The diseases of early modern Japan (the Tokugawa period) are of particular interest to the history and geography of disease. The Japanese Islands, situated as they are at the far eastern periphery of East Asia, had relatively little contact with the people of other world regions until the late nineteenth century. Historically Japan’s isolation afforded the people some measure of protection from exposure to certain of the world’s diseases, and in the early seventeenth century, the Tokugawa shoguns reinforced this natural protection when they imposed severe restrictions on foreign contacts. They limited official foreign trade to the port of Nagasaki, restricted the number and the nationality of ships that could enter that port, denied mobility beyond the port to the crews of foreign ships, and prohibited the Japanese from going abroad and returning to Japan. These policies were a response, in part, to the unwelcome activities of Westerners who had begun to reach the islands in the second half of the sixteenth century. They remained in effect until a U.S. fleet forced Japan to open its ports to international commerce in the 1850s.

Elsewhere explorers, adventurers, traders, and settlers were circumnavigating the globe, carrying new diseases to previously unexposed peoples, and causing waves of high mortality among the populations of many world regions. By 1850 the increasing volume of international contacts had produced a worldwide system of disease dissemination, but Japan, remaining aloof from world affairs, had also remained largely unaffected by the epidemiological events of the early modern world.