Comparison of Norovirus RNA Levels in Outbreak-Related Oysters with Background Environmental Levels
Comparison of Norovirus RNA Levels in Outbreak-Related Oysters with Background Environmental Levels
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DOI：
10.4315/0362-028x.jfp-11-360
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发表时间：
2012-02-01
影响因子：
2
通讯作者：
Lees, David N.
中科院分区：
文献类型：
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作者：
Lowther, James A.;Gustar, Nicole E.;Lees, David N.
诺如病毒是世界范围内双壳贝类胃肠病的主要病原。许多使用PCR的研究表明，在牡蛎和其他双壳贝类生产区和即食产品中，诺如病毒污染的比例很大。相比之下，经流行病学证实的贝类相关疫情数量相对较少。这表明，除了病毒RNA的简单存在或不存在之外，其他因素也是报告的疾病数量的重要贡献者。这项研究比较了与诺如病毒或诺如病毒型疾病密切相关的牡蛎样本中的诺如病毒RNA水平与商业生产区（非爆发相关样本）中通常发现的水平。观察到两组样品中诺如病毒水平之间存在统计学显著差异。疫情样本中的几何平均水平（每克1，048个拷贝）几乎比非疫情相关的阳性样本（每克121个拷贝）高出一个数量级。此外，虽然与疫情相关的样本中没有一个含有低于每克152个拷贝，但与疫情无关的样本的大多数阳性结果都低于这一水平。这些观察结果支持贝类中诺如病毒RNA水平的剂量反应概念，并有助于为风险管理的阈值标准的建立提供信息。
Norovirus is the principal agent of bivalve shellfish associated gastroenteric illness worldwide. Numerous studies using PCR have demonstrated norovirus contamination in a significant proportion of both oyster and other bivalve shellfish production areas and ready-to-eat products. By comparison, the number of epidemiologically confirmed shellfish-associated outbreaks is relatively low. This suggests that factors other than the simple presence or absence of virus RNA are important contributors to the amount of illness reported. This study compares norovirus RNA levels in oyster samples strongly linked to norovirus or norovirus-type illness with the levels typically found in commercial production areas (non outbreak-related samples). A statistically significant difference between norovirus levels in the two sets of samples was observed. The geometric mean of the levels in outbreak samples (1,048 copies per g) was almost one order of magnitude higher than for positive non outbreak-related samples (121 copies per g). Further, while none of the outbreak-related samples contained fewer than 152 copies per g, the majority of positive results for non-outbreak-related samples was below this level. These observations support the concept of a dose-response for norovirus RNA levels in shellfish and could help inform the establishment of threshold criteria for risk management.