Vital elements for the successful control of foot-and-mouth disease by vaccination
Introduction
In the 70 years which have elapsed since the first publications appeared on vaccination against foot-and-mouth disease (FMD)[1], major advances have been made in virtually all aspects of our understanding of the virus, the disease and the methods for its control. Studies in areas including: the molecular biology of the virus; the pathogenesis of the disease; the excretion, dissemination and persistence of the virus; the epidemiology of the disease; the immune response; the genetic and antigenic relationships between strains of virus and the reliable production of safe and potent vaccines[2]have all provided information which has been applied in increasingly effective approaches to the control of FMD. Nevertheless, and despite spectacular success in many countries where the disease was formerly endemic, large areas of the globe continue to suffer the depredations of FMD. The reasons for these failures are complex, but insufficient attention to basic elements of planning and resource in the prosecution of control schemes can be critically important.
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Centralised planning and control
While control schemes for FMD may be aimed initially at the local reduction of infection, of disease severity and of disease incidence and prevalence, the ultimate aim should be the total eradication of the disease. In endemic areas the approach taken will vary according to local circumstances. However, the ultimate goal is inevitably attained in stages. Thus the disease and measures for its control progress from endemicity at the initiation of mass vaccination, moving through increasing
Epizootiological intelligence and diagnosis
Comprehensive and up-to-date epizootiological information is a prerequisite for effective disease control. Within a country or region, information on the status of a particular disease can be gathered by veterinarians, in both the private and public sectors, and even earlier and more effectively by an educated livestock community. In the case of FMD the notification procedure is usually reinforced by the designation of the disease in national legislation as being compulsorily notifiable on the
Diagnostic laboratory capability
Many countries maintain virological laboratories equipped for the diagnosis of FMD and the serological surveillance for both the disease and the immune status of herds and flocks in which vaccination has been applied.
Much of this work can today be effected without the necessity to employ live virus by the use of inactivated viruses and non-infectious viral components. This approach is to be commended. However, it is to be noted that where the work involves material which is known, or suspected,
Selection of FMD vaccine
There are currently a number of commercially manufactured vaccines available of differing strain composition, antigenic content, adjuvant formulation and cost[2]. All are produced using inactivated antigens. Vaccine is available as fully formulated and tested product or, more usually in emergency situations, it can be freshly formulated from concentrated, inactivated antigen(s) stored at low temperature in vaccine banks maintained by commercial manufacturers or by national and international
The cold chain
FMD vaccines must be maintained under refrigeration for the optimal retention of antigenic potency, usually at 4±2°C. The antigen loses immunogenic activity progressively as the storage temperature increases above these levels[26]. In addition freezing and thawing of FMD vaccines damages their integrity and can also cause the breakage of both aluminium hydroxide gels and oil emulsions, decreasing and possibly destroying the immunogenicity of the vaccines. The efficiency of the cold chain is
Training and education
Veterinarians, animal technicians and vaccinators should be educated, trained and tested to appropriate levels in good vaccination practice, good hygienic practice, disease control and legislation. Plans, contingency plans and SOPs are valuable aids in this area. Topics to be covered may include:
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The disease and its effects.
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The care of vaccine and vaccination equipment, including the sterilisation of syringes and needles.
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Vaccine application (site(s) of inoculation, dose rates for different
Logistics of supply and distribution
Ideally vaccine will be ordered with the maximum remaining shelf life and in quantities appropriate to a given phase of the vaccination campaign. The aim should be to attain at least 80% and preferably 100% vaccine coverage of susceptible livestock. Lesser levels of coverage and the use of vaccines of poor potency are likely to be associated with inefficient control and, importantly, with the selection of antigenic mutants in partially immune animal populations. It is to be recognised, however,
Public relations
The commitment of the farming community to schemes of animal disease control can greatly facilitate success. Conversely, the lack of their commitment renders the task much more difficult. This is particularly evident when there is an element of cost to the farmer. For these reasons it is important to use all available means to publicise control measures for FMD and to explain the rationale, the legal requirements, the timetable and the benefits which are expected to accrue from their
Conclusions
Despite the complexity of FMD in terms of the multiplicity of types and strains, the wide host range and the highly contagious nature of the disease, vaccination campaigns combined with other zoo-sanitary control measures have been attended with notable success in many parts of the world. A conspicuous example is found in continental Europe where mass compulsory vaccination together with the control of the movement of live animals and of animal products, sometimes combined with the slaughter
Acknowledgements
I thank Dr. A.I. Donaldson for his critical review of the manuscript.
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Cited by (29)
Efficacy of a high quality O<inf>1</inf>/Campos foot-and-mouth disease vaccine upon challenge with a heterologous Korean O Mya98 lineage virus in pigs
2018, VaccineCitation Excerpt :Infection or vaccination with one serotype does not cross-protect against the other serotypes and may fail to protect fully against some strains within serotypes [5,6]. Inactivated vaccines are widely used to control, eradicate and prevent FMD [7,8]. Historically, serotype O vaccine strains can be included within two main groups.
Emergence of antigenic variants of Foot-and-Mouth Disease Virus serotype O in Ecuador and preliminary evaluation of a field strain as a vaccine candidate
2014, VaccineCitation Excerpt :Infection or vaccination with one serotype does not cross-protect against other serotypes and may also fail to protect fully against other strains of the same serotype [5,6]. Inactivated vaccines are widely used to control, eradicate and prevent FMD [7,8]. Selection of vaccine strains that are as immunogenic and cross reactive as possible is essential not only for systematic vaccination programs but also for the incorporation to strategic FMDV inactivated frozen antigens for rapid formulation into vaccines for use in case of an emergency (i.e. antigen banks) [9].
Characterization of a type O foot-and-mouth disease virus re-emerging in the year 2011 in free areas of the Southern Cone of South America and cross-protection studies with the vaccine strain in use in the region
2013, Veterinary MicrobiologyCitation Excerpt :Serotypes O, A and C have been recorded in South America. Vaccination is widely applied to control, eradicate and prevent FMD (Garland, 1999; Bergmann et al., 2005). Moreover, a considerable transformation is ongoing regarding the acceptance of the benefits of vaccination as an alternative to stamping out policies, particularly after recurrence of the disease in free regions (Bergmann et al., 2005).
Characterization of foot-and-mouth disease virus from outbreaks in Ecuador during 2009-2010 and cross-protection studies with the vaccine strain in use in the region
2011, VaccineCitation Excerpt :The disease has an important socio-economic impact in countries where it is endemic [10,11], provokes huge economic consequences when outbreaks occur in disease free regions [12,13] and is considered one of the most important constrains to international trade of livestock and animal products. Vaccination is widely used to control, eradicate and prevent FMD [14,15]. Moreover, a considerable transformation is ongoing regarding the acceptance of the benefits of vaccination as an alternative to stamping out policies, particularly after recurrence of the disease in free regions [15].
A review of the effectiveness of vaccine potency control testing
2003, International Journal for Parasitology