The salmonella variant was likely brought to South Korea from the UK, according to researchers.
Scientists analyzed the entire genome sequences of Salmonella Enteritidis isolates in South Korea that had a specific pulsed-field gel electrophoresis (PFGE) pattern that emerged and has been circulating in South Korea since 2020, leading to two fatal infections.
Isolates with this pattern were sent to the Korea Disease Control and Prevention Agency (KDCA). Both deaths occurred in patients who had no documented medical conditions, according to KDCA clinical data.
Research published in New infectious diseasesincluding isolates from eight outbreaks between 2020 and 2023, other Salmonella Enteritidis strains from poultry farms in South Korea, and human isolates from the UK.
Data from the Food and Agriculture Organization of the United Nations showed that between 2015 and 2020, South Korea imported an average of 177,000 live chickens per year from the UK. Scientists say this trade route is a plausible route.
Breeding cattle trade
In South Korea, Salmonella Enteritidis is a leading cause of foodborne illness. Poultry products, especially eggs, are consistently identified as major sources of infection transmission.
In 2020, surveillance of Salmonella Enteritidis in PulseNet Korea shifted from pulsed-field gel electrophoresis (PFGE) to the use of whole genome sequencing (WGS).
The frequency of isolates with the studied pattern increased from 3.2 percent in 2018 to 96.5 percent by August 2024. The percentage of outbreaks associated with them increased from 33.3 percent in 2020 to 91.7 percent in 2024. Among the 23 outbreaks reported between 2020 and 2024, 13 were caused by egg-related food, nine were from unknown sources and one was from another type of food.
The researchers compared isolates from the study to 223 other Salmonella Enteritidis genome sequences from South Korea or 1,230 global genome sequences.
Isolates from South Korea within a defined clade shared recent common ancestors with human isolates from the UK. The analysis confirmed the likelihood of Salmonella Enteritidis being introduced into South Korea from the UK. Following importation, poultry products played a role in the spread of the strain, leading to outbreaks of foodborne illness.
“Strengthened biosecurity is necessary to prevent the introduction and spread of Salmonella Enteritidis in the poultry industry; the role that human activities can play in spread should not be underestimated. Continued genomic surveillance remains invaluable for monitoring the spread of foodborne pathogens; such efforts may help develop improved prevention strategies,” the researchers said.
