This paper identifies paradigmatic shifts in the conceptualisation of fevers in British Ceylon, from agues and fevers in the early 1800s and fevers of particular regions in the mid-1800s to a powerful notion of malaria in the early 1900s. In the early colonial records, agues and fevers were seen primarily as a threat to European visitors to the tropics, including the colonisers. In contrast, the fevers of specific regions were identified as localised ailments endemic among the local population and somehow connected to the specifics of local ecology and the indolent nature of the natives.