The political economy of bovine tuberculosis in Great Britain.

A brief history of bovine tuberculosis (bTB) and its control in Great Britain (GB) is presented. Numerous diverse policies to control the disease in humans, cattle and wildlife have been pursued over the last 100 years and many millions of pounds have been spent. After notable success in reducing the incidence and prevalence of bTB in cattle in GB from the 1950s to the mid-1980s, the geographical spread of the disease and the number of cattle slaughtered have increased continually since that time, with a high point of bTB incidence in 2008. This increase appeared to coincide with changing policy regarding the control of the disease in badgers, with a more humane approach adopted and with strengthened protection for badgers through legislation. Indeed, there has been much controversy in the debate on the role of badgers in disease transmission to cattle and the need for their control as vectors of the disease. The issue has attracted the attention of the media and there have been various commissioned research projects, trials and public consultations. The findings of two social science investigations presented as examples showed that citizens generally believed that bTB in cattle is an important issue that needs to be tackled, but objected to badgers being killed, whilst cattle farmers were willing to pay around £17/animal/year for a bTB cattle vaccine. It is noted that successes regarding the control of bTB in other countries have combined both cattle and wildlife controls and involved industry working in close partnership with government.

L'auteur retrace brièvement l'histoire de la tuberculose bovine et de la lutte contre cette maladie en Grande-Bretagne. Diverses mesures sanitaires ont été appliquées au cours des cent dernières années afin de maîtriser la maladie chez l'homme, chez les bovins et dans la faune sauvage, pour une dépense totale de plusieurs millions de livres. Après la chute remarquable de l'incidence et de la prévalence de la tuberculose bovine en Grande-Bretagne enregistrée depuis les années 50, la situation s'est inversée au milieu des années 80 et tant la distribution géographique de la maladie que le nombre de bovins abattus n'ont cessé de croître depuis cette date, l'année 2008 marquant le pic de l'incidence de la tuberculose bovine. Il est désormais établi que cette hausse a coïncidé avec l'évolution des politiques de lutte contre la tuberculose chez les blaireaux, à la faveur d'une approche plus respectueuse du bien-être animal qui s'est traduite par une protection renforcée des blaireaux dans la législation. En effet, le rôle des blaireaux dans la transmission de la tuberculose aux bovins et l'impératif de lutter contre les blaireaux en tant que vecteurs ont fait l'objet de très fortes controverses. Cette question a attiré l'attention des médias et il y a eu de nombreux projets de recherche commandités sur le sujet, d'expériences et de consultations publiques. D'après deux enquêtes sociologiques citées par l'auteur, les citoyens étaient généralement convaincus de l'importance de la tuberculose chez les bovins et de la nécessité de s'y attaquer mais ils s'opposaient aux mesures d'abattage des blaireaux, tandis que les éleveurs de bovins étaient disposés à payer environ 17 livres par bovin et par année pour pouvoir vacciner leurs bovins contre la tuberculose bovine. L'auteur fait observer que les succès enregistrés dans d'autres pays dans la lutte contre la tuberculose bovine sont liés à l'application combinée de mesures de contrôle chez les bovins et dans la faune sauvage et à une étroite collaboration entre les éleveurs et le gouvernement.

El autor repasa sucintamente la historia de la tuberculosis bovina y de su control en Gran Bretaña. En los últimos 100 años se han aplicado numerosas y variadas políticas y se han invertido muchos millones de libras para combatir la enfermedad en el ser humano, el ganado vacuno y la fauna silvestre. Entre mediados del decenio de 1950 y mediados del de 1980 se trabajó con notable éxito para reducir la incidencia y prevalencia de la enfermedad en el ganado vacuno británico. Pero a partir de ahí hubo una progresión constante en la propagación geográfica de la enfermedad y en el número de cabezas de ganado sacrificadas, con un máximo de incidencia registrado en 2008. Tal incremento parece coincidir con una inflexión de la política aplicada para luchar contra la enfermedad en los tejones, con la adopción de métodos más clementes y de medidas legislativas que instauraban un mayor nivel de protección de los tejones. Ha habido en efecto una gran controversia acerca del papel de los tejones en los procesos de transmisión de la enfermedad al ganado vacuno y la necesidad de controlar a esos animales como vectores de la infección. El tema ha suscitado gran atención mediática y ha sido objeto de una serie de proyectos de investigación, experimentos y consultas públicas. Según demuestran las conclusiones de dos investigaciones de ciencias sociales presentadas como ejemplo, en general los ciudadanos pensaban que la tuberculosis bovina en el ganado era un problema importante al que había que dar respuesta, pero se oponían al sacrificio de los tejones, a la vez que los ganaderos estaban dispuestos a pagar alrededor de 17 libras/animal/año por la vacunación antituberculosa de sus rebaños vacunos. El autor señala que los éxitos obtenidos en otros países a la hora de combatir la tuberculosis bovina pasan por instaurar controles a la vez en el ganado y en la fauna silvestre y por lograr que la industria trabaje en estrecha asociación con las instancias públicas.

