Gumel Abba B, Ruan Shigui, Day Troy, Watmough James, Brauer Fred, van den Driessche P, Gabrielson Dave, Bowman Chris, Alexander Murray E, Ardal Sten, Wu Jianhong, Sahai Beni M
Institute of Industrial and Mathematical Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada.
Proc Biol Sci. 2004 Nov 7;271(1554):2223-32. doi: 10.1098/rspb.2004.2800.
Severe acute respiratory syndrome (SARS), a new, highly contagious, viral disease, emerged in China late in 2002 and quickly spread to 32 countries and regions causing in excess of 774 deaths and 8098 infections worldwide. In the absence of a rapid diagnostic test, therapy or vaccine, isolation of individuals diagnosed with SARS and quarantine of individuals feared exposed to SARS virus were used to control the spread of infection. We examine mathematically the impact of isolation and quarantine on the control of SARS during the outbreaks in Toronto, Hong Kong, Singapore and Beijing using a deterministic model that closely mimics the data for cumulative infected cases and SARS-related deaths in the first three regions but not in Beijing until mid-April, when China started to report data more accurately. The results reveal that achieving a reduction in the contact rate between susceptible and diseased individuals by isolating the latter is a critically important strategy that can control SARS outbreaks with or without quarantine. An optimal isolation programme entails timely implementation under stringent hygienic precautions defined by a critical threshold value. Values below this threshold lead to control, but those above are associated with the incidence of new community outbreaks or nosocomial infections, a known cause for the spread of SARS in each region. Allocation of resources to implement optimal isolation is more effective than to implement sub-optimal isolation and quarantine together. A community-wide eradication of SARS is feasible if optimal isolation is combined with a highly effective screening programme at the points of entry.
严重急性呼吸综合征（SARS）是一种新型、高传染性的病毒性疾病，于2002年末在中国出现，并迅速蔓延至32个国家和地区，在全球范围内造成了超过774人死亡和8098人感染。由于缺乏快速诊断测试、治疗方法或疫苗，对确诊为SARS的患者进行隔离以及对疑似接触SARS病毒的人员进行检疫，被用于控制感染的传播。我们使用一个确定性模型，对多伦多、香港、新加坡和北京爆发SARS期间隔离和检疫措施对控制疫情的影响进行了数学分析。该模型能够紧密模拟前三个地区的累计感染病例和与SARS相关的死亡数据，但在北京直到4月中旬才开始更准确地报告数据之前，无法模拟北京的数据。结果表明，通过隔离患者来降低易感人群与患病个体之间的接触率，是控制SARS疫情的一项至关重要的策略，无论是否进行检疫都能发挥作用。一个最优的隔离方案需要在由临界阈值定义的严格卫生预防措施下及时实施。低于该阈值的值能够实现疫情控制，而高于该阈值则会导致新的社区疫情爆发或医院感染的发生，这是每个地区SARS传播的一个已知原因。分配资源实施最优隔离比同时实施次优隔离和检疫更为有效。如果将最优隔离与在入境点实施的高效筛查计划相结合，在全社区根除SARS是可行的。
