Extinction Dynamics of the Foot-and-Mouth Disease Virus Carrier State Under Natural Conditions

Bertram, Miranda R.; Yadav, Shankar; Stenfeldt, Carolina; Delgado, Amy H.; Arzt, Jonathan

doi:10.3389/fvets.2020.00276

Cited by 12 publications

(11 citation statements)

References 42 publications

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“…Animals sampled in slaughterhouses and farms did not have clinical signs of FMD at the time of sampling, and thus detection of virus in such animals represented either persistent infections in carrier animals or early (acute) sub-clinical (neoteric) infections [1]. Related to this, the recovery of viruses in OPF samples collected from persistently infected carriers introduces some uncertainty in the dating of the incidence of infection, as the sample collection date was surely later than the infection date [6,42,43]. This could potentially have impacted the date estimates in the time-scaled phylogenies, though we do not think that it changes our general conclusions about the representativeness and timeliness of slaughterhouse-based surveillance.…”

Section: Discussionmentioning

confidence: 99%

“…Farm-based active surveillance through randomized sampling would be considered the benchmark of understanding the prevalence and distribution of livestock diseases. Various studies have reported farm-based genomic surveillance of subclinical FMDV strains in endemic regions [5][6][7][8]. However, routine farm-based surveillance is often impractical due to logistical complexity and expense, particularly in rural settings with sub-optimal infrastructure.…”

Section: Introductionmentioning

confidence: 99%

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Use of Slaughterhouses as Sentinel Points for Genomic Surveillance of Foot-and-Mouth Disease Virus in Southern Vietnam

Gunasekara

Bertram

Dung

et al. 2021

Viruses

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The genetic diversity of foot-and-mouth disease virus (FMDV) poses a challenge to the successful control of the disease, and it is important to identify the emergence of different strains in endemic settings. The objective of this study was to evaluate the sampling of clinically healthy livestock at slaughterhouses as a strategy for genomic FMDV surveillance. Serum samples (n = 11,875) and oropharyngeal fluid (OPF) samples (n = 5045) were collected from clinically healthy cattle and buffalo on farms in eight provinces in southern and northern Vietnam (2015–2019) to characterize viral diversity. Outbreak sequences were collected between 2009 and 2019. In two slaughterhouses in southern Vietnam, 1200 serum and OPF samples were collected from clinically healthy cattle and buffalo (2017 to 2019) as a pilot study on the use of slaughterhouses as sentinel points in surveillance. FMDV VP1 sequences were analyzed using discriminant principal component analysis and time-scaled phylodynamic trees. Six of seven serotype-O and -A clusters circulating in southern Vietnam between 2017–2019 were detected at least once in slaughterhouses, sometimes pre-dating outbreak sequences associated with the same cluster by 4–6 months. Routine sampling at slaughterhouses may provide a timely and efficient strategy for genomic surveillance to identify circulating and emerging FMDV strains.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Use of Slaughterhouses as Sentinel Points for Genomic Surveillance of Foot-and-Mouth Disease Virus in Southern Vietnam

Gunasekara

Bertram

Dung

et al. 2021

Viruses

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“…The annual incidence was calculated as the prevalence divided by the average duration of infection in days times 365 days per year. The average duration of infection was specified as a function of the probability that an infection was acute or persistent and the associated duration of an acute infection (D) or persistent infection (Pert distribution with minimum of six months, maximum of 24 months, and most likely value of 13 months [41][42][43]).…”

Section: Are Cattle Infected When Leaving the Herd Of Origin? (P1)mentioning

confidence: 99%

Assessment of the Risk of Foot and Mouth Disease among Beef Cattle at Slaughter from East African Production Systems

