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The Dynamics of Norovirus Outbreak Epidemics: Recent Insights  [PDF]
John A. Marshall,Leesa D. Bruggink
International Journal of Environmental Research and Public Health , 2011, DOI: 10.3390/ijerph8041141
Abstract: Noroviruses are a major cause of gastroenteritis outbreaks worldwide. Norovirus outbreaks frequently occur as epidemics which appear to be related to both genetic and environmental factors. This review considers recent progress in understanding these factors. The norovirus genome undergoes continuous change and this appears to be important in the persistence of the virus in the community. Studies on the common GII.4 genotype have shown that some norovirus outbreak epidemics involving this genotype are correlated with specific changes in the genome. In contrast to the growing understanding of the role of genetic factors in norovirus outbreak epidemics, the role of environmental factors is less well understood. Topics reviewed here include long term excretion of norovirus in some individuals, long term survivability of norovirus in the environment, the role of meteorological factors in the control of norovirus outbreaks and the possible zoonotic transmission of the virus.
An outbreak of gastroenteritis in a holiday resort in Italy: epidemiological survey, implementation and application of preventive measures  [PDF]
Giacomo Migliorati,Vincenza Prencipe,Alessandro Ripani,Cristina Di Francesco
Veterinaria Italiana , 2008,
Abstract: A major gastroenteritis outbreak was reported in a vacation resort in Central Italy in 2003. A total of 183 cases were identified. The case-control study identified a statistically significant correlation between the disease and sea bathing, use of sanitary facilities in bungalows and of common showers. Stool samples taken from people affected were found positive for Norovirus (68%, 13 of 19 samples), Rotavirus (38%, 1 of 14 samples) and Campylobacter (7%, 3 of 8 samples). Environmental investigations revealed serious faecal contamination of the groundwater and the presence of Norovirus in the seawater near the resort. The mixing of groundwater and seawater with the non-drinking water system - which was also found to be connected to the drinking water system - had a primary role in the onset and spread of infection within the village. The complete absence of any gastroenteritis epidemics among the site guests since 2006 demonstrates the effectiveness of the environmental corrective measures taken.
Electronic Outbreak Surveillance in Germany: A First Evaluation for Nosocomial Norovirus Outbreaks  [PDF]
Anja M. Hauri,Hans-Jürgen Westbrock,Herman Claus,Steffen Geis,Siegfried Giernat,Michael Forβbohm,Helmut Uphoff
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0017341
Abstract: In Germany, surveillance for infectious disease outbreaks is integrated into an electronic surveillance system. For 2007, the national surveillance database contains case-based information on 201,224 norovirus cases, three-quarters of which are linked to outbreaks. We evaluated the data quality of the national database in reflecting nosocomial norovirus outbreak (NNO) data available in 19 Hessian local public health authorities (LPHAs) and the influence of differences between LPHA's follow-up procedures for laboratory notifications of Norovirus positive stool samples on outbreak underascertainment.
Foodborne norovirus outbreak: the role of an asymptomatic food handler
Irene Barrabeig, Ariadna Rovira, Javier Buesa, Rosa Bartolomé, Rosa Pintó, Hortènsia Prellezo, àngela Domínguez
BMC Infectious Diseases , 2010, DOI: 10.1186/1471-2334-10-269
Abstract: A retrospective cohort study was designed. Personal or telephone interview was carried out to collect demographic, clinical and microbiological data of the exposed people, as well as food consumption in the suspected lunch. Food handlers of the mentioned summer camp were interviewed.Ten stool samples were requested from symptomatic exposed residents and the three food handlers that prepared the suspected food. Stools were tested for bacteries and noroviruses. Norovirus was detected using RT-PCR and sequence analysis.Attack rate, relative risks (RR) and its 95% confidence intervals (CI) were calculated to assess the association between food consumption and disease.The global attack rate of the outbreak was 55%. The main symptoms were abdominal pain (90%), nausea (85%), vomiting (70%) and diarrhoea (42.5%). The disease remitted in 24-48 hours. Norovirus was detected in seven faecal samples, one of them was from an asymptomatic food handler who had not eaten the suspected food (round of beef), but cooked and served the lunch. Analysis of the two suspected foods isolated no pathogenic bacteria and detected no viruses. Molecular analysis showed that the viral strain was the same in ill patients and in the asymptomatic food handler (genotype GII.2 Melksham-like).In outbreaks of foodborne disease, the search for viruses in affected patients and all food handlers, even in those that are asymptomatic, is essential. Health education of food handlers with respect to hand washing should be promoted.The consumption of food contaminated by microorganisms is a common cause of gastroenteritis outbreaks in developed countries. Historically, bacteria have been the most-frequent causal agents, although the causal microorganism is not identified on many occasions [1-3].Norovirus, a member of the Caliciviridae family, is considered the major cause of acute gastroenteritis in all age groups worldwide [4]. The majority of human noroviruses can be classified into two genogroups, I (GI) and
Influence of Novel Norovirus GII.4 Variants on Gastroenteritis Outbreak Dynamics in Alberta and the Northern Territories, Canada between 2000 and 2008  [PDF]
Xiaoli L. Pang,Jutta K. Preiksaitis,Sallene Wong,Vincent Li,Bonita E. Lee
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0011599
Abstract: Norovirus GII.4 is the predominant genotype circulating worldwide over the last decade causing 80% of all norovirus outbreaks with new GII.4 variants reported in parallel with periodic epidemic waves of norovirus outbreaks. The circulating new GII.4 variants and the epidemiology of norovirus outbreaks in Alberta, Canada have not been described. Our hypothesis is that the periodic epidemic norovirus outbreak activity in Alberta was driven by new GII.4 variants evolving by genetic drift.
