Highly drug resistant strains of typhoid fever have been discovered in Bangladesh, raising concerns that antibiotics could be rendered an ineffective treatment for the disease within just a few years.

Each year there are more than 17 million new cases of typhoid, which is a highly contagious disease caused by Salmonella Typhi bacteria. Typhoid spreads through contaminated food and water, and areas with poor sanitation are the worst affected.

While there is a typhoid vaccine, antibiotics are most commonly used to treat the disease, as it is difficult to accurately target a vaccination campaign to protect those most at risk.

The use of antibiotics has helped to ensure that less than one per cent of people who have typhoid fever die.

But if the drugs stop working this could rise to around 15 per cent - causing between three and four million deaths a year - the report published in mBio on Tuesday warned.

“We see resistance arise most where disease is endemic and use of antibiotics is not regulated,” said Prof Hubert Endtz, scientific director at Mérieux Foundation and professor of tropical bacteriology at Erasmus University Medical Center.

“If we go back to the pre-antibiotic era, we could be talking about up to four million deaths a year in the worst case scenario," he added.