Press release
A new study by researchers at the Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine and partners has shed light on the genetic diversity of Mycobacterium tuberculosis complex (MTBC) strains circulating in The Gambia and their implications for drug resistance and tuberculosis (TB) control.
Published in Nature Scientific Reports, the research characterised the population structure and drug resistance landscape of MTBC strains circulating in The Gambia over nearly two decades (2002–2021). By analysing the genomes of about 2000 TB bacteria, the study offers insights into lineage distribution, mutation patterns and the evolving landscape of drug resistance.
Tuberculosis remains one of the world’s leading infectious killers. In 2024, there were an estimated 10.7 million people who developed TB globally, with 1.23 million deaths reported by the World Health Organisation (WHO). West Africa continues to carry a substantially disproportionate burden of the disease, making it a significant public health concern, particularly in The Gambia.
The study examined mutations associated with resistance to key anti-TB drugs. Researchers identified several resistance-related genetic variants, including some whose clinical significance remains uncertain according to the current mutation catalogue of the WHO. Some variants were found to occur frequently in the Gambian dataset, suggesting they may be locally enriched and potentially important for understanding resistance patterns in the region.
To explore these mutations further, the research team applied structural bioinformatics and computational modelling approaches to assess how specific genetic changes might affect the stability and function of drug-target proteins. These analyses provide early insights into how certain mutations could influence the effectiveness of TB treatments or contribute to the emergence of drug resistance.
The analysis also revealed demographic trends consistent with global TB patterns. Most cases were identified in male patients, who accounted for more than 70% of infections, while the highest burden of disease occurred among adults aged 18 to 44 years. This highlights the significant impact of TB on economically active population groups in the country.
Dr. Leopold Djomkam Tientcheu, Assistant Professor at MRCG at LSHTM and the study’s corresponding author said: “Understanding the genetic diversity of tuberculosis strains circulating in The Gambia is critical for improving diagnosis, treatment and surveillance. Our findings highlight the importance of sustained genomic monitoring to detect locally emerging resistance patterns and support more effective ‘End TB’ strategies.”
The researchers emphasised that integrating genomic surveillance into national TB control programmes will be essential for strengthening the detection and management of drug-resistant TB. Region-specific interpretation of resistance mutations, particularly those not yet confirmed in global catalogues, could help refine diagnostic tools and optimise treatment regimen selection, ensuring they remain effective.
The study also highlights the need for further research to clarify the clinical and epidemiological significance of certain locally enriched mutations. Targeted laboratory investigations will help determine whether these variants influence treatment outcomes, transmission potential, or bacterial fitness.
While the study provides valuable insights into the genomic landscape of TB in The Gambia, the authors note some limitations. Sampling across the study period was uneven, with most isolates collected between 2012 and 2015 and the majority originating from the Greater Banjul Area. As a result, the dataset may not fully capture TB diversity in rural regions of the country.
Despite these limitations, the research represents the largest collection of MTBC whole-genome sequences in a West African country and an important step forward in understanding the genetic diversity and drug-resistance landscape of TB in The Gambia and the West African sub-region. The findings reinforce the importance of sustained genomic surveillance to support national and regional efforts to control the disease and advance global ‘End TB’ strategies.
The research was supported by funding from the National Institute of Health, the Royal Society, the African Academy of Sciences, the Francis Crick Institute through the Crick Africa Network, and LifeArc.
MRC Gambia
