Modeling the effects of climate on plague. In the top plot, the solid black line represents plague activity in the central Asian rodent population (Y(mean)) over the past 1,500 years, as estimated from the authors' model of the effects of climate (including via observably correlated vegetation indices) on this natural reservoir (sylvatic) plague activity. The broken gray lines show 95% quantiles and the red line represents the multi-frequency (2 to 60 years) Gaussian moving average. The dark-blue plot represents the long-term (2 to 400 years) multi-frequency mean, with the maximum (upper broken line, Y(max)), minimum (lower broken line, Y(min)) and sum of minimum and maximum (solid line, Y(qu.)). The periods leading up to the Justinian Plague (1), the Black Death (2), the 19th-century pandemic (3) and the Manchurian epidemics (4) are shaded in pale blue. The third plot shows the index of conflict between Chinese and nomad societies (solid black line, War). Below this are shown the coverage of the climatic data used in the modeling: glacial series (blue), tree-ring index (green), and the decadal coverage in the monsoon proxy (brown). Taken from Figure 3d of Kausrud et al. .
McMichael BMC Biology 2010 8:108 doi:10.1186/1741-7007-8-108