Nav: Home

Mystery of Yemen cholera epidemic solved

January 02, 2019

The most likely source of the cholera epidemic in Yemen has been discovered by scientists. Through the use of genomic sequencing, scientists at the Wellcome Sanger Institute and Institut Pasteur estimate the strain of cholera causing the current outbreak in Yemen - the worst cholera outbreak in recorded history - came from Eastern Africa and entered Yemen with the migration of people in and out of the region.

The results, published today (2 January) in Nature show that genomic data and technologies can enable researchers to estimate the risk of future cholera outbreaks in regions like the Yemen and ultimately be used to better target interventions.

Yemen is facing the worst epidemic of cholera since records began. The disease has affected over 1 million people and caused almost 2,500 deaths*. The United Nations estimate that 16 million of the 29 million people in Yemen lack access to safe water and basic sanitation**.

The population in Yemen has experienced two outbreaks of cholera; the first occurred between September 2016 and April 2017, and the second began later in April 2017 and has since resulted in more than 1 million suspected cases.

To understand the nature of the strain of bacteria behind these devastating cholera outbreaks, researchers from the Wellcome Sanger Institute, Institut Pasteur and their collaborators sequenced the genomes of Vibrio cholerae from cholera samples collected in Yemen and nearby regions.

The team sequenced 42 V. cholerae samples from both Yemen outbreaks. To do this samples were collected in Yemen itself and from a Yemeni refugee centre on the Saudi Arabia-Yemen border, along with 74 other cholera samples from South Asia, the Middle East and Eastern and Central Africa.

Researchers compared these genomic sequences to a global collection of over 1000 cholera samples from the current and ongoing pandemic, known as the seventh cholera pandemic, which began in the 1960s and is caused by a single lineage of V. cholerae, called 7PET.

Scientists discovered that the cholera strain causing the Yemen epidemic is related to a strain first seen in 2012 in South Asia that has spread globally, but the Yemeni strain did not arrive directly from South Asia or the Middle East. This particular cholera strain was circulating and causing outbreaks in Eastern Africa between 2013 and 2014, prior to appearing in Yemen in 2016.

Professor Nick Thomson, from the Wellcome Sanger Institute and London School of Hygiene and Tropical Medicine, said: "Genomics enabled us to discover that the strain of cholera behind the devastating and ongoing epidemic in Yemen is likely linked to the migration of people from Eastern Africa into Yemen. Knowing how cholera moves globally gives us the opportunity to better prepare for future outbreaks. This information can help inform strategies for more targeted interventions with the ultimate aim of reducing the impact of future epidemics."

Dr. François-Xavier Weill, Head of the Institut Pasteur's Enteric Bacterial Pathogens Unit, said: "Genomic analysis continues to show its power to provide a high resolution, detailed view of the bacteria that causes cholera, Vibrio cholerae, which is critical to tackling this devastating disease. Like the other major cholera outbreaks around the world, we discovered that the atypical strain of bacteria behind the Yemeni cholera epidemic is linked to the single lineage called 7PET, which is responsible for the current and ongoing global pandemic. This potentially enables us to focus our research and direct interventions towards this particular lineage of Vibrio cholerae to greater effect."

Contrary to previous theories that the two outbreaks of cholera in Yemen were caused by two different strains, this study revealed they were caused by the same strain of the Vibrio cholerae bacterium that entered the Yemen in 2016. While most strains of cholera that are causing epidemics are resistant to many antibiotics, the team discovered the unusual finding that the Yemeni cholera strain was susceptible to many of these antibiotics.

Dr Daryl Domman, a visiting scientist at the Wellcome Sanger Institute, now based at the Los Alamos National Laboratory in the United States, said: "Surprisingly, we discovered the cholera strain causing the Yemen outbreaks is less resistant to antibiotics than related strains. The strain causing the Yemeni cholera epidemic has deleted four genes responsible for resistance to clinically relevant antibiotics, making itself more vulnerable to treatment."

Dr Marie-Laure Quilici, a scientist in the Institut Pasteur's Enteric Bacterial Pathogens Unit and Head of the National Reference Center for Vibrios and Cholera, said: "This study illustrates again the key role of genomic microbial surveillance and cross-border collaborations in understanding global cholera spread. All countries need to be aware of this and act accordingly if they are to achieve the targets set by WHO's Global Task Force on Cholera Control, which aims to reduce the cholera death toll by 90 per cent by the year 2030."
-end-
Notes to Editors:

*World Health Organisation Outbreak update - Cholera in Yemen, 19 July 2018 http://www.emro.who.int/pandemic-epidemic-diseases/cholera/outbreak-update-cholera-in-yemen-19-july-2018.html

**United Nations Office for the Coordination of Humanitarian Affairs - About OCHA Yemen https://www.unocha.org/yemen/about-ocha-yemen

Publication:

François-Xavier Weill, Daryl Domman et al. (2018) Genomic insights into the 2016-2017 cholera epidemic in Yemen. Nature. DOI: 10.1038/s41586-018-0818-3

Funding:

This study was supported by the Institut Pasteur, Santé publique France, the French government's Investissement d'Avenir programme, Laboratoire d'Excellence 'Integrative Biology of Emerging Infectious Diseases' (ANR-10-LABX-62-IBEID), Wellcome (098051) and the Indian Council of Medical Research, New Delhi, India.

