一起诺瓦克病毒感染引起的急性胃肠炎暴发的流行病学调查

目的 调查某幼儿园14名儿童发生以呕吐为主要症状的集体性急性胃肠炎的发病原因。方法 采用流行病学调查方法对病例进行时间、年龄、班级分布情况、进食史分析,对可疑剩饭菜、病人呕吐物和粪便进行肠道病毒检测、食物中毒常规致病菌检测,对病人进行血白细胞计数、血液胆碱酯酶活性检测。结果 14名患者均有共同进食史,发病罹患率为41．18％(14／34),以3岁组发病人数最多,为8例,病例集中在小班,为11例,流行时间1d;采集的15份样品中3份病人呕吐物、2份大便样本检测出诺瓦克病毒,8份样本诺瓦克病毒PCR阳性。结论 这是一起由诺瓦克病毒感染引起的急性胃肠炎暴发流行。     

Waterborne outbreak of Norwalk-like virus gastroenteritis at a tourist resort,Italy

In July 2000, an outbreak of gastroenteritis occurred at a tourist resort in the Gulf of Taranto in southern Italy. Illness in 344 people, 69 of whom were staff members, met the case definition. Norwalk-like virus (NLV) was found in 22 of 28 stool specimens tested. The source of illness was likely contaminated drinking water, as environmental inspection identified a breakdown in the resort water system and tap water samples were contaminated with fecal bacteria. Attack rates were increased (51.4%) in staff members involved in water sports. Relative risks were significant only for exposure to beach showers and consuming drinks with ice. Although Italy has no surveillance system for nonbacterial gastroenteritis, no outbreak caused by NLV has been described previously in the country.     

Widespread environmental contamination with Norwalk-like viruses (NLV) detected in a prolonged hotel outbreak of gastroenteritis

A protracted outbreak of Norwalk-like virus (NLV)-associated gastroenteritis occurred in a large hotel in North-West England between January and May 1996. We investigated the pattern of environmental contamination with NLV in the hotel during and after the outbreak. In the ninth week, 144 environmental swabs taken from around the hotel were tested for NLV by nested RT-PCR. The sites were categorized according to the likelihood of direct contamination with vomit/faeces. The highest proportion of positive samples were detected in directly contaminated carpets, but amplicons were detected in sites above 1.5 m which are unlikely to have been contaminated directly. The trend in positivity of different sites paralleled the diminishing likelihood of direct contamination. A second environmental investigation of the same sites 5 months after the outbreak had finished were all negative by RT-PCR. This study demonstrates for the first time the extent of environmental contamination that may occur during a large NLV outbreak.     

An outbreak of food-borne gastroenteritis in two hospitals associated with a Norwalk-like virus.

Two connected outbreaks of gastroenteritis in separate hospitals associated with a small round structured virus morphologically indistinguishable from the Norwalk virus are described. The virus was most probably introduced on chicken sandwiches prepared by a member of the kitchen staff who was incubating the disease.     

A Norwalk-like virus outbreak on the Appalachian Trail

In May and June 1999, an outbreak of acute gastrointestinal illness occurred among long-distance hikers on the Appalachian Trail between Catawba and Troutville, Virginia. An investigation found that 45 out of 70 hikers had become ill within two days of arriving in Catawba, Virginia. Water samples were collected from a general store frequented by the hikers and from several nearby buildings and a popular all-you-can-eat restaurant. Symptoms were consistent with those caused by Norwalk-like viruses, and laboratory diagnosis detected Norwalk-like viruses in stool and serum specimens. People who consumed food items prepared at the general store were almost twice as likely to become ill as persons who did not consume those foods. Environmental sampling of water from the taps inside and outside the general store and from several surrounding establishments in Catawba found contamination by fecal coliform bacteria but not by Norwalk-like virus. Since several hikers reported illness prior to arriving at Catawba, person-to-person transmission of a highly contagious agent such as Norwalk-like virus could not be ruled out. Poor sanitation, scarce water supplies, and crowding can increase the risk of gastrointestinal illness among long-distance hikers.     

A large outbreak of gastroenteritis associated with a small round structured virus among schoolchildren and teachers in Japan

In March 1989 a large outbreak of acute gastroenteritis occurred simultaneously among schoolchildren and teachers at nine elementary schools in Toyota City, Japan. Illness was observed in 3236 (41.5%) of 7801 schoolchildren and 117 (39.4%) of 297 teachers. The main clinical symptoms were diarrhoea, vomiting, nausea and abdominal pain. Gastroenteritis was significantly associated with the consumption of school lunch served by one particular lunch preparation centre. One food handler at the centre suffered from gastroenteritis during the outbreak. Small round structured virus (SRSV) was detected in 4 of 8 stool specimens from sick persons. The school lunch contaminated by the infected food handler is the most probable source of this outbreak due to SRSV.     

