TY - JOUR AU - Prow, Natalie AU - Edmonds, Judith AU - Williams, David AU - Setoh, Yin AU - Bielefeldt-Ohmann, Helle AU - Suen, Willy AU - Hobson-Peters, Jody AU - van den Hurk, Andrew AU - Pyke, Alyssa AU - Hall-Mendelin, Sonja AU - Northill, Judith AU - Johansen, Cheryl AU - Warrilow, David AU - Wang, Jianning AU - Kirkland, Peter AU - Doggett, Stephen AU - Andrade, Christy AU - Brault, Aaron AU - Khromykh, Alexander AU - Hall, Roy T1 - Virulence and Evolution of West Nile Virus, Australia, 1960–2012 T2 - Emerging Infectious Disease journal PY - 2016 VL - 22 IS - 8 SP - 1353 SN - 1080-6059 AB - 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. KW - West Nile virus KW - virulence KW - evolutionary markers KW - viruses KW - Australia KW - encephalitis KW - zoonoses KW - flavivirus KW - vector-borne infections DO - 10.3201/eid2208.151719 UR - https://wwwnc.cdc.gov/eid/article/22/8/15-1719_article ER - End of Reference