Historical Epidemics Cartography Generated by Spatial Analysis: Mapping the Heterogeneity of Three Medieval "Plagues" in Dijon

ObjectivesThis work was designed to adapt Geographical Information System-based spatial analysis to the study of historical epidemics. We mapped "plague" deaths during three epidemics of the early 15th century, analyzed spatial distributions by applying the Kulldorff's method, and determined their relationships with the distribution of socio-professional categories in the city of Dijon.Materials and MethodsOur study was based on a database including 50 annual tax registers (established from 1376 to 1447) indicating deaths and survivors among the heads of households, their home location, tax level and profession. The households of the deceased and survivors during 6 years with excess mortality were individually located on a georeferenced medieval map, established by taking advantage of the preserved geography of the historical center of Dijon. We searched for clusters of heads of households characterized by shared tax levels (high-tax payers, the upper decile; low-tax payers, the half charged at the minimum level) or professional activities and for clusters of differential mortality.ResultsHigh-tax payers were preferentially in the northern intramural part, as well as most wealthy or specialized professionals, whereas low-tax payers were preferentially in the southern part. During two epidemics, in 1400–1401 and 1428, areas of higher mortality were found in the northern part whereas areas of lower mortality were in the southern one. A high concentration of housing and the proximity to food stocks were common features of the most affected areas, creating suitable conditions for rats to pullulate. A third epidemic, lasting from 1438 to 1440 had a different and evolving geography: cases were initially concentrated around the southern gate, at the confluence of three rivers, they were then diffuse, and ended with residual foci of deaths in the northern suburb.ConclusionUsing a selected historical source, we designed an approach allowing spatial analysis of urban medieval epidemics. Our results fit with the view that the 1400–1401 epidemic was a Black Death recurrence. They suggest that this was also the case in 1428, whereas in 1438–1440 a different, possibly waterborne, disease was involved.研究目标 本研究旨在将基于地理信息系统（Geographical Information System）的空间分析方法适配于历史流行病研究领域。我们对15世纪早期三次流行病期间的“鼠疫”死亡病例进行了空间制图，采用库尔道夫空间扫描统计法（Kulldorff's method）分析其空间分布特征，并探究其与第戎市社会职业类别分布之间的关联。 材料与方法 本研究依托一套涵盖50份年度税务登记册（建立于1376年至1447年之间）的数据库展开，该数据库记录了户主的死亡与存活情况、家庭住址、纳税等级及职业信息。针对6个死亡率超额的年份，我们将当时死亡与存活户主的家庭住址逐一匹配至经地理配准的中世纪第戎市中心历史街区地图，该地图依托留存至今的第戎历史中心地理风貌构建而成。我们分别筛查了具有共同纳税等级（高纳税群体：收入前10%阶层；低纳税群体：纳税额处于最低档的半数人群）或职业类别的户主集群，以及死亡率存在差异的集群。 研究结果 高纳税群体及多数富裕或专业从业者主要集中于城内北部区域，而低纳税群体则多分布于南部区域。在1400-1401年与1428年的两次流行病中，高死亡率区域均位于北部，低死亡率区域则集中在南部。高密度聚居区与紧邻粮食储备区是受疫情影响最严重区域的共同特征，为鼠类大量繁殖创造了适宜条件。第三次流行病（1438年至1440年）的空间分布特征则截然不同且呈现动态变化：疫情初期病例集中于三河交汇处的南门周边区域，随后扩散至全城，最终仅在北郊残留零星死亡病例。 研究结论 本研究依托精选的历史史料，构建了一套可用于中世纪城市流行病空间分析的研究方法。研究结果支持1400-1401年的流行病为黑死病复发的观点，同时表明1428年的流行病也属于同类情况；而1438-1440年的疫情则由另一种可能经水传播的疾病引发。