Paul Morley Morley at
Thu Dec 8 09:28:37 EST 1994

In article <3c2k78$lc1 at> nyneve at (deborah wisti-peterson) writes:
>From: nyneve at (deborah wisti-peterson)
>Newsgroups: bionet.virology
>Subject: Re: horse
>Date: 6 Dec 1994 21:14:16 GMT
>Organization: University of Washington
>Lines: 29
>Message-ID: <3c2k78$lc1 at>
>References: <303933495wnr at>

>In article <303933495wnr at>,
>Rob Lambkin <Rob at> wrote:
>>A few weeks ago there were news reports concerning a fatal viral infection of horses that may or 
>>may not have been transmitted to a human trainer. I went of on my hols and news coverage seems 
>>to have dried up, does anyone have any info on this. Thanks in advance.
>>Rob Lambkin
>>Rob at
>>Rob at
>>Voice & Fax 01273 670189
>>       whatever it takes.... to have a nice day

>this is the result of hantavirus. it appears that several (12?) 
>australian race horses and their trainer (all from the same stable) 
>were infected with hantavirus and subsequently died from it. the 
>entire barn was heavily infested with rats. the original post may
>still be on your newsreader on rec.equestrian (it was posted a
>approximately a month ago).

>                         Deborah Wisti-Peterson
>           nyneve at  or wisti at
>   Department of Zoology, NJ-15, University of Washington, Seattle, WA 98195
>=-=-=-=-=-=-=-Grad School: it's not just a job, it's an indenture!=-=-=-=-=-=-=

I believe that you are mistaken.  This was thought to be caused by a 
morbillivirus.  I have attached a posting from the chief veterinary officer of 
Australia to the OIE.  

Paul Morley
Morley at
Western College of Veterinary Medicine, University of Saskatchewan, Canada

12 October 1994

Dr Jean Blancou
Director General
Office International des Epizooties

Dear Dr Blancou

Acute Equine Respiratory Syndrome in Brisbane, Queensland

I would like to inform you of a condition which has
occurred in the period from 7 to 26 September 1994,
during which fourteen thoroughbred horses died or were
euthanased after becoming seriously ill with an "acute
equine respiratory syndrome".

The condition has been restricted to properties directly
associated with 1 stable in the suburb of Hendra in
Brisbane The situation as of 12 October 1994 is
summarised in the following table:

Location     Descripti  No. of   No.      No. in-  Tot
             on         horses   dead or  contact  al
                        recover  euthana   Healthy
                        ed       sed
* Hendra 1   IP1        4        11       9        24
* Hendra 2   neighbour  1        1         10      12
(Brisbane)   to IP1
* Hendra 3   neighbour  0        0         7       7
(Brisbane)   to IP1
Cannon Hill  holding    0        1         14      15
(Brisbane)   associate
             d with
Kenilworth   holding    1        1        300      302
(150 kms     associate
north of     d with
Brisbane)    IP1
Samford      holding    1        0        20       21
             d with

   These 3 stables are immediately adjacent to each other

   Although there are 300 horses on this holding, the 2
   affected horses from IP1 have not been in-contact
   with the other horses on this spelling property.

       All negative to Serum Neutralisation test

The 7 recovered horses are positive on SNT

Extensive investigations have been undertaken by
government veterinary authorities and private veterinary
experts and known endemic and exotic diseases of horses
have been excluded.

Clinical Signs

Of the 21 cases known to date, 14 have presented as an
acute respiratory syndrome with death in 1 to 3 days. A
further 4 animals have been clinically affected but
recovered, while 3 have been virtually inapparent
infections.  Clinical cases have been inappetant and
pyrexic (up to 410C) with shallow respiration and most
having a frothy nasal discharge varying from clear to
blood tinged. Mucous membranes have usually been dark to
cyanotic and sometimes slightly jaundiced. Several
animals were reported to have dependent oedema (angle of
jaw, legs, sheath), ataxia and head pressing. Terminal
animals have usually died in extremis with a copious
frothy nasal discharge.


The common feature at gross necropsy has been severe lung
congestion and oedema with blood-stained stable froth in
the airways. Other findings have been petechial and
ecchymotic haemorrhages in various organs as well as
slight jaundice.  Microscopically, lesions are those of
an acute interstitial pneumonia with damage to
endothelial linings of small blood vessels, haemorrhage
and foci of early necrosis.


