Tracking Marine sources of a Cholera outbreak using high throughput molecular methods on archival samples

Lead Research Organisation: Marine Biological Association
Department Name: CPR Survey

Abstract

Vibrio cholerae is a marine bacteria living and feeding on the surfaces of tiny microscopic animals called zooplankton in the upper oceans. Zooplankton are dispersed by ocean currents and so Vibrio cholerae bacteria can spread to different regions via this route potentially spreading infections. Vibrio bacteria increase in numbers when sea surface temperatures have increased and tiny microscopic animals called zooplankton are at high abundance. In humans, V. cholerae causes Cholera, a diarrhoeal disease along with skin infections, meningitis and septicaemia if contaminated seafood is consumed or by bathing in contaminated waters. V. cholerae can also live in fresh or brackish water and so can infect people drinking contaminated freshwater too. There are many different variant forms of V. cholerae. In warmer climates, epidemic O1 and 0139 variants exist and are endemic. These cause severe gastrointestinal disease leading to fatalities. However, a multitude of non-severe variants exist in temperate Northern oceanic regions, such as UK and Canada, and these have a more favourable outcome. However non-severe types can evolve to become pathogenic thus it is important to monitor strain types to better predict and provide early warning for potential infectious events. Genetic methods are the best way to measure and track the multitude of ever changing Vibrio cholerae strains and several databases exist mapping the global distribution of different strains, including the European Union Reference Laboratory (EURL) hosted by CEFAS, the UK government lab that tests for food and water safety in UK waters. A recent outbreak of V. cholera occured in April 2018 in Vancouver Island, British Columbia on the Northwest coast of Canada causing four people to suffer cholera infection after consuming fish eggs. This is a rare occurence in temperate oceanic waters. This event happened soon after a recent unusal marine heatwave in this region between 2014-2016 and we are interested in determining whether the higher sea surface temperatures had altered zooplankton communities to enable pathogenic V. cholerae to thrive. Such events may happen in UK water as the English Channel and North sea are the fastest warming waters surrounding the UK.
The waters surrounding BC Canada are regularly sampled by the Continuous Plankton Recorder (CPR) survey that also records zooplankton species and additionally by the Department of Fisheries and Oceans (DFO) in Canada that have captured water very near the site of infection. Although CPR samples are preserved in formalin which makes genetic detection difficult, we have nevertheless been able to quantify and detect variants of Vibrio from CPR samples. We propse a pilot study to concentrate up Vibrio cholerae using Whole Genome Enrichment in these samples to allow all of the variants of this bacteria to be detected using high-throughput sequencing. This will allow us to detect the infectious types and, by comparing them with strains from EURL, find out where they came from, whether the strain started out as infectious and if they are found elsewhere (such as UK waters) and the route they travelled to end up in Vancouver Island.

We will also find out if the extent that increased sea surface temperatures allow human infectious Vibrio cholerae to increase and persist in local waters and in wider oceanic regions. As zooplankton act as hosts to Vibrio cholerae, we will determine if there are certain zooplankton species or groups of zooplankton that harbour this pathogen and facilitate its dispersal and persistence in oceanic waters. This will allow us to work out if this is these human infectious Vibrio cholerae strains are a transient or persistent threat and the environmental conditions in which they thrive. We will trasnmit this information to local governmental monitoring agencies to allow them to set up an early warning system if they find this bacteria again.

Planned Impact

Who could potentially benefit from the proposed research over different timescales?
Dr. Batten has obtained letters of support in BC, Canada from Dr. I. Perry at Fisheries and Oceans (DFO), Dr. T. Kosatsky & Dr. E. Galanis at the Centre for Disease Control, Dr. P. Hasselback from Island Health and Dr. Swinkels & L. Pollworth from First Nations Health Authority (FNHA). We expect to collaborate with these stakeholders for up to 5 years. Project partner, Dr. J. Martinez-Urtaza at the Centre for Environment, Fisheries and Aquaculture Science (CEFAS) has obtained £10K analysis money and staff time support from Dr. R. Hartnell at CEFAS (see letter of support). He also obtained support from Dr. J.A. Trinanes managing NOAAs coastwatch/oceanwatch programme and Dr. J. Semenza at the European Centre for Disease Prevention and Control, ECDC, (see their letters of support, whom we expect to work with over the next 5 years. Scientific advisory groups ICES Working Group on Phytoplankton and Microbial Ecology, UK Marine Climate Change Impacts Partnership (MCCIP) and United Nations Worlds Ocean Assessment (WAO).
How might the potential beneficiaries benefit?
1. Food security and human health: Seafood consumption is closely linked to human health The FNHA, who detected the illness from herring eggs and water in BC are concerned for food security as seafood harvesting is an important resource for First Nations. Seasonal information on Vibrio abundance near harvesting sites provided by DFO will be allow them to develop risk assessments and monitoring approaches. BC Centre for Disease Control have a one-health approach to diagnosing illness from marine foods to support First Nations self-harvesters of seafood. They want to improve their monitoring and response times to self-harvesters and develop better risk control strategies. Our baseline seasonal data on Vibrio will allow them to do this and to link marine conditions from this event with a concurrent Norovirus outbreak. CEFAS has n interest in identifying marine pathogens and risk assessment of marine food to humans. Strain and genomic information from this study feeds into their EU Reference Laboratory programme that reports food sanitation risks to the Food and Agriculture Organisation (FAO) of the United Nations to improve monitoring of pathogenic strains in the UK and globally. The ECDC is interested in our baseline seasonal information of populations of Vibrio for their quasi real-time Vibrio monitoring platform to deliver better early-warning responses for public health. Information from microbial pathogens will be useful to members of ICES WGPME on indicator development and to improve awareness of Vibrio risks to fisheries.
2. Ecosystem impacts: DFO, Canada would benefit immediately from knowledge of oceanic conditions that allow V. cholerae to thrive to develop indicators of ocean health that can inform policy on ocean management. ECDC is interested in how climate change will impact on Vibrio abundance and our baseline seasonal data will allow them to use our data to develop better predictive risks of Vibrio to public health. Scientific advisory bodies MCCIP synthesises scientific data to advice UK government on climate change whilst United Nations WAO was formed to provide sound scientific decisions based on a framework of national and regional assessments of the oceans. Our baseline information on Vibrio and their response to sea surface temperatures will be helpful in delivering sound policy advice after results are synthesized over 2 years.
3. Scientific services: NOAAs coastwatch/oceanwatch programme uses satellite and in situ data to produce value-added produces through inter-operable services and tools. This includes global Vibrio risk indexes through Vibrio map viewer. They are interested in integrating our baseline seasonal data with their findings to improve risk analysis of Vibrio and eventually to generating a better operational product.

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