Fig. 2

Time-series of malaria datasets against climate variables. Malaria datasets from three data sources (Tabellverket 1749–1859, Bergman 1749–1820, Flensburg Stockholm 1826–1890) and the relations to meteorological data. Malaria-attributed deaths of in the datasets from Tabellverket and Bergman represents the entire country, while Flensburg’s malaria cases were from the capital city, Stockholm. The meteorological data was moved backward with one year (–1). Only positive values of temperature data (orange line) and negative values of precipitation data (blue line) are shown to emphasise the correlations against the malaria datasets. Malaria-attributed deaths in the datasets of Tabellverket and Bergman have been standardized to their common period 1749–1820; the other series are standardized over their own respective period for the purpose of comparison. The drop in the number of malaria-attributed deaths after 1831 in the datasets from Tabellverket is a result of the way death registering had changed, the details are described in the Method section