Cost-effectiveness evaluation of bovine tuberculosis surveillance in wildlife in France (Sylvatub system) using scenario trees.

Bovine tuberculosis (bTB) is a common disease in cattle and wildlife, with health, zoonotic and economic implications. Infected wild animals, and particularly reservoirs, could hinder eradication of bTB from cattle populations, which could have an important impact on international cattle trade. Therefore, surveillance of bTB in wildlife is of particular importance to better understand the epidemiological role of wild species and to adapt the control measures. In France, a bTB surveillance system for free-ranging wildlife, the Sylvatub system, has been implemented since 2011. It relies on three surveillance components (SSCs) (passive surveillance on hunted animals (EC-SSC), passive surveillance on dead or dying animals (SAGIR-SSC) and active surveillance (PSURV-SSC)). The effectiveness of the Sylvatub system was previously assessed, through the estimation of its sensitivity (i.e. the probability of detecting at least one case of bTB infection by each SSC, specie and risk-level area). However, to globally assess the performance of a surveillance system, the measure of its sensitivity is not sufficient, as other factors such as economic or socio-economic factors could influence the effectiveness. We report here an estimation of the costs of the surveillance activities of the Sylvatub system, and of the cost-effectiveness of each surveillance component, by specie and risk-level, based on scenario tree modelling with the same tree structure as used for the sensitivity evaluation. The cost-effectiveness of the Sylvatub surveillance is better in higher-risk departments, due in particular to the higher probability of detecting the infection (sensitivity). Moreover, EC-SSC, which has the highest unit cost, is more efficient than the surveillance enhanced by the SAGIR-SSC, due to its better sensitivity. The calculation of the cost-effectiveness ratio shows that PSURV-SSC remains the most cost-effective surveillance component of the Sylvatub system, despite its high cost in terms of coordination, sample collection and laboratory analysis.

Tuberculosis, Brucellosis and Leucosis in Cattle: A Cost Description of Eradication Programmes in the Region of Lazio, Italy.

The eradication of tuberculosis, brucellosis and leucosis in cattle has not yet been achieved in the entire Italian territory. The region of Lazio, Central Italy, represents an interesting case study to evaluate the evolution of costs for these eradication programmes, as in some provinces the eradication has been officially achieved, in some others the prevalence has been close to zero for years, and in still others disease outbreaks have been continuously reported. The objectives of this study were i) to describe the costs for the eradication programmes for tuberculosis, brucellosis and leucosis in cattle carried out in Lazio between 2007 and 2011, ii) to calculate the ratio between the financial contribution of the European Union (EU) for the eradication programmes and the estimated total costs and iii) to estimate the potential savings that can be made when a province gains the certification of freedom from disease. For the i) and ii) objectives, data were collected from official sources and a costing procedure was applied from the perspective of the Regional Health Service. For the iii) objective, a Bayesian AR(1) regression was used to evaluate the average percentage reduction in costs for a province that gained the certification. The total cost for the eradication programmes adjusted for inflation to 1 January 2016 was estimated at 18 919 797 euro (5th and 95th percentiles of the distribution: 18 325 050-19 552 080 euro). When a province gained the certification of freedom from disease, costs decreased on average by (median of the posterior distribution) 47.5%, 54.5% and 54.9% for the eradication programmes of tuberculosis, brucellosis and leucosis, respectively. Information on possible savings from the reduction of control costs can help policy makers operating under budget constraints to justify the use of additional resources for the final phase of eradication.

Control and eradication of tuberculosis in cattle: a systematic review of economic evidence.

Bovine tuberculosis (TB) is a disease of zoonotic importance for which control and eradication programmes have been carried out in many countries for decades. While the impact of these programmes on public health is still uncertain, the impact on trade is significant because of movement restrictions for animals, costs of testing and culling. The objective of this systematic review was to provide a contribution to the general debate over costs against benefits for the control and eradication of bovine TB in cattle. The search strategy was performed on four electronic databases following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The selection process, data abstraction and quality appraisal were carried out according to the Cochrane Collaboration guidelines. The search identified 66 articles out of which eight fulfilled the inclusion criteria. The evidence gathered in this review by combining the conclusions of the most methodologically sound articles supports the idea that, when multiple cost and benefit components are taken into account, efforts to control or eradicate bovine TB may be effective in reducing disease prevalence, economically viable and worth doing.

