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Published Date: 2011-05-19 18:35:58
Subject: PRO/AH/EDR> Equine herpesvirus - North America: (USA, Canada)
Archive Number: 20110519.1516

EQUINE HERPESVIRUS - NORTH AMERICA: (USA, CANADA)
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International Society for Infectious Diseases
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[1]
Date: Tue 17 May 2011
Source: The Miami Herald, Associated Press (AP) report [edited]
http://www.miamiherald.com/2011/05/17/2220624/western-states-canada-warned-of.html

Horse owners and organizations nationwide are watching anxiously and
some are shutting down shows and other events in an effort to keep a
deadly horse virus outbreak that began in Utah [USA] from spreading
beyond a handful of Western states and Canada.

So far, at least 17 horses in the USA (Idaho, Utah, Colorado,
California, Washington) and Canada have been infected with the highly
contagious equine herpesvirus-1, and at least 3 have died. The disease
poses no threat to people but is easily spread among horses, alpacas,
and llamas because it can be airborne and transmitted by touch or by
sharing feed, brushes, bits [on bridles], and other equipment.

The infected horses were among roughly 400 that attended the National
Cutting Horse Association [NCHA] Western National Championships in
Ogden, Utah, earlier this month [May 2011]. Now, officials in several
states are quarantining infected animals and asking owners of other
horses that were at the event to closely monitor the animals for
clinical signs. Organizers also are cancelling horse shows and classes
in Texas, Utah, and elsewhere in an effort to stem the disease's
spread.

The outbreak has horse owners across the West worried, said Preston
Skaar, president of the Idaho Cutting Horse Association. "It's a hard
deal, but all you can do is have your horses stay home and wait it
out," he said.

Officials with the National Cutting Horse Association couldn't be
immediately reached, but a statement on the group's website said
members are closely monitoring the situation and that all
NCHA-approved shows scheduled for this weekend [21-22 May 2011] have
been canceled by the affiliates or show producers putting on the
events.

"The NCHA appreciates this proactive move by show producers in a
nationwide show of precaution and solidarity," the group said. "While
reported cases of the virus are currently in Western states, the
interstate transport of infected horses could cause a much wider
spread of the virus if we are not all very cautious at this time."

Cutting competitions -- in which horses and riders are judged on
their cattle-handling skills -- involve quarter horses or other
stock-horse breeds. But all horses are susceptible to the virus.

Idaho Department of Agriculture spokeswoman Pam Juker said 26 horses
from Idaho were at the Utah event. Of those, 2 have died of the
disease and at least 6 others were infected, state veterinarian Bill
Barton said.

All of the Idaho owners have voluntarily quarantined their animals,
Barton said, and they're being told to take precautions such as
disinfecting things that come into contact with the animals and
limiting contact between horses.

Colorado, which has had 2 confirmed cases of the virus, is now
requiring permits for any horses being brought into the state. One of
the 2 horses was so ill it had to be euthanized, officials said.

The outbreak also has prompted Colorado State University's Veterinary
Teaching Hospital to ban all non-emergency appointments for horses as
a precaution. The university's Equine Sciences Center has cancelled 2
riding clinics and temporarily restricted horses from entering or
leaving the campus.

Washington state veterinarian Leonard Eldridge said a horse that was
treated at the Washington State University Veterinary Teaching
Hospital in Pullman tested positive for the virus. Testing is being
done on several other horses in the state that also attended the Utah
event.

Oregon has no reported cases of the virus but is keeping an eye on 18
horses that attended the championships, said Oregon Department of
Agriculture spokesman Bruce Pokarney.

Nebraska's state veterinarian has placed 5 horse farms under
quarantine because they had horses that attended the competition. And
officials in Montana are asking the owners of about 35 horses that
attended the event to watch for any signs of the disease.

In Utah, the Bureau of Land Management announced it is postponing its
13th annual Wild Horse and Burro Festival until August [2011] because
of the outbreak. The event, which includes horse shows and adoptions,
was set to take place this weekend [21-22 May 2011] near Salt Lake
City. But organizers said state officials asked them to contain their
horses for at least 2 more weeks to prevent potential exposure.

The virus can usually survive for about a week on surfaces, Barton
said, though under the right conditions it could last as long as 30
days. That makes it particularly tricky to fight, because even the
snort of an infected horse could spray nearby equipment or feed with
the virus, said Debra Sellon, a veterinarian at Washington State
University's Veterinary Teaching Hospital.

Generally, fewer than half the animals that get the virus come down
with the most serious neurological signs, Sellon said. She added it's
too soon to know exactly how many animals have been sickened in this
outbreak. "There's just too much rumor out there to tell what's
accurate. It may be when the worst is over before we can pull together
accurate numbers," Sellon said.

Abby Yigzaw, with the USDA's Animal and Plant Health Inspection
Service, said the agency is assisting state veterinarians in compiling
numbers and other data about the sick animals. But she said the agency
didn't have any immediate numbers on how many horses were infected.

Infected animals usually get sick between 2 and 14 days after they
are exposed to the virus. Clinical signs include fever, sneezing,
staggering, and partial paralysis.

[Byline: Rebecca Boone]

--
Communicated by:
HealthMap Alerts via ProMED-mail
<promed@promedmail.org>

******
[2]
Date: Tue 17 May 2011
Source: Q2 News, KTVQ.com [edited]
http://www.ktvq.com/news/veterinarians-monitor-outbreak-of-fatal-equine-virus/

The Montana Department of Livestock is monitoring an outbreak of
equine herpesvirus (EHV-1) that has led to the death of horses in
several states.

