This paper adds to a relatively new line of research investigating inadvertent transformations of urban colonial space generated by collective trauma. To the now classic iterative, and racial dynamics of Neild's ‘accommodation’ in the development of Madras,1 and of Yeoh's ‘contesting’ of the built environment in Singapore2—specifically in the tugging and pulling between local and colonial influences within the spatial discourse of colonial port cities—needs to be added that of single or multiple-event collective trauma. Such trauma, perceived as brought upon by unexpected external causes, might consolidate, perhaps accelerate, or even sever a previous sequence of spatial negotiation, particularly if that sequence was politically vulnerable or immature. The paper is a focused account of such an occurrence: the small-scale yet intensely traumatic events of Hong Kong Island while still in its colonial infancy in 1843, the year of the ‘Hongkong Fever’. It argues that a new conception of malaria—considered then a miasma—now linked both to location and construction, led to the first reactive, yet decisive, reconfiguring of a previously improvised urban colonization process, consequently salvaging Hong Kong's position within a wider imperial context.