First Farr London student is awarded PhD

Congratulations to Farr student Catherine Smith, who has successfully sustained her viva and has been awarded a doctorate with typographical corrections only.

Thesis Title: 'Investigating tuberculosis transmission using spatial methods'

Abstract

Background: Tuberculosis remains a leading infectious cause of death worldwide. Reducing transmission requires an increased focus on local control measures informed by spatial data. Effective use of spatial methods will improve understanding of tuberculosis transmission and support outbreak investigations.

Methods: I conducted a systematic literature review to describe spatial methods that have been used in previous outbreak investigations (Chapter 2). I developed and evaluated a novel interactive mapping tool, written using the R programming language (Chapter 3). Using multinomial logistic regression and spatial scan statistics, I investigated molecular and spatial clustering of tuberculosis in London (Chapter 4). I described the evolution of a large outbreak of drug-resistant tuberculosis in London in space and time (Chapter 5). Through three case studies, I assessed the utility of a novel spatial tool, geographic profiling, which aims to identify the locations of sources of infectious disease using locations of linked cases (Chapter 6). I analysed the spatial accessibility of tuberculosis services in London using travel time data (Chapter 7).

Key findings

• Spatial methods provide an important complementary tool to epidemiological analyses, but are currently under-used (less than half a percent of published outbreak investigations used spatial methods).
• Large numbers of tuberculosis cases in London have resulted from local transmission, with more than one in ten cases part of large clusters.
• Social complexity and area-level deprivation are associated with transmission of tuberculosis in large clusters.
• Geographic profiling may assist with epidemiological investigations of infectious diseases in some circumstances by prioritising areas for investigation.
• Pan-London commissioning could improve tuberculosis services by enhancing spatial accessibility.

Conclusions

Spatial methods provide many valuable contributions to investigations of tuberculosis. Development of new tools and wider use of existing methods could limit the public health impacts of infectious disease outbreaks.