Get the latest market trends in your inbox

Stay on top of the latest market trends and economic insights with the Axios Markets newsletter. Sign up for free.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Catch up on coronavirus stories and special reports, curated by Mike Allen everyday

Catch up on coronavirus stories and special reports, curated by Mike Allen everyday

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Denver news in your inbox

Catch up on the most important stories affecting your hometown with Axios Denver

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Des Moines news in your inbox

Catch up on the most important stories affecting your hometown with Axios Des Moines

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Minneapolis-St. Paul news in your inbox

Catch up on the most important stories affecting your hometown with Axios Minneapolis-St. Paul

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Tampa-St. Petersburg news in your inbox

Catch up on the most important stories affecting your hometown with Axios Tampa-St. Petersburg

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Cholera patients in a clinic in Harare, Zimbabwe, in January 2009. Photo: Tsvangirayi Mukwazhi / AP

The planet is in the midst of its seventh cholera pandemic — one that affects about 3 million people each year and, unlike past pandemics that faded away, persists. Stopping its spread hinges on tracking its movements.

By analyzing the genomes of bacteria isolated from samples collected during cholera outbreaks over the past half-century, scientists have now determined that outbreaks in Africa and the Americas were sparked by strains that arrived from Asia. Tracing the paths into and around these regions offers new targets for efforts to control the disease.

The back story: The seventh pandemic began in Indonesia in 1961, then spread to South Asia (1963), Africa (1970), Latin America (1991) and then Haiti (2010). A current outbreak in Yemen just surpassed that in Haiti, and is nearing 1 million cases in the war-torn country.

The challenge: "When cholera was imported into Africa in 1970, it was easy to spot introduction routes and propagation routes because it was a new disease. At some point, the signal was lost because it was everywhere and you weren't able to link the outbreaks to each other," says Francois-Xavier Weill from the Institut Pasteur in Paris, who was involved in both studies.

The bacteria responsible for cholera, Vibrio cholerae, doesn't change much over time, so differences in the DNA of one strain compared to another are hard to spot. So the researchers turned to whole genome sequencing to analyze 714 samples collected on the three continents.

What they found: In Africa, cholera epidemics were traced to at least 11 different introductions from Asia since 1970. (The last five were multi-drug resistant strains.) And, it tended to enter through East/Southern Africa and West Africa.

"All the action should be taken there first," Weill says of public health surveillance efforts. Knowing the genetic fingerprint of the pandemic-producing strain could also inform decisions about when and where to use a global stockpile of cholera vaccine.

The researchers also found that one strain caused an outbreak in Africa that lasted 28 years. Both papers indicate that there's no local reservoir for cholera, meaning if a strain disappears at some point and another isn't introduced, cholera could be eliminated from the region, says Weill.

What's next: Until now, models of cholera's pathways were based on tens of samples. "Not only does the analysis provide more insight into how cholera moves but it also adds samples for others to make inferences so more researchers will be able to study its movement," says Andrew Azman from Johns Hopkins University, who was not involved in the research but studies cholera's epidemiology in East Africa. He says by adding the whole genome sequences of hundreds of strains to the public domain researchers can further understand the dynamics of how cholera is transmitted. Azman plans to pair Weill's results with detailed analysis of cases of cholera in Africa.

Go deeper

Dion Rabouin, author of Markets
Updated 2 hours ago - Economy & Business

Our make-believe economy is here to stay

Illustration: Eniola Odetunde/Axios

The Federal Reserve and global central banks are remaking the world's economy in an effort to save it, but have created something of a monster.

Why it matters: The Fed-driven economy relies on the creation of trillions of dollars — literally out of thin air — that are used to purchase bonds and push money into a pandemic-ravaged economy that has long been dependent on free cash and is only growing more addicted.

Mike Allen, author of AM
4 hours ago - Politics & Policy

Why Trump may still fire Barr

Photo: Jabin Botsford/The Washington Post via Getty Images

Attorney General Barr may be fired or resign, as President Trump seethes about Barr's statement this week that no widespread voter fraud has been found.

Behind the scenes: A source familiar with the president's thinking tells Axios that Trump remains frustrated with what he sees as the lack of a vigorous investigation into his election conspiracy theories.

Mike Allen, author of AM
4 hours ago - World

Scoop: Trump's spy chief plans dire China warning

Xi Jinping reviews troops during a military parade in Beijing last year. Photo: Thomas Peter/Reuters

Director of National Intelligence John Ratcliffe on Thursday will publicly warn that China's threat to the U.S. is a defining issue of our time, a senior administration official tells Axios.

Why it matters: It's exceedingly rare for the head of the U.S. intelligence community to make public accusations about a rival power.