The Australian Animal Health Laboratory (AAHL) and the
Animal Research Institute, Queensland have isolated the
same virus from 5 cases. Since the initial virus
isolation, all further work with potentially infective
material has been undertaken at AAHL. Studies at AAHL
have shown this virus (AERS virus) belongs to the
Paramyxoviridae family and may be a member of the
Morbillivirus genus. Evidence for this includes:

   electron microscopy shows a nucleocapsid with a
  herring bone pattern typical of the Paramyxoviridae;
   AERS virus haemagglutinates guinea pig red cells but
  results are variable with red cells from other species;
   AERS virus does not possess neuraminidase which is
  consistent with the Morbillivirus genus;
   nucleotide sequencing studies suggest that the virus
  is a Morbillivirus but work is continuing in this area;
   immunofluorescent antibody studies on virus infected
  monolayers using antibodies to turkey rhinotracheitis,
  rinderpest, Newcastle disease, respiratory syncitial,
  mumps, measles, canine distemper, and parainfluenza 3
  viruses were negative;
   immuno electron microscopy shows virus nucleocapsids
  to bind to labelled antibody to the isolated virus.
  Antibodies to parainfluenza types 1, 2 and 3 produce
  low level binding.

Transmission tests in 4 horses at AAHL have shown the
isolated virus is the cause of the syndrome.  Evidence
for this includes:

   no bacterial pathogen or toxin could be detected;
   African horse sickness, equine influenza, equine
  herpes virus, equine viral arteritis and the equine
  viral encephalitides were eliminated;
   AERS virus was isolated from the lungs of 5 to 6
   specific antibody to AERS virus is present in 4
  recovered cases and 3 in-contacts believed to have
  suffered a very mild and transient illness, but not in
  other horses;
   positive transmission tests to 4 horses, 2 of which
  received pure virus culture, with subsequent recovery
  of the virus at autopsy.

Natural History

The incubation period in the natural cases was mostly 8
to 11 days with a maximum possible of 16 days. With the
AAHL transmission tests, the incubation period was 3-12
days. Two suspect human cases had a putative incubation
period of 5-8 days.

All the other cases (20) in horses and the suspect human
cases can be linked to the original index case which was
first observed sick on 7 September and died on 9

>From the pathogenesis, clinical picture and pattern of
spread, natural transmission is most likely direct via
frothy nasal discharges as a consequence of close contact
or mechanical transfer. Aerosol transmission seems
unlikely - the upper respiratory tract does not have
lesions and coughing is not a feature of the syndrome.

Available evidence suggests that this virus is not highly
contagious under conditions of natural transmission.

To date there is no evidence as to the possible source of
the virus.

Serological Surveillance Results

AAHL has developed a Serum Neutralisation and an
Immunofluorescence test and to date 1265 samples have
been collected for testing. Results of 587 tests
finalised to date, have shown that the only positive
horses have been those located on, or originating from,
the infected Hendra racing stable in suburban Brisbane.
All horses within a 1 kilometre radius of this infected
premises are being tested for presence of antibodies to
this virus. Further results are expected within the next
48 hours. Blood samples have been submitted from areas
outside the proclaimed Infected Area with all results to
date being negative.

Movement Controls

Based upon surveillance results, the infected area has
been reduced from a broad area of southeast Queensland to
a 5 kilometre around the index premises and premises
associated with direct movement of horses from the index
stable. Limited horse race meetings have resumed in
Brisbane and based on serological survey results
indicating no seroconversion in horses not on quarantined
premises all movement restrictions, except those applying
to quarantine premises, have been lifted from midnight on
11 October 1994.

Public Health

The trainer of the horses also became affected with a
severe respiratory condition and died on the 27 September
1994. The trainer, a stablehand, and the consulting
veterinarian have seroconverted to the isolated virus.
The stablehand exhibited influenza-like symptoms, but the
veterinarian remained in normal health.

Blood samples from 18 other humans associated with this
suburban location have remained sero-negative.

Transmission is believed to have been caused by very
close contact with infected horses, for example hands in
the mouth, and close contact with infected saliva.

The Queensland Director of Public Health has assured the
general public that there is no public health risk from
the equine virus.

I will keep you informed as further information becomes

Yours sincerely

Australian Chief Veterinary Officer

Paul S. Morley
Department of Veterinary Internal Medicine
Western College of Veterinary Medicine
University of Saskatchewan
Saskatoon, Saskatchewan  S7N 0W0  CANADA
E-mail: Morley at Admin3.Usask.CA
Telephone: (306)966-7178
Fax: (306)966-7174

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