Pathways Of Dispersal for Cholera And Solution Tools (PODCAST)

Lead Research Organisation: Plymouth Marine Laboratory
Department Name: Remote Sensing Group


Cholera is a waterborne epidemic disease in humans. It is a major public health threat, affecting 1.3 to 4 million people each year worldwide, with 21,000 to 143,000 reported fatalities. Outbreaks are caused by the bacterial pathogen Vibrio cholerae, found in many coastal, estuarine, and brackish waters around the world. The origin of the current pandemic of cholera was a single population of pathogens in the north-eastern Indian Ocean basin, which spread globally, in several transmission events. Transmission pathways include direct human-to-human infection, and human-environment interactions, including ingestion of contaminated water, aggravated by emerging antimicrobial resistance through release of antibiotics into the environment. Vibrio pathogens are found as free-floating forms or attached to living (plankton) and non-living (sediment) hosts. They flourish under warm temperature, moderate salinity and turbidity. The major environmental reservoirs of Vibrios, their connectivity, how they might be affected by climate variability and the associated impact on human health remain largely unknown. There is a clear imperative to reduce human risk from cholera bacteria to meet Global Goals related to 3-human health, 6-water quality, 13-climate and 14-life under water.
Focusing on the northern Indian Ocean, currently a hotbed of outbreaks of cholera and related diseases, the PODCAST project will pinpoint the impact of large-scale oceanic and climatic processes on the transmission dynamics of cholera (Goals 6, 13, 14) and their impact on public health (Goal 3). Scientists from India, Japan and the UK will work collaboratively to: 1) identify environmental reservoirs of Vibrio cholerae as well as possible advective transport via ocean currents and long-distance transmission routes for cholera outbreaks; 2) characterise the influence of climate perturbations on cholera outbreaks and environmental transmission routes; 3) build an epidemiological model integrating environmental and human-to-human transmission routes; and 4) produce forecasts for cholera outbreaks in coastal regions.
The research will be developed in consultation with end-users, including local communities relying on water resources for livelihoods, income generation and recreation; governments; health services; intergovernmental agencies; and policy makers for whom we will provide tools and Vibrio disease risk map products that will support evidence-based policy decisions and actions to achieve Global Goals.
The work will be organised in four Work Packages. WP1 (Abdulaziz-India; Sathyendranath-UK) will generate new in situ observations of biophysical variables (including Vibrio pathogens and antibiotics) at selected sites in open-ocean and coastal locations; and process satellite data (ocean-colour, salinity, altimeter and temperature) over entire northern Indian Ocean. WP2 (Platt-UK; Clark-UK; Nonaka-Japan), focussing on models and using data from WP1, will develop an epidemiological model including components of human-to-human and environmental transmission routes of cholera outbreaks; a particle-tracking model to study sources and connectivity between environmental reservoirs of Vibrios; and a climate-variability model to generate past and future indices of large-scale patterns of climate variability. WP3 (Racault-UK), based on the influence of environmental conditions, regional circulation and climate variability on risks of outbreaks at coastal locations in the northern Indian Ocean (WP 2), will focus on producing a cholera-outbreak prediction system for coastal regions of the northern Indian Ocean. The user-engagement, policy information and practice interventions will be addressed in WP4 (Menon-India; George-India) in which we will engage with local communities, policy-makers, and intergovernmental agencies (WHO, IPCC) to identify needs, assess benefits, best practices and uptake of results from PODCAST to reduce risks of Vibrio diseases to public health.

Planned Impact

Detailed descriptions of the approaches that will be taken to achieve Impact, along with identified beneficiaries from the public, practitioners, third sector, and policy communities are provided in the Pathways to Impact. Here, we explain the Impact that we will generate in relation to the official Targets of the UN's Sustainable Development Goals addressed in the project and to the international dimensions of the consortium:

Goal 3-Health-Targets
Improve knowledge on the diversity and antimicrobial resistance patterns of the Vibrio cholerae pathogens in the northern Indian Ocean: the information will be useful for the health services to help provide the most adapted and efficient treatment for the affected local populations, and to increase chances of recovery.
Improve surveillance systems and strengthen capacity of India and northern Indian Ocean RIM countries to produce early warning and risk maps for cholera outbreaks: the forecast system will be delivered to an agency for operational use and the risk warning will be placed in the public domain to reduce public health risks for the millions of people living in coastal areas.
The Indicators of the Impact generated will be the reduction in the number of people requiring treatment against Vibrio disease, the reduction in mortality rate associated with exposure to contaminated water, and the increase in capacity for disaster mitigation in affected areas.

Goal 6-Water Quality-Targets:
Provide evidence on Vibrio disease hotspots that can help government authorities to identify areas where microbial and antibiotic pollution should be treated as a priority.
Improve knowledge of the transmission routes and dynamics of cholera pathogens in the northern Indian Ocean coastal ecosystem in relation to climate variability and disease outbreaks: this information will develop increased preparedness along the transmission routes, and will integrate locally-targeted water sanitation control measures that will help to interrupt the transmission routes.
The Indicators of Impact will be an increase in the number of actions taken by local administrations to treat sources of pollution, and to engage the local communities in water and sanitation management.

Goal 13-Climate-Targets:
Improve knowledge of the influence of extreme weather events and climate variability on the incidence of cholera outbreaks and the contamination routes of Vibrio pathogens: this will help to prioritise policy measures for health service preparedness and population awareness when high-risk climate events occur, and hence improve cholera-disaster risk mitigation.
Provide evidence of the influence of climate change on the risk of Vibrio diseases for human health for use by the IPCC to inform governments and support development of policy measures to reduce climate-related risk to public health.
The indicators of the Impact will be an increase in the number of countries that recognise the need to integrate climate-related risk in their early warning systems for cholera outbreaks, and in their adaptation and mitigation plans (to reduce impact and risk of cholera outbreaks).

Goal 14-Oceans-Targets:
Provide evidence on the extent to which coastal communities are suffering from Vibrio diseases, that can be used to support development of sustainable management plans.
The Indicator will be an increase in the number of countries that incorporate ecosystem-based management in their stewardship of coastal ecosystems and their resources.

In addition to these elements of impact classify according to the SDGs, a complementary impact will derive from the trilateral collaboration at the international level. The collaboration will grow through reciprocal visits, knowledge exchange and capacity building, as well as through joint work on scientific papers, on follow-up proposals, and on synthesising results for the benefit of society at large.


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