Selected websites:

About the Institut Pasteur and the Institut Pasteur International Network

The Institut Pasteur, a private foundation with officially recognized charitable status set up by Louis Pasteur in 1887 and inaugurated on November 14th, 1888, has been, for the past 130 years, an internationally renowned center for biomedical research with a network of 33 institutes worldwide. In the pursuit of its mission to prevent and fight against diseases in France and throughout the world, the Institut Pasteur operates in four main areas: scientific and medical research, public health and health monitoring, teaching, and business development and technology transfer.

More than 2,500 people work on its Paris campus. The Institut Pasteur is a globally recognized leader in infectious diseases, microbiology, and immunology. Its 130 units also focus their research on certain cancers, genetic and neurodegenerative diseases, genomics and developmental biology. This research aims to expand our knowledge of living organisms in a bid to lay the foundation for new prevention strategies and novel therapeutics. Since its inception, 10 Institut Pasteur scientists have been awarded the Nobel Prize for Medicine, including two in 2008 for the 1983 discovery of the human immunodeficiency virus (HIV) that causes AIDS. http://www.pasteur.fr/en

The Wellcome Sanger Institute

The Wellcome Sanger Institute is one of the world's leading genome centres. Through its ability to conduct research at scale, it is able to engage in bold and long-term exploratory projects that are designed to influence and empower medical science globally. Institute research findings, generated through its own research programmes and through its leading role in international consortia, are being used to develop new diagnostics and treatments for human disease. To celebrate its 25th year in 2018, the Institute is sequencing 25 new genomes of species in the UK. Find out more at http://www.sanger.ac.uk or follow @sangerinstitute

Wellcome

Wellcome exists to improve health for everyone by helping great ideas to thrive. We're a global charitable foundation, both politically and financially independent. We support scientists and researchers, take on big problems, fuel imaginations and spark debate. http://www.wellcome.ac.uk

Wellcome Trust Sanger Institute

Related Cholera Articles:

Soft shelled turtles, food in China, likely spread cholera
The pathogen, Vibrio cholerae can colonize the surfaces, as well as the intestines of soft shelled turtles.
Drinking iced tea may boost cholera risk in endemic countries
After more than a decade of declining cholera incidence, Vietnam faced an increase in cases of the diarrheal disease during 2007-2010.
El Nino shifts geographic distribution of cholera cases in Africa
Cholera cases in East Africa increase by roughly 50,000 during El Niño, the cyclical weather occurrence that profoundly changes global weather patterns, new Johns Hopkins Bloomberg School of Public Health research suggests.
Cholera bacteria stab and poison enemies at predictable rates
Living systems that have dynamics about as predictable as a chemical reaction: Bacteria that stab and poison for defense and conquest are charted using math equations that apply to phase separation of metals.
Cocktail of bacteria-killing viruses prevents cholera infection in animal models
Oral administration of a cocktail of three viruses, all of which specifically kill cholera bacteria, protects against infection and prevents cholera-like symptoms in animal model experiments.
Cholera bacteria infect more effectively with a simple twist of shape
Princeton University researchers have discovered that the bacteria behind the life-threatening disease cholera initiates infection by coordinating a wave of mass shapeshifting that allows them to more effectively penetrate their victims' intestines.
New method helps compare cholera vaccine costs
Advances in water supply and sanitation are thought to be the ideal way to control the spread of cholera, but a handful of vaccines have also been developed -- or are in development -- to prevent the disease.
Cameroon's cholera outbreaks vary by climate region
For more than four decades, cholera has recurred in Cameroon, affecting tens of thousands of people a year.
Ancient strain of cholera likely present in Haiti since colonial era
A non-virulent variant of the deadly Vibrio cholerae O1 strain has likely been present in Haitian aquatic environments for several hundred years, with the potential to become virulent through gene transfer with the toxigenic strain introduced by UN peacekeepers, according to research published today by scientists at the University of Florida's Emerging Pathogens Institute.
Study may explain why people with type O blood more likely to die of cholera
People with blood type O often get more severely ill from cholera than people of other blood types.

Related Cholera Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Digital Manipulation
Technology has reshaped our lives in amazing ways. But at what cost? This hour, TED speakers reveal how what we see, read, believe — even how we vote — can be manipulated by the technology we use. Guests include journalist Carole Cadwalladr, consumer advocate Finn Myrstad, writer and marketing professor Scott Galloway, behavioral designer Nir Eyal, and computer graphics researcher Doug Roble.
Now Playing: Science for the People

#529 Do You Really Want to Find Out Who's Your Daddy?
At least some of you by now have probably spit into a tube and mailed it off to find out who your closest relatives are, where you might be from, and what terrible diseases might await you. But what exactly did you find out? And what did you give away? In this live panel at Awesome Con we bring in science writer Tina Saey to talk about all her DNA testing, and bioethicist Debra Mathews, to determine whether Tina should have done it at all. Related links: What FamilyTreeDNA sharing genetic data with police means for you Crime solvers embraced...