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Queensland Primary Industries and Fisheries
Epidemiology, surveillance and control
of Hendra virus
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
HUME FIELD Biosecurity Queensland, Australia
Queensland Primary Industries and Fisheries
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
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
known spillovers..
Mackay
2 horses & one human
August 1994
Brisbane (Hendra)
20 horses & two humans
September 1994
Cairns (Trinity Beach)
1 horse
January 1999
Cairns (Gordonvale)
1 horse* & one human
October 2004
Townsville
1 horse
December 2004
Peachester
1 horse
June 2006
Murwillimbah
1 horse
October 2006
Peachester
1 horse
June 2007
Cairns (Clifton Beach)
1 horse
July 2007
Brisbane (Redlands)
5 horses* & two humans
June 2008
Proserpine
3 horses*
July 2008
Cawarral
4 horses & one human
July 2009
Bowen
2 horses
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Aug 2009
Queensland Primary Industries and Fisheries
spatial pattern..
o Cairns 1999, 2004, 2007
o Townsville 2004
Bowen 2009 o o Proserpine 2008
o Mackay 1994
o Cawarral 2009
o Peachester 2006, 2007
o
Brisbane 1994, 2008
o Murwillumbah 2006
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
..temporal pattern
b
e
t
w
e
e
n
y
e
a
r
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
1,1
0
0
0
0
1
0
0
0
0
1,1
0
1,1
1,1
1,1
1,1
w
i
t
h
i
n
y
e
a
r
jan
feb
mar
apr
may
jun
jul
aug
sep
oct
nov
dec
1
0
0
0
0
1,1,1
1,1,1
1,1
1
1,1
1
0
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
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
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
31% (95% CI 19-46)
..HeV antibody prevalence
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
Vertical hatching
Solid black
Broken line
P. alecto
P. poliocephalus
P. conspicillatus
P. scapulatus (southern inland limit)
Map adapted from Hall and Richards (2000). Data from Field (2005)
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
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?
potentialv
iral load
effective
contact
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
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.
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
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
Photo:
direct transmission.
Ian Temby
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Hendra virus
phylogenetic analysis..
Hendra (SEQ) 1994
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 in red italics.
[Ina Smith, AAHL]
SEQ 2009
Redlands (SEQ) 2008
Peachester (SEQ) 2007
FNQ 2008
Proserpine (FNQ) 2008
Cairns (FNQ) 2007
Queensland Primary Industries and Fisheries
infection dynamics in bats..
antibody prevalence studies
bat level variables
• age
p=0.0028
• season
p=0.0025
[Andrew Breed, 2005.]
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
infection dynamics in bats..
• UC Davis
• US NSF funding
[Raina Plowright, 2002.]
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
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.
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
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.
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
research directions..
•
•
•
•
•
•
infection dynamics in bats.
drivers for virus emergence from bats.
modes of transmission.
exposure risk management.
early detection methods.
therapeutics.
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
drivers for emergence..
• emergence or awareness?
• the more you look, the more you find?
• St. George (1989) suggested the possibility of a rabieslike 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’.
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
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.]
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
increasing urbanization..
• major shift in the
distribution of
flying foxes into
urban areas.
• perception of
plague proportions.
Plowright, Foley, Field et al 2009 (submitted)
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
changed risk of spill-over..
in urban areas,
more flying foxes
plus higher contact rates
means larger outbreaks
=
more infectious
individuals,
a greater total viral
load, and
a greater probability
of exposure and
infection
Plowright, Foley, Field et al 2009 (submitted)
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
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)
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
Queensland Primary Industries and Fisheries
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 horses
Version 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 far
Research participants, progress, challenges and current work.
Hendra virus: the initial research
This information sheet reports on the emergence of Hendra virus in horses and
on State
research
into reservoir
and transmission
studies
in fruit 2009
© The
of Queensland,
Department hosts
of Employment,
Economic Development
and Innovation,
bats, horses and cats.
Queensland Primary Industries and Fisheries
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.
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2009