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Home / Equine Research Bank / Front Public Health / The Australian Public is Still Vulnerable to Emerging Virule...
Frontiers in public health2014; 2; 146; doi: 10.3389/fpubh.2014.00146

The Australian Public is Still Vulnerable to Emerging Virulent Strains of West Nile Virus.

Abstract: The mosquito-borne West Nile virus (WNV) is responsible for outbreaks of viral encephalitis in humans and horses with particularly virulent strains causing recent outbreaks in Eastern Europe, the Middle East, and North America. In Australia, a strain of WNV, Kunjin (WNVKUN), is endemic in the north and infection with this virus is generally asymptomatic. However, in early 2011, following extensive flooding, an unprecedented outbreak of WNVKUN encephalitis in horses occurred in South-Eastern Australia, resulting in more than 1,000 cases and a mortality of 10-15%. Despite widespread evidence of equine infections, there was only a single mild human case reported during this outbreak. To understand why clinical disease was seen in horses without similar observations in the human population, a serosurvey was conducted using blood donor samples from areas where equine cases were reported to assess level of flavivirus exposure. The seroprevalence to WNVKUN in humans was low before the outbreak (0.7%), and no significant increase was demonstrated after the outbreak period (0.6%). Due to unusual epidemiological features during this outbreak, a serosurvey was also conducted in rabbits, a potential reservoir host. Out of 675 animals, sampled across Australia between April 2011 and November 2012, 86 (12.7%) were seropositive for WNVKUN, with the highest prevalence during February of 2012 (28/145; 19.3%). As this is the first serological survey for WNVKUN in Australian feral rabbits, it remains to be determined whether wild rabbits are able to develop a high enough viremia to actively participate in WNV transmission in Australia. However, they may constitute a sentinel species for arbovirus activity, and this is the focus of on-going studies. Collectively, this study provides little evidence of human exposure to WNVKUN during the 2011 outbreak and indicates that the Australian population remains susceptible to the emergence of virulent strains of WNV.
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Publication Date: 2014-09-17 PubMed ID: 25279370PubMed Central: PMC4166114DOI: 10.3389/fpubh.2014.00146Google Scholar: Lookup
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  • Journal Article

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 study explores the low human exposure level to a strain of West Nile Virus in Australia, named WNVKUN, despite a significant outbreak in horses in 2011. This indicates that the Australian population remains susceptible to the introduction of more potent strains of this virus.

Context and Purpose of the Study

  • The research aims to understand the discrepancy between the prevalence of West Nile Virus (WNV) infection in horses and its significantly lower level in humans. WNV is a mosquito-borne virus resulting in viral encephalitis mainly in horses and humans. A strain named WNVKUN is predominant in Australia, mainly in the northern part, and often doesn’t present symptoms upon infection.
  • After extensive flooding in 2011, a significant outbreak of WNVKUN encephalitis occurred in South-Eastern Australia’s horses, resulting in over 1000 cases and a mortality rate of 10-15%. The study seeks to understand why clinical disease was evident in horses while human populations remained largely unaffected.
  • Additionally, the researchers investigated the role of wild rabbits, a potential reservoir host for the virus.

Methodology and Findings

  • A serosurvey using blood donor samples from areas where equine cases were reported was conducted to assess the level of flavivirus exposure. The seroprevalence of WNVKUN was found to be low in humans before the outbreak (0.7%) and did not significantly increase after it (0.6%).
  • Considering potential epidemiological factors, the researchers also conducted a serosurvey in rabbits, testing 675 animals across Australia. Out of these, 86 (12.7%) tested positive for WNVKUN, with the highest prevalence recorded in February 2012 (19.3%). At this point, it’s unclear if rabbits can develop high enough viremia to participate actively in WNV transmission, though they could serve as sentinel species for arbovirus activity, prompting further studies.

Conclusion

  • Despite the significant outbreak in horses, little evidence points to increased human exposure to WNVKUN. This indicates that the Australian population remains largely unexposed, and thus susceptible, to more virulent strains of West Nile Virus should they be introduced.

Cite This Article

APA
Prow NA, Hewlett EK, Faddy HM, Coiacetto F, Wang W, Cox T, Hall RA, Bielefeldt-Ohmann H. (2014). The Australian Public is Still Vulnerable to Emerging Virulent Strains of West Nile Virus. Front Public Health, 2, 146. https://doi.org/10.3389/fpubh.2014.00146

Publication

Frontiers in public health
ISSN: 2296-2565
NlmUniqueID: 101616579
Country: Switzerland
Language: English
Volume: 2
Pages: 146
PII: 146

Researcher Affiliations

Prow, Natalie A
  • School of Chemistry and Molecular Biosciences, The University of Queensland , St Lucia, QLD , Australia ; Australian Infectious Diseases Research Centre, The University of Queensland , St Lucia, QLD , Australia.
Hewlett, Elise K
  • School of Chemistry and Molecular Biosciences, The University of Queensland , St Lucia, QLD , Australia ; Australian Infectious Diseases Research Centre, The University of Queensland , St Lucia, QLD , Australia.
Faddy, Helen M
  • Research and Development, Australian Red Cross Blood Service , Kelvin Grove, QLD , Australia.
Coiacetto, Flaminia
  • School of Veterinary Science, The University of Queensland , Gatton, QLD , Australia.
Wang, Wenqi
  • School of Veterinary Science, The University of Queensland , Gatton, QLD , Australia.
Cox, Tarnya
  • Vertebrate Pest Research Unit, NSW Department of Primary Industries , Orange, NSW , Australia ; Invasive Animals Cooperative Research Centre, University of Canberra , Bruce, ACT , Australia.
Hall, Roy A
  • School of Chemistry and Molecular Biosciences, The University of Queensland , St Lucia, QLD , Australia ; Australian Infectious Diseases Research Centre, The University of Queensland , St Lucia, QLD , Australia.
Bielefeldt-Ohmann, Helle
  • Australian Infectious Diseases Research Centre, The University of Queensland , St Lucia, QLD , Australia ; School of Veterinary Science, The University of Queensland , Gatton, QLD , Australia.

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