An outbreak of norovirus infection in a long-term care facility in Brazil  [PDF]
Fernando Gatti de Menezes,Vanessa Maria da Silva de Poli Correa,Fábio Gazelato de Mello Franco,Miriam Ikeda Ribeiro
Einstein (S?o Paulo) , 2010,
Abstract: Objective: To describe a norovirus outbreak in a Brazilian longtermcare facility from July 8 to 29, 2005. Methods: In thefirst 48 to 72 hours after onset of symptoms in inpatients andemployees, the main infection control strategies were staffeducation, emphasis on hand washing, implementing contactprecautions up to 48-72 hours after resolution of symptoms,complete cleaning of the rooms and exclusion of symptomaticemployees from work until 48-72 hours after resolution of theirsymptoms. Epidemiological and clinical characteristics of thenorovirus infections were described based on chart review.Results: The incidence among inpatients and employees was41.3% and 16.25%, respectively. The main symptom was diarrhea,affecting 100% of inpatients and employees. Forty-four percent ofspecimens were positive by RIDASCREEN Norovirus analyses,and identified as norovirus genogroup GII. Seventy percent ofinpatients were women and their age range was 51-98 years.Inpatients had in average two comorbid conditions – 87.3% withcardiovascular or chronic pulmonary condition and 47.6% withdementia. There was not relapse or death. Conclusions: The earlyinfection-control measures associated to surveillance are requiredto keep long-term care facilities free of noroviruses and to protectthose who are most vulnerable.
Norovirus gastroenteritis general outbreak associated with raw shellfish consumption in South Italy
Rosa Prato, Pier Lopalco, Maria Chironna, Giovanna Barbuti, Cinzia Germinario, Michele Quarto
BMC Infectious Diseases , 2004, DOI: 10.1186/1471-2334-4-37
Abstract: A retrospective cohort study was performed in order to assess risk factors associated with illness. All households where a case occurred were included in the study. Faecal specimens were collected from ill individuals. NV-specific RT-PCR was performed. Eleven samples of mussels were collected from fish-markets involved in the outbreak. A nested PCR was used for mussel samples.One hundred and three cases, detected by means of active surveillance, met the case definition. Raw shellfish eating was the principal risk factor for the disease, as indicated by the analytic issues (Risk Ratio: 1.50; IC 95%: 1.18 – 1.89; p < 0.001). NVs were found by means of RT-PCR of all the stool specimens from the 24 patients tested. Eleven samples of shellfish from local markets were tested for the presence or NVs; six were positive by nested PCR and genotypes were related to that found in patients' stools.This is the first community outbreak caused by NVs related to sea-food consumption described in Italy. The study confirms that the present standards for human faecal contamination do not seem to be a reliable indicator of viral contaminants in mussels.Norovirus (NV, previously "Norwalk-like viruses"), one of four genera in the Caliciviridae family, includes a group of morphologically similar but genetically different single-stranded RNA viruses. NVs represent the most important cause of non-bacterial gastroenteritis worldwide. In industrialised countries NVs may be responsible for up to 80% of all outbreaks of gastroenteritis [1]. Outbreaks may affect all age groups and generally occur in crowded communities such as restaurants, tourist resorts, hospitals, schools and nursing homes.Contaminated food or water commonly represents the main source of infection. Epidemics spread by the faecal-oral route, even if transmission may also occur through direct person-to-person contact or aerosolised viral particles.The incubation period of NV gastroenteritis is 24–48 hours and symptoms include vo
Clinical and Virological Descriptive Study in the 2011 Outbreak of Dengue in the Amazonas, Brazil  [PDF]
Valquiria do Carmo Alves Martins, Michele de Souza Bastos, Rajendranath Ramasawmy, Regina Pinto de Figueiredo, Jo?o Bosco Lima Gimaque, Wornei Silva Miranda Braga, Mauricio Lacerda Nogueira, Sergio Nozawa, Felipe Gomes Naveca, Luiz Tadeu Moraes Figueiredo, Maria Paula Gomes Mour?o
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0100535
