Since ancient times, Yersinia pestis has wreaked havoc on the human population. In this article in Microbiology Today (pdf) Petra Oyston asks what can the transmission and evolution of this unusual pathogen teach us about how we might prepare for future emergent pathogens?
Cycles of plague have swept across the world in three documented pandemics. The first pandemic is known as the Justinian Plague (AD 541–544). The plague arrived in Egypt from Ethiopia, and then spread through North Africa, Europe, Arabia, and Central and Southern Asia. Epidemics spread in 8- to 12-year cycles, often repeatedly infecting the same areas. The second pandemic started in the 14th century, spreading from the steppes of Central Asia westward along trade routes. The plague then spread northwards in Europe, killing an estimated 40% of the population and earning it the name the Black Death. The third pandemic appears to have originated in the Chinese province of Yunnan in 1855, spreading due to war and troop movements to the southern coast, reaching Hong Kong in 1894. Maritime routes allowed the global spread of infection, and the Americas were infected for the first time; stable enzootic foci were established on every major continent with the exception of Australia. The vestigial remnants of the third pandemic persist to the present day, although the numbers of cases are much reduced, largely due to effective public health measures and the introduction of antibiotics.