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Dive into the research topics where Stephen P. Carter is active.

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Featured researches published by Stephen P. Carter.


Proceedings of the Royal Society of London B: Biological Sciences | 2007

Culling-induced social perturbation in Eurasian badgers Meles meles and the management of TB in cattle: an analysis of a critical problem in applied ecology.

Stephen P. Carter; Richard J. Delahay; Graham C. Smith; David W. Macdonald; Philip Riordan; Thomas R. Etherington; Elizabeth R. Pimley; Neil J. Walker; Chris L. Cheeseman

The Eurasian badger (Meles meles) is implicated in the transmission of bovine tuberculosis (TB) to cattle in the UK and Republic of Ireland. Badger culling has been employed for the control of TB in cattle in both countries, with varying results. Social perturbation of badger populations following culling has been proposed as an explanation for the failure of culling to consistently demonstrate significant reductions in cattle TB. Field studies indicate that culling badgers may result in increased immigration into culled areas, disruption of territoriality, increased ranging and mixing between social groups. Our analysis shows that some measures of sociality may remain significantly disrupted for up to 8 years after culling. This may have epidemiological consequences because previous research has shown that even in a relatively undisturbed badger population, movements between groups are associated with increases in the incidence of Mycobacterium bovis infection. This is consistent with the results from a large-scale field trial, which demonstrated decreased benefits of culling at the edges of culled areas, and an increase in herd breakdown rates in neighbouring cattle.


Current Biology | 2013

Badger social networks correlate with tuberculosis infection

Nicola Weber; Stephen P. Carter; Sasha R. X. Dall; Richard J. Delahay; Jennifer L. McDonald; Stuart Bearhop; Robbie A. McDonald

Although disease hosts are classically assumed to interact randomly [1], infection is likely to spread across structured and dynamic contact networks [2]. We used social network analyses to investigate contact patterns of group-living European badgers, Meles meles, which are an important wildlife reservoir of bovine tuberculosis (TB). We found that TB test-positive badgers were socially isolated from their own groups but were more important for flow, potentially of infection, between social groups. The distinctive social position of infected badgers may help explain how social stability mitigates, and social perturbation increases, the spread of infection in badgers.


Trends in Ecology and Evolution | 2008

Perturbing implications of wildlife ecology for disease control

Robbie A. McDonald; Richard J. Delahay; Stephen P. Carter; Graham C. Smith; C. L. Cheeseman

Britains Randomised Badger Culling Trial provides robust evidence of the role badgers have in transmission of Mycobacterium bovis to cattle. Culling badgers perturbed their social structure, and brought positive and negative effects for bovine tuberculosis incidence in cattle, leading to the conclusion that culling could not make a meaningful contribution to disease control. The RBCT highlights the complexities of disease transmission in social animals and the importance of host ecology for controlling wildlife diseases.


PLOS ONE | 2012

BCG vaccination reduces risk of tuberculosis infection in vaccinated badgers and unvaccinated badger cubs.

Stephen P. Carter; Mark A. Chambers; Stephen Rushton; Mark Shirley; Pia Schuchert; Stéphane Pietravalle; Alistair Murray; Fiona Rogers; G. Gettinby; Graham C. Smith; Richard J. Delahay; R. Glyn Hewinson; Robbie A. McDonald

Wildlife is a global source of endemic and emerging infectious diseases. The control of tuberculosis (TB) in cattle in Britain and Ireland is hindered by persistent infection in wild badgers (Meles meles). Vaccination with Bacillus Calmette-Guérin (BCG) has been shown to reduce the severity and progression of experimentally induced TB in captive badgers. Analysis of data from a four-year clinical field study, conducted at the social group level, suggested a similar, direct protective effect of BCG in a wild badger population. Here we present new evidence from the same study identifying both a direct beneficial effect of vaccination in individual badgers and an indirect protective effect in unvaccinated cubs. We show that intramuscular injection of BCG reduced by 76% (Odds ratio = 0.24, 95% confidence interval (CI) 0.11–0.52) the risk of free-living vaccinated individuals testing positive to a diagnostic test combination to detect progressive infection. A more sensitive panel of tests for the detection of infection per se identified a reduction of 54% (Odds ratio = 0.46, 95% CI 0.26–0.88) in the risk of a positive result following vaccination. In addition, we show the risk of unvaccinated badger cubs, but not adults, testing positive to an even more sensitive panel of diagnostic tests decreased significantly as the proportion of vaccinated individuals in their social group increased (Odds ratio = 0.08, 95% CI 0.01–0.76; P = 0.03). When more than a third of their social group had been vaccinated, the risk to unvaccinated cubs was reduced by 79% (Odds ratio = 0.21, 95% CI 0.05–0.81; P = 0.02).


