Vaccination against foot-and-mouth disease I: epidemiological consequences.

An epidemic of foot-and-mouth disease (FMD) can have devastating effects on animal welfare, economic revenues, the export position and society as a whole, as occurred during the 2001 FMD epidemic in the Netherlands. Following the preemptive culling of 260,000 animals during this outbreak, the Dutch government adopted emergency vaccination as preferred control policy. However, a vaccination-to-live strategy has not been applied before, posing unprecedented challenges for effectively controlling the epidemic, regaining FMD-free status and minimizing economic losses. These three topics are covered in an interdisciplinary model analysis. In this first part we evaluate whether and how emergency vaccination can be effectively applied to control FMD epidemics in the Netherlands. For this purpose we develop a stochastic individual-based model that describes FMD virus transmission between animals and between herds, taking heterogeneity between host species (cattle, sheep and pigs) into account. Our results in a densely populated livestock area with >4 farms/km(2) show that emergency ring vaccination can halt the epidemic as rapidly as preemptive ring culling, while the total number of farms to be culled is reduced by a factor of four. To achieve this reduction a larger control radius around detected farms and a corresponding adequate vaccination capacity is needed. Although sufficient for the majority of simulated epidemics with a 2 km vaccination zone, the vaccination capacity available in the Netherlands can be exhausted by pig farms that are on average ten times larger than cattle herds. Excluding pig farms from vaccination slightly increases the epidemic, but more than halves the number of animals to be vaccinated. Hobby flocks - modelled as small-sized sheep flocks - do not play a significant role in propagating the epidemic, and need not be targeted during the control phase. In a more sparsely populated livestock area in the Netherlands with about 2 farms/km(2) the minimal control strategy of culling only detected farms seems sufficient to control an epidemic.

[1]  M. Keeling.  Models of foot-and-mouth disease , 2005, Proceedings of the Royal Society B: Biological Sciences.

[2]  M C M de Jong,et al.  Foot and mouth disease virus transmission during the incubation period of the disease in piglets, lambs, calves, and dairy cows. , 2009, Preventive veterinary medicine.

[3]  N. Ferguson,et al.  Transmission Parameters of the 2001 Foot and Mouth Epidemic in Great Britain , 2007, PloS one.

[4]  J. Pacheco,et al.  Vaccination against foot-and-mouth disease virus confers complete clinical protection in 7 days and partial protection in 4 days: Use in emergency outbreak response. , 2005, Vaccine.

[5]  M. Keeling,et al.  Modeling Infectious Diseases in Humans and Animals , 2007 .

[6]  M C M de Jong,et al.  Quantification of foot and mouth disease virus excretion and transmission within groups of lambs with and without vaccination. , 2007, Vaccine.

[7]  Kitching Rp,et al.  Clinical variation in foot and mouth disease: sheep and goats. , 2002 .

[8]  P. F. De Klerk.  Carcass disposal: lessons from the Netherlands after the foot and mouth disease outbreak of 2001 , 2002 .

[9]  Mark C Thurmond,et al.  Description of an epidemic simulation model for use in evaluating strategies to control an outbreak of foot-and-mouth disease. , 2003, American journal of veterinary research.

[10]  Christl A. Donnelly,et al.  The Foot-and-Mouth Epidemic in Great Britain: Pattern of Spread and Impact of Interventions , 2001, Science.

[11]  Neil M Ferguson,et al.  Epidemiological inference for partially observed epidemics: the example of the 2001 foot and mouth epidemic in Great Britain. , 2009, Epidemics.

[12]  Christl A. Donnelly,et al.  Transmission intensity and impact of control policies on the foot and mouth epidemic in Great Britain , 2001, Nature.

[13]  Rob Deardon,et al.  Optimal reactive vaccination strategies for a foot-and-mouth outbreak in the UK , 2006, Nature.

[14]  T Mikkelsen,et al.  Relative risks of the uncontrollable (airborne) spread of FMD by different species , 2001, Veterinary Record.

[15]  A. Donaldson,et al.  Exposure of sheep to natural aerosols of foot-and-mouth disease virus. , 1986, Research in veterinary science.

[16]  P. Sutmoller,et al.  Experimental foot-and-mouth disease in sheep and goats: An epizootiological model , 2005, Archiv für die gesamte Virusforschung.

