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1.
Carpenter TE 《American journal of veterinary research》2001,62(2):202-205
OBJECTIVE: To evaluate the application of a vaccine in a population of animals. SAMPLE POPULATION: Field-trial data from the literature. PROCEDURE: A spreadsheet simulation model was constructed to estimate the impact of a vaccination program, assuming various population sizes, transmission rates, and vaccine efficacies. RESULTS: Total effectiveness (proportion of affected animals [ie, cases] avoided) increased with the vaccinated proportion of the population. However, with a highly efficacious vaccine, this relationship discontinued after a sufficient vaccination proportion was reached, reflecting herd immunity. Evaluation of a case study indicated that what may be considered a poor vaccine on the basis of its low efficacy may protect a substantial portion of the population if the vaccine is administered to a sufficient number of susceptible animals. Further investigation of a case study of horses indicated that evaluating a vaccine based solely on its efficacy could greatly underestimate its value. CONCLUSIONS AND CLINICAL RELEVANCE: When evaluating a vaccine applied to a population, in addition to the vaccine efficacy, the vaccination rate, cost of the vaccine, potential disease transmission rate, and number and cost of cases avoided must also be considered. Efficacy may underestimate vaccine value in terms of the reduction of indirect cases typically avoided when vaccination is applied in a population. 相似文献
2.
Barnett P Garland AJ Kitching RP Schermbrucker CG 《Comparative immunology, microbiology and infectious diseases》2002,25(5-6):345-364
Emergency vaccination is one of several measures which may be deployed to control outbreaks of foot-and-mouth disease. It can be a valuable adjunct to the application of the essential zoosanitary controls which must include rapid diagnosis, tracing, movement control and disinfection and which may also include slaughter of infected and in-contact animals and their safe disposal. Criteria which determine the successful application of emergency vaccination include access to vaccine(s) that (i) contain virus strain(s) of sufficient antigenic relatedness to the outbreak strain(s) (ii) are of the required type of vaccine formulation (iii) have acceptable innocuity and potency (iv) have appropriate availability, including quantity and immediacy of supply and (v) meet considerations of cost. Contingency planning should include provision for emergency vaccination and must address the complex decisions of not only when, where, and how to apply vaccine but also its economic consequences. Computer modelling may be a useful aid to cost benefit and decision support systems in this context. Planning must be detailed and regularly reviewed and should ensure, (i) that the legal and financial aspects are catered for (ii) that any contractual supply agreements are in place (iii) that information is collected and its currency maintained on the species, numbers and whereabouts of susceptible livestock (iv) that vaccination teams are formed and trained (v) that the vaccine cold chain is established and maintained (vi) that supplies of vaccination equipment are held in readiness and (vii) that briefing materials are available to inform the various stakeholders on relevant aspects of emergency vaccination. Knowledge concerning the characteristics and performance of emergency vaccines is summarised and areas identified for further research. 相似文献
3.
Immunisation against listeriosis in sheep using a live, attenuated vaccine was introduced in Norway in 1984. Since then 65,000 to 80,000 animals have been vaccinated annually. Information obtained by a questionnaire showed that the incidence of listeriosis decreased from approximately 4.0 per cent before the introduction of the vaccine to 1.5 per cent after vaccination started. The incidence of abortions was 0.7 per cent in vaccinated flocks compared to 1.1 per cent in unvaccinated flocks. There were a few adverse reactions in the vaccinated sheep. 相似文献
4.
For decades researchers have been targeting prevention of Rhodococcus equi (Rhodococcus hoagui/Prescottella equi) by vaccination and the horse breeding industry has supported the ongoing efforts by researchers to develop a safe and cost effective vaccine to prevent disease in foals. Traditional vaccines including live, killed and attenuated (physical and chemical) vaccines have proved to be ineffective and more modern molecular‐based vaccines including the DNA plasmid, genetically attenuated and subunit vaccines have provided inadequate protection of foals. Newer, bacterial vector vaccines have recently shown promise for R. equi in the mouse model. This article describes the findings of key research in R. equi vaccine development and looks at alternative methods that may potentially be utilised. 相似文献
5.
