Comparison of the number of Norovirus genome copies in patients and healthy persons

In viral gastroenteritis outbreaks occurred by Norovirus (NV), NV was detected not only from patients but also from healthy persons who have taken the same food, and also detected from healthy staff members working at community places such as hospital, school and nursing home. The number of fecal NV genome copies of patients, healthy persons and food handlers are examined by real-time PCR method, to investigate foodborne gastroenteritis and person to person transmission outbreaks. There is no significant difference on the number of NV genome copies in feces between patients, and NV-detected healthy persons. Those result indicate asymptomatic carrier of NV who were working as food handlers or staff members at community places will become an origin of food-borne gastroenteritis or person to person transmission outbreaks.     

A point-source norovirus outbreak caused by exposure to fomites

We investigated a norovirus outbreak (genotype GII.2) affecting 9 members of a soccer team. Illness was associated with touching a reusable grocery bag or consuming its packaged food contents (risk difference, 0.636; P?相似文献   

诺如病毒新重组株GⅡ.P16/GⅡ.2引起福建省2016年冬季病毒性胃肠炎暴发

目的 本文旨在鉴定福建省2016年冬季导致病毒性胃肠炎暴发的病原体,并对病原体进行分子特征研究.方法 对疫情暴发地上送的福建省2016年胃肠炎暴发急性病例标本,采用荧光PCR初步判定病原体,常规RT-PCR检测诺如病毒RNA聚合酶和衣壳蛋白基因片段,并进行序列测定和分子特征分析.结果 在3起暴发疫情中18份标本经荧光PCR检测均为诺如病毒核酸阳性,其中15份标本RT-PCR检测判为GⅡ型诺如病毒,9份标本成功测序.分析测序结果,证实引起本轮疫情为诺如病毒新重组株,该重组株有别于本地散发流行及全球暴发流行的优势基因型GⅡ.4.毒株RNA聚合酶核苷酸序列与2016年日本的GⅡ.4悉尼变异株Kawasaki194毒株的同源性最高,达98％,为GⅡ.P16亚型;衣壳蛋白核苷酸序列与2008年比利时的IPH2161-08VG06毒株同源性最高(97.7％～98.8％),为GⅡ.2亚型.结论 这是福建省首次报道诺如病毒重组株GⅡ.P16/ GⅡ.2的检出,并引起病毒性胃肠炎暴发.     

Age, viral copy number, and immunosuppressive therapy affect the duration of norovirus RNA excretion in inpatients diagnosed with norovirus infection

Norovirus is one of the leading causes of acute gastroenteritis worldwide. Although it is becoming clear that viral excretion in the stool continues even after the clinical symptoms have disappeared, the factors that determine its duration remain unknown. Between 2007 and 2009, all inpatients and medical staff at our hospital who showed symptoms of a new onset of gastroenteritis were asked to submit a sample for norovirus testing by real-time RT-PCR. One of the 273 patients included tested positive for GI norovirus, and a further 89 were positive for GII norovirus. Of these 90 norovirus-positive individuals, 76% excreted norovirus RNA in the stool for more than 7 days. The inpatient group contained more long shedders than the medical staff group (5/32 versus 1/39, P<0.05). The median viral shedding duration was 19.3 and 15.2 days for inpatients and medical staff, respectively. Among hospitalized patients, younger individuals, those with a higher viral copy number, and individuals receiving immunosuppressive therapy tended to require a longer time to eliminate the virus. These patients should therefore be monitored and managed carefully to prevent nosocomial spread of the disease.     