一起诺瓦克样病毒性胃肠炎的流行病学调查

目的探讨2004年广州市番禺区一起由诺瓦克样病毒引起的学校胃肠炎疫情暴发特征. 方法采用现场流行病学调查方法,对该起疫情进行调查分析. 结果该起疫情共报告病例30例 ,其中3例患者的粪便或肛拭标本检出诺瓦克病毒抗原. 结论本次胃肠炎暴发疫情由诺瓦克样病毒引起,传染来源尚未查明.     

Practical lessons from the management of an outbreak of small round structured virus (Norwalk-like virus) gastroenteritis

An outbreak of viral gastroenteritis caused illness in 92 people during October 2000. All the cases had an association with one hotel and 80% of cases identified had attended one of two buffet meals on 18th October 2000. Cohort analysis did not implicate any particular foodstuff in this outbreak. All bacteriological tests on food samples were negative. Small round structured virus (SRSV)/Norwalk-like virus (NLV) particles were seen by electron microscopy in 6 out of 27 stool samples submitted for analysis. This paper describes the outbreak and in particular the lessons learned from the management and control of it. These include practical points with regard to the outbreak control team, liaison with the microbiology laboratory, handling data, agreeing a case definition, and occupational health issues. All can be applied elsewhere by those responsible for managing outbreaks at a local level.     

A gastroenteritis outbreak due to norovirus associated with a Colorado hotel

Describing the system components of norovirus outbreaks is important in understanding how to prevent future outbreaks. Investigation of these components includes environmental, epidemiologic, and laboratory perspectives. This study describes how an investigation from these three perspectives was conducted and the significance of each component in understanding norovirus outbreaks. On May 23, 2000, members of a professional group attending two meetings at a local hotel in Englewood, Colorado, began to complain of gastrointestinal illness. Sixty-nine illnesses were reported among 133 attendees. Eight hotel employees also complained of illness. Staff from the Tri-County Health Department and the Centers for Disease Control and Prevention investigated the outbreak. Three stool specimens collected from ill attendees contained norovirus. While the epidemiologic component did not identify a specific vehicle of transmission, the environmental investigation revealed food-handling practices, food handler perceptions, and hotel policies that may have contributed to disease transmission.     

Investigation of an outbreak of gastroenteritis caused by Norwalk-like virus, using solid phase immune electron microscopy

In February 1993, 95 persons (47 patients and 48 staff members) were affected by an hospital outbreak of viral gastroenteritis. Using direct electron microscopy (EM) the causative agent was identified as a small round structured virus. This was confirmed as a Norwalk-like virus using solid phase immune electron microscopy (SPIEM). Of 94 stool samples examined, 12 (13%) samples containing small round structured viruses (SRSV) were SPIEM positive for Norwalk-like virus. A further 25 (27%) samples contained small round featureless virus (SRFV) identified by direct EM and were negative on SPIEM. The illness was characterized by preceding influenza-like symptoms in 76% of cases followed by vomiting (76%), diarrhoea (79%) and abdominal pain (79%). One fatality was recorded. The outbreak lasted for 15 days, with a peak incidence of new cases amongst patients and staff occurring on day 5. It was controlled through a combination of ward closures, patient cohorting, suspension of duties for affected staff and disinfection procedures. Difficulties were encountered in the education of staff and in the implementation of environmental control measures. Screening of hospital catering services and a case control study, carried out among affected staff members, failed to identify a foodborne source. Consumption of tap water in the hospital was commoner among affected staff members than among controls, but this did not reach significance (P = 0.1).     

A school outbreak of Norwalk-like virus: evidence for airborne transmission

An outbreak of gastroenteritis affected a school attended by children aged 4-11 years. Epidemiological features suggested this was due to Norwalk-like virus (NLV) and this was confirmed by polymerase chain reaction (PCR). Nucleotide sequence analysis of the PCR amplicons revealed identical strains in all five positive stool samples. Pupils were significantly more likely to become ill following an episode of vomiting within their classroom (adjusted odds ratio 4.1, 95% CI 1.8-9.3). The times from exposure to illness were consistent with direct infection from aerosolized viral particles where exposure to vomiting was high. Cleaning with quaternary ammonium preparations made no impact on the course of the outbreak. However, the outbreak stopped after the school closed for 4 days and was cleaned using chlorine-based agents. This study confirms the importance of vomiting in the transmission of NLV and provides evidence that direct infection with aerosolized viral particles occurs.     

