Published On: Sun, Sep 30th, 2012

Novel invasive salmonella disease in Africa intensified by HIV epidemic, according to study

A study published Sept. 30 in the journal Nature Genetics shows that the emergence of an invasive Salmonella infection in sub-Sahara Africa may have been intensified by the concurrent HIV epidemic on the continent.



A international team of researchers found that invasive non-Typhoidal Salmonella (iNTS) disease is caused by a new form of the bacteria Salmonella Typhimurium that has spread from two different focal hubs in Southern and Central Africa beginning 52 and 35 years ago, respectively.

Prof Gordon Dougan, from the Sanger Institute in Cambridge in the UK, told the BBC: “It quite clearly parallels the emergence of HIV in Africa.”

In addition, they also found that one of the major contributing factors for the successful spread of iNTS was the acquisition of genes that afford resistance to several front line drugs, such as chloramphenicol,  used to treat blood-borne infection such as iNTS.

One in four people in Africa infected with the novel strain died; however, everywhere else on the globe, the infection is typically a “self-limiting” diarrheal infection with a fatality rate of less than 1%.

Malnutrition, HIV and malaria, ever present in sub-Sahara Africa, intensifies the Salmonella infection.

According to Chinyere Okoro, joint first author from the Wellcome Trust Sanger Institute, “The immune system susceptibility provided by HIV, malaria and malnutrition at a young age, may provide a population in sub-Saharan Africa that is large enough for this detrimental pathogen to enter, adapt, circulate and thrive.

“We used whole genome sequencing to define a novel lineage of Salmonella Typhimurium that is causing a previously unrecognized epidemic across the region. Its genetic makeup is evolving into a more typhoid like bacteria, able to efficiently spread around the human body”

Researchers created a “family tree” by analyzing the genetic code of scores of samples and found the epidemic came in two waves 52 and 35 years ago, as mentioned earlier.

“The HIV epidemic in sub-Saharan Africa is thought to have begun in a central region and underwent expansion eastwards, a strikingly similar dynamic to that observed for the second iNTS wave,” said Okoro’s colleague, Robert Kingsley.

“Our findings suggest the current epidemic of iNTS and its transmission across sub-Saharan Africa may have been potentiated by an increase in the critical population of susceptible immune-compromised people.”

Professor Dougan said, “There has been some evidence that this disease can be passed from human to human. Now the race is on to discover how NTS is actually transmitted in sub-Saharan Africa so that effective intervention strategies can be implemented.”

Wellcome Trust Sanger Institute press release

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About the Author

- Writer, Co-Founder and Executive Editor of The Global Dispatch. Robert has been covering news in the areas of health, world news and politics for a variety of online news sources. He is also the Editor-in-Chief of the website, Outbreak News Today and hosts the podcast, Outbreak News Interviews on iTunes, Stitcher and Spotify Robert is politically Independent and a born again Christian Follow @bactiman63


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