Adamchick

Rich

Pérez

2021

Viruses

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Endemic foot and mouth disease (FMD) in East African cattle systems is one factor that limits access to export markets. The probability of FMD transmission associated with export from such systems have never been quantified and there is a need for data and analyses to guide strategies for livestock exports from regions where FMD remains endemic. The probability of infection among animals at slaughter is an important contributor to the risk of FMD transmission associated with the final beef product. In this study, we built a stochastic model to estimate the probability that beef cattle reach slaughter while infected with FMD virus for four production systems in two East African countries (Kenya and Uganda). Input values were derived from the primary literature and expert opinion. We found that the risk that FMD-infected animals reach slaughter under current conditions is high in both countries (median annual probability ranging from 0.05 among cattle from Kenyan feedlots to 0.62 from Ugandan semi-intensive systems). Cattle originating from feedlot and ranching systems in Kenya had the lowest overall probabilities of the eight systems evaluated. The final probabilities among cattle from all systems were sensitive to the likelihood of acquiring new infections en route to slaughter and especially the probability and extent of commingling with other cattle. These results give insight into factors that could be leveraged by potential interventions to lower the probability of FMD among beef cattle at slaughter. Such interventions should be evaluated considering the cost, logistics, and tradeoffs of each, ultimately guiding resource investment that is grounded in the values and capacity of each country.

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“…The official data from the World Organisation for Animal Health (WOAH) of more than 57 thousand outbreaks in 99 counties from 1996 until 2012 show that 68% of the cases were associated with cattle, 22% with swine, and 21% with small ruminants and other species (Santos et al, 2017). Even with strong evidence indicating that all susceptible species can drive large FMD epidemics (Bertram et al, 2020; Tildesley et al, 2012) for example, the 2001 UK epidemic was traced back to an infected Essex swine slaughterhouse (Davies, 2002) control measures and surveillance programs have mostly been developed to target dissemination within cattle populations, thus neglecting the role of other species in FMD transmission (Naranjo and Cosivi, 2013; Santos et al, 2017; Seymour et al, 2022; Singanallur et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Modeling foot-and-mouth disease dissemination in Brazil and evaluating the effectiveness of control measures

Cárdenas

Lopes

Machado

2022

Preprint

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Foot-and-mouth disease (FMD) infects multiple food-animal species, thus capable of disseminating among ungulate species with distinct transmission rates. Here present a multilevel compartmental stochastic model, taking into account births and deaths and explicit representation of species-specific transmission dynamics. The model considered two major modes of dissemination, between-farm animal and spatial transmission. Our model outcomes are the number of secondary infected animals and farms, spatial dissemination distances, and effectiveness of depopulation and vaccination along with surveillance and movement restrictions. We demonstrated that after 20 days of FMD dissemination, the median number of infected farms was 8 (IQR: 3-22), of which 7 (IQR: 3-22) were bovine, 3 (IQR: 1-6) swine farms, and 1 (IQR: 1-1) small ruminants. We demonstrate that animal movement dominated dissemination in the first days of epidemics, while at ten days the spatial transmission dominated bovine infections, whilst between-farm led to most swine infections. We have also shown the median distances between seeded and secondary infections was 5.77 km (IQR: 1-10.29 km), with some long-range dissemination at 695.40 km. We estimated that depopulating 12 and vaccinating 15,000 farms per day faded out 98.3% of the epidemics, however, was insufficient to contain large-scale epidemics (> 248 infected farms). The estimated effectiveness of a baseline control scenario eliminated 93.4% of the epidemics with a median of 9 (IQR: 3-23, max: 221) infected farms. Our results demonstrated that the depopulation alone against epidemics with more than 74 infected farms had limited success, stamping out less than 80% of simulations. The developed transmission model allows for cross-species transmission to be considered in FMD policy-making, and the software implementation facilitates the adaption of scientific-based support to FMD planning and response throughout other Brazilian states.

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Extinction Dynamics of the Foot-and-Mouth Disease Virus Carrier State Under Natural Conditions

Cited by 12 publications

References 42 publications

Use of Slaughterhouses as Sentinel Points for Genomic Surveillance of Foot-and-Mouth Disease Virus in Southern Vietnam

Use of Slaughterhouses as Sentinel Points for Genomic Surveillance of Foot-and-Mouth Disease Virus in Southern Vietnam

Assessment of the Risk of Foot and Mouth Disease among Beef Cattle at Slaughter from East African Production Systems

Modeling foot-and-mouth disease dissemination in Brazil and evaluating the effectiveness of control measures

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