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）是引发医疗照护与儿童照护场所急性胃肠炎暴发的常见病原体，同时在邮轮上也频繁出现连续暴发疫情。此前学界尚未对诺如病毒经环境传播与直接人际传播的相对贡献度进行量化分析。研究目标：本研究构建了一种新型诺如病毒传播数学模型，并将该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，同时评估旨在降低环境传播与/或直接传播的潜在防控策略的相对效果。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]。直接传播绝大多数源于乘客间的接触传播，但船员可作为航次间的感染储存宿主。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规范的情况下，环境传播可维持邮轮上连续暴发疫情的持续流行，但直接传播仍占据主导地位。本研究发现，大力推广规范洗手行为或可有效预防暴发疫情。隔离患病乘客与环境清洁均有助于疫情防控，但在暴发控制中的实际效果似乎相对较弱。