New invasive non-Typhoidal Salmonella epidemic identified in sub-Saharan Africa
Geospatial transmission of invasive Salmonella Typhimurium isolates in sub-Saharan Africa. (a,b) Phylogeographic diffusion of lineages I (a) and II (b) across sub-Saharan Africa over time based on a discrete geospatial model with associated geographic coordinates. [DOI: 10.1038/ng.2423]
(Medical Xpress)—A new study out today reveals that the emergence and spread of a rapidly evolving invasive intestinal disease, that has a significant mortality rate (up to 45%) in infected people in sub-Saharan Africa, seems to have been potentiated by the HIV epidemic in Africa.
The team 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. 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 used to treat blood-borne infection such as iNTS.
iNTS is a blood-borne infection that kills approximately one of four people in sub-Saharan Africa who catch it. Yet, in the rest of the world, NTS is a leading cause of acute inflammatory diarrhoea that is self-limiting and tends to be fatal in less than 1 per cent of people infected. The disease is more severe in sub-Saharan Africa than the rest of the world because of factors such as malnutrition, co-infection with malaria or HIV and potentially the novel genotype of the Salmonella bacteria.
"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," says Chinyere Okoro, joint first author from the Wellcome Trust Sanger Institute. "We used whole genome sequencing to define a novel lineage of Salmonella Typhimurium that is causing a previously unrecognised epidemic across the region. Its genetic makeup is evolving into a more typhoid like bacteria, able to efficiently spread around the human body"
From sequenced samples, the team created a phylogenetic or 'family tree', depicting the pathogen's evolution, dating when each sample first emerged and overlaying this with geographical information about where these samples came from. They found that this invasive disease comprises of two very closely related waves; the first wave originated from a possible south-eastern hub, about 52 years ago and the second originated about 35 years ago, possibly from the Congo Basin.
"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 second iNTS wave," says Dr Robert Kingsley, joint first author from the Wellcome Trust Sanger Institute. "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."
The team identified that the vast majority of samples from the second wave of iNTS contains a gene that makes them resistant to chloramphenicol, a frontline antibiotic in the treatment of Salmonella. This gene was not present in the samples from the first wave of iNTS. This observation suggests that iNTS acquired this gene early on in the evolution of the second wave, probably around the time of its spread from the Congo basin.
"Because it acquired resistance to chloramphenicol, this pathogen has much greater opportunity to survive and spread across the region," says Professor Gordon Dougan, lead author from the Wellcome Trust Sanger Institute. "This is the first time that the power of whole-genome sequencing has been used to track the spread of iNTS. Our research highlights the power this approach has to monitor the emergence and spread of dangerous pathogens both locally and globally over time."
"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."
More information: Chinyere K. Okoro, Robert A. Kingsley, Thomas R. Connor et al. 'Intra-continental spread of human invasive Salmonella Typhimurium pathovariants in sub-Saharan Africa'. Published in Nature Genetics 30 September 2012. DOI: 10.1038/ng.2423
Journal reference: Nature Genetics
Provided by Wellcome Trust Sanger Institute
- Biology of emergent Salmonella exposed Nov 30, 2009 | not rated yet | 0
- Prevalence of HIV in Africa is leading to new strains of Salmonella, say scientists Apr 12, 2010 | not rated yet | 0
- HIV patients hold clues to Salmonella vaccine development Apr 22, 2010 | not rated yet | 0
- Scientists track evolution and spread of deadly fungus, one of the world's major killers May 03, 2011 | not rated yet | 0
- Methods developed to enable large-scale analysis of malaria parasite genomes from patient blood samples Jun 13, 2012 | not rated yet | 0
- Motion perception revisited: High Phi effect challenges established motion perception assumptions Apr 23, 2013 | 3 / 5 (2) | 2
- Anything you can do I can do better: Neuromolecular foundations of the superiority illusion (Update) Apr 02, 2013 | 4.5 / 5 (11) | 5
- The visual system as economist: Neural resource allocation in visual adaptation Mar 30, 2013 | 5 / 5 (2) | 9
- Separate lives: Neuronal and organismal lifespans decoupled Mar 27, 2013 | 4.9 / 5 (8) | 0
- Sizing things up: The evolutionary neurobiology of scale invariance Feb 28, 2013 | 4.8 / 5 (10) | 14
Classical and Quantum Mechanics via Lie algebras
Apr 15, 2011 I'd like to open a discussion thread for version 2 of the draft of my book ''Classical and Quantum Mechanics via Lie algebras'', available online at http://lanl.arxiv.org/abs/0810.1019 , and for the...
- More from Physics Forums - Independent Research
More news stories
University of Minnesota Medical School researchers from the Masonic Cancer Center, University of Minnesota, in partnership with the University's Brain Tumor Program, have developed a new mouse model of malignant peripheral ...
Genetics May 20, 2013 | 5 / 5 (1) | 0 |
Northwestern University scientists have shown a gene involved in neurodegenerative disease also plays a critical role in the proper function of the circadian clock.
Genetics May 16, 2013 | 3 / 5 (1) | 1 |
Informed consent is the backbone of patient care. Genetic testing has long required patient consent and patients have had a "right not to know" the results. However, as 21st century medicine now begins to use the tools of ...
Genetics May 16, 2013 | 5 / 5 (1) | 3 |
Ethicists provide framework supporting new recommendations on reporting incidental findings in gene sequencing
In a paper published in Science Express, a group of experts led by bioethicists in the Center for Medical Ethics and Health Policy at Baylor College of Medicine provide a framework for the new American College of Medical Geneti ...
Genetics May 16, 2013 | not rated yet | 0
The use of genome-wide analysis (GWA), where the entirety of an individual's DNA is examined to look for the genomic mutations or variants which can cause health problems is a massively useful technology for diagnosing disease. ...
Genetics May 16, 2013 | not rated yet | 0
(Medical Xpress)—Native peoples in regions where cameras are uncommon sometimes react with caution when their picture is taken. The fear that something must have been stolen from them to create the photo ...
9 hours ago | 4 / 5 (4) | 0 |
An experimental sleeping pill from US drug company Merck is effective at helping people fall and stay asleep, according to reviewers at the US Food and Drug Administration, which could soon approve the new drug.
3 hours ago | 5 / 5 (1) | 0
(Medical Xpress)—Despite spending billions of dollars on research and development, drug companies have been unable to come up with effective treatments for dementia and Alzheimer's Disease (AD). Now, A. ...
7 hours ago | 4.8 / 5 (6) | 0 |
Activating an enzyme known to play a role in the anti-aging benefits of calorie restriction delays the loss of brain cells and preserves cognitive function in mice, according to a study published in the May ...
3 hours ago | 5 / 5 (3) | 0 |
A drug commonly used to treat depression and anxiety may improve a stress-related heart condition in people with stable coronary heart disease, according to researchers at Duke Medicine.
4 hours ago | not rated yet | 0 |
Australian scientists have charted the path of insulin action in cells in precise detail like never before. This provides a comprehensive blueprint for understanding what goes wrong in diabetes.
9 hours ago | 4.8 / 5 (4) | 0 |