Cost-benefit analysis of vaccination against Mycobacterium avium ssp. paratuberculosis in dairy cattle, given its cross-reactivity with tuberculosis tests.

Johne's disease (JD), or paratuberculosis, is a chronic enteric disease of ruminants, caused by infection with Mycobacterium avium ssp. paratuberculosis (MAP). Johne's disease causes considerable economic losses to the US dairy industry, estimated to be over $200 million annually. Available control strategies include management measures to improve calf hygiene, test-and-cull strategies, and vaccination. Although the first 2 strategies have shown to reduce the prevalence of MAP, they require dedicated and long-term efforts from dairy producers, with often relatively slow progress. As a result, uptake of both strategies has not been as wide as expected given the economic benefits especially of improved hygiene. Vaccination has also been found to reduce the prevalence and economic losses of JD, but most economic estimates have been based on simulation of hypothetical vaccines. In addition, if an animal is vaccinated, cross-reactivity between MAP antibodies and bovine tuberculosis (BTB) antigens may occur, decreasing the specificity of BTB tests. Therefore, MAP vaccination would cause additional indirect costs to the BTB surveillance and control program. The objective of the present study was to use data from a MAP vaccine trial together with an epidemiologic and economic model to estimate the direct on-farm benefits of MAP vaccination and to estimate the indirect costs of MAP vaccination due to the cross-reactivity with BTB tests. Direct economic benefits of MAP vaccination were estimated at $8.03 (90% predictive interval: -$25.97 to $41.36) per adult animal per year, all accruing to the dairy producers. This estimate is likely an underestimation of the true direct benefits of MAP vaccination. In addition, indirect economic costs due to cross-reactivity were $2.14 per adult animal per year, making MAP vaccination economically attractive. Only in regions or states with a high frequency of BTB testing (because of, for example, Mycobacterium bovis outbreaks in a wild deer population) and areas where typically small groups of animals are BTB tested would MAP vaccination not be economically attractive.

Risk-based testing of imported animals: A case study for bovine tuberculosis in The Netherlands.

In intra-EU trade, the health status of animals is warranted by issuing a health certificate after clinical inspection in the exporting country. This certificate cannot provide guarantee of absence of infection, especially not for diseases with a long incubation period and no overt clinical signs such as bovine tuberculosis (bTB). The Netherlands are officially free from bTB since 1999. However, frequent reintroductions occurred in the past 15 years through importation of infected cattle. Additional testing (AT) of imported cattle could enhance the probability of detecting an imported bTB infection in an early stage. The goal of this study was to evaluate the effectiveness of risk-based AT for bTB in cattle imported into The Netherlands. A generic stochastic import risk model was developed that simulates introduction of infection into an importing country through importation of live animals. Main output parameters are the number of infected animals that is imported (Ninf), the number of infected animals that is detected by testing (Ndet), and the economic losses incurred by importing infected animals (loss). The model was parameterized for bTB. Model calculations were optimized to either maximize Ndet or to minimize loss. Model results indicate that the risk of bTB introduction into The Netherlands is very high. For the current situation in which Dutch health checks on imported cattle are limited to a clinical inspection of a random sample of 5-10% of imported animals, the calculated annual Ninf=99 (median value). Random AT of 8% of all imported cattle results in Ndet=7 (median value), while the median Ndet=75 if the sampling strategy for AT is optimized to maximize Ndet. However, in the latter scenario, loss is more than twice as large as in the current situation, because only calves are tested for which cost of detection is higher than the expected gain of preventing a possible outbreak. When optimizing the sampling strategy for AT to minimize loss, only breeding and production cattle are selected for AT resulting in Ndet=1 (median value). Loss is; however, reduced by 75% if compared to the current situation. We conclude that the effectiveness of AT can greatly be improved by risk-based sampling. The optimal sampling strategy for risk-based AT for bTB is highly dependent on the objective of AT. If economic losses are to be contained, AT should focus on breeding and production cattle originating from high-risk countries.

Minimum cost to control bovine tuberculosis in cow-calf herds.

