Division of Infectious Disease, Qingdao City Center for Disease Control and Prevention, Qingdao, Shandong, China.
Key Laboratory of Surveillance and Early Warning on Infectious Disease, Division of Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China.
PLoS Negl Trop Dis. 2020 Dec 2;14(12):e0008757. doi: 10.1371/journal.pntd.0008757. eCollection 2020 Dec.
The emergence and re-emergence of scrub typhus has been reported in the past decade in many global regions. In this study, we aim to identify potential scrub typhus infection risk zones with high spatial resolution in Qingdao city, in which scrub typhus is endemic, to guide local prevention and control strategies.
METHODOLOGY/PRINCIPAL FINDINGS: Scrub typhus cases in Qingdao city during 2006-2018 were retrieved from the Chinese National Infectious Diseases Reporting System. We divided Qingdao city into 1,101 gridded squares and classified them into two categories: areas with and without recorded scrub typhus cases. A boosted regression tree model was used to explore environmental and socioeconomic covariates associated with scrub typhus occurrence and predict the risk of scrub typhus infection across the whole area of Qingdao city. A total of 989 scrub typhus cases were reported in Qingdao from 2006-2018, with most cases located in rural and suburban areas. The predicted risk map generated by the boosted regression tree models indicated that the highest infection risk areas were mainly concentrated in the mid-east and northeast regions of Qingdao, with gross domestic product (20.9%±1.8% standard error) and annual cumulative precipitation (20.3%±1.1%) contributing the most to the variation in the models. By using a threshold environmental suitability value of 0.26, we identified 757 squares (68.7% of the total) with a favourable environment for scrub typhus infection; 66.2% (501/757) of the squares had not yet recorded cases. It is estimated that 6.32 million people (72.5% of the total population) reside in areas with a high risk of scrub typhus infection.
CONCLUSIONS/SIGNIFICANCE: Many locations in Qingdao city with no recorded scrub typhus cases were identified as being at risk for scrub typhus occurrence. In these at-risk areas, awareness and capacity for case diagnosis and treatment should be enhanced in the local medical service institutes.
过去十年，许多全球区域都有丛林斑疹伤寒的出现和再现。在这项研究中，我们旨在确定青岛市这一地方性丛林斑疹伤寒流行地区具有高空间分辨率的潜在丛林斑疹伤寒感染风险区域，以指导当地的预防和控制策略。
方法/主要发现：从中国国家传染病报告系统中检索到 2006-2018 年青岛市的丛林斑疹伤寒病例。我们将青岛市划分为 1101 个网格，并将它们分为两类：有记录的丛林斑疹伤寒病例的区域和没有记录的丛林斑疹伤寒病例的区域。使用增强回归树模型来探索与丛林斑疹伤寒发生相关的环境和社会经济协变量，并预测整个青岛市的丛林斑疹伤寒感染风险。2006-2018 年期间，青岛市共报告了 989 例丛林斑疹伤寒病例，大多数病例位于农村和郊区。增强回归树模型生成的预测风险图表明，感染风险最高的区域主要集中在青岛市的中东部和东北部地区，国内生产总值（20.9%±1.8%标准误差）和年累积降水量（20.3%±1.1%）对模型变化的贡献最大。使用环境适宜性阈值为 0.26，我们确定了 757 个方格（占总数的 68.7%）具有有利于丛林斑疹伤寒感染的环境；其中 66.2%（501/757）的方格尚未记录病例。估计有 632 万人（总人口的 72.5%）居住在丛林斑疹伤寒感染高风险地区。
结论/意义：确定了许多没有记录丛林斑疹伤寒病例的青岛市地点存在丛林斑疹伤寒发生的风险。在这些高风险地区，应加强当地医疗机构的病例诊断和治疗意识和能力。
