Department of Applied Mathematics, Hong Kong Polytechnic University, Hong Kong (SAR), China.
Stat Methods Med Res. 2018 Jul;27(7):1968-1978. doi: 10.1177/0962280217746442.
Middle East respiratory syndrome coronavirus has been persistent in the Middle East region since 2012. Abundant scientific evidence showed that dromedary camels are the primary host of the virus. Majority of human cases (i.e., 75% or 88%) are due to human-to-human transmission, while the others are due to camel-to-human transmission. Mathematical modeling of Middle East respiratory syndrome coronavirus camel-to-camel transmission was lacking. Using the plug-and-play likelihood-based inference framework, we fitted a susceptible-exposed-infectious-recovered-susceptible model of camels to the reported human cases with a constant proportion of human cases from camels (i.e., either 25% or 12%). We considered two scenarios: (i) the transmission rate among camels is time-varying with a constant spill-over rate from camels to human or (ii) the spill-over rate is time-varying with a constant transmission rate among camels. Our estimated loss-of-immunity rate and prevalence of Middle East respiratory syndrome coronavirus infections among camels largely matched with previous serological or virological studies, shedding light on this issue. We recommended including dromedary camels in animal surveillance and control of Middle East respiratory syndrome coronavirus in Saudi Arabia which could help reduce their sporadic introductions to humans.
中东呼吸综合征冠状病毒自 2012 年以来一直在中东地区持续存在。大量科学证据表明，单峰骆驼是该病毒的主要宿主。大多数人类病例（即 75%或 88%）是由于人与人之间的传播，而其他病例则是由于骆驼传染给人类。中东呼吸综合征冠状病毒在骆驼之间的传播的数学模型还不完善。利用基于插补的似然推理框架，我们根据报告的人类病例，为骆驼建立了一个易感-暴露-感染-恢复-易感模型，其中从骆驼传染给人类的病例比例保持不变（即 25%或 12%）。我们考虑了两种情况：（i）骆驼之间的传播率随时间变化，而骆驼传染给人类的溢出率保持不变；（ii）溢出率随时间变化，而骆驼之间的传播率保持不变。我们估计的骆驼免疫力丧失率和中东呼吸综合征冠状病毒感染率与之前的血清学或病毒学研究大致相符，这为解决这一问题提供了线索。我们建议在沙特阿拉伯将单峰骆驼纳入中东呼吸综合征冠状病毒的动物监测和控制中，这有助于减少它们偶尔传染给人类的情况。
