London, Nov 12 (IANS): A team of Swedish researchers has mapped the spread of the strains of a deadly diarrhoea bacteria that is being considered a major step towards the development of a new vaccine.

Enterotoxigenic Escherichia coli (ETEC) bacteria is responsible each year for around 400 million cases of diarrhoea and 400,000 deaths in the world's low-and middle-income countries. This bacteria also cause diarrhoea in nearly one in two travellers visiting these regions.

Children under five years of age are the most affected.

Researchers at the University of Gothenburg's Sahlgrenska Academy used comprehensive DNA analyses to reveal the ETEC bacteria's genetic composition - an analysis that also makes it possible to map how the bacteria spreads.

"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.

"The vaccine that we are developing on the basis of the most common types of bacteria will be of global benefit," Mentzer added.

The present study saw the researchers focusing 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, which would suggest that the new vaccine could work for all three groups," Mentzer said.

The work at Sahlgrenska Academy is supported by colleagues from the Wellcome Trust Sanger Institute in the UK, the Karolinska Institutet in Sweden and universities in Japan, Germany and the US.

The study appeared in the journal Nature Genetics.