Bovine tuberculosis (bTB) outbreaks in US cattle herds, while rare, are expensive to control. A stochastic model for bTB control in US cattle herds was adapted to more accurately represent cow-calf herd dynamics and was validated by comparison to 2 reported outbreaks. Control cost calculations were added to the model, which was then optimized to minimize costs for either the farm or the government. The results of the optimization showed that test-and-removal costs were minimized for both farms and the government if only 2 negative whole-herd tests were required to declare a herd free of infection, with a 2-3 month testing interval. However, the optimal testing interval for governments was increased to 2-4 months if the model was constrained to reject control programs leading to an infected herd being declared free of infection. Although farms always preferred test-and-removal to depopulation from a cost standpoint, government costs were lower with depopulation more than half the time in 2 of 8 regions. Global sensitivity analysis showed that indemnity costs were significantly associated with a rise in the cost to the government, and that low replacement rates were responsible for the long time to detection predicted by the model, but that improving the sensitivity of slaughterhouse screening and the probability that a slaughtered animal's herd of origin can be identified would result in faster detection times.

Minimization of bovine tuberculosis control costs in US dairy herds.

The objective of this study was to minimize the cost of controlling an isolated bovine tuberculosis (bTB) outbreak in a US dairy herd, using a stochastic simulation model of bTB with economic and biological layers. A model optimizer produced a control program that required 2-month testing intervals (TI) with 2 negative whole-herd tests to leave quarantine. This control program minimized both farm and government costs. In all cases, test-and-removal costs were lower than depopulation costs, although the variability in costs increased for farms with high holding costs or small herd sizes. Increasing herd size significantly increased costs for both the farm and the government, while increasing indemnity payments significantly decreased farm costs and increasing testing costs significantly increased government costs. Based on the results of this model, we recommend 2-month testing intervals for herds after an outbreak of bovine tuberculosis, with 2 negative whole herd tests being sufficient to lift quarantine. A prolonged test and cull program may cause a state to lose its bTB-free status during the testing period. When the cost of losing the bTB-free status is greater than $1.4 million then depopulation of farms could be preferred over a test and cull program.

Diminishing returns in bovine tuberculosis control.

Mycobacterium bovis causes bovine tuberculosis (bTB) in many mammals including cattle, deer and brushtail possum. The aim of this study was to estimate the strength of association, using model selection (AICc) regression analyses, between the proportion of cattle and farmed deer herds with bTB in New Zealand and annual costs of TB control, namely disease control in livestock, in wildlife or in a combination of the two. There was more support for curved (concave up) than linear models which related the proportion of cattle and farmed deer herds with bTB to the annual control costs. The curved, concave-up, best-fitting relationships showed diminishing returns with no positive asymptote and implied TB eradication is feasible in New Zealand.

Cost estimate of bovine tuberculosis to Ethiopia.

While bovine tuberculosis (BTB) has been eliminated in some industrialized countries, it prevails worldwide, particularly in Africa. In Ethiopia, BTB is prevalent as numerous studies have shown its occurrence in livestock and in abattoirs but it has not been demonstrated in wildlife and only very few cases have been found in humans. The objective of this study is to estimate the cost of BTB to Ethiopia with the aim of informing Ethiopian policy on options for BTB control. BTB in livestock affects both animal productivity and herd demographic composition. The Livestock Development Planning System (LDPS2, FAO) was modified to allow for stochastic simulation of parameters. We performed an incremental cost of disease analysis, comparing livestock production with and without BTB. For the rural scenario we considered an endemically stable 4 % comparative intradermal test (CIDT) prevalence and for the urban scenario an endemically stable 32 % CIDT prevalence among cattle. The net present value of rural Ethiopian livestock products in 2005 is estimated at 65.7 billion (thousand million) Ethiopian Birr (95 % Confidence Interval (CI) 53.8-77.7 billion Birr), which is the equivalent of 7.5 billion US$ (95 %CI 6.1-8.9 billion US$) at a rate of 8.7 Birr per US$ in 2005. The cost of BTB ranges from 646 million Birr (75.2 million US$) in 2005 to 3.1 Billion Birr in 2011 (358 million US$) but is within the range of uncertainty of our estimate and can thus not be distinguished from zero. The cost of disease in the urban livestock production ranges from 5 to 42 million Birr (500,000-4.9 million US$) between 2005 and 2011 but is also within the range of uncertainty of our estimate. Our study shows no measurable loss in asset value or cost of disease due to BTB in rural and urban production systems in Ethiopia. This does not mean that there is not a real cost of disease, but the variability of the productivity parameters and prices are high and would require more precise estimates. This study does not preclude in any way the urgent need to control BTB in the urban dairy herd of Addis Ababa for other than financial reasons.

Modelling the feasibility of bovine tuberculosis eradication in Argentina.

