/2022] Open
Abstract
Norovirus infections are a leading cause of acute gastroenteritis outbreaks worldwide and across all age groups, with two main genogroups (GI and GII) infecting humans. The aim of our study was to investigate the occurrence of norovirus in saliva samples from individuals involved in outbreaks of acute gastroenteritis in closed and semiclosed institutions, and its relationship with the virus strain, virus shedding in stool, the occurrence of symptoms, age, and the secretor status of the individual. Epidemiological and clinical information was gathered from norovirus outbreaks occurring in Catalonia, Spain during 2017–2018, and stool and saliva samples were collected from affected and exposed resident individuals and workers. A total of 347 saliva specimens from 25 outbreaks were analyzed. Further, 84% of individuals also provided a paired stool sample. For GII infections, norovirus was detected in 17.9% of saliva samples from symptomatic cases and 5.2% of asymptomatic individuals. Positivity in saliva occurred in both secretors and nonsecretors. None of the individuals infected by norovirus GI was positive for the virus in saliva. Saliva positivity did not correlate with any of the studied symptoms but did correlate with age ≥ 65 years old. Individuals who were positive in saliva showed higher levels of virus shedding in stool. Mean viral load in positive saliva was 3.16 ± 1.08 log10 genome copies/mL, and the predominance of encapsidated genomes was confirmed by propidium monoazide (PMA)xx-viability RTqPCR assay. The detection of norovirus in saliva raises the possibility of oral-to-oral norovirus transmission during the symptomatic phase and, although to a lesser extent, even in cases of asymptomatic infections.
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