强化犬只狂犬病免疫工作是从源头控制狂犬病的最有效措施。近年来,上海市按照《上海市养犬管理条例》的要求,通过严把免疫资质准入、规范内部管理、落实疫情报告责任、推进免疫质量考核等举措,使犬只狂犬病认定免疫点的布局日趋合理,文明服务更加规范,这已成为上海市民犬只狂犬病免疫的主渠道,免疫数量和质量逐年提升,构筑了良好的免疫屏障。今后在犬只狂犬病认定免疫点管理方面,上海市应强化疫苗源头管理,加大非法免疫惩处力度,合理认定免疫点整体布局,规范引导免疫行为和内部运行。 相似文献
6.
Vaccination against bovine tuberculosis is likely to become an important disease control strategy in developing countries, which cannot afford a test and slaughter control programme, or in countries which have a wildlife reservoir of Mycobacterium bovis infection. In the past decade, considerable progress has been made in the development and evaluation of tuberculosis vaccines for cattle and for a range of wildlife maintenance hosts including possums, badgers, deer and African buffaloes. Experimental challenge systems have been established for the different target species and the resulting disease process has mimicked that seen in the field. In cattle, neonatal vaccination with BCG appeared to be more effective than vaccination of 6-month-old calves and in most situations no other vaccine has been shown to be better than BCG. However, prime-boost strategies involving combinations of BCG with a protein or DNA vaccine, to improve on BCG vaccination alone, have produced very encouraging results. Differential diagnostic tests have been developed using mycobacterial antigens that are only present in virulent M. bovis to differentiate between BCG-vaccinated and M. bovis-infected cattle. BCG vaccine has been shown to reduce the spread of tuberculous lesions in a range of wildlife species and a prototype oral bait delivery system has been developed. Prospects for the development of improved vaccines against bovine tuberculosis are promising and vaccination approaches could become very valuable in the control and eradication of bovine tuberculosis. 相似文献
7.
OBJECTIVE: To assess relative costs and benefits of vaccination and preemptive herd slaughter to control transmission of foot-and-mouth disease (FMD) virus (FMDV). SAMPLE POPULATION: 2,238 herds and 5 sale yards located in Fresno, Kings, and Tulare counties of California. PROCEDURE: Direct costs associated with indemnity, slaughter, cleaning and disinfecting livestock premises, and vaccination were compared for various eradication strategies. Additional cost, total program cost, net benefit, and benefit-cost value (B/C) for each supplemental strategy were estimated, based in part on results of published model simulations for FMD. Sensitivity analyses were conducted. RESULTS: Mean herd indemnity payments were estimated to be dollars 2.6 million and dollars 110,359 for dairy and nondairy herds, respectively. Cost to clean and disinfect livestock premises ranged from dollars 18,062 to dollars 60,205. Mean vaccination cost was dollars 2,960/herd. Total eradication cost ranged from dollars 61 million to dollars 551 million. All supplemental strategies involving use of vaccination were economically efficient (B/C range, 5.0 to 10.1) and feasible, whereas supplemental strategies involving use of slaughter programs were not economically efficient (B-C, 0.05 to 0.8) or feasible. CONCLUSIONS AND CLINICAL RELEVANCE: Vaccination with a highly efficacious vaccine may be a cost-effective strategy for control of FMD if vaccinated animals are not subsequently slaughtered and there is no future adverse economic impact, such as trade restrictions. Although less preferable than the baseline eradication program, selective slaughter of highest-risk herds was preferable to other preemptive slaughter strategies. However, indirect costs can be expected to contribute substantially more than direct costs to the total cost of eradication programs. 相似文献
8.
口蹄疫是由口蹄疫病毒引起的偶蹄动物的一种急性、热性、高度接触性一类传染病,具有发病急、蔓延快、传播广、危害大等特点。我国对本病采取了100%注射疫苗强制免疫的措施,有效地控制了本病的发生及蔓延。然而在注苗免疫过程中,因个体差异等原因,个别家畜往往出现不同程度的过敏反应,有时因救治不及时或治疗方法不当造成死亡,给养殖户带来一定的经济损失,也影响了防疫工作的有效推进。文章通过一例牛口蹄疫免疫过敏病例的救治,介绍了牛在接种口蹄疫疫苗后可能出现的应激反应,并提出了解救措施,为及时、有效处理口蹄疫疫苗应激反应提供参考。 相似文献
9.
