Whole-Genome Analysis to Identify Previously Unseen Tuberculosis Transmission Links

The Korea Disease Control and Prevention Agency (KDCA) is expanding its analysis of tuberculosis bacteria from partial to whole-genome sequencing to more precisely identify transmission routes between patients.

On the 4th, the KDCA said it would overhaul its tuberculosis genotyping system to use whole-genome sequencing (WGS) to more definitively identify routes of tuberculosis transmission.

Whole-genome sequencing reads and analyzes the entire genome of the tuberculosis bacterium. About 17,000 new tuberculosis cases were reported in South Korea last year. The government aims to reduce the incidence of tuberculosis to 20 or fewer cases per 100,000 people by 2027.

Currently, when a suspected tuberculosis outbreak occurs in places such as schools and nursing homes, the KDCA analyzes the genetic relatedness of the bacteria to provide scientific evidence for identifying transmission routes. However, the current method compares only part of the tuberculosis bacterium’s genetic information, limiting its ability to identify transmission routes among patients for whom contact has not been confirmed.

The newly introduced whole-genome sequencing analyzes all approximately 4.4 million base pairs of the tuberculosis bacterium to precisely assess how similar the bacteria identified in different patients are. By detecting subtle genetic differences that were difficult to distinguish with previous analyses, the method will make it possible to more precisely identify transmission links between patients that are difficult to determine through epidemiological investigations alone.

The KDCA plans to apply whole-genome sequencing to drug-resistant tuberculosis cases with unclear transmission routes. It also plans to use accumulated genomic information to continuously analyze the spread of tuberculosis bacteria in South Korea and trends in drug-resistant tuberculosis outbreaks.

KDCA Commissioner Seung-kwan Lim said, "The introduction of whole-genome sequencing will enable more precise analysis of transmission patterns between tuberculosis patients," adding, "We hope to link the analysis results with epidemiological investigations to identify tuberculosis transmission early and use the findings to help stop its spread."