Abstract: Background Dengue is a vector-borne disease in the tropical and subtropical region of the world and is transmitted by the mosquito Aedes aegypti. In the state of Amazonas, Brazil during the 2011 outbreak of dengue all the four Dengue virus (DENV) serotypes circulating simultaneously were observed. The aim of the study was to describe the clinical epidemiology of dengue in Manaus, the capital city of the state of the Amazonas, where all the four DENV serotypes were co-circulating simultaneously. Methodology Patients with acute febrile illness during the 2011 outbreak of dengue, enrolled at the Funda??o de Medicina Tropical Dr. Heitor Viera Dourado (FMT-HVD), a referral centre for tropical and infectious diseases in Manaus, were invited to participate in a clinical and virological descriptive study. Sera from 677 patients were analyzed by RT-nested-PCRs for flaviviruses (DENV 1–4, Saint Louis encephalitis virus-SLEV, Bussuquara virus-BSQV and Ilheus virus-ILHV), alphavirus (Mayaro virus-MAYV) and orthobunyavirus (Oropouche virus-OROV). Principal Findings Only dengue viruses were detected in 260 patients (38.4%). Thirteen patients were co-infected with more than one DENV serotype and six (46.1%) of them had a more severe clinical presentation of the disease. Nucleotide sequencing showed that DENV-1 belonged to genotype V, DENV-2 to the Asian/American genotype, DENV-3 to genotype III and DENV-4 to genotype II. Conclusions Co-infection with more than one DENV serotype was observed. This finding should be warning signs to health authorities in situations of the large dispersal of serotypes that are occurring in the world.
Use of prohibition order after a large outbreak of gastroenteritis caused by a norovirus among function attendees  [cached]
Praveena Gunaratnam,Catriona Furlong,Kirsty Hope,Leena Jupta
Western Pacific Surveillance and Response , 2012,
Abstract: Introduction: In May 2011, an outbreak of acute gastroenteritis occurred among guests attending two functions (Function A and B) at a local function centre in Sydney, Australia. The Sydney South West Public Health Unit and the New South Wales (NSW) Food Authority sought to determine the cause of the outbreak and implement control measures.Methods: A retrospective cohort study was planned. A complete guest list was unavailable, so guests who could be contacted were asked to provide details of other guests. Attendee demographics, symptom profile and food histories were obtained using a standard response questionnaire. Stool samples were requested from symptomatic guests. The NSW Food Authority conducted a site inspection.Results: Of those interviewed, 73% of Function A guests and 62% of Function B guests were ill, with mean incubation times of 27 and 23 hours respectively. Diarrhoea was the most common symptom. Three stool samples and four environmental swabs were positive for norovirus. One food handler reported feeling ill before and during the functions. A prohibition order was used to stop food handlers implicated in the outbreak from preparing food.Discussion: This outbreak strongly suggests transmission of norovirus, possibly caused by an infected food handler. Regulatory measures such as prohibition orders can be effective in enforcing infection control standards and minimising ongoing public health risk.
Host, Weather and Virological Factors Drive Norovirus Epidemiology: Time-Series Analysis of Laboratory Surveillance Data in England and Wales  [PDF]
Ben Lopman, Ben Armstrong, Christina Atchison, Jim J. Gray
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0006671
Abstract: Norovirus, the most commonly identified cause of both sporadic cases and outbreaks of infectious diarrhoea in developed countries, exhibits a complex epidemiology and has a strong wintertime seasonality. Viral populations are dynamic and evolve under positive selection pressure. Methods Time series-adapted Poisson regression models were fitted to daily counts of laboratory reports of norovirus in England and Wales from 1993 to 2006. Findings Inverse linear associations with daily temperature over the previous seven weeks (rate ratio (RR) = 0.85; 95% CI: 0.83 to 0.86 for every 1°C increase) and relative humidity over the previous five weeks (RR = 0.980; 95% CI: 0.973 to 0.987 for every 1% increase) were found, with temperature having a greater overall effect. The emergence of new norovirus variants (RR = 1.16; 95% CI: 1.10 to 1.22) and low population immunity were also associated with heightened norovirus activity. Temperature and humidity, which may be localised, had highly consistent effects in each region of England and Wales. Conclusions These results point to a complex interplay between host, viral and climatic factors driving norovirus epidemic patterns. Increases in norovirus are associated with cold, dry temperature, low population immunity and the emergence of novel genogroup 2 type 4 antigenic variants.
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