Baigent SJ Smith LP Nair VK Currie RJ 《Veterinary immunology and immunopathology》2006,112(1-2):78-86
Marek's disease is an economically important lymphoid neoplasm of chickens, caused by oncogenic strains of Marek's disease herpesvirus. The disease can be successfully controlled by vaccination with attenuated or non-pathogenic MDV strains. However, vaccine failures do occur as field strains continue to evolve towards pathotypes of greater virulence, and this evolution is likely to be driven by the vaccines themselves. Two general strategies can be considered to improve protection by vaccination. Firstly by the development of novel vaccines, and secondly by maximizing the potential of existing vaccines. This second goal requires investigation of optimal timing and vaccine delivery route, and optimal vaccination regimes for different breeds of chick. Accurate quantitation of Marek's disease vaccine virus in vaccinated chicks will contribute significantly to our understanding of vaccinal protection. We recently developed a real-time polymerase chain reaction (PCR) assay for quantitation of CVI988 vaccine virus in the feather tips, a rich source of viral DNA which can easily be sampled in a non-invasive manner. This PCR test is now used commercially to confirm the successful vaccination of chicks. We have also used the PCR to examine various aspects of vaccination in experimental chicks and commercial chicks with a view to determining how vaccine level in feathers correlates with protection against challenge, and for identifying optimal timing and vaccine delivery route, and optimal vaccination regimes for different breeds of chick. In this article we review some aspects of the current vaccinal control of Marek's disease, before highlighting some of the problems associated with current vaccines and vaccination strategies, and the challenges for the future. We go on to discuss the development and use of our real-time PCR feather test, its current applications and potential opportunities in Marek's disease vaccine research. 相似文献
10.
Häsler B Howe KS Di Labio E Schwermer H Stärk KD 《Preventive veterinary medicine》2012,103(2-3):93-111
Empirical analyses founded on sound economic principles are essential in advising policy makers on the efficiency of resource use for disease mitigation. Surveillance and intervention are resource-using activities directed at mitigation. Surveillance helps to offset negative disease effects by promoting successful intervention. Intervention is the process of implementing measures (e.g. vaccination or medication) to reduce or remove a hazard in a population. The scale and ratios in which the two are combined affect the efficiency of mitigation, its costs, benefits, and thus net effect on society's well-being. The Swiss national mitigation programme for bluetongue virus serotype 8 was used as case study to investigate the economic efficiency of mitigation. In 2008, Switzerland implemented a vaccination programme to avoid and reduce disease and infection in its ruminant population. To monitor the vaccination programme and the vector dynamics, a surveillance system consisting of serological and entomological surveillance was established. Retrospective analyses for the years 2008-2009 and prospective analyses for the years 2010-2012 were conducted to investigate if the mitigation programme was economically beneficial. In the retrospective analysis, the implemented programme (=comparative scenario) was compared to a hypothesised baseline scenario of voluntary vaccination and surveillance. In the prospective analysis, the comparative scenario assumed to continue was compared to two baseline scenarios: one of voluntary vaccination combined with surveillance and one of no vaccination combined with surveillance. For each scenario, monetary surveillance, intervention and disease costs were calculated. The comparison of baseline and comparative scenarios yielded estimates for the total benefit (=disease costs avoided), margin over intervention cost and the net value of the programme. For 2008-2009, in aggregate, the mean biannual total benefit was 17.46 m Swiss francs (CHF) (1CHF=0.66€ at the time of analysis) and the mean net benefit after subtraction of the intervention and surveillance cost was 3.95 m CHF. For the three years 2010-2012, overall net costs were estimated at 12.93 m and 8.11 m CHF, respectively, for comparison of the implemented mitigation programme with the two baseline scenarios. It was concluded that the surveillance and intervention programme implemented in 2008-2009 was economically beneficial, while its continuation in the same form in 2010-2012 would produce net costs. These costs were due to the mean intervention cost remaining constant at a level of approximately 11 m CHF per year while the mean total benefit would be gradually reduced in 2010-2012 due to the reduced occurrence of disease in a fully vaccinated population. 相似文献
11.
