Billgren M, Christenson B, Hedlund K-O, Vinjé J
Department of Communicable Disease Control, Karolinska Hospital, Stockholm, Sweden.
J Infect. 2002 Jan;44(1):26-32. doi: 10.1053/jinf.2001.0946.
Outbreaks of acute gastroenteritis associated with 'Norwalk-like viruses' (NLVs) cause significant health problems in hospitals. Hospital outbreaks in the Stockholm area in 1996 were investigated, in order to identify the magnitude of the problem, the mode of transmission, the effect of control measures and the genetic variability of outbreak strains. Determining the epidemiological and clinical significance involves a broad range of possibilities.
Ten hospitals, representing 66% of the hospitals in the Stockholm area, participated in the study, which included 211 wards. Of these, 18 were selected as control. A standardized protocol that included personal contacts was administered. Outbreak wards were visited between 5 and 10 times. Wards that had reported outbreaks in 1996 were prospectively followed through 1999 by personal contacts, and the available data from 1991 on outbreak reports were collected. A total of 253 stool samples from outbreaks in 1996 were analyzed by electron microscopy (EM) for the presence of NLVs. Positive samples were confirmed by the reverse transcriptase-polymerase chain reaction (RT-PCR).
In total, 4 326 patients and 1 119 staff were exposed on the 43 wards that reported 54 outbreaks. The mean attack rate was 13% for patients and 21% for staff. The number of outbreaks in 1996 outnumbered the reported outbreaks in the preceding years (4-70%) and later years (35-40%). Admission to 24 (56%) of the outbreak wards was stopped. The mean duration of illness for patients was 35 hours and for staff, 30 hours. The main symptoms were diarrhoea (80%) and vomiting (68%). Genotyping revealed that the majority of the hospital outbreaks in the Stockholm area in 1996 were caused by a single NLV strain.
The study confirmed that outbreaks of NLV are an increasing public-health problem in hospitals. The risk of being affected by an outbreak was significantly greater on wards that had reported outbreaks in the previous year. It was not obvious which measures had helped to shorten the outbreaks to any appreciable extent. Different managements must therefore be carefully interpreted and adapted to the prevailing circumstances. Genotyping of strains is an important tool of getting a better insight into transmission routes and the mechanism behind the appearance of epidemic strains.
与“诺如病毒样病毒”（NLVs）相关的急性胃肠炎暴发在医院中引发了严重的健康问题。对1996年斯德哥尔摩地区医院的暴发情况进行调查，以确定问题的严重程度、传播方式、控制措施的效果以及暴发菌株的基因变异性。确定其流行病学和临床意义涉及多种可能性。
代表斯德哥尔摩地区66%医院的10家医院参与了该研究，其中包括211个病房。其中，18个被选为对照。实施了一项包括个人接触情况的标准化方案。对暴发病房进行了5至10次走访。通过个人接触对1996年报告有暴发的病房进行前瞻性追踪，直至1999年，并收集了1991年以来有关暴发报告的可用数据。对1996年暴发的253份粪便样本进行电子显微镜（EM）分析，以检测是否存在NLVs。阳性样本通过逆转录聚合酶链反应（RT-PCR）进行确认。
在报告了54起暴发的43个病房中，共有4326名患者和1119名工作人员暴露。患者的平均感染率为13%，工作人员为21%。1996年的暴发次数超过了前几年（4%-70%）和后几年（35%-40%）报告的暴发次数。24个（56%）暴发病房停止收治患者。患者的平均患病时长为35小时，工作人员为30小时。主要症状为腹泻（80%）和呕吐（68%）。基因分型显示，1996年斯德哥尔摩地区医院的大多数暴发是由单一NLV菌株引起的。
该研究证实，NLV暴发在医院中是一个日益严重的公共卫生问题。上一年报告有暴发的病房受暴发影响的风险显著更高。目前尚不清楚哪些措施在多大程度上有助于明显缩短暴发时间。因此，必须仔细解读不同的管理方法并使其适应当前情况。菌株基因分型是更好地了解传播途径和流行菌株出现背后机制的重要工具。
