Evaluation of Strategies to Control a Potential Outbreak of Foot-and-Mouth Disease in Sweden

Abstract

To minimize the potential consequences of an introduction of foot-and-mouth disease (FMD) in Europe, European Union (EU) member states are required to present a contingency plan. This study used a simulation model to study potential outbreak scenarios in Sweden and evaluate the best control strategies. The model was informed by the Swedish livestock structure using herd information from cattle, pig, and small ruminant holdings in the country. The contact structure was based on animal movement data and studies investigating the movements between farms of veterinarians, service trucks, and other farm visitors. All scenarios of outbreak control included depopulation of detected herds, 3 km protection and 10 km surveillance zones, movement tracing, and 3 days national standstill. The effect of availability of surveillance resources, i.e., number of field veterinarians per day, and timeliness of enforcement of interventions, was assessed. With the estimated currently available resources, an FMD outbreak in Sweden is expected to be controlled (i.e., last infected herd detected) within 3 weeks of detection in any evaluated scenario. The density of farms in the area where the epidemic started would have little impact on the time to control the outbreak, but spread in high density areas would require more surveillance resources, compared to areas of lower farm density. The use of vaccination did not result in a reduction in the expected number of infected herds. Preemptive depopulation was able to reduce the number of infected herds in extreme scenarios designed to test a combination of worst-case conditions of virus introduction and spread, but at the cost of doubling the number of herds culled. This likely resulted from a combination of the small outbreaks predicted by the spread model, and the high efficacy of the basic control measures evaluated, under the conditions of the Swedish livestock industry, and considering the assumed control resources available. The results indicate that the duration and extent of FMD outbreaks could be kept limited in Sweden using the EU standard control strategy and a 3 days national standstill.

Environmental persistence of foot‐and‐mouth disease virus applied to endemic regions

“…For example, poliovirus is infective at pH values of 3.0, while FMDV is labile below pH values of 6.0 (Racaniello, 2013). Additionally, while both, poliovirus and FMDV have been shown to persist longer when the virus was inoculated onto a faecal media, and conditions in TA B L E 1 This table provides references by grouping for current models used for strategic policy development and studies that were either removed from further analysis or included for the full statistical analysis References Group # of Studies (Andel, 2018;Dórea, Nöremark, Widgren, & Frössling, 2017;East et al, 2016;Gale et al, 2015;Garner & Beckett, 2005;Harvey et al, 2007;Hayama, Yamamoto, Kobayashi, Muroga, & Tsutsui, 2013;Keeling et al, 2001;SANSON et al, 2011;Stevenson et al, 2013;Tildesley & Ryan, 2012;Traulsen, Rave, Teuffert, & Krieter, 2011) Current Policy Models - (Barlow, 1972;Barlow & Donaldson, 1973;Donaldson, 1972;Donaldson & Ferris, 1975) Removed 4 (Alexandersen et al, 2002;Bedson et al, 1927;Bøtner & Belsham, 2012;Donaldson et al, 1970;Eisner & McVicar, 1980;Grzitdnov, 1957;Hyslop, 1965;Kindiakov, 1960;McColl et al, 1995;Nauryzbaev, 1966;Olitsky et al, 1928;Pacheco et al, 2017;Rozov, 1966;Sellers & Parker, 1969;Shil'nikov, 1959;Wagener, 1928) Included 16…”

Impact of truck contamination and information sharing on foot-and-mouth disease spreading in beef cattle production systems

“…Bate et al [ 7 ] simulated FMD transmission in a three-county area in California, demonstrating the effectiveness of preemptive culling of highest-risk herds and ring vaccination. This model was widely used and later adapted to analyze FMD mitigation strategies in other countries, including Sweden [ 21 ] and Denmark [ 11 ]. Other stochastic, state-transition simulation models included the NAADSM [ 22 ], AusSpread [ 23 ], InterSpreadPlus [ 24 ], and AADIS [ 25 ], which involve multiple animal species and pathways for disease spreading.…”

Understanding the effects of contact structures and information sharing on the FMD transmission among beef cattle farms

“…Pendell et al estimated a loss of 18 around $16-140 billion for an outbreak in the Midwestern U.S. originating from the 19 proposed National Bio and Agri-Defense Facility in Kansas [13]. 20 Liu et al [6] presented a spatially explicit agent-based simulator for synthesizing 21 beef cattle movements, and provided insight into the influence of network dynamics on 22 epidemic dynamics. It was shown that the new infections were driven by the trading 23 behavior, and that the removing rate determined whether the virus could survive long 24 enough to infect others.…”

“…The parameters used in this model are specified as follow: infectious rate for direct 107 contact β dir = 0.95day −1 calf −1 [20],λ = 1/3.59day −1 [21] which means that the 108 average incubation time is 3.59 days. For the infection rate of indirect contact β ind , we 109 use β ind = 0.1day −1 calf −1 for the base scenario, since no specific value is available in the literature.…”