Virulence and evolution of West Nile Virus, Australia, 1960-2012

Natalie A. Prow, Judith H. Edmonds, David T. Williams, Yin X. Setoh, Helle Bielefeldt-Ohmann, Willy W. Suen, Jody Hobson-Peters, Andrew F. van den Hurk, Alyssa T. Pyke, Sonja Hall-Mendelin, Judith A. Northill, Cheryl A. Johansen, David Warrilow, Jianning Wang, Peter D. Kirkland, Stephen Doggett, Christy C. Andrade, Aaron Brault, Alexander A. Khromykh, Roy A. Hall

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Worldwide, West Nile virus (WNV) causes encephalitis in humans, horses, and birds. The Kunjin strain of WNV (WNVKUN) is endemic to northern Australia, but infections are usually asymptomatic. In 2011, an unprecedented outbreak of equine encephalitis occurred in southeastern Australia; most of the ≈900 reported cases were attributed to a newly emerged WNVKUN strain. To investigate the origins of this virus, we performed genetic analysis and in vitro and in vivo studies of 13 WNVKUN isolates collected from different regions of Australia during 1960-2012. Although no disease was recorded for 1984, 2000, or 2012, isolates collected during those years (from Victoria, Queensland, and New South Wales, respectively) exhibited levels of virulence in mice similar to that of the 2011 outbreak strain. Thus, virulent strains of WNVKUN have circulated in Australia for ≥ 30 years, and the first extensive outbreak of equine disease in Australia probably resulted from a combination of specific ecologic and epidemiologic conditions.

Original languageEnglish (US)
Pages (from-to)1353-1362
Number of pages10
JournalEmerging Infectious Diseases
Issue number8
StatePublished - Aug 1 2016

ASJC Scopus subject areas

  • Epidemiology
  • Microbiology (medical)
  • Infectious Diseases


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