The plague bacterium Yersinia pestis may have lurked in a Medieval European reservoir for at least 300 years, researchers suggest January 13 in PLOS ONE.

The second of two major plague pandemics hit Europe from the 14th to 16th centuries, peaking during the Black Death from 1346 to 1353. The new study weighs in on a longstanding debate over what fed the pandemic, strains of the bacterium traveling on waves of trade from Asia via the Silk Road or a homegrown biological reservoir such as lice.

Researchers analyzed DNA from 30 skeletal remains spanning the 14th to 17th centuries. Eight carried strains of Y. pestis, and all bore genetic similarity to each other and to those found in previously sampled European plague victims. Strains from Asia would have injected more genetic variety. Instead, the results suggest that at least one strain of Y. pestis stuck around in Europe for a long time, researchers write.

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