Multiple incursions of foot-and-mouth disease virus serotype O into the Republic of Korea between 2010 and 2019.

This study characterised type O foot-and-mouth disease (FMD) viruses recovered from outbreaks that were reported between 2010 and 2019 in the Republic of Korea. We used 96 newly generated whole-genome sequences (WGS) along with 131 already published WGSs from samples collected from countries in East and Southeast Asia. We identified at least eight independent introductions of O/SEA/Mya-98 and O/ME-SA/Ind-2001e FMDV strains into the Republic of Korea during the study period, which were closely related to the sequences of viruses circulating in the East and Southeast Asia neighbourhood with over 97 % nucleotide identity. Spatial-temporal transitions of O/SEA/Mya-98 lineage viruses recovered from the largest outbreak (2014-16) showed that after initial cases were detected within a 15-day period in July 2014, a single introduction of the same virus during December 2014 generated extensive forward virus transmission between farms that lasted until March 2016. We estimated that secondary transmissions were responsible for infection on 44 % FMD affected farms, over a total of 14 generations of infection. The median evolutionary rate of 2.51 × 10-5 nt/site/day, which is similar for other FMD epidemic scenarios. These findings suggest that regular incursions of different FMDV lineages into the Republic of Korea have posed a continuous threat from endemic countries of East and Southeast Asia. These data highlight the importance of active cooperation and information exchange on FMD situation within Asian countries and assessment about the likely risk routes of virus movement is highly necessary to prevent further incursion and virus spread of FMDV in the Republic of Korea.