Emergence and genomic insights of non-pandemic O1 in Zhejiang, China.

It is well recognized that only O1 causes cholera pandemics. However, not all O1 strains cause pandemic-level disease. In this study, we analyzed non-pandemic O1 isolates from the 1960s to the 1990s from China and found that they fell into three lineages, one of which shared the most recent common ancestor with pandemic O1 strains. Each of these non-pandemic O1 lineages has unique properties that contribute to their capacity to cause cholera. The findings of this study enhanced our understanding of the emergence and evolution of both pandemic and non-pandemic O1 .