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Monday 21st May 2018

Typhoid genome cracked

4th August 2008

An international team of scientists has finished sequencing the genome of Salmonelli typhi, the bacteria responsible for typhoid fever, paving the way for possible new vaccinations.


Typhoid persists in some countries because of antibiotic resistance in some countries, especially in southeast Asia, although it is controlled by vaccination and antibiotics in others.

The genome sequencing will improve diagnosis and tracking of the disease, according to the team of researchers led by the UK's Wellcome Trust Sanger Institute.

Typhoid typically kills 10-30% of those it infects, amounting to around 600,000 deaths from typhoid fever annually.

Researchers found the microorganism had evolved little since its emergence around 15,000 years ago. After sequencing 19 isolates of Salmonella typhi from 10 countries, they said the genome's stability was consistent with its niche as a bacterium infecting only humans, with asymptomatic carriers the main source of infection.

They said these characteristics rendered it susceptible to potential eradication through vaccination.

Typhi bacteria can now be classified in the field to determine the strain of Typhi causing an outbreak of typhoid fever. Researchers can then identify individual organisms spreading the disease in given populations, and use Google Earth maps to plot potential outbreaks.

One way in which such mapping can be used is in the design of more successful vaccination campaigns, according to the findings published in Nature Genetics.

Study senior author Gordon Dougan said the new technique meant that individual viruses or bacteria or whole populations could be studied real-time in the field, because the evolutionary fingerprints in the DNA of the bacteria were now visible.

It could help developing countries beef up their monitoring and vaccination programmes in the management of diseases like typhoid fever, he added.

The mapping technology is easily accessible to scientists from the developing world, who will be able to use the databases of The Sanger Institute through its open access policy.


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