A Foodborne Norovirus Outbreak Due To Manually Prepared Salad, Austria 2006

Abstract Background: Norovirus is increasingly being recognized as a leading cause of foodborne disease. Nevertheless, welldocumented foodborne outbreaks due to norovirus are rarely found in the literature. Material and Methods: A retrospective cohort study was conducted for identifying the source of a gastroenteritis outbreak. A total of 325 persons were identified as the atrisk group. Results: The overall attack rate was 56% (182/325). Of the four working days of possible foodborne exposure to norovirus (Monday till Thursday), Wednesday (risk ratio [RR]: 18.82; 95%CI 11.82–29.96) and Thursday (RR 2.14; 95%CI 1.65–2.79) turned out to be the most likely days on which infections with norovirus occurred. The day-by-day food specific cohort analyses yielded consumption of salad on Wednesday (adjusted RR 2.82; 95%CI 1.0–7.94) to be associated with highest risk of illness. The most likely source of food contamination is a kitchen assistant having prepared salad manually. She fell ill with symptoms of gastroenteritis on Wednesday during the early working hours and continued working. Human stool samples obtained from five out of six outbreak cases, including the sick kitchen assistant, were RT-PCR positive for norovirus genotype GGII.7 (Leeds-like). Conclusion: This foodborne norovirus outbreak underlines the drastic consequences of neglecting the rules of basic kitchen hygiene. Food handlers working despite manifest diarrhea or vomiting – often in fear of job loss – are a common cause of foodborne norovirus outbreaks.     

Norovirus outbreaks in a teaching hospital: the role of infection control

In January 2004, 20 patients and 19 staff in one ward became ill in an outbreak of norovirus-related gastroenteritis over a 12-day period. The epidemic curve indicated person-to-person transmission. Infection control measures were instituted in consultation with the government health authorities. A prompt rigorous response may have prevented spread to other wards. In March 2004, 54 staff and 1 member of a patient's family became ill in an outbreak of gastroenteritis. The source of norovirus contamination was associated with food served at the hospital restaurant. Secondary infection was prevented because the outbreak was recognized early and staff members with gastroenteritis symptoms were asked to stay home. Immediate control measures, such as identification and announcement of the outbreak, isolation of symptomatic individuals from others, personal protection, helped control the infection.     

Pathogenesis of noroviruses, emerging RNA viruses

Human noroviruses in the family Caliciviridae are a major cause of epidemic gastroenteritis. They are responsible for at least 95% of viral outbreaks and over 50% of all outbreaks worldwide. Transmission of these highly infectious plus-stranded RNA viruses occurs primarily through contaminated food or water, but also through person-to-person contact and exposure to fomites. Norovirus infections are typically acute and self-limited. However, disease can be much more severe and prolonged in infants, elderly, and immunocompromised individuals. Norovirus outbreaks frequently occur in semi-closed communities such as nursing homes, military settings, schools, hospitals, cruise ships, and disaster relief situations. Noroviruses are classified as Category B biodefense agents because they are highly contagious, extremely stable in the environment, resistant to common disinfectants, and associated with debilitating illness. The number of reported norovirus outbreaks has risen sharply since 2002 suggesting the emergence of more infectious strains. There has also been increased recognition that noroviruses are important causes of childhood hospitalization. Moreover, noroviruses have recently been associated with multiple clinical outcomes other than gastroenteritis. It is unclear whether these new observations are due to improved norovirus diagnostics or to the emergence of more virulent norovirus strains. Regardless, it is clear that human noroviruses cause considerable morbidity worldwide, have significant economic impact, and are clinically important emerging pathogens. Despite the impact of human norovirus-induced disease and the potential for emergence of highly virulent strains, the pathogenic features of infection are not well understood due to the lack of a cell culture system and previous lack of animal models. This review summarizes the current understanding of norovirus pathogenesis from the histological to the molecular level, including contributions from new model systems.     

