Tracking changes in diseases over time is an increasingly important topic given changes in global temperature. Put simply, is a warmer world a sicker world? Reported rates of disease may increase over time but it is difficult to distinguish between better reporting of disease, and true increases in disease prevalence. A new study in Frontiers in Ecology and the Environment now highlights the critical role of natural history collections, which contain many millions of specimens, in piecing together true rates of disease over deep time (many centuries). New methods allow for the detection of parasites through DNA sequencing, within fossils, inside fossilized feces, and within preserved museum specimens. Such methods allow for baseline estimates of disease that can be compared to present-day levels, greatly expanding the time scale of disease detection. The new paper was written by Alaina Harmon of the Museology Graduate Program at the University of Washington; Tim Littlewood of the Natural History Museum in London; and SAFS professor Chelsea Wood.