Lindahl Johanna F. Young Jarrah Wyatt Amanda Young Mary Alders Robyn Bagnol Brigitte Kibaya Augustino Grace Delia 《Tropical animal health and production》2019,51(1):213-220
Poultry are important for many poor households in developing countries, but there are many constraints to poultry production, including disease. One of the most important diseases of chickens is Newcastle disease (ND). Even though there are effective vaccines against this disease available in most countries, uptake by small-scale poultry keepers is often low. In this study, two areas in Kenya and Tanzania were studied, where some villages had received additional support to get vaccination and other villages had not. In Kenya, 320 households from 10 villages were interviewed, of which half of the villages had active promotion of vaccination through village-based advisors. In Tanzania, 457 households were interviewed, of which 241 came from villages that have had active support through either a project or government extension services. Knowledge about vaccines and the attitudes towards vaccinating against ND was evaluated using mixed multivariable logistic models. Results indicate that in Kenya, the most important determinants for understanding the function of a vaccine were having had support in the village and to have knowledge about ND signs, while in Tanzania gender and previous vaccine use were important in addition to having had support. Attitudes towards vaccination were mainly determined by knowledge, where more knowledge about how vaccines work in general or about ND contributed to more positive attitudes. Among Kenyan farmers that had never used the vaccine before, the amount of birds they lost to disease and predators also influenced attitudes. In conclusion, this study supports the notion that knowledge is a very important component of extension support and that simply making vaccines available may not be sufficient for high levels of uptake.
相似文献12.
Michael Muleme Robert Barigye Margaret L. Khaitsa Eugene Berry Anthony W. Wamono Chrisostom Ayebazibwe 《Tropical animal health and production》2012,45(1):35-43
Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals. In Uganda, FMD outbreaks are mainly controlled by ring vaccination and restriction of animal movements. Vaccination stimulates immunity and prevents animals from developing clinical signs which include lameness, inappetence, and decreased production. Ring vaccination and restriction of animal movements have, however, not successfully controlled FMD in Uganda and outbreaks reoccur annually. The objective of this study was to review the use of FMD virus (FMDV) vaccines and assess the effectiveness of vaccination programs for controlling FMD in Uganda (2001–2010), using retrospective data. FMD vaccine distribution patterns in Uganda (2001–2010) matched occurrence of outbreaks with districts reporting the highest number of outbreaks also receiving the largest quantity of vaccines. This was possibly due to “fire brigade” response of vaccinating animals after outbreaks have been reported. On average, only 10.3 % of cattle within districts that reported outbreaks during the study period were vaccinated. The average minimum time between onset of outbreaks and vaccination was 7.5 weeks, while the annual cost of FMDV vaccines used ranged from US $58,000 to 1,088,820. Between 2001 and 2010, serotyping of FMD virus was done in only 9/121 FMD outbreaks, and there is no evidence that vaccine matching or vaccine potency tests have been done in Uganda. The probability of FMDV vaccine and outbreak mismatch, the delayed response to outbreaks through vaccination, and the high costs associated with importation of FMDV vaccines could be reduced if virus serotyping and subtyping as well as vaccine matching were regularly done, and the results were considered for vaccine manufacture. 相似文献
13.
Canine parvovirus (CPV) is a highly contagious cause of serious and often fatal disease in dogs worldwide despite the availability of safe and efficacious vaccines. Although a number of studies have focussed on identifying risk factors in disease development, risk factors associated with death from CPV are largely unknown. In this study we analysed a total of 1451 CPV cases reported from an Australian surveillance system - using univariate and multivariate techniques - to determine significant risk factors associated with death and euthanasia. A crude case fatality rate of 42.3% was estimated - higher than has been reported previously. We found that 3.3% of CPV cases had a history of vaccination in the previous 12 months, despite having completed the primary puppy vaccination course. The majority (89.5%) of these cases occurred in dogs <12 months of age, indicating failure of the primary vaccination course to provide protective immunity (most likely due to interference of the vaccine antigen with maternal antibodies but other reasons are discussed). Extending the age at which the final puppy vaccination is administered might be one of several strategies to consider. The final multivariate model showed that in non-litter CPV cases, risk of death was significantly associated with season of diagnosis (summer) and pedigree type (hounds and non-sporting dogs). Euthanasia in non-litter CPV cases was significantly associated with season of diagnosis (summer), state of residence (Northern Territory/South Australia/Tasmania combined), age (相似文献
14.