[17]  G. Davies,et al.  The foot and mouth disease (FMD) epidemic in the United Kingdom 2001. , 2002, Comparative immunology, microbiology and infectious diseases.

[18]  M C M de Jong,et al.  Foot and mouth disease virus transmission among vaccinated pigs after exposure to virus shedding pigs. , 2007, Vaccine.

[19]  J. W. Wilesmith,et al.  Descriptive epidemiology of the 2001 foot-and-mouth disease epidemic in Great Britain: the first five months , 2001, Veterinary Record.

[20]  M. D. de Jong,et al.  The foot-and-mouth disease epidemic in The Netherlands in 2001. , 2003, Preventive veterinary medicine.

[21]  J. Salt,et al.  Emergency vaccination of sheep against foot-and-mouth disease: protection against disease and reduction in contact transmission. , 1998, Vaccine.

[22]  J.A. Backer,et al.  Vaccination against foot-and-mouth disease II: Regaining FMD-free status. , 2012, Preventive veterinary medicine.

[23]  M. D. de Jong,et al.  A meta-analysis quantifying transmission parameters of FMDV strain O Taiwan among non-vaccinated and vaccinated pigs. , 2008, Preventive veterinary medicine.

[24]  Phaedra Eblé,et al.  Quantification of within- and between-pen transmission of Foot-and-Mouth disease virus in pigs. , 2006, Veterinary research.

[25]  M. D. de Jong,et al.  The effect of vaccination on foot and mouth disease virus transmission among dairy cows. , 2007, Vaccine.

[26]  B. Charleston,et al.  Options for control of foot-and-mouth disease: knowledge, capability and policy , 2009, Philosophical Transactions of the Royal Society B: Biological Sciences.

[27]  M. Schoenbaum,et al.  Modeling alternative mitigation strategies for a hypothetical outbreak of foot-and-mouth disease in the United States. , 2003, Preventive veterinary medicine.

[28]  S. Cornell,et al.  Dynamics of the 2001 UK Foot and Mouth Epidemic: Stochastic Dispersal in a Heterogeneous Landscape , 2001, Science.

[29]  M. D. de Jong,et al.  Transmission risks and control of foot-and-mouth disease in The Netherlands: spatial patterns. , 2010, Epidemics.

[30]  Lei.  Land- en tuinbouwcijfers 2004 , 2002 .

[31]  P. Barnett,et al.  Emergency vaccination against foot-and-mouth disease: rate of development of immunity and its implications for the carrier state. , 1994, Vaccine.

[32]  A Bouma,et al.  Vaccination of pigs two weeks before infection significantly reduces transmission of foot-and-mouth disease virus. , 2004, Vaccine.

[33]  R. Kitching,et al.  Clinical variation in foot and mouth disease: pigs. , 2002, Revue scientifique et technique.

[34]  Rowland R Kao,et al.  The role of mathematical modelling in the control of the 2001 FMD epidemic in the UK. , 2002, Trends in microbiology.

[35]  R. May,et al.  Modelling vaccination strategies against foot-and-mouth disease , 2003, Nature.

[36]  Zhidong Zhang,et al.  Quantities of infectious virus and viral RNA recovered from sheep and cattle experimentally infected with foot-and-mouth disease virus O UK 2001. , 2002, The Journal of general virology.

[37]  M. D. de Jong,et al.  Estimation of foot and mouth disease transmission parameters, using outbreak data and transmission experiments. , 2011, Revue scientifique et technique.

[38]  Annemarie Bouma,et al.  Rate of Foot‐and‐Mouth Disease Virus Transmission by Carriers Quantified from Experimental Data , 2008, Risk analysis : an official publication of the Society for Risk Analysis.

[39]  R. Bergevoet,et al.  Vaccination against Foot-and-Mouth Disease : differentiating strategies and their epidemiological and economic consequences , 2009 .

[40]  M. D. de Jong,et al.  Modelling the effectiveness and risks of vaccination strategies to control classical swine fever epidemics , 2009, Journal of The Royal Society Interface.

[41]  M. D. de Jong,et al.  Vaccination against foot and mouth disease reduces virus transmission in groups of calves. , 2005, Vaccine.

[42]  S. Reid,et al.  Protection against direct-contact challenge following emergency FMD vaccination of cattle and the effect on virus excretion from the oropharynx. , 2005, Vaccine.