Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden.
PLoS Med. 2011 Aug;8(8):e1001083. doi: 10.1371/journal.pmed.1001083. Epub 2011 Aug 30.
Population movements following disasters can cause important increases in morbidity and mortality. Without knowledge of the locations of affected people, relief assistance is compromised. No rapid and accurate method exists to track population movements after disasters. We used position data of subscriber identity module (SIM) cards from the largest mobile phone company in Haiti (Digicel) to estimate the magnitude and trends of population movements following the Haiti 2010 earthquake and cholera outbreak.
Geographic positions of SIM cards were determined by the location of the mobile phone tower through which each SIM card connects when calling. We followed daily positions of SIM cards 42 days before the earthquake and 158 days after. To exclude inactivated SIM cards, we included only the 1.9 million SIM cards that made at least one call both pre-earthquake and during the last month of study. In Port-au-Prince there were 3.2 persons per included SIM card. We used this ratio to extrapolate from the number of moving SIM cards to the number of moving persons. Cholera outbreak analyses covered 8 days and tracked 138,560 SIM cards. An estimated 630,000 persons (197,484 Digicel SIM cards), present in Port-au-Prince on the day of the earthquake, had left 19 days post-earthquake. Estimated net outflow of people (outflow minus inflow) corresponded to 20% of the Port-au-Prince pre-earthquake population. Geographic distribution of population movements from Port-au-Prince corresponded well with results from a large retrospective, population-based UN survey. To demonstrate feasibility of rapid estimates and to identify areas at potentially increased risk of outbreaks, we produced reports on SIM card movements from a cholera outbreak area at its immediate onset and within 12 hours of receiving data.
Results suggest that estimates of population movements during disasters and outbreaks can be delivered rapidly and with potentially high validity in areas with high mobile phone use.
灾害发生后人口流动可能会导致发病率和死亡率显著上升。如果不了解受灾人群的位置，救援工作就会受到影响。目前还没有快速、准确的方法来跟踪灾害后的人口流动。我们利用海地最大的移动电话公司 Digicel 的用户身份模块（SIM）卡的位置数据，来估计 2010 年海地地震和霍乱疫情后的人口流动规模和趋势。
通过 SIM 卡连接的移动电话塔的位置来确定 SIM 卡的地理位置。我们在地震前 42 天和地震后 158 天跟踪了 SIM 卡的日常位置。为了排除未激活的 SIM 卡，我们只包括在地震前和研究最后一个月至少打过一次电话的 190 万个 SIM 卡。在太子港，每个 SIM 卡对应 3.2 人。我们利用这一比例，根据移动 SIM 卡的数量推断出移动人数。霍乱疫情分析持续了 8 天，追踪了 138560 个 SIM 卡。据估计，地震当天在太子港的 63 万人（197484 张 Digicel SIM 卡）在地震后 19 天已经离开。估计的净流出人数（流出人数减去流入人数）相当于太子港震前人口的 20%。从太子港流出的人口的地理分布与一项大型回顾性、基于人群的联合国调查结果非常吻合。为了展示快速估计的可行性，并确定疫情爆发风险增加的潜在地区，我们在接到数据后的 12 小时内，从霍乱疫情地区立即开始制作 SIM 卡流动报告。
结果表明，在移动电话使用率高的地区，灾难和疫情期间的人口流动估计可以快速、有效地提供，且具有潜在的高可信度。
