Effect of culling and vaccination on bovine tuberculosis infection in a European badger (Meles meles) population by spatial simulation modelling

Robertson

et al. 2017

Preprint

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.We 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-Guérin 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.We 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.In 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.This 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.not peer-reviewed)

Section: Discussionmentioning

confidence: 99%

Estimating wildlife vaccination coverage using genetic methods

Robertson

et al. 2017

Preprint

“…Badgers are protected by law in the UK and Ireland which limits the public acceptability and practicality of culling and for disease control, and culling of badgers in England and Ireland has sometimes delivered conflicting results that likely reflect subtle differences in the epidemiology of the disease locally ( 104 ). Vaccination of badgers against TB has the potential to be an effective TB control measure, especially in combination with other control measures ( 105 ) and considerable progress has been made in testing the efficacy of BCG vaccine in badgers.…”

Section: Bcg Vaccination Of Wildlifementioning

confidence: 99%

Efficacy and Safety of BCG Vaccine for Control of Tuberculosis in Domestic Livestock and Wildlife

et al. 2018

Bovine tuberculosis (TB) continues to be an intractable problem in many countries, particularly where “test and slaughter” policies cannot be implemented or where wildlife reservoirs of Mycobacterium bovis infection serve as a recurrent source of infection for domestic livestock. Alternative control measures are urgently required and vaccination is a promising option. Although the M. bovis bacille Calmette-Guérin (BCG) vaccine has been used in humans for nearly a century, its use in animals has been limited, principally as protection against TB has been incomplete and vaccination may result in animals reacting in the tuberculin skin test. Valuable insights have been gained over the past 25 years to optimise protection induced by BCG vaccine in animals and in the development of tests to differentiate infected from vaccinated animals (DIVA). This review examines factors affecting the efficacy of BCG vaccine in cattle, recent field trials, use of DIVA tests and the effectiveness of BCG vaccine in other domestic livestock as well as in wildlife. Oral delivery of BCG vaccine to wildlife reservoirs of infection such as European badgers, brushtail possums, wild boar, and deer has been shown to induce protection against TB and could prove to be a practical means to vaccinate these species at scale. Testing of BCG vaccine in a wide range of animal species has indicated that it is safe and vaccination has the potential to be a valuable tool to assist in the control of TB in both domestic livestock and wildlife.

“…In the first, the impact of rodent vaccination may be enhanced by coupling the distribution of vaccine laced baits with intensive rodent culling. By reducing the number of foraging rodents using relatively cheap culling methods (e.g., snap traps), this strategy may substantially reduce the number of vaccine baits required to reduce or eliminate pathogen infection, at least over the short term (e.g., Abdou et al 2016). In some cases where culling has been employed and studied, however, it has been shown to have potentially counter-intuitive impacts, potentially increasing the prevalence of the target pathogen (Streicker et al 2012; Amman et al 2014).…”

Section: Discussionmentioning

confidence: 99%

Bayesian estimation of Lassa virus epidemiological parameters: implications for spillover prevention using wildlife vaccination

Nuismer

Remien

Basinski

et al. 2019

Preprint

32Lassa virus is a significant burden on human health throughout its endemic region in 33 West Africa, with most human infections the result of spillover from the primary rodent 34 reservoir of the virus, the natal multimammate mouse, M. natalensis. Here we develop a 35 Bayesian methodology for estimating epidemiological parameters of Lassa virus within its 36 rodent reservoir and for generating probabilistic predictions for the efficacy of rodent 37 vaccination programs. Our approach uses Approximate Bayesian Computation (ABC) to 38 integrate mechanistic mathematical models, remotely-sensed precipitation data, and Lassa 39 virus surveillance data from rodent populations. Using simulated data, we show that our 40 method accurately estimates key model parameters, even when surveillance data are available 41 from only a relatively small number of points in space and time. Applying our method to 42 previously published data from two villages in Guinea estimates the time-averaged of Lassa 0 43 virus to be 1.658 and 1.453 for rodent populations in the villages of Bantou and Tanganya, 44 respectively. Using the posterior distribution for model parameters derived from these 45 Guinean populations, we evaluate the likely efficacy of vaccination programs relying on 46 distribution of vaccine-laced baits. Our results demonstrate that effective and durable 47 reductions in the risk of Lassa virus spillover into the human population will require repeated 48 distribution of large quantities of vaccine. 49 3 50 Author Summary 51 Lassa virus is a chronic source of illness throughout West Africa, and is considered to be a threat 52 for widespread emergence. Because most human infections result from contact with infected 53 rodents, interventions that reduce the number of rodents infected with Lassa virus represent 54 promising opportunities for reducing the public health burden of this disease. Evaluating how 55 well alternative interventions are likely to perform is complicated by our relatively poor 56 understanding of viral epidemiology within the reservoir population. Here we develop a novel 57 statistical approach that couples mathematical models and viral surveillance data from rodent 58 populations to robustly estimate key epidemiological parameters. Applying our method to 59 existing data from Guinea yields well-resolved parameter estimates and allows us to simulate a 60 variety of rodent vaccination programs. Together, our results demonstrate that rodent 61 vaccination alone is unlikely to be an effective tool for reducing that public health burden of 62 Lassa fever within West Africa. 63 65 Lassa virus is a zoonotic pathogen endemic to West Africa where it poses a significant 66 burden on human health (Buckley et al. 1970). Although only a relatively small proportion of 67 human cases result in severe symptoms and mortality, human infection is common, with 8-52% 68 of the human population within Sierra Leone seropositive (McCormick et al. 1987; Bausch et al. 69 2001; Dan-Nwafor et al. 2019), indicative of past...