Recently, a group of researchers, including from India and the U.K., have studied the genome of O139 and traced the reason for its dying down after taking over from O1.
- They trace it to two key genomic evolutionary changes that took place in O139, the first related to the type of cholera toxin it produced and the second related to a loss of anti-microbial resistance.
- The study points to AMR as a factor that can decide the success of certain populations of bacteria that go on to produce large outbreaks of disease.
- Cholera is caused by a comma-shaped bacterium known as Vibrio cholerae.
- More than 200 serogroups of this bacterium are known, of which only O1 and O139 are known to cause such infection that leads to epidemics and pandemics.
- O1 was responsible for seven pandemic waves, only to be temporarily displaced by O139.
- This emerged late and came up around 1992.
- It was first spotted in Chennai (then Madras). It was anticipated that this would cause the eighth round of pandemic but it subsided as mysteriously as it had originated.
(Source: The Hindu)