Influenza Vaccine: Epidemiology of norovirus and viral gastroenteritis in Ontario,Canada, 2009–2014

BackgroundNorovirus is the most common cause of acute gastroenteritis in Canada. The illness causes great morbidity and high societal costs. The objective of this article is to describe the epidemiology of norovirus in the province of Ontario, Canada from 2009 to 2014.MethodsTo assess activity of norovirus and viral gastroenteritis (VGE) in Ontario, three datasets were acquired from the provincial government: two traditional surveillance datasets (outbreak and laboratory) and syndromic surveillance data (telehealth), all spanning 2009–2014. All outbreaks, laboratory submissions and telehealth calls were first assessed for total VGE. Norovirus and norovirus-like illness totals were calculated as a proportion of VGE to estimate agent-specific activity levels. Affected institution types, sexes and age groups were also analyzed.ResultsBetween 2009 and 2014, 41.5% of VGE outbreaks, 63.4% of VGE laboratory submissions and 36.6% of all acute gastroenteritis-related (not restricted to viral causes) telehealth calls were attributed to norovirus and norovirus-like illness in Ontario. The most commonly affected institution type was long-term care homes and the most commonly affected age groups were younger (younger than five years) and older (older than 65 years) individuals. Females were slightly more frequently affected than males.ConclusionNorovirus and norovirus-like illnesses were the leading cause of VGE in Ontario between 2009 and 2014. They comprised the greatest percentage of VGE when compared with all other VGE-associated viruses. Additional work is needed to determine all component costs and necessary public health actions to reduce the burden of disease.     

Identification of Norovirus as the Top Enteric Viruses Detected in Adult Cases with Acute Gastroenteritis

To elucidate the importance of the norovirus and other enteric viruses, and the difference of the genetic relatedness on norovirus between the outbreak and sporadic cases, a total of 557 stool samples, consisting of 503 sporadic cases and 54 samples of 4 outbreaks were collected and tested for norovirus and other enteric viruses in Beijing, China, July 2007–June 2008. The data showed norovirus, rotavirus, astrovirus, and sapovirus, were detected in 26.6%, 6.1%, 1.8%, and 0.5%, respectively. Norovirus was detected almost throughout the surveillance period, norovirus co-infecting with rotavirus, astrovirus, and sapovirus, respectively, were identified both in outbreak and the sporadic cases. GII.4/2006 was identified as the predominant strain circulating both in outbreak and sporadic cases. The results showed that norovirus was rather the important agent than other enteric viruses affected adults with acute gastroenteritis; no significant genetic relatedness of the dominant strains was found between the outbreak and sporadic cases.     

Norovirus infection outbreaks in Kyoto City--2006-2007

We studied 96 mass outbreaks of infectious gastroenteritis due to Norovirus in winter 2006-2007. Of these, 56 occurred in welfare institutions for aging adults 31 in hospitals, and 9 in other facilities such as kinder gardens. Affected staff accounted for 25.9% and users (inpatients, etc.) for 74.1%. The shortest outbreak lasted 10 days and the longest 67 days. We found a positive corelation between periods from the beginning of an outbreak to warnings by public health centers and periods from the beginning to the end of outbreaks. The sooner advice was aired by public health centers, the sooner outbreaks ended. Dementia among users and insufficient knowledge and skills of staff were high risk factors in outbreaks. All 74 of specimens which we examined showed the GII4 genotype. We observed reoutbreaks at three institutions. We compared first and second specimens from the same institution. Two specimens from the second outbreak belonged to the same cluster as the first outbreak. We analyzed 310 bases of RT-PCR products in Capsid regions in both specimens, finding three point mutations accompanied by amino acids changes. This may change the antigenicity of Capsid protein, and may be why reoutbreaks occurred so quickly.     

A nosocomial sapovirus-associated outbreak of gastroenteritis in adults

The human caliciviruses norovirus and sapovirus are leading causes of acute, non-bacterial gastroenteritis. In contrast to norovirus, sapovirus is known to give infections mainly in infants and young children. We describe a nosocomial outbreak of gastroenteritis associated with sapovirus involving 23 adult patients and medical staff. The mean age of the patients and medical staff was 52 y and the major signs and symptoms were nausea, diarrhoea, vomiting, abdominal cramp, headache, myalgia and fever. More patients had diarrhoea (72%) than vomiting (56%) and the mean duration of symptoms was 6 d. A secondary attack rate of 45% was seen affecting in all 10 persons with a mean age of 29 y. Sequences of the capsid gene revealed a 97% nucleotide homology to the sapovirus genogroup IV reference strain Chiba/000671T/1999. This is one of the first reported nosocomial outbreaks of sapovirus infection among adults and shows that a diagnostic test for sapovirus should be included in investigation of gastroenteritis among adults.     

