Typhoid 'Superbug' Reaches Epidemic Levels In Africa

An antibiotic-resistant strain of the bacteria that causes typhoid fever has reached epidemic levels in Africa, according to a new study.

Writing in the journal Nature Genetics, scientists sounded the alarm after sequencing more than 1,800 samples of typhoid bacteria from 63 countries. They concluded that in many parts of Asia and Africa, where typhoid is endemic, a multidrug-resistant strain of typhoid called H58 has displaced other typhoid strains that have been around for centuries.

Of the 63 countries the researchers looked at, 21 had H58.

Symptoms of typhoid can include fever, headaches, constipation or diarrhoea, rose-coloured spots on the chest, and an enlarged spleen or liver. Symptoms can be mild or severe, but some people can carry the germ yet not fall sick.

It is caused by the highly contagious bacterium Salmonella typhi, spread from person to person by food and water that is contaminated with traces of infected faeces or urine.

H58 has recently acquired mutations that blunt newer drugs such as ciprofloxacin and azithromycin with the family tree of H58 suggesting it spread out of South Asia to Southeast and western Asia and then to East Africa, the study added.

“Multidrug resistant typhoid has been coming and going since the 1970s and is caused by the bacteria picking up novel antimicrobial resistance genes, which are usually lost when we switch to a new drug,” said study author Kathryn Holt in a statement. “In H58, these genes are becoming a stable part of the genome, which means multiply antibiotic-resistant typhoid is here to stay.”

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Tactics used to fight typhoid in these countries appear to have led to increased antibiotic resistance, said study author Vanessa Wong, a microbiologist at the University of Cambridge in England.

"Vaccinations are not currently in widespread use in typhoid-endemic countries," she said. "Instead, antibiotics are commonly used as a preventive measure. As a consequence, there is a rise in antibiotic resistance to many pathogens and in particular a resurgence of multidrug-resistant typhoid has been observed in some areas, including parts of Africa."

In a paper published in PLOS Neglected Tropical diseases, Gordon Dougan, a geneticist at the Wellcome Trust Sanger Institute in Hinxton, U.K, and other scientists tracked the emergence of H58 in one hospital in Malawi. From 1998 to 2010, there were, on average,14 diagnoses of typhoid fever a year at the hospital. About seven per cent of the isolates were resistant to multiple drugs.

In 2014 there were 782 diagnoses, 97 per cent with multidrug resistance. “As soon as this arrives in your country, you have to turn to more expensive antimicrobials,” says Dougan.

A spokeswoman for the World Health Organization said: "Limiting the inappropriate use of antibiotics is part of the solution, and surveillance systems to identify antibiotic-resistant bacteria need to be improved to identify hotspots and intensify prevention and control measures."

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