An economic model to evaluate the mitigation programme for bovine viral diarrhoea in Switzerland

Economic analyses are indispensable as sources of information to help policy makers make decisions about mitigation resource use. The aim of this study was to conduct an economic evaluation of the Swiss national mitigation programme for bovine viral diarrhoea virus (BVDV), which was implemented in 2008 and concludes in 2017. The eradication phase of the mitigation programme comprised testing and slaughtering of all persistently infected (PI) animals found. First, the whole population was antigen tested and all PI cattle removed. Since October 2008, all newborn calves have been subject to antigen testing to identify and slaughter PI calves. All mothers of PI calves were retested and slaughtered if the test was positive. Antigen testing in calves and elimination of virus-carriers was envisaged to be conducted until the end of 2011. Subsequently, a surveillance programme will document disease freedom or detect disease if it recurs. Four alternative surveillance strategies based on antibody testing in blood from newborn calves and/or milk from primiparous cows were proposed by Federal Veterinary Office servants in charge of the BVDV mitigation programme. A simple economic spreadsheet model was developed to estimate and compare the costs and benefits of the BVDV mitigation programme. In an independent project, the impact of the mitigation programme on the disease dynamics in the population was simulated using a stochastic compartment model. Mitigation costs accrued from materials, labour, and processes such as handling and testing samples, and recording results. Benefits were disease costs avoided by having the mitigation programme in place compared to a baseline of endemic disease equilibrium. Cumulative eradication costs and benefits were estimated to determine the break-even point for the eradication component of the programme. The margin over eradication cost therefore equalled the maximum expenditure potentially available for surveillance without the net benefit from the mitigation programme overall becoming zero. Costs of the four surveillance strategies and the net benefit of the mitigation programme were estimated. Simulations were run for the years 2008-2017 with 20,000 iterations in @Risk for Excel. The mean baseline disease costs were estimated to be 16.04m CHF (1 Swiss Franc, CHF=0.73 € at the time of analysis) (90% central range, CR: 14.71-17.39m CHF) in 2008 and 14.89m CHF (90% CR: 13.72-16.08m CHF) in 2009. The break-even point was estimated to be reached in 2012 and the margin over eradication cost 63.15m CHF (90% CR: 53.72-72.82m CHF). The discounted cost for each surveillance strategy was found to be smaller than the margin, so the mitigation programme overall is expected to have a positive net economic benefit irrespective of the strategy adopted. For economic efficiency, the least cost surveillance alternative must be selected.     

Eradication of Aujeszky's disease from a large-scale pig farm

Eradication of Aujeszky's disease from a large-scale pig farm by the 'test-and-cull' eradication procedure based on the use of gene-deleted vaccines and serological monitoring using gE ELISA is described. Aujeszky's disease free status was successfully achieved on a farrow-to-finish type farm characterised by three difficulties interfering with the success of eradication: (i) weaned (30-day-old) piglets remained in the farrowing house until 65 days of age; (ii) the farm did not use nursery rearing; (iii) fatteners were kept together with the breeding gilts. Thus, the immunisation programme had to be adjusted to the management technology used on the farm, and by regular serological monitoring it had to be periodically modified to make it suitable for attaining the goals. This meant that breeding animal candidates of a wide age range and kept in the same air space had to be provided with a continuously high-level immunity by regular vaccination sufficient even for rectifying potential human errors. The immunisation programme was designed by taking into consideration the disappearance of maternal immunity, and a strict vaccination programme was applied during the rearing of breeding gilts kept together with the fattening pigs. Frequent immunisation applied during the rearing of the own breeding animal replacements proved to be of decisive importance for the eradication of Aujeszky's disease from the entire herd. In addition to the accurate implementation of the vaccination programme, regular serological monitoring also made a major contribution to the success of eradication.     