PLOS ONE | 2012

Performance of Proximity Loggers in Recording Intra and Inter-Species Interactions: A Laboratory and Field- Based Validation Study

Julian A. Drewe; Nicola Weber; Stephen P. Carter; Stuart Bearhop; Xavier A. Harrison; Sasha R. X. Dall; Robbie A. McDonald; Richard J. Delahay

Knowledge of the way in which animals interact through social networks can help to address questions surrounding the ecological and evolutionary consequences of social organisation, and to understand and manage the spread of infectious diseases. Automated proximity loggers are increasingly being used to record interactions between animals, but the accuracy and reliability of the collected data remain largely un-assessed. Here we use laboratory and observational field data to assess the performance of these devices fitted to a herd of 32 beef cattle (Bos taurus) and nine groups of badgers (Meles meles, n  = 77) living in the surrounding woods. The distances at which loggers detected each other were found to decrease over time, potentially related to diminishing battery power that may be a function of temperature. Loggers were highly accurate in recording the identification of contacted conspecifics, but less reliable at determining contact duration. There was a tendency for extended interactions to be recorded as a series of shorter contacts. We show how data can be manipulated to correct this discrepancy and accurately reflect observed interaction patterns by combining records between any two loggers that occur within a 1 to 2 minute amalgamation window, and then removing any remaining 1 second records. We make universally applicable recommendations for the effective use of proximity loggers, to improve the validity of data arising from future studies.


Veterinary Microbiology | 2011

Advances and prospects for management of TB transmission between badgers and cattle

Gavin J. Wilson; Stephen P. Carter; Richard J. Delahay

Bovine tuberculosis (bTB) is the most serious endemic disease facing the livestock industry in the United Kingdom (UK) and Republic of Ireland (RoI), where its management has been confounded by the presence of persistent infection in the Eurasian badger (Meles meles). Field evidence suggests that the social structure of badger populations can have an important influence on disease dynamics, and on the outcome of management interventions. Recent, large-scale badger culling experiments in the UK and RoI had complex epidemiological outcomes. In the UK, proactive culling led to reduced bTB incidence in cattle herds inside culled areas, but a temporary increase in adjacent areas. Reactive culling in response to herd breakdowns was associated with an increase in the incidence of bTB in cattle. In contrast, badger culling in RoI was reported to have only beneficial effects on bTB incidence in cattle. The reasons for these differences are not clear. The complexity of the evidence base for culling is highlighted by the different management approaches currently being adopted by the different authorities of the UK and RoI. It is generally accepted that a holistic approach to bTB management, which targets both cattle and wildlife, is necessary. Consequently recent research activities have also focussed on cattle and badger vaccines, and biosecurity on farms. This paper describes recent advances in our understanding of the epidemiology of bTB in badgers and the consequences of culling, and current research to develop approaches for the vaccination of badgers, and methods of managing the risks of contact between badgers and cattle in farm buildings.


Veterinary Record | 2014

Vaccination against tuberculosis in badgers and cattle: an overview of the challenges, developments and current research priorities in Great Britain

Mark A. Chambers; Stephen P. Carter; Gavin J. Wilson; G. Jones; E. Brown; R. G. Hewinson; Martin Vordermeier

Bovine tuberculosis (TB) is a significant threat to the cattle industry in England and Wales. It is widely acknowledged that a combination of measures targeting both cattle and wildlife will be required to eradicate bovine TB or reduce its prevalence until European official freedom status is achieved. Vaccination of cattle and/or badgers could contribute to bovine TB control in Great Britain, although there are significant gaps in our knowledge regarding the impact that vaccination would actually have on bovine TB incidence. Laboratory studies have demonstrated that vaccination with BCG can reduce the progression and severity of TB in both badgers and cattle. This is encouraging in terms of the prospect of a sustained vaccination programme achieving reductions in disease prevalence; however, developing vaccines for tackling the problem of bovine TB is challenging, time-consuming and resource-intensive, as this review article sets out to explain.


