Scientists from the University of Oslo conducted an experiment, assessing the potential transmission routes for the deadly “Black Death” plague that occurred between the 14th and 19th centuries in Europe. They discovered that the parasites that carried the disease were more likely to have come from humans than rats. The model that featured the spread of the disease via human fleas and lice matched the death rates of the actual Black Death much more closely than the model that had parasite-carrying rats. (https://cnn.it/2Mhnwc9)