Towards a complex ecology: an essay on plague history in Brazil (1890s-1970s).

This paper offers a periodization of the history of plague in Brazil. It is based on the ways in which experts and public health officers framed the disease, the elements they considered responsible for its spread, and changes in these elements over time. In accordance with this periodization, the article first argues that the ecology of plague became progressively more complex in the 20th century, suggesting the rise of a more ecological-oriented view among Brazilian doctors. It then proposes that political and institutional transformations also shaped this intellectual change in the epidemiological reasoning about pla gue in Brazil. The periodization is divided into three phases. The first phase ex tends from 1897, with the start of discussions about the risk of plague arriving in Brazil from Asia, to 1920, with a substantial reduction in the number of plague cases in coastal cities. In this initial phase, the framing of the plague transitioned from a disease spread by humans and the objects they touched to one spread by rats and their fleas. The second phase, from 1920 to 1950, was characterized by the hegemony of rats in epidemiological explanations for the presence of plague in cities and rural areas of Brazil. The third and final phase, from 1951 to the early 1970s, was characterized by the progressive inclusion of wild rodents into scientific explanations for the spread and especially persistence of plague in some foci, mainly in the North-East. At the end of this phase, the scientific consensus in Brazil was that wild rodents constituted the main plague reservoir.