Abstract：
BACKGROUND: Norovirus is frequently introduced to the hospital and is a frequent cause of hospital outbreaks. Recognition of the factors that facilitate or impede norovirus transmission is an important step to effectively prevent hospital outbreaks.
OBJECTIVE: To investigate risk factors for norovirus outbreaks in hospital settings.
METHODS: Clinical data, ward setting, and norovirus genotype were collected from all 65 norovirus-positive index cases in outbreaks and all 186 sporadic norovirus cases at 192 wards in southern Sweden during 2010-2012 in a nested case-control study. Uni- and multivariate statistical analyses were conducted.
RESULTS: Outbreak was independently associated with the number of patients sharing a room with the norovirus case (odds ratio (OR): 1.9 per additional patient in the room; P < 0.01), vomiting (OR: 2.6; P = 0.04), age >80 years (OR: 3.2; P < 0.01), comorbidity (OR: 2.3; P = 0.05), and onset of symptoms after admission to the ward (OR: 3.5; P < 0.01) in the multivariate analysis. Infection with genotype GII.4 was found to be strongly associated with outbreak in the univariate analysis (OR: 5.7; P < 0.01). Moreover, associations between GII.4 and vomiting (OR: 2.5; P = 0.01) and old age (OR: 4.3: P < 0.01) were found.
CONCLUSIONS: This is the first study to investigate clinical, ward and genotype risk factors for norovirus hospital outbreaks. Recognition of these factors may help direct and prioritize infection control actions based on the outbreak risk. The results also suggest that the outbreak association with GII.4 partly may be explained by an enhanced ability to induce vomiting.
OBJECTIVE: To investigate risk factors for norovirus outbreaks in hospital settings.
METHODS: Clinical data, ward setting, and norovirus genotype were collected from all 65 norovirus-positive index cases in outbreaks and all 186 sporadic norovirus cases at 192 wards in southern Sweden during 2010-2012 in a nested case-control study. Uni- and multivariate statistical analyses were conducted.
RESULTS: Outbreak was independently associated with the number of patients sharing a room with the norovirus case (odds ratio (OR): 1.9 per additional patient in the room; P < 0.01), vomiting (OR: 2.6; P = 0.04), age >80 years (OR: 3.2; P < 0.01), comorbidity (OR: 2.3; P = 0.05), and onset of symptoms after admission to the ward (OR: 3.5; P < 0.01) in the multivariate analysis. Infection with genotype GII.4 was found to be strongly associated with outbreak in the univariate analysis (OR: 5.7; P < 0.01). Moreover, associations between GII.4 and vomiting (OR: 2.5; P = 0.01) and old age (OR: 4.3: P < 0.01) were found.
CONCLUSIONS: This is the first study to investigate clinical, ward and genotype risk factors for norovirus hospital outbreaks. Recognition of these factors may help direct and prioritize infection control actions based on the outbreak risk. The results also suggest that the outbreak association with GII.4 partly may be explained by an enhanced ability to induce vomiting.
摘要：
背景：诺如病毒经常被引入医院，是医院爆发的常见原因。认识到促进或阻碍诺如病毒传播的因素是有效预防医院暴发的重要步骤。
目的：调查医院环境中诺如病毒暴发的危险因素。
方法：临床数据，病房设置，在一项巢式病例对照研究中,收集了2010-2012年瑞典南部192个病区所有65例诺如病毒阳性指数病例和186例散发性诺如病毒病例的诺如病毒基因型.进行单因素和多因素统计分析。
结果：爆发与诺如病毒病例共用一个房间的患者数量独立相关（优势比（OR）：每个房间中的额外患者1.9；P<0.01），呕吐（OR：2.6；P=0.04），年龄>80岁（OR：3.2；P<0.01），合并症（OR：2.3；P=0.05），在多因素分析中，入院后出现症状（OR：3.5；P<0.01）。单因素分析发现基因型GII.4感染与爆发密切相关(OR:5.7;P<0.01)。此外，发现GII.4与呕吐（OR：2.5；P=0.01）和老年（OR：4.3：P<0.01）之间存在关联。
结论：这是第一项研究临床，诺如病毒医院暴发的病房和基因型危险因素。对这些因素的识别可能有助于根据爆发风险指导和优先考虑感染控制措施。结果还表明，与GII.4的爆发有关的部分原因可能是引起呕吐的能力增强。
目的：调查医院环境中诺如病毒暴发的危险因素。
方法：临床数据，病房设置，在一项巢式病例对照研究中,收集了2010-2012年瑞典南部192个病区所有65例诺如病毒阳性指数病例和186例散发性诺如病毒病例的诺如病毒基因型.进行单因素和多因素统计分析。
结果：爆发与诺如病毒病例共用一个房间的患者数量独立相关（优势比（OR）：每个房间中的额外患者1.9；P<0.01），呕吐（OR：2.6；P=0.04），年龄>80岁（OR：3.2；P<0.01），合并症（OR：2.3；P=0.05），在多因素分析中，入院后出现症状（OR：3.5；P<0.01）。单因素分析发现基因型GII.4感染与爆发密切相关(OR:5.7;P<0.01)。此外，发现GII.4与呕吐（OR：2.5；P=0.01）和老年（OR：4.3：P<0.01）之间存在关联。
结论：这是第一项研究临床，诺如病毒医院暴发的病房和基因型危险因素。对这些因素的识别可能有助于根据爆发风险指导和优先考虑感染控制措施。结果还表明，与GII.4的爆发有关的部分原因可能是引起呕吐的能力增强。
