African horse sickness caused by genome reassortment and reversion to virulence of live, attenuated vaccine viruses, South Africa, 2004–2014

Camilla T. Weyer, John D. Grewar, Phillippa Burger, Esthea Rossouw, Carina Lourens, Christopher Joone, Misha Le Grange, Peter Coetzee, Estelle Venter, Darren P. Martin, Nigel J Maclachlan, Alan J. Guthrie

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

African horse sickness (AHS) is a hemorrhagic viral fever of horses. It is the only equine disease for which the World Organization for Animal Health has introduced specific guidelines for member countries seeking official recognition of disease-free status. Since 1997, South Africa has maintained an AHS controlled area; however, sporadic outbreaks of AHS have occurred in this area. We compared the whole genome sequences of 39 AHS viruses (AHSVs) from field AHS cases to determine the source of 3 such outbreaks. Our analysis confirmed that individual outbreaks were caused by virulent revertants of AHSV type 1 live, attenuated vaccine (LAV) and reassortants with genome segments derived from AHSV types 1, 3, and 4 from a LAV used in South Africa. These findings show that despite effective protection of vaccinated horses, polyvalent LAV may, paradoxically, place susceptible horses at risk for AHS.

Original languageEnglish (US)
Pages (from-to)2087-2096
Number of pages10
JournalEmerging Infectious Diseases
Volume22
Issue number12
DOIs
StatePublished - Dec 1 2016

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ASJC Scopus subject areas

  • Epidemiology
  • Microbiology (medical)
  • Infectious Diseases

Cite this

Weyer, C. T., Grewar, J. D., Burger, P., Rossouw, E., Lourens, C., Joone, C., Le Grange, M., Coetzee, P., Venter, E., Martin, D. P., Maclachlan, N. J., & Guthrie, A. J. (2016). African horse sickness caused by genome reassortment and reversion to virulence of live, attenuated vaccine viruses, South Africa, 2004–2014. Emerging Infectious Diseases, 22(12), 2087-2096. https://doi.org/10.3201/eid2212.160718