Eradication programme for bovine viral diarrhoea virus in Orkney 2001 to 2008

The strategies used and the results obtained in Orkney's bovine viral diarrhoea virus (BVDV) eradication programme over eight years (2001 to 2008) are presented and discussed. The venture was undertaken by local veterinary practices and the Orkney Livestock Association (OLA) with the financial support of the Orkney Islands Council. Participation is voluntary; the programme comprises screening of youngstock, a whole-herd test if required, elimination of persistently infected animals and strict biosecurity measures and/or vaccination. BVDV-free herds are certified, and certification is updated annually by retesting the youngstock. The programme aims to minimise economic losses, thereby increasing the competitiveness of the Orcadian cattle industry and to improve animal health and welfare by eliminating virus circulation. Information from databases of the Scottish Agricultural College, Biobest Laboratories and OLA show that despite a significant reduction in the overall prevalence of BVDV on Orkney during the initial stages of the eradication programme, there has been little progress made since 2006 and that some difficulties have been encountered, with herd BVDV breakdowns following initial eradication. These results highlight the need for continued motivation of farmers, strict application of biosecurity measures and/or systematic vaccination of all seronegative breeding animals.     

Animal welfare and ethical issues relevant to the humane control of vertebrate pests

Vertebrate pests and pest control impact on people, animals and the environment, so any ethical consideration of vertebrate pest control must incorporate the interests of all three. The necessity of intervention, whether it involves killing animals or not, must be properly evaluated. Justification for pest control is only tenable if all of the negative impacts (harms) on people, animals and the environment are minimised and all of the positive impacts (benefits) are maximised as far as can be feasibly achieved. In all cases, the most humane control methods possible must be used; we must actively seek ways to improve the humaneness of existing methods and to find new methods that are more humane. There are six major principles that guide the design and execution of ethically sound vertebrate pest control programmes. (1) The aims or benefits and the harms of each control programme must be clear. (2) Control must only be undertaken if the aims can be achieved. (3) The methods that most effectively achieve the aims of the control programme must be used. (4) The methods must be applied in the best possible way. (5) Whether or not each control programme actually achieved its precise aim must be assessed. (6) Once the desired aims or benefits have been achieved, steps must be taken to maintain the beneficial state. An ideal pest control method would be effective and easy to use, affordable, safe for human users and for people exposed to it, humane, specific to the target species or individuals, and safe for the environment. Although such a gold standard is difficult to achieve, we can only retain ethical credibility if we conscientiously strive to make incremental improvements towards that gold standard.     

Eradication of Mycoplasma hyopneumoniae from infected swine herds joining the LSO 2000 health class

The study was conducted in order to determine if eradication of swine enzootic pneumoniae (SEP) had succeeded with different variants of partial depopulation during the eradication programme on swine farrowing farms joining a health class, LSO 2000. The farms in the health class need to be free from swine enzootic pneumoniae, swine dysentery, sarcoptic mange and atrophic rhinitis. Twenty-one eradication attempts for M. hyopneumoniae were carried out using different variants based on separating adult animals for 2 weeks from infected young pigs which were not returned to the herd. The infected young pigs were kept in the same building (variant 1) in 4 herds and on the same compound (variant 2) as disease-free pigs in 12 herds. The infected young pigs were finally all sold. In 5 herds only adult animals were present during the eradication (variant 3). The eradication attempt succeeded in 81% and failed or remained uncertain in 19% of the herds. The result was confirmed with 1) frequent clinical follow-up of the health status in the herds (both the farrowing and the finishing units) joining the LSO 2000 health class 2) milk and/or blood serology. Possible causes of the failure of the eradication attempt were described: a short distance between infected and uninfected animals, the time period between diagnosis of SEP and initiation of the programme, the age of the youngest animal kept on the farm, the period of time when animals with different status were reared close to each other, the medications used, the cleaning of the facilities during the programme and the season. Further, a good cooperation between the farmer, the local veterinarian and the animal health service of the slaughterhouse was an essential part of the initiation and the follow-up of the programme. The secondary aim of the study was to collect information about the expenses during the programme. Only 57% of the farmers gave some estimates for the expenses on their farms. For variants 1, 2 and 3 the expenses were 879, 1110 and 1274 FIM per sow (1 USD = 5.5 FIM), respectively (p > 0.1).     

