Travelers play a role in triggering epidemics of imported dengue fever because they can carry the virus to other countries during the incubation period. If a traveler carrying dengue virus visits open green space and is bitten by mosquitoes, a local outbreak can ensue. In the present study, we aimed to understand the movement patterns of international travelers in Tokyo using mobile phone data, with the goal of identifying geographical foci of dengue transmission. We analyzed datasets based on mobile phone access to WiFi systems and measured the spatial distribution of international visitors in Tokyo on two specific dates (one weekday in July 2017 and another weekday in August 2017). Mobile phone users were classified by nationality into three groups according to risk of dengue transmission. Sixteen national parks were selected based on their involvement in a 2014 dengue outbreak and abundance of Aedes mosquitoes. We found that not all national parks were visited by international travelers and that visits to cemeteries were very infrequent. We also found that travelers from countries with high dengue prevalence were less likely to visit national parks compared with travelers from dengue-free countries. Travelers from countries with sporadic dengue cases and countries with regional transmission tended to visit common destinations. By contrast, the travel footprints of visitors from countries with continuous dengue transmission were focused on non-green spaces. Entomological surveillance in Tokyo has been restricted to national parks since the 2014 dengue outbreak. However, our results indicate that areas subject to surveillance should include both public and private green spaces near tourist sites.

中文翻译：

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分析东京的国际旅行者流动模式以确定登革热风险的地理焦点

旅行者在引发输入性登革热流行方面发挥了作用，因为他们可以在潜伏期内将病毒携带到其他国家。如果携带登革热病毒的旅行者前往空旷的绿地并被蚊子叮咬，当地可能会爆发疫情。在本研究中，我们旨在使用手机数据了解东京国际旅行者的移动模式，目的是确定登革热传播的地理焦点。我们分析了基于手机接入 WiFi 系统的数据集，并测量了东京国际游客在两个特定日期（2017 年 7 月的一个工作日和 2017 年 8 月的另一个工作日）的空间分布。根据登革热传播的风险，手机用户按国籍分为三组。根据参与 2014 年登革热爆发和大量伊蚊的情况选择了 16 个国家公园。我们发现并非所有国家公园都有国际游客参观，而且参观墓地的频率非常低。我们还发现，与来自无登革热国家的旅行者相比，来自登革热流行国家的旅行者不太可能去国家公园。来自有零星登革热病例的国家和有区域传播的国家的旅行者倾向于访问共同的目的地。相比之下，来自登革热持续传播国家的游客的旅行足迹集中在非绿色空间。自 2014 年登革热爆发以来，东京的昆虫学监测一直仅限于国家公园。然而，