In nineteenth-century medical, management and official discourse, the foothills of the Darjeeling (and the plains beyond), Terai and Duars were represented as sites of disease, fevers and fatalities. Malaria and blackwater fever, a particularly vicious form of fever, were widely prevalent among the planters as well as the labourers, although the indigenous Meches were supposed to have been immune from them. This chapter studies a particular historical moment in the formation of the plantation enclave, when its modes of functioning were challenged by a team of malariologists who were commissioned by the government of India to find out why malaria and blackwater fever were endemic to the plantations and to advise how to control the diseases. The medical experts’ recommendations challenged the recruitment system, wage structure, and finally, the planters’ autonomy within the plantations. In the time of interventionist external medical surveys and malaria research in the twentieth century, the modes of functioning of the plantation enclave were challenged. These surveys identified that diseases in the plantation system were due to the systems of recruitment, wage structure, and the autonomous paternalism of the planter class. In response, the planters provided an alternative vision of the ‘moral economy’ of the plantation system within which disease medical infrastructure and the livelihood of labourers could be managed by the paternalistic planter. The government's response was to compromise and impose a legislation that broadly confirmed the planters’ vision of their enclaves.