Vector-borne disease systems: from mapping to understanding

Lead Research Organisation: University of Southampton
Department Name: School of Geography

Abstract

Vector-borne disease systems are complex. This means that they are dynamic and involve many interacting components and feedback mechanisms. In particular, vector-borne disease systems involve a parasite which moves between animals and humans via a vector (e.g., a mosquito or fly). This makes their modelling difficult and limits comprehensive understanding, while at the same time presenting challenges to the scientific community.
This project focuses on sleeping sickness (SS) in Uganda as an exemplar of a vector-borne disease system in which the animal is cattle and the vector is the tsetse fly. A serious problem in Uganda is that there are two forms of the disease (Rhodesian SS and Gambian SS) that are currently separated, but are moving closer together. Overlap would cause serious problems because diagnostic and treatment methods differ between the two forms and differentiation between them is very difficult.
To increase understanding of the disease system, to predict the risk of overlap of the two forms of disease and to develop control strategies that mitigate the risks effectively, an integrated approach is required. This project will combine mathematical and statistical modelling, extensive data collection and a range of collaborating experts including end users at the Ministry of Health, Uganda.
Risk mapping uses cutting edge spatial statistical approaches to model the relationships between the spatial distributions of (i) SS prevalence (or density) and (ii) vector density, and a range of environmental, biological, ecological, social and climatic spatial covariates (or factors). By doing this, we can predict susceptibility to SS spatially, identify areas at risk of overlap of the two forms and forecast the changing susceptibility to SS under future climate change scenarios.
Agent-based modelling can represent explicitly the processes of animal, vector and human movements, contact, transmission and development of parasite and disease in humans. This type of model accounts for both large scale and local processes (e.g., movement of cattle between markets infrequently and across farmsteads daily). While difficult to calibrate because of the requirement for many forms of intensive data that are expensive to acquire, the advantage once calibrated is that the model can be used to test what-if scenarios including a range of different intervention and control strategies.
A range of experts will consider these and alternative approaches, assess the data requirements and create an integrated solution to the SS problem in Uganda that should be applicable to vector-borne diseases generally.

Technical Summary

Sleeping sickness is a neglected, tsetse transmitted, parasitic disease. Two subspecies infect humans: T. b. rhodesiense (acute disease) and T. b. gambiense (chronic disease). Uganda has active foci for both forms, which are not believed to overlap at this time. Convergence would severely compromise disease management due to differences in diagnostic and treatment procedures. T. b. rhodesiense has recently re-emerged in Uganda; its northwards spread since the late 1980s has resulted in the disease becoming endemic in eight previously unaffected districts. This extension of the T. b. rhodesiense focus has been linked to the movement of infected, untreated cattle (the primary reservoir of T. b. rhodesiense) from endemic areas. The result is a narrowing of the buffer zone between Rhodesian and Gambian sleeping sickness to approximately 150 km. Previous research in Uganda has demonstrated correlations between T. b. rhodesiense sleeping sickness and environment, landscape, climate and population density. It is widely accepted that tsetse vectors and sleeping sickness are very much constrained by environmental and climatic factors.
This project aims to bring together a multi-disciplinary team, including human and veterinary epidemiologists, environmental and social scientists, climatologists and spatial analysts to enable a unique inclusive view of Rhodesian sleeping sickness transmission systems and the spatio-temporal dynamics of the disease?s distribution. The use of a multi-faceted research approach will enable integration of multiple aspects relating to the interactions between humans, livestock and vectors in heterogeneous landscapes with varying climatic influences which ultimately lead to the establishment of sleeping sickness transmission and the spread of the disease.
The formation of this research network will allow the investigation of several potential methods, including risk mapping and agent-based modelling, and their potential application to Rhodesian sleeping sickness. By encompassing aspects from each of the fields of research included within the team (e.g. epidemiology, geostatistics and climatology), a robust analytical framework can be developed to help describe and explain the observed spatio-temporal dynamics of sleeping sickness in terms of environment, climate, ecology, human behaviour, livestock trading and other factors. The forwarding of our understanding of this complex transmission system will greatly benefit Ugandan communities that are currently living in sleeping sickness endemic areas, or that live in areas at risk of sleeping sickness if further spread was to occur, by allowing the development of evidence-based control measures to combat the spread of the disease.
 
