Dr Sandra Telfer

Research Overview

I maintain a broad interest in population ecology, wildlife disease and zoonotic disease. My specific interests include host-pathogen interactions, the dynamics of disease in fragmented populations, landscape epidemiology and the threat posed to animal and human populations by disease. I believe that combining ecological studies with analyses of host and pathogen genetic variability has considerable potential for understanding disease transmission processes.  

Current Research

Plague epidemiology, with Minoarisoa Rajerison and Nohal Elissa (Institut Pasteur Madagascar), Jean-Marc Duplantier and Carine Brouat (IRD, CBGP Montpellier), Dave Wagner (Northern Arizona University)

Funded by the Wellcome Trust, I am investigating plague epidemiology in Madagascar. Plague still persists in many parts of the world where the disease circulates in wild rodent populations and can be transmitted to humans. Rural Madagascar has one of the highest incidences of plague in the world, with susceptible black rats acting as the natural reservoir for the disease. In this project I am investigating how the disease manages to persist and spread within a reservoir that typically dies following infection. I am focussing on the role of abundance and movement of black rats and two species of flea. The project integrates field studies and genetic analyses of host, vector and pathogen with epidemiological modelling. I am also a co-supervisor of a PhD student investigating the influence of climate on plague epidemiology in Madagascar.

Environmental and socio-economic drivers of zoonotic disease risk in Madagascar, Minoarisoa Rajerison, Benoit Garin, Jean-Michel Heraud, Ronan Jambou, Rindra Randremanana (Institut Pasteur Madagascar), Matthew Baylis (University of Liverpool)

Most emerging diseases are zoonotic and the threat of zoonoses from wildlife is increasing. The threat is most severe in developing countries, where many zoonoses are hugely under-reported, even though they can cause significant disease burdens. Vulnerability to such diseases is influenced by both environmental and socio-economic factors and there is mounting evidence that changes in climate and land-use are associated with increased risk. The relative importance of different factors for disease risk is still poorly understood, especially at local scales.

Rodents are reservoirs for many  zoonoses and their commensal nature and widespread distribution facilitates disease transfer between wild animals, livestock and humans. As rodents are abundant and easy to catch they also make an ideal model system to explore factors influencing transmission rates at the human-animal interface. The project is using this approach in Madagascar, comparing factors associated with infection for four rodent-borne zoonoses with contrasting transmission routes and examining exposure risk in both rodents and humans. The four pathogens are plague, leptospirosis, hantavirus and murine typhus. In rodent populations we are investigating how climate, habitat, landscape and land-use change affect infection prevalence, and exploring whether observed relationships are mediated by effects on host abundance, diversity or movement. In human populations, we are investigating the relative importance of environmental and socio-economic factors, and exploring the scale at which these factors operate.  

Parasite dynamics in metapopulations, PhD student. Claire Davies 

Parasites and pathogens are widely accepted to affect host survival and fecundity and can contribute to declines in some species. Host population spatial structure has profound consequences for host-parasite dynamics, with parasite persistence depending on both host factors (dispersal patterns, development of host immunity, the number, size, distribution and turnover rate of local populations) and parasite factors (host-specificity, transmission route, infectious period and virulence). Such factors will influence parasite dynamics within local populations and transmission between populations. Despite several theoretical studies of host-parasite dynamics in fragmented systems, there is a lack of empirical data from wild populations with which to test models.

In this project we are investigating parasite dynamics within water vole metapopulations in upland Scotland. Fragmented water vole populations are amongst the best characterized mammalian metapopulations, with considerable variation in population size and isolation within and between metapopulations. Water vole populations are infected with a range of parasites (helminths, nematodes, viruses, bacteria and protozoa) and we are investigating how local host density, alternative host density, isolation and previous occupation history influence the prevalence of different infections.

Invasive species: parasite dynamics and control, PhD student. Amelia Brereton 

The decline of red squirrels in the UK is largely attributable to transmission of squirrel pox (SQPV) from the invasive grey squirrel, with reds declining 17-25 times faster in areas with infected greys compared to areas with uninfected greys. The continuing spread of SQPV into previously uninfected areas has led to widespread but disparate grey squirrel control. In some areas the management aim is primarily to halt further disease spread, whilst in other areas the aim is for grey squirrel eradication.

Although theoretical models have been developed of the grey squirrel invasion process and disease transmission, their utility for management is limited due to a lack of empirical data for model parameterisation. Specifically, grey squirrel dispersal patterns and rates, and the impact of control on dispersal and disease transmission are poorly understood.

This project is working with squirrel control programmes in Scotland to examine the effectiveness of different control strategies and the impact of control on disease dynamics.

Host-parasite dynamics, with Mike Begon (University of Liverpool), Richard Birtles (University of Salford) and Xavier Lambin (University of Aberdeen)   

The transmission of disease between wildlife, livestock and humans has important repercussions for human health, farming and conservation. Prediction of the risk posed by such diseases requires a thorough understanding of disease dynamics within wild populations of reservoir hosts. However, whilst there have been considerable advances in the theory of host-microparasite interactions, empirical studies of wild populations are rare. We are addressing this by investigating host-pathogen dynamics in wild field vole populations at Kielder in Northumberland. 

Co-infection, with Mike Begon, Steve Paterson (University of Liverpool)

Although most parasite studies focus on single host - single pathogen systems, most individuals in natural populations will spend the majority of their life co-infected with more than one parasite species. Interactions between co-infecting parasite species may be mediated by interference competition, resource competition or by the host’s immune system and can have important implications for host and parasite fitness and parasite community structure. I am using longitudinal data from the field vole populations at Kielder to investigate the impact of co-infection on host-parasite interactions

Funding and Grants

2011 - 2016 Wellcome Trust Senior Fellowship in Basic Biomedical Sciences: 'Zoonotic disease risk in Madagascar'

2007 - 20011 Wellcome Trust Research Career Development Fellowship: ‘Plague risk in the heterogeneous rural landscape of Madagascar’