An entry risk assessment of African horse sickness virus into the controlled area of South Africa through the legal movement of equids.

Autor: Grewar JD; Department of Production Animal Studies, University of Pretoria, Pretoria, Gauteng, South Africa.; South African Equine Health and Protocols NPC, Cape Town, Western Cape Province, South Africa., Kotze JL; Department of Production Animal Studies, University of Pretoria, Pretoria, Gauteng, South Africa., Parker BJ; South African Equine Health and Protocols NPC, Cape Town, Western Cape Province, South Africa., van Helden LS; Veterinary Services, Western Cape Department of Agriculture, Elsenburg, Western Cape Province, South Africa., Weyer CT; South African Equine Health and Protocols NPC, Cape Town, Western Cape Province, South Africa.; Department of Veterinary Tropical Diseases, University of Pretoria, Pretoria, Gauteng, South Africa.
Jazyk: angličtina
Zdroj: PloS one [PLoS One] 2021 May 26; Vol. 16 (5), pp. e0252117. Date of Electronic Publication: 2021 May 26 (Print Publication: 2021).
DOI: 10.1371/journal.pone.0252117
Abstrakt: South Africa is endemic for African horse sickness (AHS), an important health and trade-sensitive disease of equids. The country is zoned with movement control measures facilitating an AHS-free controlled area in the south-west. Our objective was to quantitatively establish the risk of entry of AHS virus into the AHS controlled area through the legal movement of horses. Outcomes were subcategorised to evaluate movement pathway, temporal, and spatial differences in risk. A 'no-control' scenario allowed for evaluation of the impact of control measures. Using 2019 movement and AHS case data, and country-wide census data, a stochastic model was developed establishing local municipality level entry risk of AHSV at monthly intervals. These were aggregated to annual probability of entry. Sensitivity analysis evaluated model variables on their impact on the conditional means of the probability of entry. The median monthly probability of entry of AHSV into the controlled area of South Africa ranged from 0.75% (June) to 5.73% (February), with the annual median probability of entry estimated at 20.21% (95% CI: 15.89%-28.89%). The annual risk of AHSV entry compared well with the annual probability of introduction of AHS into the controlled area, which is ~10% based on the last 20 years of outbreak data. Direct non-quarantine movements made up most movements and accounted for most of the risk of entry. Spatial analysis showed that, even though reported case totals were zero throughout 2019 in the Western Cape, horses originating from this province still pose a risk that should not be ignored. Control measures decrease risk by a factor of 2.8 on an annual basis. Not only do the outcomes of this study inform domestic control, they can also be used for scientifically justified trade decision making, since in-country movement control forms a key component of export protocols.
Competing Interests: SAEHP functions through public private partnership agreement with the Western Cape Department of Agriculture: Veterinary Services. The ECOD case numbers used in this evaluation reflect the reporting system numbers and do not necessarily reflect the official totals as reported by South Africa’s Veterinary Services. The authors have declared that no competing interests exist.
Databáze: MEDLINE
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