Should we be worried by a deadly typhoid superbug spreading across Africa and Asia?

The term “superbug” started life as a semi-hysterical label used by the non-scientific press to describe dangerous microbes with a resistance to antibiotics.

Should we be worried by a deadly typhoid superbug spreading across Africa and Asia?

However we’re increasingly hearing the term being used today, presumably because a) we’re more aware of them, and b) we’re getting more and more scared of them.

But do antibiotic-resistant microbes really deserve this all-out existential terror? We look at a strain of typhoid that researchers say is posing a global threat.

What do we know about this typhoid superbug?

Microscope
(Lauren Hurley/PA)

The rise of antibiotic-resistant typhoid is driven by a single clade or “family” of the bacteria. This causes the disease which is known as H58, which is responsible for a previously unreported wave of infections in eastern and southern Africa that may represent an ongoing epidemic.

The microbe is an especially nasty form of the S. enterica bacteria that commonly cause food poisoning. It is chiefly spread by swallowing contaminated water.

Scientists mapped the genetic codes of 1,832 samples of the typhoid bug Salmonella Typhi collected from 63 countries between 1992 and 2013. Results showed 47% of the samples analysed belonged to the resistant H58 clade.

So it’s common, but is it new?

Philippines typhoid outbreak
Typhoid patients, mostly children, recuperate in hospital after n outbreak in Calamba city, Philippines (Bullit Marquez/AP)

We’ve only recently become fully aware of H58, but it’s been with us for a good few decades. The concern is over how prevalent it’s become.

The strain emerged in South Asia 25 to 30 years ago and spread to south-east Asia, western Asia, east and South Africa, and Fiji.

Professor Gordon Dougan, a member of the the Wellcome Trust Sanger Institute in Hinxton, Cambridgeshire, said: “H58 is an example of an emerging multiple drug resistant pathogen which is rapidly spreading around the world.”

Dr Kathryn Holt, one of the researchers from the University of Melbourne, said: ”In H58, these genes are becoming a stable part of the genome, which means multiply antibiotic-resistant typhoid is here to stay.”

Who is vulnerable to this superbug?

A child receives a typhoid vaccination in Liberia
A child receives a typhoid vaccination in Liberia (Abbas Dulleh/AP)

The populations most at risk from this strain of typhoid live in developing countries where vaccinations aren’t readily available. Instead they rely on antimicrobial drugs which the bacteria is becoming increasingly resistant to.

Typhoid affects around 30 million people each year, mostly in developing nations. However, although typhoid is not an immediate threat in countries where vaccines are available, the way this strain is sweeping across the globe and becoming more permanently resistant is a stark warning about other diseases we haven’t yet developed vaccines for.

Is there any silver lining to this research?

Experiment

It’s an over-used sentiment, but in cases like this knowledge really is power – at least as far as the researchers are concerned.

Lead researcher Dr Vanessa Wong, also from the Sanger Institute, said: “The data was produced by a consortium of 74 collaborators from the leading laboratories working on typhoid and describes one of the most comprehensive sets of genome data on a single human infectious agent.”

Prof Dougan added: “In this study we have been able to provide a framework for future surveillance of this bacterium, which will enable us to understand how antimicrobial resistance emerges and spreads intercontinentally.”

So how can this super-typhoid be stopped?

Dirty river
Sanitation could be the key (Felipe Dana/AP)

With this genome research as a foundation, there are a few ways to combat this deadly bacteria – and the best way forward would be to deploy all three.

The development of effective antimicrobials is one, and the introduction of vaccines another. But considering this disease is transmitted via contaminated water, better water and sanitation programmes would be a huge help.

As co-author of the research Dr Stephen Baker said: ”These results reinforce the message that bacteria do not obey international borders and any efforts to contain the spread of antimicrobial resistance must be globally co-ordinated.”

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