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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.
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.
Serial Foodborne Norovirus Outbreaks Associated with Multiple Genotypes  [PDF]
Jianwei Huang, Xuerong Xu, Qinyun Weng, Huarong Hong, Zhinan Guo, Shuizhen He, Jianjun Niu
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0063327
Abstract: Noroviruses (NoV) have been recognized as an important pathogen associated with acute gastroenteritis worldwide during the past three decades. In the spring of 2012, a series of foodborne outbreaks in tourist groups were reported to Xiamen Center for Disease Control and Prevention, Xiamen, Fujian province, China. Among a total of 268 tourists in 7 groups, the prevalence rate of acute gastroenteritis was 16.0% (43/268). Twenty-three feces or anal swabs were collected for laboratory tests of causative agents, no bacterial pathogen was identified, while 22 of them were positive for NoV RNA. In addition, thirteen NoV fragments were recovered from positive specimens and sequenced, belonging to five genotypes such as GI.3, GI.4, GII.4, GII.6, and GII.14, respectively. However, NoV fragments obtained from locally infected patients showed distinct genotypes. Therefore, epidemiological investigation and laboratory analyses demonstrated that the serial foodborne NoV outbreaks in tourists were co-infection of multiple genotypes induced acute gastroenteritis linked to a restaurant.
Epidemiology of foodborne Norovirus outbreaks in Catalonia, Spain
Ana Martinez, Angela Dominguez, Nuria Torner, Laura Ruiz, Neus Camps, Irene Barrabeig, Cesar Arias, Josep Alvarez, Pere Godoy, Pilar Jorgina Bala?a, Analia Pumares, Rosa Bartolome, Dolors Ferrer, Unai Perez, Rosa Pinto, Javier Buesa, The Catalan Viral Gastroenteritis Study Group
BMC Infectious Diseases , 2008, DOI: 10.1186/1471-2334-8-47
Abstract: In all reported outbreaks of gastroenteritis associated with food consumption, faecal samples of persons affected were analysed for bacteria and viruses and selectively for parasites. Study variables included the setting, the number of people exposed, age, sex, clinical signs and hospital admissions. The study was carried out from October 2004 to October 2005.Of the 181 outbreaks reported during the study period, 72 were caused by Salmonella and 30 by norovirus (NoV); the incidence rates were 14.5 and 9.9 per 100,000 person-years, respectively. In 50% of the NoV outbreaks and 27% of the bacterial outbreaks (p = 0.03) the number of persons affected was ≥10; 66.7% of NoV outbreaks occurred in restaurants; no differences in the attack rates were observed according to the etiology. Hospitalizations were more common (p = 0.03) in bacterial outbreaks (8.6%) than in NoV outbreaks (0.15%). Secondary cases accounted for 4% of cases in NoV outbreaks compared with 0.3% of cases in bacterial outbreaks (p < 0.001)Norovirus outbreaks were larger but less frequent than bacterial outbreaks, suggesting that underreporting is greater for NoV outbreaks. Food handlers should receive training on the transmission of infections in diverse situations. Very strict control measures on handwashing and environmental disinfection should be adopted in closed or partially-closed institutions.Diseases resulting from the consumption of contaminated food cause a considerable disease burden in developed countries [1], and thus it is important to determine their etiology and food vehicles. Although there are difficulties in associating a specific food with the appearance of cases or outbreaks of gastroenteritis [2], reports agree that noroviruses (NoV) (formerly Norwalk-like viruses) are one of the foremost biological agents involved in cases of gastroenteritis associated with food consumption [3].The stability of NoV in various environmental conditions means that they can remain infectious in frozen
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.
A typhoid fever outbreak in a slum of South Dumdum municipality, West Bengal, India, 2007: Evidence for foodborne and waterborne transmission
Rama Bhunia, Yvan Hutin, Ramachandran Ramakrishnan, Nishith Pal, Tapas Sen, Manoj Murhekar
BMC Public Health , 2009, DOI: 10.1186/1471-2458-9-115
Abstract: We defined a suspected case of typhoid fever as occurrence of fever for ≥ one week among residents of ward 1 of South Dumdum during February – May 2007. We searched for suspected cases in health care facilities and collected blood specimens. We described the outbreak by time, place and person. We compared probable cases (Widal positive >= 1:80) with neighbourhood-matched controls. We assessed the environment and collected water specimens.We identified 103 suspected cases (Attack rate: 74/10,000, highest among 5–14 years old group, no deaths). Salmonella (enterica) Typhi was isolated from one of four blood specimens and 65 of 103 sera were >= 1:80 Widal positive. The outbreak started on 13 February, peaked twice during the last week of March and second week of April and lasted till 27 April. Suspected cases clustered around three public taps. Among 65 probable cases and 65 controls, eating milk products from a sweet shop (Matched odds ratio [MOR]: 6.2, 95% confidence interval [CI]: 2.4–16, population attributable fraction [PAF]: 53%) and drinking piped water (MOR: 7.3, 95% CI: 2.5–21, PAF-52%) were associated with illness. The sweet shop food handler suffered from typhoid in January. The pipelines of intermittent non-chlorinated water supply ran next to an open drain connected with sewerage system and water specimens showed faecal contamination.The investigation suggested that an initial foodborne outbreak of typhoid led to the contamination of the water supply resulting in a secondary, waterborne wave. We educated the food handler, repaired the pipelines and ensured chlorination of the water.Typhoid fever is an acute febrile illness caused by Salmonella (enterica) Typhi [1,2]. The incubation period ranges from three days to one month [3]. Early symptoms include progressive onset of fever, headache, abdominal discomfort, loss of appetite, constipation followed by diarrhea, dry cough, malaise and rash along with relative bradycardia [2,3]. The case fatality ratio is 1
Foodborne disease outbreak among soldiers in Ni garrison associated with the consumption of coleslaw  [PDF]
?ekanac Radovan,?obelji? Miloje,Opa?i? Dolores
Vojnosanitetski Pregled , 2006, DOI: 10.2298/vsp0606564c
Abstract: Aim/Background. Large outbreaks of foodborne diseases are always focused by the general public who expect experts to rapidly explain both the causes of the disease and its growth. This article presents the results of the investigation of an outbreak of foodborne disease that has attracted much of the electronic and written media attention. Methods. The data on food items consumed by intoxicated and healthy soldiers were obtained by the adapted questionnaire during a field investigation performed on November 3-4, 2005. On the same occasion other relevant data were also collected. For microbiological investigations stool samples from the ill persons were collected, as well as food specimen and swabs from the working surfaces and utensils in the kitchen where the food had been prepared. Results. In the outbreak of foodborne disease, which started on November 2, 2005, and terminated on the next day, 103 ill soldiers were registered in 7 units scattered over 4 locations in the garrison of Ni . The attack rate varied in the affected units from 33 to 338‰, with the mean value of 109.7‰. The clinical course of the disease was predominantly light including vomiting, diarrhea and fever as the most frequent signs of illness. All the affected soldiers were hospitalized, treated with symptomatic therapy, and discharged fully recovered. By comparing dishes that had been consumed by the ill and the healthy persons before the beginning of the outbreak, the greatest statistical significance (p < 0.0001), and the only significant relative risk (RR = 3.43) were related to the consumption of the coleslaw served for lunch on November 1, 2005. In addition, two control groups with the total of 151 persons who had not consumed the coleslaws were identified no one of them was affected. An microbiological investigation did not reveal any bacterial enteropathogens. Conclusion. In the described foodborne disease outbreak a causative agent was not identified although coleslaw was the way of transmission probably secondarily contaminated by the improper hygiene practice during its processing.
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
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