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PloS one2016; 11(3); e0151757; doi: 10.1371/journal.pone.0151757

Quantitative Risk Assessment for African Horse Sickness in Live Horses Exported from South Africa.

Abstract: African horse sickness (AHS) is a severe, often fatal, arbovirus infection of horses, transmitted by Culicoides spp. midges. AHS occurs in most of sub-Saharan Africa and is a significant impediment to export of live horses from infected countries, such as South Africa. A stochastic risk model was developed to estimate the probability of exporting an undetected AHS-infected horse through a vector protected pre-export quarantine facility, in accordance with OIE recommendations for trade from an infected country. The model also allows for additional risk management measures, including multiple PCR tests prior to and during pre-export quarantine and optionally during post-arrival quarantine, as well as for comparison of risk associated with exports from a demonstrated low-risk area for AHS and an area where AHS is endemic. If 1 million horses were exported from the low-risk area with no post-arrival quarantine we estimate the median number of infected horses to be 5.4 (95% prediction interval 0.5 to 41). This equates to an annual probability of 0.0016 (95% PI: 0.00015 to 0.012) assuming 300 horses exported per year. An additional PCR test while in vector-protected post-arrival quarantine reduced these probabilities by approximately 12-fold. Probabilities for horses exported from an area where AHS is endemic were approximately 15 to 17 times higher than for horses exported from the low-risk area under comparable scenarios. The probability of undetected AHS infection in horses exported from an infected country can be minimised by appropriate risk management measures. The final choice of risk management measures depends on the level of risk acceptable to the importing country.
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Publication Date: 2016-03-17 PubMed ID: 26986002PubMed Central: PMC4795756DOI: 10.1371/journal.pone.0151757Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research discusses a risk assessment model for evaluating the probability of exporting a horse infected with African Horse Sickness (AHS) from South Africa, where this disease is endemic. This model considers various risk management measures, including multiple PCR tests and quarantine facilities, to reduce the risk of disease transmission.

Objective of the Research

The main objective of the study was to develop a stochastic risk model for estimating the probability of accidentally exporting a horse from South Africa that’s infected with African Horse Sickness (AHS) but remains undetected. Specifically, it looked at how the application of additional risk mitigation strategies, such as pre-export and post-arrival PCR tests and quarantine measures, affects this probability.

About African Horse Sickness

  • AHS is a severe viral infection that can be fatal to horses.
  • The disease is transmitted by Culicoides species midges and is prevalent in most regions of Sub-Saharan Africa.
  • Since the disease is widespread in South Africa, it poses substantial challenges to the export of live horses from the country.

Key Findings of the Research

  • The model estimated that if one million horses were exported from a low-risk area without post-arrival quarantine, the median number of infected horses would be around 5.4.
  • The annual probability of exporting an infected horse is 0.0016 if 300 horses are exported per year from a low-risk area.
  • An additional PCR test during vector-protected post-arrival quarantine could reduce this risk by approximately 12-fold.
  • For horses exported from an area where AHS is endemic, the probabilities were much higher, approximately 15 to 17 times higher than for horses from the low-risk area under similar scenarios.

Implications of the Research

  • The research indicates that the risk of undetected AHS infection in horses exported from an infected country can be significantly reduced through appropriate risk management measures.
  • These measures include multiple PCR tests before and during pre-export quarantine, as well as during post-arrival quarantine, if necessary.
  • The selection of appropriate risk management measures depends largely on the level of risk the importing country deems acceptable.

Cite This Article

APA
Sergeant ES, Grewar JD, Weyer CT, Guthrie AJ. (2016). Quantitative Risk Assessment for African Horse Sickness in Live Horses Exported from South Africa. PLoS One, 11(3), e0151757. https://doi.org/10.1371/journal.pone.0151757

Publication

PloS one
ISSN: 1932-6203
NlmUniqueID: 101285081
Country: United States
Language: English
Volume: 11
Issue: 3
Pages: e0151757

Researcher Affiliations

Sergeant, Evan S
  • AusVet Animal Health Services, Canberra, Australian Capital Territory, Australia.
Grewar, John D
  • Veterinary Services, Western Cape Department of Agriculture, Elsenburg, South Africa.
Weyer, Camilla T
  • Equine Research Centre, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa.
Guthrie, Alan J
  • Equine Research Centre, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa.

MeSH Terms

  • African Horse Sickness / diagnosis
  • African Horse Sickness / epidemiology
  • African Horse Sickness / transmission
  • African Horse Sickness Virus / isolation & purification
  • Animals
  • Horses
  • Insect Vectors / virology
  • Quarantine
  • Risk Assessment
  • Seasons
  • South Africa / epidemiology

Conflict of Interest Statement

Competing Interests: The authors have the following interests: The participation of ES in this research was funded by private donors through the Equine Health Fund of South Africa, a division of Wits Health Consortium (Pty) Ltd (http://www.equinehealthfund.co.za/Home.aspx). The Equine Research Centre is supported by South African horse industry funding, through the Equine Health Fund. ES is employed by AusVet Animal Health Services. There are no patents, products in development or marketed products to declare. This does not alter the authors\' adherence to all the PLOS ONE policies on sharing data and materials.

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Citations

This article has been cited 7 times.
  1. Marques ARP, Gonzalez Villeta L, Simons R, Horigan V, de Vos C, Conrady B. Quantitative risk assessment for infectious disease introduction in animal populations: a comprehensive review. Front Vet Sci 2025;12:1648695.
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  2. Amenu K, McIntyre KM, Moje N, Knight-Jones T, Rushton J, Grace D. Approaches for disease prioritization and decision-making in animal health, 2000-2021: a structured scoping review. Front Vet Sci 2023;10:1231711.
    doi: 10.3389/fvets.2023.1231711pubmed: 37876628google scholar: lookup
  3. Nelson E, Thurston W, Pearce-Kelly P, Jenkins H, Cameron M, Carpenter S, Guthrie A, England M. A Qualitative Risk Assessment for Bluetongue Disease and African Horse Sickness: The Risk of Entry and Exposure at a UK Zoo. Viruses 2022 Feb 28;14(3).
    doi: 10.3390/v14030502pubmed: 35336912google scholar: lookup
  4. Grewar JD, Kotze JL, Parker BJ, van Helden LS, Weyer CT. An entry risk assessment of African horse sickness virus into the controlled area of South Africa through the legal movement of equids. PLoS One 2021;16(5):e0252117.
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