Published Date: 2004-06-13 23:50:00
Subject: PRO/AH/EDR> Equine infectious anemia - Australia (QLD)
Archive Number: 20040613.1590
EQUINE INFECTIOUS ANEMIA - AUSTRALIA (QUEENSLAND)
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A ProMED-mail post
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ProMED-mail, a program of the
International Society for Infectious Diseases
<http://www.isid.org>
Date: 11 Jun 2004
From: ProMED-mail <promed@promedmail.org>
Source: Australian Broadcasting Company 8 Jun 2004 accessed 11 Jun 2004
[edited]
<http://www.abc.net.au/news/newsitems/s1127211.htm>
Rare horse virus found in Queensland
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A debilitating horse virus has been detected on a property on the state's
central coast.
3 horses on a Flaggy Rock property south of Mackay have tested positive for
equine infectious anaemia, which experts say is rarely found along the
Queensland coast.
Dr Keven Seppanen from the Department of Primary Industries says flies
transmit the disease from a carrier horse to another close by. He is
encouraging local property owners to check their stock.
"At this point in time we don't know whether it's just a one-off or whether
it's going to establish again," he said. "The saving grace is that biting
insects don't carry the virus too far."
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ProMED-mail
<promed@promedmail.org>
[Equine infectious anemia (EIA) is a viral disease producing anemia,
intermittent fever, and severe weight loss. Members of the equidae family
(horses, ponies, mules, and donkeys) are the only animals known to be
affected by the virus. Once an animal becomes infected, it remains infected
for life, regardless of the severity of the symptoms. There is no
effective treatment.
The virus enters the bloodstream, then invades the lymphocytes, where it
reproduces until the cell bursts. Thus more virus is released into the
blood, and the cycle repeats. The animal produces antibodies against the
virus, but the antibody is not effective in eliminating the virus from the
body. Furthermore, enough lymphocytes are destroyed over time to reduce the
effectiveness of the immune system. When the animal reaches this stage, it
usually succumbs to other bacterial or viral infection. The death rate of
infected equidae varies from 30 to 70 percent, and is usually higher when
the virus is introduced into a new geographical region.
The anemia sometimes accompanying this disease is caused by the animal's
immune system attacking the cells in the bone marrow responsible for
producing red blood cells. The reasons for this are unknown.
Other common names are swamp fever, slow fever, mountain fever, and even
Coggins disease.
Transmission of EIA is by the exchange of certain bodily fluids, usually
blood, from an infected to a noninfected animal. Insect bites are one mode
of transmission. Horseflies, stable flies, and deer flies are blood
feeders. The bite of these insects is painful and the animal often
interrupts the insects' feeding, forcing them to relocate. Residual blood
is often on the fly's mouth parts from an interrupted meal. If the fly
moves from an infected to a noninfected animal, the virus may be introduced
into the noninfected animal when the insect breaks the skin.
The virus may be transmitted by mechanical means, such as instruments, hoof
knives, needles (tattooing or bleeding), syringes, etc. Blood transfusions
have also been implicated in transmitting the virus.
Transplacental infection of the foal is possible if the levels of virus in
the blood are high enough during gestation. About 10 percent of foals
delivered from infected mares are infected at birth and remain virus
carriers their entire life. Because of the presence of maternal antibodies
to the virus in the mare's colostrum, foals born to infected mares will
themselves be antibody-positive within 24 hours. Maternally acquired
passive antibodies should be gone by 6 months of age. If the foal is
infected at birth, its own antibodies will persist after 6 months. - Mod.TG]
See Also
2002----
Equine infectious anemia - USA (Georgia) 20020825.5148
Equine infectious anemia, law change - USA (Texas) 20020501.4062
2000
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West Nile virus, horse - USA (New Jersey) 20000906.1525
Equine infectious anemia - USA (Montana) (02) 20000624.1040
Equine infectious anemia - USA (Montana) 20000619.0998
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