The control of bovine leukosis in denmark, Epidemiologic and diagnostic aspects.

The Danish programme to control bovine enzootic leukosis was initiated in 1959 and intensified in 1969. The programme has resulted in a sharp decline in total and relative numbers of leukotic tumor cases in adult animals. However, total eradication of bovine leukosis has not yet been achieved, and the statistics from recent years seem to indicate that the present programme based on haematological and histological examinations will control but not eradicate the disease. An immunodiffusion test based on an internal protein (p 24) antigen has been used experimentally. This test is a valuable tool in herd diagnosis, but it is not sensitive enough for accurate single animal diagnosis.     

Automation of data processing

Data processing can be time‐consuming when experiments with advanced designs are employed. This, coupled with a shortage of research workers, necessitates automation. It is suggested that with automation the first step is to determine how the data must be analysed. The second step is to determine what programmes are available. If a programme is not available it will be necessary to write a new programme. An example of research work where both animal and botanical data are analysed, is given.     

Veterinary epidemiology--a key to sustainable pig production in Switzerland

Sustainable animal production requires a healthy production system including healthy animals producing wholesome products. Epidemiology as a discipline is concerned with the occurrence of disease or disease indicators in populations as well as with factors influencing disease occurrence. By providing this information, epidemiology contributes significantly to the development and maintenance of healthy livestock. This is illustrated with the example of the enzootic pneumonia (EP) eradication programme of Switzerland. A series of observational studies were conducted in order to obtain the necessary knowledge to implement an area-wide EP eradication programme. The issues of economical eradication strategies at the herd level and the risk of re-infections were addressed. Simulation modelling and economical analysis were also applied. These research projects led to the successful start of a national eradication programme. The example of the EP eradication programme illustrates that applied epidemiological research provides critical information for the planning, implementation and evaluation of disease control programmes and is thus a key tool in developing sustainable animal production.     

Eradication of targeted species of internal parasites

Eradication can be defined as the permanent reduction to zero of the incidence of infection caused by a specific agent as a result of deliberate efforts. Eradication strategies must be designed to increase access to and utilization of veterinary and animal health support services beyond that normally achieved by routine services. Consequently, before undertaking an eradication program, proponents must be certain that they can be sure of a commitment of resources sufficient to complete the project. A helminth eradication campaign would require the application of anthelmintics to all hosts at a level aimed at killing heterozygote resistant individuals. This strategy runs counter to the prevailing opinion that resistance to chemicals will always occur and control schemes should accept some production loss by letting a proportion of parasites escape selection (in refugia) and thereby increase the useful life of the chemical. Under certain circumstances, environmental constraints may make some species of parasitic nematodes vulnerable to an eradication program. Anthelmintics have been used to exploit these constraints in past control programs and have lead to local eradication of several species of gastro-intestinal parasitic nematodes. Also, there are at present eradication programs for nematode parasites of human that are based on anthelmintic treatment. However, the suppressive pesticide treatment required to bring about the virtual elimination of species is a high-risk strategy and should only be undertaken if eradication is an achievable goal. It is also important to plan an exit strategy if eradication fails.     

Dynamics of infection and immunity in a dairy cattle population undergoing an eradication programme for Infectious Bovine Rhinotracheitis (IBR)

Several countries within the European Union (EU) have successfully eradicated Infectious Bovine Rhinotracheitis (IBR), while others (e.g. Germany) are making efforts to achieve IBR-free status. EU member states IBR eradication programmes must meet Community legislation requirements that ban breeding farms from purchasing positive animals, from using whole-virus IBR vaccines, and from inseminating cows with semen from positive bulls. A follow-up study from 2002 to 2005 was carried out in the province of Trento (Italy), where a compulsory programme for IBR eradication was started in 1998. IBR outbreaks (identified on the basis of seroconversion of sentinel animals) were concentrated in larger positive herds. A higher incidence was recorded between 2003 and 2004. An association between markedly high temperatures in the summer of 2003 and virus reactivation has been suggested but is yet to be confirmed. The practice of driving cattle to common alpine pastures for the summer season did not play a significant epidemiological role in IBR transmission. Premising that only seronegative animals are allowed to enter dairy farms, animal movement increases the infection risk to a moderate extent. The long-term persistence of IBR antibodies was more pronounced in animals positive for antibodies to the glycoprotein E (gE). Scattered seroconversions, occurring mostly in positive herds, require careful interpretation in order to avoid overestimating the incidence of the infection at herd level.     

