Data from: Quantifying the relative effects of environmental and direct transmission of norovirus

Background: Norovirus is a common cause of outbreaks of acute gastroenteritis in health- and child-care settings, with serial outbreaks also frequently observed aboard cruise ships. The relative contributions of environmental and direct person-to-person transmission of norovirus has hitherto not been quantified. Objective: We employ a novel mathematical model of norovirus transmission, and fit the model to daily incidence data from a major norovirus outbreak on a cruise ship, and examine the relative efficacy of potential control strategies aimed at reducing environmental and/or direct transmission. Results: The reproduction number for environmental and direct transmission combined is Rtot = 7.2 [6.1,9.5], and of environmental transmission alone is Renviron = 1.6 [0.9,2.6]. Direct transmission is overwhelmingly due to passenger-to-passenger contacts, but crew can act as a reservoir of infection from cruise-to-cruise. Implications: This is the first quantification of the relative roles of environmental and direct transmission of norovirus. While environmental transmission has the potential to maintain a sustained series of outbreaks aboard a cruise ship in the absence of strict sanitation practices, direct transmission dominates. We find that intensive promotion of good hand washing practices may prevent outbreaks. Isolation of ill passengers and cleaning are beneficial, but appear to be less efficacious at outbreak control.背景：诺如病毒（Norovirus）是医疗保健与儿童照护场所急性胃肠炎暴发的常见病因，在邮轮上也频繁出现连续性暴发事件。迄今为止，学界尚未量化诺如病毒环境传播与直接人际传播的相对贡献占比。 目标：本研究采用一种新型诺如病毒传播数学模型，将模型拟合至某邮轮上大规模诺如病毒暴发的每日发病数据，并评估旨在降低环境传播和/或直接传播的潜在防控策略的相对有效性。 研究结果：环境传播与直接传播合并的基本再生数（reproduction number）为Rtot=7.2 [6.1,9.5]，仅环境传播的基本再生数为Renviron=1.6 [0.9,2.6]。直接传播主要源于乘客间的接触传播，但船员可作为跨航次感染的储存宿主。 研究启示：本研究首次量化了诺如病毒环境传播与直接传播的相对作用。尽管在缺乏严格卫生防控措施的情况下，环境传播可维持邮轮上连续性暴发的持续发生，但直接传播仍占主导地位。本研究发现，大力推广良好的手部卫生习惯可有效预防暴发。隔离患病乘客与环境清洁均有助于疫情防控，但在暴发控制中的效果似乎相对较弱。