广东省2005年诺瓦克样病毒感染暴发疫情

目的分析广东省2005年群体性诺瓦克样病毒性胃肠炎流行特征,为今后预防控制提供科学依据。方法采用描述性分析方法,对广东省2005年群体性诺瓦克样病毒性胃肠炎疫情进行调查分析。结果2005年广东省共报告12起群体性诺瓦克样病毒性胃肠炎疫情,共发病469例,无死亡病例。疫情全部发生在学校。发生时间除1起发生在3月份外,11起集中发生在9~12月份。症状以呕吐为主。12起疫情中病例数最多的1起达190例,罹患率最高的1起达53.3%(23/43)。11起疫情患者有共同的进餐史,1起疫情患者没有共同的食物暴露史。每起疫情均从部分患者粪便标本中检出诺瓦克样病毒核酸或抗原。结论学校是诺瓦克样病毒暴发疫情的好发地方,食物传播、接触呕吐物和粪便传播是可能的主要传播途径,因此控制诺瓦克样病毒暴发疫情的关键是抓好学校的饮食卫生和妥善处理呕吐物和粪便。     

Managing the challenge of an acute gastroenteritis outbreak caused by a Norwalk-like virus in a 239 bed long-term care facility

Outbreak management in long-term care facilities (LTCFs) highlights the differences between the ’ideal’ and ’real’ practicalities of implementing appropriate control measures. Infection control practitioners must develop workable strategies in an environment where it may not be possible to adopt traditional outbreak management procedures.This paper documents events during a large, prolonged outbreak of Norwalk-like virus, genotype II, affecting residents and staff of a 239 bed LTCF in Queensland. Diagnosis was confirmed from one faecal specimen. The case rate was 37 per cent with a total of 76 residents and 25 staff and volunteers meeting the criteria set in the case definition. Three peaks of infection were noted. Implementing standard mechanisms to isolate and cohort affected residents was not possible due to psychosocial and environmental factors in the setting. In addition, staffing shortages already in existence were compounded due to illness.The lack of facility-specific outbreak policies and procedures contributed to the slow resolution of the outbreak. An education programme focused on developing a collaborative, problem solving relationship among all disciplines. The result was the development of specific gastroenteritis outbreak management guidelines that reflect the realities of managing an outbreak event in a LTCF. This article outlines the management issues, solutions and outcomes associated with this outbreak.     

An outbreak of Norwalk-like gastroenteritis associated with contaminated drinking water at a caravan park

Abstract: During the 1989 Christmas holiday period, a large outbreak of gastroenteritis occurred among persons staying at a caravan park in southern New South Wales. Review of local hospital records found that 77 per cent of patients presenting with infective diarrhoea between 29 December and 3 January had stayed at the caravan park. In a retrospective cohort study we compared rates of illness among caravan park patrons exposed to different water sources. Stools were tested for pathogens and convalescent sera for viral antibodies. Rain and reticulated river water sampled from the caravan park were tested for bacteria and viruses. Of 351 persons interviewed at the caravan park, 305 (87 per cent) reported an illness characterised by diarrhoea, vomiting and abdominal pain. Of 196 persons who used reticulated river water for drinking or ablutions, 175 (89 per cent) became ill compared with 47 of 72 persons (65 per cent) who did not use this water (relative risk 1.4, 95 per cent confidence interval 1.2 to 1.6). The outbreak was probably caused by a 27–28 nm small round structured virus found in the stool from one ill person. High levels of faecal coliforms in the reticulated river water and enterovirus in sediment samples suggest that the outbreak was caused by sewage contaminating the reticulated river water through a break in the pipe directly over the underground water tanks. To prevent such outbreaks, poor water and sewerage system layouts should be avoided and nonpotable water should be clearly labelled. Where feasible, all camping-ground water should stem from town supplies.     

Hospitalizations among employees in the Danish hotel and restaurant industry

BACKGROUND: The aim of the present study was to provide a broad picture of the morbidity among employees in the Danish hotel and restaurant industry. METHODS: Cohorts of all 20-59-year-old employees in the Danish hotel and restaurant industry in the years 1981, 1986, 1991 and 1994 were formed to calculate age-standardized hospitalization ratios (SHR) and time trends (1981-1997) for many different diagnoses. RESULTS: Both for women and men, significantly higher SHRs were found for infectious and parasitic diseases, neoplasms, diseases in the nervous system and sense organs, diseases of the circulatory system, diseases of the respiratory system, diseases of the digestive system and diseases of the musculoskeletal system among employees in hotels and restaurants than in the digestive system and diseases of the musculoskeletal system among employees in hotels and restaurants than in the working population at large. Furthermore, among women a significantly elevated risk was found for injuries in the lower extremities, injuries in the upper extremities and head injuries, and among men a high risk was found for head injuries and a low risk for ruptures in ligaments and muscles. The trend assessments did not detect any significant changes in SHRs over time. CONCLUSION: Employment in the Danish hotel and restaurant industry is associated with an elevated hospitalization risk due to many diseases, which may be related to occupation and lifestyle. In line with the official policy of reducing inequality in health, focus should be placed on the health problems in this group.