Non-technical constraints to eradication: the Italian experience

Although technical constraints to eradication of bovine tuberculosis are well-recognised, non-technical constraints can also delay progress towards eradication, leading to inefficiency and increased programme costs. This paper seeks to analyse the main non-technical constraints that can interfere with the successful implementation of tuberculosis eradication plans, based on experiences from an area of high tuberculosis prevalence in Regione Piemonte, Italy. The main social and economic constraints faced in the past 20 years are reviewed, including a social reluctance to recognise the importance of seeking eradication as the goal of disease control, effective communication of technical issues, the training and the organization of veterinary services, the relationship between the regional authority and farmers and their representatives, and data management and epidemiological reporting. The paper analyses and discusses the solutions that were applied in Regione Piemonte and the benefits that were obtained. Tuberculosis eradication plans are one of the most difficult tasks of the Veterinary Animal Health Services, and non-technical constraints must be considered when progress towards eradication is less than expected. Organizational and managerial resources can help to overcome social or economic obstacles, provided the veterinary profession is willing to address technical, but also non-technical, constraints to eradication.     

Bovine viral diarrhea (BVD) eradication in Switzerland--experiences of the first two years

A national eradication programme was designed with the aim of achieving total freedom from bovine viral diarrhea virus (BVDV) infection in the Swiss cattle population. The eradication programme consisted of testing every Swiss bovine for antigen, culling virus-positive animals and applying movement restrictions. Starting in 2008, the campaign achieved the goal of reducing the proportion of newborn calves that were virus-positive from 1.8% to under 0.2% within two years (situation in September 2010). Both good data flow between the parties involved as well as speed and efficiency (e.g. concerning the application of tests, movement restrictions and slaughter) are central to the success of the programme. Since the beginning of the programme 2.85 million cattle have been tested for bovine viral diarrhea virus (BVDV). The BVD-prevalence in cattle at the individual and herd levels following the implementation of the eradication programme was assessed. Using data collected during this campaign a risk factor analysis was conducted in order to identify factors associated with the appearance of virus positive newborn calves in herds where BVD had not previously been detected; these risk factors would allow targeting of future surveillance. Herd size, early death rate (i.e. the number of animals that either die before 15 days of age or are stillborn per number of newborns per year), buying in stock, using communal summer grazing, production type, age structure and management strategy were factors associated with the appearance of new cases of infection. Testing of newborn calves for antigen will continue to be conducted until the end of 2011, this is combined with outbreak investigation of newly infected herds (consisting of re-testing dams of virus-positive calves and if necessary all cattle on or that recently left the farm). This process is done to identify infected animals that may have been missed during prior testing (false negatives), it also serves to identify other factors that may be responsible for the introduction of BVDV onto the farm. Since October 2009, testing of calves for antigen combined with outbreak investigation has led to the detection of 55 infected animals that had tested negative (presumably false negative) during previous rounds of testing.     

gIII antibody responses in pigs following vaccination and challenge to Aujeszky's disease.

Serological responses to a genetically engineered Aujeszky's disease "marker" vaccine (dl gIII + dl tk) were monitored using a blocking-ELISA (B-ELISA), a serum neutralisation test (SNT) and an indirect ELISA (I-ELISA). The B-ELISA is capable of differentiating pigs vaccinated with the above vaccine from natural infection. The SNT and the I-ELISA indicated that the pigs responded to vaccination and challenge. All three tests showed that the controls and the in-contact pigs always reacted negative for antibodies. The B-ELISA was able to detect pigs challenged with a field isolate 24 days post-challenge. These pigs remained positive until 110 days post-challenge when last tested. These findings indicate that the B-ELISA could be used successfully with this vaccine in a control eradication programme. This trial also shows that the vaccine virus did not spread to the in-contact pigs and also the vaccinated and challenged pigs did not transmit the disease to other susceptible pigs when they were introduced 14 days after challenge.     

