Biology subjects

Smith, G. C.

Publications and source records attributed to Smith, G. C..

4 recordsLinked to original sources

bioRxiv2018

Status of urban feral cats Felis catus in England: A comparative study

This study sought to determine whether a change in the abundance of feral cats (Felis catus) in three areas of England had occurred between the completion of a survey undertaken by the Ministry for Agriculture Fisheries and Food in 1986/7 and the turn of the century. In the event of a rabies outbreak occurring in Britain, feral cats would be one vector of the disease that would need to be controlled under the Rabies (control) Order 1974. A total of 741 \"high risk sites\", found to provide appropriate conditions for feral cats, were surveyed between 1999 and 2000. The total number of feral cat colonies located within the survey areas was found to have fallen by 37% from 68 in 1986 to 43 in 1999/2000, translating to an estimated 212-247 fewer individual feral cats. Factories/trading estates and industrial premises continued to be the most common sites associated with urban feral cat colonies. However, the closing down of many traditional industries, such as mills and dockyards, and their replacement by more secure and insulated modern buildings, less amenable to feral cats finding warmth and food, had assisted the observed fall in numbers along with the effectiveness of neutering programs which are now taking place on many sites. Through this study information regarding feral cat colonies in urban landscapes as well colony size was gathered and fed into rabies contingency plans to help keep Britain rabies free into the future.

zoology↗

bioRxiv2018

Disease transmission mode has little effect on simulated canine rabies elimination

Disease transmission in animal populations can be affected by density or by frequency of contacts between individuals, although many models assume linear density-dependent transmission. We used rabies and free-roaming dogs (Canis familiaris) in two Nepalese cities as a model system to explore the impact of linear and non-linear density-dependent disease transmission on disease elimination achieved through rabies vaccination or vaccination and sterilisation. Strongly non-linear transmission approximated realistic frequency dependent transmission. Free roaming dogs, abundant in many parts of the developing world, are responsible for most cases of rabies transmission to humans. Most models of rabies transmission assume that the disease transmission rate is linearly density-dependent, although a recent empirical study did not find evidence to support this assumption. Rabies vaccination, culling and dog sterilisation are employed to eliminate rabies or to reduce the numbers of human cases. We created a continuous-time deterministic compartmental model to describe rabies epidemiology within a dog population and to analyse the two modes of transmission. Under each transmission mode, we investigated the efficacy of dog vaccination and fertility control to eliminate rabies. To investigate the effect of dog density on disease control efforts, models were run for cities with high and low dog population densities using data from the Nepalese cities. The results showed that, at low population density, the amount of control effort required for disease elimination did not differ substantially between different transmission modes. At high population density, the effort required to achieve disease elimination was only higher for linear density-dependent than for non-linear transmission due to the exact value of the transmission rate, beta. The model suggests that although disease transmission mode may alter the impact of control on rabies elimination, this impact is relatively small and probably not relevant to disease management.

ecology↗

bioRxiv2017

The uptake of attractant and flavour enhanced baits by foxes (Vulpes vulpes) in rural England

Over a 15 month period the removal rates of different attractant and flavour enhanced baits, by foxes, was investigated at permanent and single use sites. All baits were composed of mechanically recovered chicken meat (MRM) and were treated with one of four additives (an attractant or flavour); untreated baits were used as experimental controls. The addition of synthetic ferment egg (SFE) increased bait removal compared with untreated and valeric acid (VA) treated bait. However, the addition of beef flavour or honey flavour to bait did not increase bait removal rates compared to untreated bait.\n\nThere was limited evidence of learning (by foxes and other species responsible for removing the bait) at one of the permanent study sites but no evidence of such behaviour at the other site. There was no evidence of consistent seasonal differences in bait removal rates.\n\nIt was concluded that the use of attractants may increase bait removal rate in areas where bait removal rate is low; but where bait removal rate is high (in most rural areas of Britain) the addition of attractants or flavours offers little advantage.

ecology↗

bioRxiv2017

Estimating Wildlife Vaccination Coverage Using Genetic Methods

Vaccination is a potentially useful approach for the control of disease in wildlife populations. The effectiveness of vaccination is contingent in part on obtaining adequate vaccine coverage at the population level. However, measuring vaccine coverage in wild animal populations is challenging and so there is a need to develop robust approaches to estimate coverage and so contribute to understanding the likely efficacy of vaccination.\n\nWe used a modified capture mark recapture technique to estimate vaccine coverage in a wild population of European badgers (Meles meles) vaccinated by live-trapping and injecting with Bacillus Calmette-Guerin as part of a bovine tuberculosis control initiative in Wales, United Kingdom. Our approach used genetic matching of vaccinated animals to a sample of the wider population to estimate the percentage of badgers that had been vaccinated. Individual-specific genetic profiles were obtained using microsatellite genotyping of hair samples which were collected both directly from trapped and vaccinated badgers and non-invasively from the wider population using hair traps deployed at badger burrows.\n\nWe estimated the percentage of badgers vaccinated in a single year and applied this to a simple model to estimate cumulative vaccine coverage over a four year period, corresponding to the total duration of the vaccination campaign.\n\nIn the year of study, we estimated that between 44-65% (95% confidence interval, mean 55%) of the badger population received a vaccine dose. Using the model, we estimated that 70-85% of the total population would have received at least one vaccine dose over the course of the four year vaccination campaign.\n\nThis study represents the first application of this novel approach for measuring vaccine coverage in wildlife. This is also the first attempt at quantifying the level of vaccine coverage achieved by trapping and injecting badgers. The results therefore have specific application to bovine tuberculosis control policy, and the approach is of significance to the wider field of wildlife vaccination.

ecology↗