A genomic and historical synthesis of plague in 18th century Eurasia

Significance

The spread and evolution of plague have been under debate in the past few years. However, very little is known of the dynamics of the plague pathogen, Yersinia pestis, during the last phase of the Second Plague Pandemic in Europe (18th and 19th century). We present nine ancient Y. pestis genomes from the Second Plague Pandemic. CHE1 is the first Second Plague Pandemic genome from the Caucasus region, an area that houses plague wildlife reservoirs to this day, making it a key strain to help elucidate the origin of Medieval and Early Modern plague. Our study documents the importance of a noneurocentric approach to historical plague dynamics and proposes an origin of plague introductions outside of Europe.

Abstract

Plague continued to afflict Europe for more than five centuries after the Black Death. Yet, by the 17th century, the dynamics of plague had changed, leading to its slow decline in Western Europe over the subsequent 200 y, a period for which only one genome was previously available. Using a multidisciplinary approach, combining genomic and historical data, we assembled Y. pestis genomes from nine individuals covering four Eurasian sites and placed them into an historical context within the established phylogeny. CHE1 (Chechnya, Russia, 18th century) is now the latest Second Plague Pandemic genome and the first non-European sample in the post-Black Death lineage. Its placement in the phylogeny and our synthesis point toward the existence of an extra-European reservoir feeding plague into Western Europe in multiple waves. By considering socioeconomic, ecological, and climatic factors we highlight the importance of a noneurocentric approach for the discussion on Second Plague Pandemic dynamics in Europe.