Some horses appear to have been exposed to the severe neurological
form of EHV-1 at the National Cutting Horse Association (NCHA) Western
National Championships in Ogden, Utah, held 30 Apr-8 May 2011.
Confirmed and suspected cases of the disease have been reported
nationwide. EHV-1 can cause a wide range of signs, from a complete
lack of clinical signs to fever, nasal discharge, incoordination,
hind-end weakness, lethargy, urine dribbling, and diminished tail
tone. It also can cause acute paralytic syndrome, which results in
high mortality.

The virus is easily spread by airborne transmission, horse-to-horse
contact, and by contact with nasal secretions on equipment, tack,
feed, and other surfaces. People can spread the virus to horses by
means of contaminated hands, clothing, shoes, and vehicles.

Currently there is no equine vaccine for protection against the
neurological strain of the virus, which poses no human health risk.

Montana horse owners who attended the event, or who have horses that
share facilities with horses that attended the event, should carefully
monitor the health of their horses for signs of the disease and/or any
unusual behavior.

Horse owners who suspect a problem should immediately contact their
local veterinarian.

"We're hopeful that no Montana horses were infected," said state
veterinarian, Dr Marty Zaluksi. "The incubation period is typically
2-14 days, so we may be in the clear. 16 horse owners and 30-35 horses
from Montana attended the event. No cases of the disease have been
reported within the state.

In an effort to be proactive and provide the maximum safety to horses
across the country, NCHA affiliate organizations and show producers in
Montana, Oregon, Oklahoma, Texas, California, Wyoming, New Mexico,
Washington, and Nevada have cancelled previously scheduled shows for
the weekend of 20-22 May 2011.

An NCHA/American Quarter Horse Association event scheduled for 4-5
Jun 2011 in Dillon has also been cancelled; a decision about an event
scheduled for July will be made at a later date.

--
Communicated by:
HealthMap Alerts via ProMED-mail
<promed@promedmail.org>

[Equine herpesvirus 1 (EHV-1) and EHV-4 comprise 2 antigenically
distinct groups of viruses previously referred to as subtypes 1 and 2
of EHV-1. Both viruses are ubiquitous in horse populations worldwide
and produce an acute febrile respiratory disease upon primary
infection, characterized by rhinopharyngitis and tracheobronchitis.
Outbreaks of respiratory disease occur annually among foals in areas
with concentrated horse populations. Most of these outbreaks in
weanlings are caused by strains of EHV-4. The age, seasonal, and
geographic distributions vary and are determined by immune status and
horse population. In individual horses, the outcome of exposure is
determined by viral strain, immune status, pregnancy status, and
possibly age. Infection of pregnant mares with EHV-4 rarely results in
abortion.

Outbreaks with specific strains of EHV-1 infection result in
neurologic disease. Clinical signs vary from mild incoordination and
posterior paresis to severe posterior paralysis with recumbency, loss
of bladder and tail function, and loss of sensation to the skin in the
perineal and inguinal areas. In exceptional cases, the paralysis may
progress to quadriplegia and death. Prognosis depends on the severity
of signs and the period of recumbency. Neurologic disease associated
with EHV-1 is thought to occur more commonly in mares after abortion
storms, but it has been reported in barren mares, stallions, geldings,
and foals after an outbreak of EHV-1 respiratory infection.

For prevention and control of EHV-4 and EHV-1-related diseases,
management practices that reduce viral spread are recommended. New
horses (or those returning from other premises) should be isolated for
3-4 weeks before commingling with resident horses, especially pregnant
mares. Management-related stress-inducing circumstances should be
avoided to prevent recrudescence of latent virus. Pregnant mares
should be maintained in a group away from the weanlings, yearlings,
and horses out of training. In an outbreak of respiratory disease or
abortion, affected horses should be isolated and appropriate measures
taken for disinfection of contaminated premises. No horse should leave
the premises for 3 weeks after recovery of the last clinical case.

Parenterally administered modified live vaccines are licensed in some
countries but banned in others. An inactivated vaccine is the only
product currently recommended by the manufacturer as an aid in
prevention of EHV-1 abortion, not neurological disease. Vaccine should
be administered during months 3, 5, 7, and 9 of pregnancy. Humoral
immunity induced by vaccination against EHV-1 and EHV-4 generally
persists for only 2-4 months. Antigenic variation within each virus
type means that available vaccines do not cover all strains to which
horses can be exposed. Vaccination should begin when foals are 3-4
months old and, depending on the vaccine used, a 2nd dose given 4-8
weeks later. Booster vaccinations may be indicated as often as every
3-6 months through maturity. Vaccination programs against EHV-1 should
include all horses on the premises.

Extracted from
http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/121302.htm.
- Mod.TG]

[Leighton Read MD <leighton@alloyventures.com> writes:
"I'm a regular reader, an irregular donor and a rare contributor to
Promedmail. This will be of interest and is causing considerable
concern among horse owners near my California ranch. It is being
widely reported now, per a quick google search for equine
herpesvirus."

Cases have now been confrimed in Arizoma, California, Idaho, Oregon,
Utah & Washington state.

Cutting horse in action
http://www.kentuckyhorse.org/attachments/wysiwyg/25/cutting-horse.JPG
- Mod.JW]

[The states mentioned can be located on the HealthMap/ProMED-mail
interactive map at http://healthmap.org/r/016l. - Sr.Tech.Ed.MJ]

See Also