Emphasis is given essentially to the presentation of recent data in terms of our total knowledge of Listeria and human and animal listeriosis. This disease of extremely varied origin can be studied in terms of two groups of subjects: females in gestation and all other categories of individuals. There was initially only a single species of Listeria, but at least five are known today, only two of which are pathogenic. Their pathogenic power is related essentially to the presence of listerolysin O, although this is not the only factor involved. Identification of Listeria is easy and can be completed with that of its serovar and lysovar. Epidemiological studies have shown that the great majority of listeriosis are anademic. The contamination of receptive subjects is due to certain forms of food. In the absence of efficient vaccination, disease prevention must be obtained by eliminating Listeria from food. 相似文献
15.
A. Zhang J.R. Young S. Suon K. Ashley P.A. Windsor R.D. Bush 《Tropical animal health and production》2017,49(4):791-806
Porcine reproductive and respiratory syndrome (PRRS) was first identified in Cambodia in 2010, causing serious problems on affected farms, although the costs of the disease have not been well defined. The household financial impact of a PRRS outbreak in Cambodia was investigated using partial budget analysis, examining the economic benefit of three proposed interventions: (i) quarterly PRRS vaccine use, (ii) biosecurity implementation, and (iii) implementation of vaccination and biosecurity. The analyses were applied to three farm models: (i) a two-sow breeder; (ii) a five-pig fattener; and (iii) a single-sow, three-pig farrow-to-finish/breeder. Data was derived from a knowledge, attitude, and practice survey of 240 smallholder farmers (61 with pigs) from 16 villages across 5 provinces, plus case studies of 12 farmers selected for more detailed financial analysis. The study indicated that financial losses associated with PRRS were severe, with a 25% mean loss to the annual household income of 61 interviewed farmers. Partial budget analysis identified a strongly positive incentive for vaccination and biosecurity to be implemented in combination, with the highest annual net benefit of USD 357.10 realised by the breeder system. However, due to current scarcity of the PRRS vaccine and its high cost to smallholders, biosecurity interventions may be more cost-effective, especially for low PRRS incidence regions. It was concluded that PRRS critically constrains the profitability of smallholder pig farms and that these findings will assist development of village-level livestock disease risk management programmes that encourage adoption of vaccination and biosecurity practices to enhance farmer livelihoods in Cambodia. 相似文献
16.
应用鸡毒支原体灭活油乳剂苗对蛋鸡进行田间免疫试验,证实该苗安全性和效果良好。免疫后在６个月内能有效抵御支原体野毒的感染。试验组与对照组相比,总发病率低２９．４％,产蛋率高１３．６％,产蛋高峰期延长２—４周,而且药物预防和治疗费用明显降低。 相似文献
17.
Sergeant ES 《New Zealand veterinary journal》1992,40(2):62-65
Decision tree analysis was used to evaluate the economic benefits of leptospirosis vaccination in beef cattle. The analysis used estimated values for the cost of vaccination, the probability of calf losses from leptospirosis and the economic losses resulting from calf mortality to calculate the expected value of vaccination. A computer spreadsheet was used to calculate the expected value of the vaccination programme over a wide range of estimated costs and probabilities and to determine the break-even point at which vaccination becomes economic. A sensitivity analysis demonstrated that the outcome of the analysis was most dependent on calf value and the probability of calf loss due to leptospirosis. The analysis was relatively insensitive to changes in vaccine cost, vaccine efficacy and herd fertility. 相似文献
18.