Description MRC Population Health Scientist Fellowship (awarded to Nicola Wardrop; Atkinson supervisor at 5% FEC)
Amount £293,000 (GBP)
Funding ID MR/J012343/1 
Organisation Medical Research Council (MRC) 
Sector Public
Country United Kingdom
Start 07/2012 
End 06/2015
 
Description ESEI sleeping sickness 
Organisation Agriculture and Veterinary Information and Analysis (AVIA-GIS)
Country Belgium 
Sector Private 
PI Contribution Coordination of activities, communication between collaborators, significant intellectual input for consortia grant application,
Collaborator Contribution Significant intellectual input and expertise for building of consortia grant application. Significant intellectual input for consortium grant applicationSignificant intellectual input to consortia grant applicationSignificant intellectual input for the ESEI consortia grant applicationAccess to data, field support, significant intellectual input to consortia grant application, assistance with stakeholder engagement activities.Significant intellectual input for a consortia grant application, field support, Assistance with stakeholder engagement activites
Impact Agreement for participation in collarborative, multidisciplinary ESEI consortia grant application. Disciplines: Medicine, Veterinary medicine, epidemiology, social science, entomology, environmental science, geography.
Start Year 2010
 
Description ESEI sleeping sickness 
Organisation Makerere University College of Health Sciences
Country Uganda 
Sector Academic/University 
PI Contribution Coordination of activities, communication between collaborators, significant intellectual input for consortia grant application,
Collaborator Contribution Significant intellectual input and expertise for building of consortia grant application. Significant intellectual input for consortium grant applicationSignificant intellectual input to consortia grant applicationSignificant intellectual input for the ESEI consortia grant applicationAccess to data, field support, significant intellectual input to consortia grant application, assistance with stakeholder engagement activities.Significant intellectual input for a consortia grant application, field support, Assistance with stakeholder engagement activites
Impact Agreement for participation in collarborative, multidisciplinary ESEI consortia grant application. Disciplines: Medicine, Veterinary medicine, epidemiology, social science, entomology, environmental science, geography.
Start Year 2010
 
Description ESEI sleeping sickness 
Organisation Ministry of Health, Uganda
Country Uganda 
Sector Public 
PI Contribution Coordination of activities, communication between collaborators, significant intellectual input for consortia grant application,
Collaborator Contribution Significant intellectual input and expertise for building of consortia grant application. Significant intellectual input for consortium grant applicationSignificant intellectual input to consortia grant applicationSignificant intellectual input for the ESEI consortia grant applicationAccess to data, field support, significant intellectual input to consortia grant application, assistance with stakeholder engagement activities.Significant intellectual input for a consortia grant application, field support, Assistance with stakeholder engagement activites
Impact Agreement for participation in collarborative, multidisciplinary ESEI consortia grant application. Disciplines: Medicine, Veterinary medicine, epidemiology, social science, entomology, environmental science, geography.
Start Year 2010
 
Description ESEI sleeping sickness 
Organisation University of Edinburgh
Department Division of Pathway Medicine
Country United Kingdom 
Sector Academic/University 
PI Contribution Coordination of activities, communication between collaborators, significant intellectual input for consortia grant application,
Collaborator Contribution Significant intellectual input and expertise for building of consortia grant application. Significant intellectual input for consortium grant applicationSignificant intellectual input to consortia grant applicationSignificant intellectual input for the ESEI consortia grant applicationAccess to data, field support, significant intellectual input to consortia grant application, assistance with stakeholder engagement activities.Significant intellectual input for a consortia grant application, field support, Assistance with stakeholder engagement activites
Impact Agreement for participation in collarborative, multidisciplinary ESEI consortia grant application. Disciplines: Medicine, Veterinary medicine, epidemiology, social science, entomology, environmental science, geography.
Start Year 2010
 
Description ESEI sleeping sickness 
Organisation University of Greenwich
Department Natural Resources Institute Greenwich
Country United Kingdom 
Sector Academic/University 
PI Contribution Coordination of activities, communication between collaborators, significant intellectual input for consortia grant application,
Collaborator Contribution Significant intellectual input and expertise for building of consortia grant application. Significant intellectual input for consortium grant applicationSignificant intellectual input to consortia grant applicationSignificant intellectual input for the ESEI consortia grant applicationAccess to data, field support, significant intellectual input to consortia grant application, assistance with stakeholder engagement activities.Significant intellectual input for a consortia grant application, field support, Assistance with stakeholder engagement activites
Impact Agreement for participation in collarborative, multidisciplinary ESEI consortia grant application. Disciplines: Medicine, Veterinary medicine, epidemiology, social science, entomology, environmental science, geography.
Start Year 2010
 
Description ESEI sleeping sickness 
Organisation University of Liverpool
Department School of Veterinary Science Liverpool
Country United Kingdom 
Sector Academic/University 
PI Contribution Coordination of activities, communication between collaborators, significant intellectual input for consortia grant application,
Collaborator Contribution Significant intellectual input and expertise for building of consortia grant application. Significant intellectual input for consortium grant applicationSignificant intellectual input to consortia grant applicationSignificant intellectual input for the ESEI consortia grant applicationAccess to data, field support, significant intellectual input to consortia grant application, assistance with stakeholder engagement activities.Significant intellectual input for a consortia grant application, field support, Assistance with stakeholder engagement activites
Impact Agreement for participation in collarborative, multidisciplinary ESEI consortia grant application. Disciplines: Medicine, Veterinary medicine, epidemiology, social science, entomology, environmental science, geography.
Start Year 2010