The researchers show that the latest cholera pandemic originated in Asia, and that most of antibiotic resistant strains come from this continent.  They recently published two studies tracing the history of cholera outbreaks in Africa, Latin America and the Caribbean from the last 60 years. This study has been published in Science.

Genomic analysis of more than 1,200 strains of Vibrio cholerae revealed for the first time the link between the different outbreaks of cholera since 1961. They help to improve understanding of how the cholera bacterium circulates, and to anticipate the risk of new outbreaks emerging and adapt control strategies accordingly.

Cholera is an acute infection of the small intestine caused by the bacterium Vibrio cholerae. It is thought of as an ancient disease yet still causes major outbreaks such as those recorded in Haiti in 2010 and the one currently ravaging Yemen. Researchers recently shed light on the link between the different cholera outbreaks affecting the African and American continents during the current (7th) pandemic that began in 1961.

Their research involved analysing the genomes of more than 1,200 current and past strains of V. cholerae collected from across the globe over the last few decades. The researchers focused on African and Latin American isolates, due to the large epidemics that have occurred in those regions. The seventh pandemic of cholera first came to Africa in 1970, and Africa has since become the continent most affected by the disease.

The researchers observed that the cholera bacterium had been introduced at least 11 times into Africa over a period of 44 years, always from Asia, and that human populations were the main vectors for disease dispersal throughout Africa. These results provide information about the regions of Africa that are most susceptible to the introduction of cholera, and that will need to be targeted to stem the wave of cholera before it sweeps the rest of the continent."

For further study, team focused on Latin America where epidemic cholera remerged in 1991 alongside sporadic cases of low level disease. This allowed the researchers to prove that different strains of V. cholerae can be assigned different risks for causing large outbreaks. The massive epidemics seen in Peru in the 1990s and Haiti in 2010 were caused by the Asian pandemic strain, whereas the sporadic cases in Latin America arose from local strains which do not seem to have epidemic potential.

The genomic tools developed during this research will help predict the epidemic potential of given V. cholerae strains and enable the health authorities on the American continent to adapt their public health response strategy.

Author concludes that the real sense of cholera movement is understood across the globe. These findings have implications for the control of cholera pandemics, but also help to better understand how a simple bacterium continues to pose such a threat to human health.