Eradication of porcine sarcoptic mange within a health declared production model

The success of a large-scale eradication programme against sarcoptic mange was evaluated in piglet producing herds belonging to the health class LSO 2000. These farms are monitored to be free from sarcoptic mange, swine enzootic pneumoniae, swine dysentery and progressive atrophic rhinitis. The local veterinarians were instructed to eradicate sarcoptic mange from the herds by 2 ivermectin injections 14 days apart or 3 treatments with phoxim pour-on 6 days apart before the farms were able to join the health class. The study consisted of a questionnaire administered to the farmers, farm visits and follow-ups associated with the regular control of the health class. A questionnaire was sent to all of the 379 accepted farrowing farms. Altogether 323 farmers had initiated an eradication programme at least 7 months before the questionnaire was distributed and 96% of them believed that the mange eradication programme had been successful. In most of the successful herds (90%), the local veterinarian had treated the animals by the recommended methods, and the majority of the farmers (88%) had cleaned and sprayed the pens with insecticides on the days of treatment. Three out of the 7 unsuccessful farms had employed methods other than those recommended. Twenty-five herds were randomly selected for an intensified control. The rubbing index was < or = 0.1 in all herds visited, indicating freedom from mange. Sows or gilts, 15-20 animals per farm, were skin scraped and no Sarcoptes scabiei was found. The same animals were blood sampled and serum antibodies to S. scabiei were measured by an indirect ELISA. All except 1 farm had low optical density (OD) values in most of the samples. The owner of that farm had become uncertain about the mange status of the herd and had recently retreated all animals with acaricides. The number of complaints about mange in the finishing units buying health class feeder pigs was low. The study demonstrates that it is possible to run an eradication programme against sarcoptic mange, in which a large number of farmers together with their veterinarians participate. It is possible to eradicate mange not only at the herd but also at the population level. The ELISA test employed proved to be a possible tool to monitor the efficacy of mange-eradication programmes.     

Experiences from the Danish programme for eradication of bovine virus diarrhoea (BVD) 1994-1998 with special reference to legislation and causes of infection

The main experiences from the Danish bovine virus diarrhoea (BVD) eradication programme over 5 years from 1994 to 1999 are presented. The last 3 years of the programme has been strongly supported by legislation. The most important regulations have been blood testing of live animals before movement to other herds, common pastures or exhibitions, and monitoring of all herds at regular intervals for the presence of the infection. Nevertheless, free herds have experienced infection, e.g., 204 dairy herds in 1998. Of herds found to be infected in the period from July 1997 through June 1998 after previously having been registered to be BVD-free, 67 herds were thoroughly investigated. Nineteen herds (28%) were found infected because of purchase of pregnant cows or heifers which delivered persistently infected (PI) calves, and 24 (36%) and two (3%) because of PI animals on neighbouring pastures or in neighbouring farm houses, respectively. In five herds (7%) pregnant heifers had become infected on one and the same common pasture, while in 17 herds (25%) no immediate cause of infection could be demonstrated. Yet, airborne spread from PI herds as a source of infection was suspected in some of these cases. It was furthermore concluded from investigations presented, that antibody-positive AI bulls were a remote but unlikely possibility. Free-living deer in Denmark had to be considered uninfected. Presence of PI-animals in sheep on infected farms has been seen and is paid attention to in individual cases. The results underline the need for legislation to be used in eradication programmes in areas with a high prevalence of infection and to be introduced right from the beginning in order to minimise the risk of infection for free herds.     

