Published Date: 2007-08-31 22:00:19
Subject: PRO/AH/EDR> Equine infectious anemia - USA (NM ex TX)
Archive Number: 20070831.2872
EQUINE INFECTIOUS ANEMIA � USA (NEW MEXICO ex TEXAS)
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: 29 Aug 2007
Source: News.Bloodhorse.com [edited]
Isolated EIA Case in New Mexico
A group of about 100 horses at Ruidoso Downs Race
Track in New Mexico has been tested for equine
infectious anemia by the New Mexico state
veterinarian's office after a horse stabled near
the track's barn area tested positive for the
virus last week [20-24 Aug 2007]. Results have
come back negative for all horses in the
immediate area that were blood-tested for EIA.
"The horse (that tested positive) came in from
Texas," said Ruidoso's general manager, Rick
Baugh. "He wasn't on the grounds of Ruidoso, but
he was within the vicinity; that's the reason we
took all the precautionary methods. I was really
upset with the (New Mexico) Livestock Board that
they let him stay where he was for so long (after they knew he was positive)."
According to state veterinarian Dr. Dave Fly, the
6 horses stabled next to the horse that tested
positive for EIA have all tested negative. "Any
additional testing being conducted is strictly a
precaution, and the state believes the one
positive test is an isolated incident," said Fly in a release.
As a further safety measure, all horses leaving
Ruidoso Downs to travel are subject to testing by
state- and federally-accredited veterinarians.
According to Fly, however, the horses housed at
the track are at an extremely low risk to contract the disease.
EIA is commonly called "swamp fever" and can be
fatal; however, it is only contagious if carried
into the bloodstream by an insect such as a
mosquito or by a contaminated needle. Because
there are no effective and safe vaccines for the
virus, many countries have established control
programs based on serologic testing.
Fly recommended any horse that might have been in
the Ruidoso Downs barn area during July and
August  be tested within the next 60 days
as an additional safeguard. Baugh said track
veterinarians started testing horses on the
backside immediately after they were notified of
the infected horse. He expects the testing to be
completed over the next couple of days.
After testing positive for EIA, the infected
horse was removed and taken to a quarantine
facility near Ruidoso, but not on the track's
grounds. No other horses are quarantined.
Baugh said this is the first case of EIA he has
been aware of near Ruidoso since he entered his
position more than 15 years ago. He noted that
horses shipping to the track for the 2 Sep 2007
Ruidoso Derby and other stakes races over Labor
Day weekend will be required to be tested before leaving the grounds.
"We've got horses here from all over the United
States, and we don't want (any viruses) leaving
here and going to some other state," said Baugh.
[Equine infectious anemia, EIA, is a reportable
disease in most states. As this is the cusp of a
very rich race (at one time the world�s richest
horse race), the veterinarians and regulatory officials are being cautious.
Because EIA can be vector-transmitted, it can be
difficult to control. Also there is very little
treatment for horses that are clinically ill. A
horse may test positive for the disease and have
no clinical signs, at least for a bit. Also,
foals may initially test positive if from a
positive dam, but after maternal antibodies clear, the foal may test negative.
EIA is an infectious and potentially fatal viral
disease of members of the horse family. The
equine infectious anemia virus (EIAV) is
categorized as a lentivirus: it contains genetic
RNA material, which it uses to produce DNA. This
DNA is then incorporated into the genetic makeup
of infected cells. Identified in France in 1843
and 1st tentatively diagnosed in the United
States in 1888, EIA has commanded a great deal of
attention over the years. No vaccine or treatment
exists for the disease. It is often difficult to
differentiate from other fever-producing
diseases, including anthrax, influenza, and equine encephalitis.
EIA is significant historically because it is the
first disease of horses proven to be caused by a
"filterable virus" -- one that can survive a
special laboratory filtering procedure and remain
infectious. EIAV is the first lentivirus-induced
disease proven to be transmitted by insects. And
EIA is the first persistent virus for which
antigenic drift was defined. (Antigenic drift is
the virus' ability to change its form
sufficiently so that it is no longer vulnerable
to existing antibodies.) Finally, EIA is the
first lentivirus-induced disease for which a diagnostic test was approved.
Portions of the above are from the USDA-APHIS fact sheet information on EIA
<http://www.aphis.usda.gov/lpa/pubs/fsheet_faq_notice/fs_aheia.html> � Mod.TG]