Norovirus outbreak among primary schoolchildren who had played in a recreational water fountain

BACKGROUND: A gastroenteritis outbreak was associated with playing in a norovirus-contaminated recreational fountain. OBJECTIVE AND STUDY DESIGN: A retrospective cohort study was performed to estimate the magnitude of the outbreak and identify its source. Epidemiological investigation included standardized questionnaires about sex, age, school, class, risk exposures, and illness characteristics. Stool samples and environmental water samples were analyzed for the presence of bacteria, viruses, and parasites. RESULTS: Questionnaires were returned for 191 schoolchildren (response rate, 83%) with a mean age of 9.2 years, of whom 47% were ill (diarrhea and/or vomiting). Children were more likely to have been ill if they had played in the recreational fountain (relative risk, 10.4). Norovirus (Birmingham) was detected in 22 (88%) stool specimens from ill children and in 6 (38%) specimens from healthy children. The water sample from the fountain contained a norovirus strain that was identical to the RNA sequence found in stools. CONCLUSIONS: Recreational water may be the source of gastroenteritis outbreaks. Adequate water treatment can prevent these types of outbreak.     

Epidemics of gastroenteritis during 2006 were associated with the spread of norovirus GII.4 variants 2006a and 2006b.

BACKGROUND: Acute gastroenteritis is commonly associated with norovirus genogroup II (GII) infection. Norovirus GII has 17 classified genotypes (GII.1-GII.17), but only 1 norovirus genotype (GII.4) is associated with global epidemics of gastroenteritis. In 2006, an increase in global norovirus activity was observed. METHODS: During the period from December 2005 through August 2006, a total of 231 fecal samples were obtained from patients with acute gastroenteritis from Australia and New Zealand. Norovirus RNA was amplified and sequenced to determine norovirus genotype and relatedness to known epidemic norovirus GII.4 variants. RESULTS: Two GII.4 variants, designated 2006a and 2006b, were identified in 61.8% and 11.3%, respectively, of the 186 cases investigated. Norovirus 2006a and 2006b have also been implicated as the predominant causes of norovirus-associated gastroenteritis across Europe in 2006. CONCLUSIONS: The global increase in norovirus-associated gastroenteritis in 2006 was linked to the emergence of 2 novel GII.4 variants, 2006a and 2006b.     

Efficient management of a norovirus outbreak causing gastroenteritis in two hotels in Spain, 2014

ObjectivesTo determine the aetiological agent causing a gastroenteritis outbreak in two hotels in Majorca (Spain) on August and September 2014.MethodsAn epidemiological study was carried out. Environmental and stool samples were analyzed for different pathogens, including norovirus.ResultsEpidemiological analysis detected 79 cases among the tourists hosted in the affected hotels over the period 18th August to 3rd September. They included 52 (attack rate: 6.4%) and 27 (attack rate: 3.0%) cases in hotel A and B, respectively. Seven of the staff members were also affected. Microbiological analyses detected genotype 2 norovirus in patient's stool samples, in rooms and in common areas’ surfaces. The specific control plan rapidly implemented at the beginning of the outbreak, and further adapted for norovirus elimination, allowed to control the outbreak.ConclusionsOur study demonstrates that the outbreak was caused by genotype 2 norovirus, and reflects the importance of a rapid analysis and response for its control.     

