This chapter studies the dynamics between colonial enclaves and Tropical Medicine in the twentieth century. Despite the acceptance of germ theory, British Indian medical discourse and practice never abandoned miasmatic and climatic theories of disease. In colonial India, Tropical Medicine continued to connect diseases with specific ‘zones’ and ‘localities’. Research in Tropical Medicine reiterated the importance of ‘local factors’ constructed through ecological, climatic or cultural modes. From their contribution to Tropical Medicine, through the ‘experiments’ and verification of disease theories in their localities, to the contribution to the control of archetypical ‘tropical’ disease in Bengal and India generally, the tea plantations were an important site for the exploration of new ideas and experimentation. In the case of research in antimalarial sanitation, a focus on the local ecological conditions of the tea plantations in Darjeeling foothills merged seamlessly with factors such as the cultural behaviour of plantation labourers – all framed in a set of conditions termed the ‘local’. Simultaneously the political economy of the tea plantations inhibited both anti-malarial sanitation as well as systematic and full use of quinine prophylaxis within these ‘local’ sites. Similarly, when the Indian Research Fund Association (IRFA) proposed a hookworm project to assess the feasibility of its eradication, the medical experts chose the Darjeeling hill plantations as their first, experimental site. The results of the hookworm survey showed a very high incidence among the plantation labourers.