Archive | 2009

Options for the Control of Disease 2: Targeting Hosts

Stephen P. Carter; Sugoto S. Roy; Dave P. Cowan; Giovanna Massei; Graham C. Smith; Weihong Ji; Sophie Rossi; Rosie Woodroffe; Gavin J. Wilson; Richard J. Delahay

Targeting the host has been the most common approach to managing disease in wildlife. This has essentially involved some form of host population reduction, achieved through dispersing, culling, or controlling reproduction. Dispersion of animals from the site of a disease outbreak has mainly been employed for birds (Wobeser 2007) but has also been attempted for some herding mammals such as bison (Bison bison) (Meagher 1989). This works best for noninfectious diseases; otherwise it requires that only susceptible individuals disperse, since the movement of infected animals will increase the geographic spread of disease. Unsurprisingly this method has had little success in practice, and is seldom likely to be of value in controlling infectious disease in wild mammals. Culling is a long established method of population reduction, for both disease and pest control. This approach assumes that reducing the population size of the targeted species results in a concomitant decrease in the prevalence (and more importantly the absolute number) of infectious individuals. If the aim is to eradicate the pathogen then the number of infectious individuals must fall below a level at which infection can be maintained. However, it may often be sufficient that infection is reduced to a level below which spillover to other host species (e.g. humans, domestic animals, or endangered species) either ceases or is tolerable. Wild mammal populations have most commonly been subjected to culling because they have been perceived as agricultural pests, and less often because they may transmit diseases.


Epidemiology and Infection | 2013

Heterogeneity in the risk of Mycobacterium bovis infection in European badger (Meles meles) cubs.

Alexandra Tomlinson; Mark A. Chambers; Stephen P. Carter; Gavin J. Wilson; Graham C. Smith; Robbie A. McDonald; Richard J. Delahay

The behaviour of certain infected individuals within socially structured populations can have a disproportionately large effect on the spatio-temporal distribution of infection. Endemic infection with Mycobacterium bovis in European badgers (Meles meles) in Great Britain and Ireland is an important source of bovine tuberculosis in cattle. Here we quantify the risk of infection in badger cubs in a high-density wild badger population, in relation to the infection status of resident adults. Over a 24-year period, we observed variation in the risk of cub infection, with those born into groups with resident infectious breeding females being over four times as likely to be detected excreting M. bovis than cubs from groups where there was no evidence of infection in adults. We discuss how our findings relate to the persistence of infection at both social group and population level, and the potential implications for disease control strategies.


Vaccine | 2017

Field evaluation of candidate baits for oral delivery of BCG vaccine to European badgers, Meles meles.

Kate L. Palphramand; Richard J. Delahay; Andrew Robertson; Sonya Gowtage; Gareth A. Williams; Robbie A. McDonald; Mark A. Chambers; Stephen P. Carter

The control of tuberculosis (TB) in cattle in the UK and Ireland is compromised by transmission of Mycobacterium bovis to cattle from the European badger (Meles meles), which acts as a wildlife reservoir. Vaccination of badgers could potentially contribute to TB control but the only licensed vaccine is injectable BadgerBCG which requires the live-capture of badgers. Current research is aimed at developing an oral TB vaccine (where vaccine is contained within bait) that is intended to be more cost-effective to deploy over large areas. In order to identify a lead product, candidate baits identified from captive badger studies were evaluated in three successive bait screening studies with wild badgers. A fourth field study, using the lead candidate bait and biomarkers, investigated the effectiveness of different carriers for their potential to deliver liquid payloads (vaccine surrogate). In each field study, bait disappearance was monitored daily for ten days and remote video surveillance was used to determine preference (i.e. the order in which baits were taken). In the carrier study, biomarkers were used to determine what proportion of subsequently trapped badgers had ingested the bait and the vaccine-carrier biomarker payload. Across all four studies, 79% (3397/4330) of baits were taken by badgers although the number varied significantly by badger social group and bait type. In all studies, bait disappearance increased over time, with 75-100% of baits being taken by day ten. In the carrier study, 75% (9/12) of trapped badgers tested positive for at least one of the biomarkers and the type of carrier did not influence bait attractiveness. Together with data from complementary laboratory and captive animal studies, this study identified a highly attractive and palatable bait (peanut-based paste bait; PT) and vaccine-carrier (hydrogenated peanut oil; HPO) combination with the potential to deliver a liquid vaccine to wild badgers.

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Richard J. Delahay

Animal and Plant Health Agency

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Mark A. Chambers

Animal and Plant Health Agency

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Graham C. Smith

Animal and Plant Health Agency

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Gavin J. Wilson

Food and Environment Research Agency

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Kate L. Palphramand

Animal and Plant Health Agency

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Sonya Gowtage

Animal and Plant Health Agency

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