Quantification of Human Norovirus GII on Hands of Mothers with Children under the Age of Five Years in Bagamoyo,Tanzania

Human noroviruses are the most common cause of viral gastroenteritis worldwide and one of the leading causes of viral diarrhea in children under the age of 5 years. Hands have been shown to play an important role in norovirus transmission. Norovirus outbreaks tend to exhibit strong seasonality, most often occurring during cold, dry months, but recently have also been documented during hot, dry winter months in the southern hemisphere. Other research suggests that rainfall is an important factor in norovirus outbreaks. This study examines the prevalence and concentration of human norovirus GII on the hands of mothers in Bagamoyo, Tanzania, during the rainy and dry seasons. Norovirus GII was detected in approximately 5% of hand rinse samples during both the rainy and dry seasons. Fecal indicator bacteria levels, Escherichia coli and enterococci, in hand rinse samples were not associated with norovirus hand contamination. Turbidity of the hand rinses was found to be associated with norovirus presence on mothers'' hands; however, this relationship was only observed during the rainy season. The results suggest mothers'' hands serve as a source of norovirus exposure for young children in Tanzanian households, and further work is needed to determine better indicators of norovirus contamination in these environments.     

Multiple outbreaks of gastroenteritis due to a single strain of genotype GII/4 norovirus in Kobe, Japan, 2006: risk factors for norovirus spread in health care settings

A large number of gastroenteritis outbreaks due to a norovirus GII/4 strain and its variants occurred during November and December 2006 in Kobe, Japan. Of the 118 outbreaks, 6 were foodborne and 112 were caused by person-to-person transmission in healthcare settings such as nursing homes and hospitals. The distribution of norovirus outbreaks in healthcare settings was skewed, particularly in the south coastal area. Moreover, several outbreaks occurred within 1 km(2) in various areas. Outbreaks in neighboring settings, especially within 1 km, and travel from the sources of outbreaks were risk factors for the spread of the norovirus. The use of ineffective disinfectants such as alcohol and benzalkonium chloride might also have helped to spread the infection.     

An outbreak of Norwalk like virus gastroenteritis in a nursing home in Rotterdam

Sixty-two per cent of elderly and disabled residents of a Dutch nursing home (74/120) and 32% of staff (33/102) became ill in an outbreak of Norwalk-like viral gastroenteritis. The outbreak spread from person to person was supported by temporal clustering     

Acute gastroenteritis outbreak caused by a GII.6 norovirus

AIM:To report an acute gastroenteritis outbreak caused by a genogroup 2 genotype 6(GII.6) strain norovirus in Shanghai,China.METHODS:Noroviruses are responsible for approximately half of all reported gastroenteritis outbreaks in many countries.Genogroup 2 genotype 4 strains are the most prevalent.Rare outbreaks caused by GII.6 strains have been reported.An acute gastroenteritis outbreak occurred in an elementary school in Shanghai in December of 2013.Field and molecular epidemiologic investigations were conducted.RESULTS:The outbreak was limited to one class in an elementary school located in southwest Shanghai.The age of the students ranged from 9 to 10 years.The first case emerged on December 10,2013,and the last case emerged on December 14,2013.The cases peaked on December 11,2013,with 21 new cases.Of 45 students in the class,32 were affected.The main symptom was gastroenteritis,and 15.6%(5/32) of the cases exhibited a fever.A field epidemiologic investigation showed the pathogen may have been transmitted to the elementary school from employees in a delicatessen via the first case student,who had eaten food from the delicatessen one day before the gastroenteritis episodes began.A molecular epidemiologic investigation identified the cause of the gastroenteritis as norovirus strain GII.6;the viral sequence of the student cases showed 100% homology with that of the shop employees.Genetic relatedness analyses showed that the new viral strain is closely related to previously reported GII.6 sequences,especially to a strain reported in Japan.CONCLUSION:This is the first report to show that norovirus strain GII.6 can cause a gastroenteritis outbreak.Thus,the prevalence of GII.6 noroviruses requires attention.