Between scheduled operations, routine transfusions, and emergency operations someone in the United States needs blood every two seconds. Unfortunately, however, recipients can’t just accept any blood; patient and donor blood types must be compatible.
The Justinian Plague lasted from 541 to 750 CE. This was the first plague pandemic and public health crisis which wiped out close to 100 million people in Asia, Africa and Europe in just 5 years. The culprit: yersinia pestis - the bacteria responsible for this pandemic and all plague pandemics since.