The ability of countries to control and eradicate bovine tuberculosis (TB) has been jeopardised by various epidemiological and ecological features of the disease. The authors have used epidemiological modelling to develop an analytical framework to assess the likely success of a national TB eradication programme in Argentina. Study results suggest that the current control programme is financially feasible in the long term. However, considering that the costs of the TB eradication programme in Argentina are entirely borne by the producer, the initial investment required and the long-term horizon needed to gain revenue may prevent producers from endorsing the programme. Regionalised programmes that allow differential control strategies to be implemented in specific regions may increase the likelihood of success. This methodological approach could be extended to design and evaluate control and eradication programmes for TB and other infectious diseases in other regions of the world.

Management of bovine tuberculosis in Michigan wildlife: current status and near term prospects.

Surveillance and control activities for bovine tuberculosis (bTB) in free-ranging Michigan white-tailed deer (Odocoileus virginianus) have now been underway for over a decade. Significant progress has been made, lowering apparent prevalence in deer in the core area by >60%, primarily via reduction of deer densities through hunting, and restrictions on public feeding and baiting of deer. These broad strategies of the Michigan Department of Natural Resources (MDNR), implemented with the cooperation of Michigan deer hunters, halved the deer population in the bTB endemic area. However, as hunters see fewer deer, their willingness to sustain aggressive harvests has waned, and public resentment of control measures has grown. During the past four years, apparent prevalence in core area deer has held approximately steady just below 2%. After bottoming out in 2004 at an estimated 10-12 deer/km(2), deer numbers have since rebounded by ∼ 30%. Public compliance with baiting and feeding restrictions has been variable. In general, hunters in the core area do not perceive bTB as a problem, in spite of 13 years of MDNR outreach. To date, MDNR has expended more than US$23 million on TB-related activities. Of late, a substantial portion of that funding has been diverted to support other programs which have suffered from budget shortfalls. Livestock herd breakdowns continue to occur sporadically, averaging 3-4 per year 2005 to present. In total, 46 cattle and 4 captive deer herds have been diagnosed bTB positive statewide, the majority yielding only 1 positive animal. Five cattle herds were twice infected, one thrice. Michigan Department of Agriculture (MDA) policy emphasis has shifted towards obtaining producer support for wildlife risk mitigation and farm biosecurity. Funding has proven a limiting factor, with the majority of the US$63 million spent to date devoted to whole herd testing. Nevertheless, some initiatives justify cautious optimism. Promising research to support eventual vaccination of wild deer continues. Some hunters and landowners have begun to recognize the costs of high deer densities and supplemental feeding. A peninsula-wide ban on baiting and feeding was enacted. Some cattle producers, recognizing their precarious circumstances, have begun work to change long-held prevailing opinions among their peers about farm biosecurity. Yet formidable challenges remain, and evidence suggests that eradication of bTB, if it can be achieved, will take decades, and will require greater public and political resolve than has been demonstrated thus far.

Cost-benefit analysis model of badger (Meles meles) culling to reduce cattle herd tuberculosis breakdowns in Britain, with particular reference to badger perturbation.

Bovine tuberculosis (TB) is an important economic disease. Badgers (Meles meles) are the wildlife source implicated in many cattle outbreaks of TB in Britain, and extensive badger control is a controversial option to reduce the disease. A badger and cattle population model was developed, simulating TB epidemiology; badger ecology, including postcull social perturbation; and TB-related farm management. An economic cost-benefit module was integrated into the model to assess whether badger control offers economic benefits. Model results strongly indicate that although, if perturbation were restricted, extensive badger culling could reduce rates in cattle, overall an economic loss would be more likely than a benefit. Perturbation of the badger population was a key factor determining success or failure of control. The model highlighted some important knowledge gaps regarding both the spatial and temporal characteristics of perturbation that warrant further research.

Herd size and bovine tuberculosis persistence in cattle farms in Great Britain.

Bovine tuberculosis (bTB) infection in cattle is one of the most complex and persistent problems faced by the cattle industry in Great Britain today. While a number of factors have been identified as increasing the risk of infection, there has been little analysis on the causes of persistent infection within farms. In this article, we use the Cattle Tracing System to examine changes in herd size and VetNet data to correlate herd size with clearance of bTB. We find that the number of active farms fell by 16.3% between 2002 and 2007. The average farm size increased by 17.9% between 2002 and 2005. Using a measure similar to the Critical Community Size, the VetNet data reveal that herd size is positively correlated with disease persistence. Since economic policy and subsidies have been shown to influence farm size, we used a simple financial model for ideal farm size which includes disease burden to conclude that increasing herd size for efficiency gains may contribute to increased disease incidence.