Slow, Wave-Like Spread after Outbreak (IMAGE) University of California - Berkeley Caption When long-distance travel is rare, epidemics spread like a slow, rippling wave, as demonstrated by the simulation (left) and the actual historical spread of the black death during the Middle Ages. Credit Simulation by Oskar Hallatschek & Daniel Fisher. Black death map courtesy of D. Sherman and J. Salisbury. Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.