Original Research

The 2011 outbreak of African horse sickness in the African horse sickness controlled area in South Africa

John D. Grewar, Camilla T. Weyer, Alan J. Guthrie, Pieter Koen, Sewellyn Davey, Melvyn Quan, Dawid Visser, Esthea Russouw, Gary Bührmann
Journal of the South African Veterinary Association | Vol 84, No 1 | a973 | DOI: https://doi.org/10.4102/jsava.v84i1.973 | © 2013 John D. Grewar, Camilla T. Weyer, Alan J. Guthrie, Pieter Koen, Sewellyn Davey, Melvyn Quan, Dawid Visser, Esthea Russouw, Gary Bührmann | This work is licensed under CC Attribution 4.0
Submitted: 21 December 2012 | Published: 15 November 2013

About the author(s)

John D. Grewar, Veterinary Services, Western Cape Department of Agriculture, South Africa
Camilla T. Weyer, Equine Research Centre, Faculty of Veterinary Science, University of Pretoria, South Africa
Alan J. Guthrie, Equine Research Centre, Faculty of Veterinary Science, University of Pretoria, South Africa
Pieter Koen, Veterinary Services, Western Cape Department of Agriculture, South Africa
Sewellyn Davey, Veterinary Services, Western Cape Department of Agriculture, South Africa
Melvyn Quan, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, South Africa
Dawid Visser, Veterinary Services, Western Cape Department of Agriculture, South Africa
Esthea Russouw, Veterinary Services, Western Cape Department of Agriculture, South Africa
Gary Bührmann, Veterinary Services, Western Cape Department of Agriculture, South Africa


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Abstract

African horse sickness (AHS) is a controlled animal disease in South Africa, and as a result of the high mortality rates experienced, outbreaks in the AHS controlled area in the Western Cape Province have a significant impact on affected properties as well as on the exportation of live horses from the AHS free zone in metropolitan Cape Town. An outbreak of AHS serotype 1 occurred in the surveillance zone of the AHS controlled area of the Western Cape during the summer of 2011. The epicentre of the outbreak was the town of Mamre in the magisterial district of Malmesbury and the outbreak was confined to a defined containment zone within this area by movement control of all equids and a blanket vaccination campaign. A total of 73 cases of AHS were confirmed during this outbreak, which included four confirmed subclinical cases. The morbidity rate for the outbreak was 16%with a mortality rate of 14%and a case fatality rate of 88%. Outbreak disease surveillance relied on agent identification using polymerase chain reaction (PCR)-based assays, which is novel for an AHS outbreak in South Africa. The source of this outbreak was never confirmed although it is believed to be associated with the illegal movement of an infected animal into the Mamre area. This detailed description of the outbreak provides a sound scientific basis to assist decision making in future AHS outbreaks in the AHS controlled area of South Africa and in countries where AHS is an exotic or emerging disease.

Keywords

equine; epidemic; subclinical; surveillance; vaccination; control; containment zone

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Crossref Citations

1. African Horse Sickness Virus: History, Transmission, and Current Status
Simon Carpenter, Philip S. Mellor, Assane G. Fall, Claire Garros, Gert J. Venter
Annual Review of Entomology  vol: 62  issue: 1  first page: 343  year: 2017  
doi: 10.1146/annurev-ento-031616-035010