Ecological drivers of a vector borne pathogen: distribution and abundance of Borrelia burgdorferi sensu lato and its vector Ixodes ricinus in Scotland

Vector-borne disease emergence in recent decades has been associated with different environmental drivers including changes in habitat, hosts and climate. Lyme borreliosis is among the most important vector-borne diseases in the Northern hemisphere and is an emerging disease in Scotland. Transmitted by Ixodid tick vectors between large numbers of wild vertebrate host species, Lyme borreliosis is caused by bacteria from the Borrelia burgdorferi sensu lato species group. Ecological studies can inform how environmental factors such as host abundance and community composition, habitat and landscape heterogeneity contribute to spatial and temporal variation in risk from B. burgdorferi s.l. In this thesis a range of approaches were used to investigate the effects of vertebrate host communities and individual host species as drivers of B. burgdorferi s.l. dynamics and its tick vector Ixodes ricinus. Host species differ in reservoir competence for B. burgdorferi s.l. and as hosts for ticks. Deer are incompetent transmission hosts for B. burgdorferi s.l. but are significant hosts of all life-stages of I. ricinus. Rodents and birds are important transmission hosts of B. burgdorferi s.l. and common hosts of immature life-stages of I. ricinus. In this thesis, surveys of woodland sites revealed variable effects of deer density on B. burgdorferi prevalence, from no effect (Chapter 2) to a possible ‘dilution’ effect resulting in lower prevalence at higher deer densities (Chapter 3). An invasive species in Scotland, the grey squirrel (Sciurus carolinensis), was found to host diverse genotypes of B. burgdorferi s.l. and may act as a spill-over host for strains maintained by native host species (Chapter 4). Habitat fragmentation may alter the dynamics of B. burgdorferi s.l. via effects on the host community and host movements. In this thesis, there was lack of persistence of the rodent associated genospecies of B. burgdorferi s.l. within a naturally fragmented landscape (Chapter 3). Rodent host biology, particularly population cycles and dispersal ability are likely to affect pathogen persistence and recolonization in fragmented habitats. Heterogeneity in disease dynamics can occur spatially and temporally due to differences in the host community, habitat and climatic factors. Higher numbers of I. ricinus nymphs, and a higher probability of detecting a nymph infected with B. burgdorferi s.l., were found in areas with warmer climates estimated by growing degree days (Chapter 2). The ground vegetation type associated with the highest number of I. ricinus nymphs varied between studies in this thesis (Chapter 2 & 3) and does not appear to be a reliable predictor across large areas. B. burgdorferi s.l. prevalence and genospecies composition was highly variable for the same sites sampled in subsequent years (Chapter 2). This suggests that dynamic variables such as reservoir host densities and deer should be measured as well as more static habitat and climatic factors to understand the drivers of B. burgdorferi s.l. infection in ticks. Heterogeneity in parasite loads amongst hosts is a common finding which has implications for disease ecology and management. Using a 17-year data set for tick infestations in a wild bird community in Scotland, different effects of age and sex on tick burdens were found among four species of passerine bird (Chapter 5). There were also different rates of decline in tick burdens among bird species in response to a long term decrease in questing tick pressure over the study. Species specific patterns may be driven by differences in behaviour and immunity and highlight the importance of comparative approaches. Combining whole genome sequencing (WGS) and population genetics approaches offers a novel approach to identify ecological drivers of pathogen populations. An initial analysis of WGS from B. burgdorferi s.s. isolates sampled 16 years apart suggests that there is a signal of measurable evolution (Chapter 6). This suggests demographic analyses may be applied to understand ecological and evolutionary processes of these bacteria. This work shows how host communities, habitat and climatic factors can affect the local transmission dynamics of B. burgdorferi s.l. and the potential risk of infection to humans. Spatial and temporal heterogeneity in pathogen dynamics poses challenges for the prediction of risk. New tools such as WGS of the pathogen (Chapter 6) and blood meal analysis techniques will add power to future studies on the ecology and evolution of B. burgdorferi s.l.

Administrative justice and the control of bureaucratic decision-making: A study investigating how decision-makers in local authority education departments respond to the work of redress mechanisms

This socio-legal thesis has explored the factors responsible for explaining whether and how redress mechanisms control bureaucratic decision-making. The research considered the three principal institutions of administrative justice: courts, tribunals, and ombudsman schemes. The field setting was the local authority education area and the thesis examined bureaucratic decision-making about admissions to school, home-to-school transport, and Special Educational Needs (SEN). The thesis adopted a qualitative approach, using interviews and documentary research, within a multiple embedded case study design. The intellectual foundations of the research were inter-disciplinary, cutting across law, socio-legal studies, public administration, organization studies, and social policy. The thesis drew on these scholarly fields to explore the nature of bureaucratic decision-making, the extent to which it can be controlled and the way that learning occurs in bureaucracies and, finally, the extent to which redress mechanisms might exercise control. The concept of control was studied across all its dimensions – in relation both to ex post control in specific cases and the more challenging notion of ex ante or structuring control. The aim of the thesis was not to measure the prevalence of bureaucratic control by redress mechanisms, but to understand the factors that might explain its presence or absence in a particular area. The findings of the research have allowed for a number of analytical refinements and extensions to be made to existing theoretical and empirical understandings. 14 factors, along with 87 supporting propositions, have been set out with the aim of making empirically derived suggestions which can be followed up in future research. In terms of the thesis’ contribution to existing knowledge, its comparative focus and its emphasis on the broad notion of control offered the potential for new insights to be developed. Overall, the thesis claims to have made three contributions to the conceptual framework for understanding the exercise of control by redress mechanisms: it emphasizes the importance of ‘feedback’ in relation to the nature of the cases referred to redress mechanisms; it calls attention to the structure of bureaucratic decision-making as well as its normative character; and it discusses how the operational modes of redress mechanisms relate to their control functions.