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Geospatial methods for advancing efforts to eliminate human African trypanosomiasis

Longbottom, Joshua (2022) Geospatial methods for advancing efforts to eliminate human African trypanosomiasis, Thesis (Doctoral), Liverpool School of Tropical Medicine.

J Longbottom PhD - Final Thesis.pdf - Accepted Version

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Gambian human African trypanosomiasis (g-HAT) is a neglected tropical disease caused by Trypanosoma brucei gambiense, transmitted by tsetse flies (Glossina). A World Health Organization (WHO) led programme to eliminate g-HAT, based on large-scale detection and treatment of cases alongside vector control, has reduced the global number of cases reported annually from a peak of 37,385 in 1998 to 565 in 2020. The WHO aims to eliminate transmission of g-HAT by 2030. To meet this goal, there is a pressing need for better mapping of cases, vectors, and interventions against g-HAT. Such maps will provide evidence that the elimination goal is being achieved and help guide interventions against persistent and/or re-emerging hotspots of transmission. g-HAT is a highly focal disease, requiring high spatial resolution analyses (<100m) which can identify vector and or transmission hotspots with high precision and accuracy. Increasing the resolution of geospatial analyses enables the utility of estimates in spatially targeted policy and programmatic decisions. This thesis aims to make an important contribution to the need for better maps and geospatial (spatially derived) models of cases, vectors and interventions in Uganda, a country which experienced an epidemic of g-HAT in the 1990s (13,842 cases, 1990-1999) but is now approaching the elimination goal (194 cases, 2010-2019). The thesis comprises four related studies. First (Chapter 2), a review of published literature on geospatial models of g-HAT and associated vectors revealed that most endemic countries have contemporary estimates of g-HAT risk, but there are large spatial and temporal discrepancies in the completeness of tsetse mapping. Second (Chapter 3), cost-distance analyses were performed to provide a rational basis for the positioning of entomological monitoring sites. The utility of satellite imagery at two different spatial resolutions (0.5 & 3m) were compared, and an improved approach for monitoring tsetse in Koboko district, Uganda was produced. Third (Chapter 4), the cost-distance approach was applied to quantify geographic access to Uganda’s national network of diagnostic facilities for g-HAT. Paired with a simulation-based method, I showed how Uganda might reduce its number of diagnostic centres from 170 to 51 and still meet the targets of ensuring that  50% of the at-risk population live within 1-hour of a diagnostic facility and  95% live within 5-hours travel. Finally (Chapter 5), a 10-year time series of tsetse catch data from 569 individual monitoring sites was analysed to produce a spatio-temporal geostatistical model of tsetse abundance. By incorporating data on the deployment of Tiny Targets to control tsetse, I estimated that this intervention has reduced the abundance of tsetse by 88%. The results from the empirical studies are discussed in the context of improved strategies and policies for monitoring the spatial and temporal dynamics of g-HAT and tsetse populations.

Item Type: Thesis (Doctoral)
Subjects: QX Parasitology > Insects. Other Parasites > QX 505 Diptera
QX Parasitology > Insects. Other Parasites > QX 600 Insect control. Tick control
WA Public Health > Preventive Medicine > WA 110 Prevention and control of communicable diseases. Transmission of infectious diseases
WB Practice of Medicine > Medical Climatology > WB 700 Medical climatology. Geography of disease
WB Practice of Medicine > Medical Climatology > WB 710 Diseases of geographic areas
WC Communicable Diseases > Tropical and Parasitic Diseases > WC 705 Trypanosomiasis
WC Communicable Diseases > Tropical and Parasitic Diseases > WC 765 Prevention and control
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Item titleItem URI
Quantifying geographic accessibility to improve efficiency of entomological monitoring
Optimising passive surveillance of a neglected tropical disease in the era of elimination: A modelling study
Trypa-NO! contributes to the elimination of gambiense human African trypanosomiasis by combining tsetse control with “screen, diagnose and treat” using innovative tools and strategies
Estimating the impact of Tiny Targets in reducing the incidence of Gambian sleeping sickness in the North-west Uganda focus
Modelling the impact of climate change on the distribution and abundance of tsetse in Northern Zimbabwe
Faculty: Department: Biological Sciences > Vector Biology Department
Depositing User: Lynn Roberts-Maloney
Date Deposited: 15 Jun 2022 11:09
Last Modified: 15 Sep 2022 01:02


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