與十九世紀相比，二十世紀以來烈性傳染病跨區域流行何以更為頻繁和迅猛，是本文探討的主要問題。就環境、生態變化與疾病的互動來看，與前人研究主要集中在疾病流行史不同，本文重點探討人類社會經濟活動帶來的影響。此外，還不同於以往研究較多注意單一時間意義上的近代經濟變遷，本文試圖將此概念置於二十世紀以來現代性經濟擴張中進行考察，重點探討其在上海、東北的具體展開，作為與帝國主義、資本主義和民族國家等發展密切相關的社會經濟生活空間結構的巨大變遷，對疾病跨區域流行產生了哪些重大影響，以及這些影響在疾病史、生命史上有何新的歷史意義。 　　相對於十九世紀社會經濟區域性的變遷，二十世紀以來上海、東北經歷的現代性經濟擴張，體現在前者步入了大工業化時代，後者則成為中國最重要糧食和工業基地，南北間跨區域經濟交往日益密切，鼠疫、霍亂也有多次在中國境內的南北一體的跨區域流行。就此，本文擬從三個方面進行討論：一、區域經濟體系擴張，致使疫情形成南北一體的流行態勢；二、鐵路成為主要交通工具，不僅加快了疫情傳播的速率，而且蔓延至以往因通行困難而被隔絕的內陸地區；三、大量流動人口聚集城市，惡劣的生活環境持續保持疫情一觸即發的嚴峻形勢。結語部份則指出，與歷史上較多由戰爭、災荒，而非主要由社會經濟變遷引發的烈性傳染病跨區域流行相比，二十世紀以來的變化表明，現代性經濟擴張已為致使烈性傳染病跨區域流行一種經常、主要的樣式。再與淪為殖民地的十七世紀美洲及十八世紀印度洋地區不同，其時中國仍為半殖民地社會，保留有相當的主權，從而致使現代性經濟擴張並非只是在華帝國主義單方面之所為，而也為中國社會自身的強烈追求和價值設定。在這個意義，相關發展對生態、環境產生的影響，及與疾病互動關係之重新建構，作為一個具有廣泛和深刻影響的趨勢和過程，並非只是一些個別和偶然的事例，而是在疾病史、生命史的意義上開啟了中國歷史上的又一大變局。

This paper explores how epidemics spread across disparate regions more frequently and violently in the early twentieth-century than that in the nineteenth century. The interactions between environmental, ecological and unprecedented social and economic changes laid a new basis for epidemics to spread. Along with Manchuria, Shanghai had reached a state of great industrialization, becoming one of the most important bases for food supplies, industry, and mining in China. Meantime, plague and cholera swept across the nation several times. Unlike previous studies which have focused mainly on the affected areas and routes of the epidemics, this paper deals with the relationship between epidemics and socio-economic change. 　　The impact that socio-economic change had on the interregional spread of epidemics can be examined from the following three aspects: first, the expansion of a regional economic system eliminated regional separation, which in turn accelerated the dissemination of epidemics; second, railways became the main form of transportation, which not only accelerated the spread of epidemics but also brought diseases to remote areas where transportation was previously unavailable; and third, the existence of a large floating population in urban areas under filthy conditions easily triggered the eruption of epidemics. In sum, before the twentieth century, the interregional spread of epidemics mainly resulted from wars and natural disasters (famine, floods, and so forth). In the twentieth century, however, socio-economic changes became the primary factor behind the dissemination of epidemics, and it also started a turning point in the history of diseases and life in China.