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HUME FIELD Biosecurity Queensland, Australia

Epidemiology, surveillance and control of Hendra virus. HUME FIELD Biosecurity Queensland, Australia. background. no evidence of infection in horses prior to 1994. 13 known spillover events. low infectivity, but high case fatality rate.

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HUME FIELD Biosecurity Queensland, Australia

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  1. Epidemiology, surveillance and control of Hendra virus HUME FIELD Biosecurity Queensland, Australia

  2. background.. no evidence of infection in horses prior to 1994. 13 known spillover events. low infectivity, but high case fatality rate. human cases attributed to close contact with infected horses. o

  3. known spillovers..

  4. spatial pattern.. oCairns 1999, 2004, 2007 oTownsville2004 Bowen 2009 o oProserpine2008 oMackay1994 oCawarral 2009 oPeachester 2006, 2007 Brisbane1994, 2008 o oMurwillumbah2006

  5. 1994 1,1 b 1995 0 e 1996 0 t 1997 0 w 1998 0 e 1999 1 e 2000 0 n 2001 0 2002 0 y 2003 0 e 2004 1,1 a 2005 0 r 2006 1,1 2007 1,1 2008 1,1 2009 1,1 w jan 1 i feb 0 t mar 0 h apr 0 i may 0 n jun 1,1,1 jul 1,1,1 y aug 1,1 e sep 1 a oct 1,1 r nov 1 dec 0 ..temporal pattern

  6. natural reservoir.. fruit bats identified as the natural host in 1996. antibodies in all 4 species. antibodies across the geographic range. no attributed clinical disease in flying foxes. antibodies in archived samples. Grey-headed flying fox

  7. ..HeV antibody prevalence 31% (95% CI 19-46) 29% (95% CI 21-39) 51% (95% CI 48-54) P. alecto 13/13 P. scap 13/13 P. polio 5/13 P. consp 3/13 27% (95% CI 17-39) Key: Horizontal hatching P. alecto Vertical hatching P. poliocephalus Solid black P. conspicillatus Broken line P. scapulatus (southern inland limit) Map adapted from Hall and Richards (2000). Data from Field (2005)

  8. risk of spillover.. probability of spillover from any given colony depends on • the proportion of susceptible flying foxes, • the colony size, • the presence of infection.. plus • the number and density of horses, • the number and density of flying foxes, • management of the horses, • the virus strain/virus dose/route of infection? potentialviral load effective contact

  9. modes of transmission.. plausible modes of direct bat-horse transmission: ingestion of partially eaten fruit. ingestion of ‘spats’. ingestion of urine-contaminated pasture/feed. licking/sniffing foetal tissues.

  10. indirect transmission via an intermediate host? improbable because • negative screening of non-bat species. • phylogenetic clustering of bat and horse virus sequence. • temporal overlap between equine cases and detection in flying foxes. • direct horse-to-horse and horse-to-human transmission via infected body fluids. • biological plausibility of direct transmission. Photo: Ian Temby

  11. Hendra (SEQ) 1994 SEQ 2009 Redlands (SEQ) 2008 Peachester (SEQ) 2007 FNQ 2008 Proserpine (FNQ) 2008 Cairns (FNQ) 2007 0.01 Hendra virusphylogenetic analysis.. for nucleotide 1500 to 2240 of the genome (carboxy terminal of the Nucleoprotein and the intergenic region) using Mega 4.0 (Neighbor-joining, p distances). Bat sequence inred italics. [Ina Smith, AAHL]

  12. infection dynamics in bats.. antibody prevalence studies bat level variables agep=0.0028 seasonp=0.0025 [Andrew Breed, 2005.]

  13. infection dynamics in bats.. • UC Davis • US NSF funding [Raina Plowright, 2002.]

  14. limiting infection in horses.. • awareness. • exposure risk minimisation strategies. • early consideration of Hendra virus. • appropriate management/PPE in suspects. • rapid rule-out/-in. • quarantine of identified case properties.

  15. limiting infection in horses.. • remains a rare infection • 2 in 200,000 horses pa. • 13 in 5 million horse-years at risk. • likelihood vs consequence.

  16. research directions.. • infection dynamics in bats. • drivers for virus emergence from bats. • modes of transmission. • exposure risk management. • early detection methods. • therapeutics.

  17. drivers for emergence.. • emergence or awareness? • the more you look, the more you find? • St. George (1989) suggested the possibility of a rabies-like virus in Australian bats in 1989.. ‘might not become evident unless active surveillance of bats was undertaken, or man or a domestic animal became infected’.

  18. changed bat population dynamics.. in recent decades, • decreased total population. • altered distribution. • change in the number and permanency of roosts. • altered frequency of contact. Plowright, Foley, Field et al 2009 (submitted) [Raina Plowright, 2002.]

  19. major shift in the distribution of flying foxes into urban areas. perception of plague proportions. increasing urbanization.. Plowright, Foley, Field et al 2009 (submitted)

  20. in urban areas, more flying foxes plus higher contact rates means larger outbreaks changed risk of spill-over.. more infectious individuals, a greater total viral load, and a greater probability of exposure and infection = Plowright, Foley, Field et al 2009 (submitted)

  21. in summary.. • landscape changes resulted in changed population dynamics that promoted emergence and spillover. • further landscape changes and climate change may further de-stabilize the system. Plowright, Foley, Field et al 2009 (submitted)

  22. QPIF Hendra virus webpage .. • If you suspect Hendra virus, please contact Biosecurity Queensland immediately on 13 25 23 or contact the Emergency Disease Watch Hotline on 1800 675 888. • Overview • Hendra virus overview • Get a copy of the report • Download: 'Independent review of Hendra virus cases' (PDF, 480 kB) • For veterinarians • Updates from the Chief Veterinary Officer:2009, April 3 | 2008, August 19 | 2008, August 8 | 2008, July 28 • Guidelines for veterinarians handling potential Hendra virus infection in horsesVersion 3, April 2009 • Submitting samples for analysis • Safe use of personal protective equipment (PPE) • For communities • Hendra virus: important information for horse owners (PDF, 262 kB)Download your copy today. • Fact sheet: important community information (PDF, 71 kB)(including advice to horse owners) • Fact sheet: Hendra virus infection(from Queensland Health) • Research • Initial experimental characterisation of HeV (Redland Bay 2008) infection in horses (PDF, 222 kB)Report authored by Deborah Middleton, CSIRO AAHL • Research into Hendra virus: the story so farResearch participants, progress, challenges and current work. • Hendra virus: the initial researchThis information sheet reports on the emergence of Hendra virus in horses and on research into reservoir hosts and transmission studies in fruit bats, horses and cats. • Scientific papersLink to the PubMed website (published research papers). Search for "Hendra virus".

  23. acknowledgements.. • Queensland Primary Industries & Fisheries/Biosecurity Queensland. • CSIRO Australian Animal Health Laboratory. • Australian Biosecurity CRC for Emerging Infectious Diseases. • Australian Dept. of Agriculture, Forestry & Fisheries. • US Wildlife Trust/Consortium for Conservation Medicine.

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