Deadly diarrhoea bacteria spread mapped

In a major step towards the development of a new vaccine for deadly diarrhoea, scientists have mapped the spread of strains of diarrhoea bacteria around the world.
Researchers used comprehensive DNA analyses to unveil the Enterotoxigenic Escherichia coli (ETEC) bacteria's genetic composition.
The study provides key information about how pathogenic bacteria arise, which will be important for the Swedish diarrhoea vaccine currently under development, researchers said.
ETEC bacteria are responsible each year for around 400 million cases of diarrhoea and 400,000 deaths in the world's low- and middle-income countries. Children under the age of five are most affected, they said.

ETEC bacteria also cause diarrhoea in nearly one in two travellers to these areas.
Researchers at the University of Gothenburg's Sahlgrenska Academy in Sweden and colleagues used comprehensive DNA analyses to unveil the ETEC bacteria's genetic composition - an analysis that also makes it possible to map how the bacteria spread.

"We can see that some of the dangerous strains of ETEC derive from a single bacterium that has divided and spread right around the world," said Astrid von Mentzer, doctoral student at the Sahlgrenska Academy.
"This may sound like bad news, but it actually means that the vaccine that we are developing on the basis of the most common types of bacteria will be of global benefit," said von Mentzer.

Researchers focused on a total of 362 strains, which were isolated from children, adults and travellers affected by diarrhoea in Africa, Asia and Latin America in the last 30 years.
"The analysis shows that children, adults and travellers are all affected to the same extent by diarrhoea caused by the different strains of ETEC," said von Mentzer.
"Which would suggest that the vaccine could work for all three groups," said von Mentzer.
The researchers were also able to demonstrate that some of the ETEC groups identified came into existence as far back as 174 years ago.
This new information about the genetic composition of ETEC bacteria and how they spread means that we are a step closer to reducing the prevalence of diarrhoeal diseases worldwide, said von Mentzer.

The study was published in the journal Nature Genetics.