L L Blythe J A Schmitz M Roelke S Skinner 《Journal of the American Veterinary Medical Association》1983,183(11):1159-1162
A chronic progressive neurologic disease was observed and monitored for 18 months in a young, tamed Bengal tiger. Clinical, serologic, and neuropathologic evidence of canine distemper virus infection was seen. Clinical signs included convulsions, myoclonus, and slowly progressive ataxia. Marked increases in neutralizing antibodies against canine distemper virus were seen in the serum and cerebrospinal fluid. Neuropathologic findings were nonsuppurative meningoencephalomyelitis, with perivascular cuffing, demyelination, and inclusion bodies typical of canine distemper virus. It was concluded that, in light of this case and an earlier report of canine distemper in lion cubs, vaccination of this subgroup of carnivores with a killed vaccine may be beneficial if exposure to other animals susceptible to canine distemper is anticipated. 相似文献
19.
Modelling influenza A H5N1 vaccination strategy scenarios in the household poultry sector in Egypt 总被引：1，自引：1，他引：0
Ihab El Masry Jolianne Rijks Marisa Peyre Nick Taylor Juan Lubroth Yilma Jobre 《Tropical animal health and production》2014,46(1):57-63
Highly pathogenic avian influenza (AI) due to H5N1 virus was first reported in Egypt in February 2006; since then, the government has allowed avian influenza vaccination in poultry. The present study evaluated the impact of AI vaccination in terms of cumulative annual flock immunity (CAFI): the percentage of bird × weeks protected by immunity. This evaluation took account of the combined effects of vaccination coverage, vaccine efficacy (VE), and different characteristics of household poultry production on the effectiveness of the adopted vaccination strategy (VS), and provided alternative options for improvement. The evaluation used a population and vaccination model that calculates the CAFI. Participatory approaches were employed in 21 villages to develop the vaccination and flock parameters required for the model. The adopted VS were compared in the model with three alternative VS scenarios in terms of the CAFI. Vaccination coverage varied among villages but was generally low (between 1 and 48 %; median 14 %). Under the adopted VS, the CAFI predicted for the villages ranged from 2 to 31 %. It was concluded that despite the enormous effort put into rural household poultry AI vaccination by the Egyptian government, village CAFI is unlikely to be maintained at the levels required to significantly reduce the virus load and restrict transmission. In HPAI-endemic countries that consider AI vaccination as one of the disease control options, the high cost of mass AI vaccination campaigns and their achievable benefits must be compared with other available control measures, which may include targeted vaccination. Achievable vaccination coverage, VE and the different characteristics of commercial and household (village) poultry production are key parameters determining the feasibility and cost-effectiveness of different AI vaccination strategies. 相似文献
20.
Numerous infectious diseases caused by bacteria or viruses persist in developed and developing countries due to ongoing transmission among wildlife reservoir species. Such diseases become the target of control and management programmes in cases where they represent a threat to public health (for example rabies, sylvatic plague, Lyme disease), or livestock production (for example bovine tuberculosis, brucellosis, pseudorabies), or where they threaten the survival of endangered animal populations. In the majority of cases, lethal control operations are neither economically feasible nor publicly supported as a practical means for disease management. Prophylactic vaccination has emerged over the last 15 years as an alternative control strategy for wildlife diseases, mainly driven by the success of widescale oral rabies vaccination programmes for meso-carnivores in North America and Northern Europe. Different methods have been trialled for the effective delivery of wildlife vaccines in the field, however oral vaccination remains the most widely used approach. Successful implementation of an oral wildlife vaccine is dependent on a combination of three components: an efficacious immunogen, a suitable delivery vehicle, and a species-specific bait. This review outlines the major wildlife disease problems for which oral vaccination is currently under consideration as a disease management tool, and also focuses on the technological challenges that face wildlife vaccine development. The major conclusion is that attenuated or recombinant live microbes represent the most widely-used vaccines that can be delivered by the oral route; this in turn places major emphasis on effective delivery systems (to maintain vaccine viability), and on selective baiting systems, as the keys to wildlife vaccine success. Oral vaccination is a valuable adjunct or alternative strategy to culling for the control of diseases which persist in wildlife reservoirs. 相似文献