A new genomic study released on April 1 reports that cholera-causing bacteria are engaged in an ongoing evolutionary arms race with a virus known as bacteriophage ICP1. The research, conducted by experts from the Wellcome Sanger Institute, icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), and the Post Graduate Institute of Medical Education & Research, highlights rapid genetic changes in cholera bacteria within the Ganges Delta region.
The findings matter because understanding how these bacteria gain and lose defenses against viruses could help predict which strains may become more dangerous or spread globally. This knowledge could support early warning systems to identify high-risk strains before they cause major outbreaks.
The study analyzed over 2,300 bacterial genomes collected across Bangladesh and North India over approximately two decades. Researchers found that it is not the Ganges Delta but rather the broader Ganges Basin that serves as a primary global source of cholera during this period. Additionally, human travel and population density appear to play larger roles than river flow in spreading cholera between regions.
Dr Amber Barton, co-first author at the Wellcome Sanger Institute, said: "Our research uncovered the evolutionary struggle between cholera bacteria in Bangladesh, and the bacteriophage that preys on them. Specifically, the discovery of rapid loss and gain of V. cholerae's protective defences and their impact on disease severity is key to understanding the factors involved in the spread of this bacterium. Without the defences, the bacteria are more dangerous to humans, and tracking this in real time, through genomics, can help us identify when the strains pose the highest risk and intervene early. Additionally, future research into cholera and microbiome interactions in other regions of the world could reveal other phages that prey on the bacteria, which may help develop new treatments in the future."
Dr Firdausi Qadri from icddr,b said: "By creating the most comprehensive genetic database of cholera bacteria samples across Bangladesh and North India, our study has shown that our understanding of the global source of cholera needs updating and refinement to consider a region that spans Bangladesh and India. We can also see that cholera spread does not follow rivers and waterways. This suggests that despite cholera being a water-borne pathogen, human travel and population density are bigger factors... Understanding this can help inform public health interventions to help stop infections."
Professor Nick Thomson at Wellcome Sanger Institute said: "The world is in its seventh global pandemic of cholera... By taking an ecological view... we have been able to dispel previous inaccuracies about ...the pandemic ...and provide a clearer picture ... This can help inform public health strategies ...to hopefully end this pandemic..."
Looking ahead, researchers suggest further studies into how these viral-bacterial interactions occur elsewhere could lead to new treatments or prevention strategies for controlling future outbreaks.