BVD approach: vaccination and eradication

The vulnerability of cattle populations that do not have adequate levels of antibodies against the bovine virus diarrhoea (BVD) virus was demonstrated in February 1999, when a contaminated vaccine against infectious bovine rhinotracheitis (IBR) was accidentally used. Only cattle with antibodies against BVD survived this unintentional challenge. A BVD infection can be detected easily with currently available laboratory techniques, but the virus is less easy to eliminate. The risk of financial loss is small, and the costs are limited, if mainly seronegative cattle, selected on the basis of sampling, are given the live vaccine. Over the last 7 years this approach has been applied to about twenty dairy farms. This approach would be compatible with a BVD eradication programme.     

Progress in tuberculosis eradication in Ireland

Ireland ran a conventional test and slaughter Bovine Tuberculosis eradication programme from 1954 until 1988. This programme fulfilled our trading requirements but failed to eradicate TB. At this point a major initiative, ERAD, was launched targeted with reducing the disease levels by half within a four-year period and devising the strategy and supports necessary to achieve final eradication. The lessons learned at that time have informed Ireland's eradication programme ever since. Eradication was not possible without developing solutions to address the wildlife disease reservoir and other identified constraints. Since 1992 the programme objectives have been restated. It is now effectively an interim control programme where significant resources have been invested in research and development aimed at overcoming the identified constraints to eradication. Policy is informed by science and debate among stakeholders is generally knowledgeable and balanced. This paper outlines developments in recent years and sets out our expectations for progress in the period ahead.     

Long-term study (2005–2010) on the vaccination with BoHV-1 glycoprotein E-deleted marker vaccine in selected two dairy herds in Turkey

A follow-up study from 2005 to 2010 was carried out in two herds where eradication programme for the bovine herpes virus-1 (BoHV-1) infection depends on the vaccination with inactivated glycoprotein E-deleted vaccine that was started in 2001 following the vaccination with inactivated conventional vaccine between 1999 and 2001. For serological screening, a total of 12,976 sera sampled over several sampling times approximately 6 months of interval during 5 years (2005–2010) were tested for glycoprotein E (gE)- and glycoprotein B-specific antibodies using ELISA. According to the serological evidence, the long-term persistence of BoHV-1 antibodies, success of marker vaccine, first vaccination time of the calves in herds regularly vaccinated, etc. were discussed in this paper. In conclusion, the vaccination programme using gE (?) marker vaccines, with making efforts to prevent the other factors about transmission of infection, was suggested for the eradication of BoHV-1 infection in Turkey as many EU countries. This is the first report on the BoHV-1 eradication programme in some dairy cattle in Turkey.     

Eradication of BHV-1 in cattle herds in Saxony-Anhalts using a vaccine lacking a marker--report of an experience

The present article reports about the experiences during the current BHV-1-eradication programme in Saxony-Anhalt started in 1996. An overview about the reasons, the basic situation, the issue and the present state of the eradication is given. Furthermore were shown, that an eradication of Bovine Herpes Virus type 1 by using gE-deleted vaccines is possible.     

Vaccination and eradication programme against Aujeszky's disease in five Swedish pig herds with special reference to herd owner attitudes

A vaccination eradication programme against Aujeszky's disease (AD), based on the use of gE-negative killed vaccine, was carried out between 1987 and 1992 in 5 Swedish weaner pig producing or farrow-to-finish herds, with 63 to 398 breeding animals. All breeding animals were tested at the start and the end of the programme. Seroprevalence to Aujeszky's disease virus (ADV) ranged between 47% and 100% in the herds at the first test. During the programme, all breeding animals were vaccinated simultaneously every 4 months and ADV-free replacement animals were vaccinated shortly after arrival and boostered within a month. In one herd only, a limited number of fatteners were vaccinated. The herds were declared free (gE-negative) 12 to 53 months after the start of the programme. When all seropositive breeding animals had been culled, the programme ended after 2 negative tests of the breeding animals. Seroconversion was limited in all herds but one, where initially no isolation unit was available for replacement animals. The attitude of the herd owners towards the programme and the special conditions prevailing in the herds are discussed. It is suggested that vaccination may promote risk behaviour of herd managers.