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-----Original Message-----From: Carla Everett
mailto:ceverett@tahc.state.tx.us
Sent: Wednesday, February 28, 2001 7:41 PM
To: Colleagues
Subject: Foot-and-Mouth Disease Marches Westward; Animal Health
Officials Fear Spread of Virus
NEWS RELEASE
Texas Animal
Health Commission
Box l2966 *Austin, Texas 78711 *(800) 550-8242* FAX (512) 719-0719
Linda Logan, DVM, PhD* Executive Director
For info, contact Carla Everett, information officer, at
1-800-550-8242, ext. 710, or
ceverett@tahc.state.tx.us |
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Animal health officials in Texas are watching
with concern the relentless westward march of foot-and-mouth disease
(FMD), the most recent outbreak of which was confirmed in late
February at several sites in England, where livestock operations
already have been financially ravaged by the brain-wasting disease,
BSE (bovine spongiform encephalopathy) and outbreaks of the viral
infection, hog cholera. Additional cases of FMD have been
detected among cattle, sheep and swine in Great Britain
(encompassing England, Wales and Scotland). In addition to the loss
of thousands of animals, British farmers may lose as much as $73
million just from the week-long ban (which could be extended) on the
transport and marketing of livestock susceptible to the disease.
FMD, which has not been seen in the U.S. since l929, is caused by a
highly infectious virus that can cause death or disabling blisters
and sores in and around the mouth, muzzle, teats and feet of
livestock with cloven or "split" hooves. Cattle, pigs, sheep, goats
and deer are highly susceptible, and can exhibit clinical disease
signs after an incubation period of only three to eight days. To
stop the spread of infection, affected or exposed animals must be
slaughtered, then burned or buried. Premises and equipment
must be disinfected to prevent disease spread. "Foot and mouth virus
poses special challenges, requiring proper disinfection and
biosecurity protocols. People who have worked around or been near
infected animals can inadvertently carry and spread the virus via
their equipment, cars, clothing, shoes, or even for a short time in
their lungs or pharynx (throat)," said Linda Logan, Texas' state
veterinarian and head of the Texas Animal Health Commission (TAHC),
the state's livestock health regulatory agency. She pointed out that
studies indicate the virus can drift up to 40 miles on the wind,
another hurdle to confining an FMD outbreak to a defined geographic
area.
"FMD is probably the most economically damaging livestock disease,"
The disease is currently affecting four of the world's seven
continents: Asia, Africa, South America and Europe, leaving only
North America, Australia and Antarctica free of the disease. "An
outbreak costs a country millions of dollars to fight, and thousands
of animals can be lost. Additionally, livestock markets must be
closed to prevent spread of infection, dairies may not be able to
operate, and transportation of livestock must cease. Furthermore,
there's the cost of depopulating and disposing of affected or
exposed animals and vaccinating 'clean animals' to create a
disease-free 'buffer zone,'" said Dr. Logan, a specialist in
tick-borne and foreign animal diseases. She also serves on a
national team reviewing how best to safeguard U.S. livestock from
foreign diseases and pests.
Dr. Logan urged livestock producers in Texas to be step up their
surveillance and to take precautions to protect herds from possible
contamination. "If you've traveled internationally, don't risk
carrying disease home to your herd. Disinfect your boots before
working with your livestock. Producers who feed wastefood to swine
should be particularly careful to ensure that all scraps are well
cooked," she said. She also suggested that producers limit vehicle
traffic and visitors onto their premise, and keep new animals
isolated for several days prior to adding them to the existing herd.
"If your livestock become lame or develop blisters or sores, call us
at 1-800-550-8242. Our emergency response within the first 24 hours
after the first signs of disease will affect our outcome over the
next six months," Dr. Logan said. The TAHC and U.S. Dept. of
Agriculture's Veterinary Services in Texas operate the toll-free
number 24 hours a day for emergency calls. While FMD vaccine
is available, Dr. Logan said it is used only in emergencies, to
create a "disease-free" buffer zone around an infected area. Because
vaccinated animals will test positive, they cannot be shipped
internationally and protocols require the animals to be destroyed as
soon as the disease is eradicated. "Most importantly, FMD
outbreaks result in trade embargoes imposed by other countries,"
said Dr. Logan. "South Korea, for instance, had been free of
FMD since l934, but was struck by the virus in late March 2000," she
reported. "Producers in that country intended to export $400 million
worth of pork in 2000, but Japan and its other trading partners
immediately shut their doors to South Korean exported animals and
products. It can take years to be declared disease-free and
reestablish international marketing opportunities."
"Consider the damage to our economy, if we were to have the disease
introduced into the U.S. and exports of live animals and meat were
prohibited. Last year, the U.S. shipped out more than $4.2 billion
worth of these commodities. Texas ranked third among all states,
shipping out more than $736 million in animals and meat products,"
she said. "For years, we worried about domestic regulatory diseases
that are 'tame' compared to the devastation of foreign animal
diseases," said Dr. Logan. "A global economy brings with it
global risks, and we must be prepared for the inevitable threats
posed by international trade and travel." "I am particularly
concerned when cases of FMD occur close to a highly populated
area--or near a major international airport," said Dr. Max Coats,
who heads up the TAHC's animal health programs and field operations.
"Because of the virus' ability to ride the wind, it's possible that
ranching or farming equipment being exported by affected countries
could be contaminated, It may sound far-fetched, but with a disease
of this impact, we're always concerned about potential scenarios.
Within 24 hours, an animal, animal product, person or piece of
equipment can be transported nearly anywhere in the world. There's
always a chance that a virus, pest or dangerous bacteria will be
hitching the ride, too." "Then there are the items travelers
like to tote on long flights, such as sandwiches, delicacies or
other food items that could be contaminated by the virus," he said.
Although direct flights from countries affected by FMD are checked
carefully, Dr. Coats said there's always a risk that contaminated
items could be smuggled or inadvertently brought into the country by
the millions of visitors and returning U.S. citizens who travel
internationally. Around 4.5 million British residents, for example,
came to the U.S. on direct flights in l999. During the
past year, more than a dozen countries have been plagued by
outbreaks of FMD, and the virus continues to migrate westward, noted
Dr. Logan. In early March 2000, Japan reported its first cases since
l908, and Japanese authorities laid blame on imported straw
contaminated with the virus. "Within two weeks of the initial case,
Japanese livestock authorities checked more than 25,000 dairies,
nearly 27,000 beef cattle farms and almost 3,700 pig farms to
determine if there was additional infection," said Dr. Logan. "If
this scenario occurred in Texas, the TAHC field staff would be
unable to handle this enormous task alone, and we would have to
summon help from private veterinary practitioners, our partners
within the state's emergency management system, and our federal
counterparts in the USDA." (Of the 215 TAHC'ers about 100 are
livestock inspectors and around 20 are veterinarians.) "Swine
are highly efficient and effective hosts for FMD," said Dr. Coats.
"And, with more than two million wild or feral swine in Texas, our
challenge would be nearly insurmountable if the disease became
established in this free-ranging population." By Valentine's
Day 2000, reports indicated that more than 500 animals had died from
the disease in eastern Mongolia, a large country bordered on the
south and east by China (also affected) and by Russia to the north.
A year later, FMD outbreaks continue in Mongolia, where winter
blizzards also wiped out more than 1.5 million animals. By
Easter last year, Russia reported cases among swine herds in its
eastern regions, and in late spring, infection was detected at a pig
farm in Kazakhstan, which shares borders with China and Russia. In
August, infection drifted southward into the small country of
Tajikistan where cases among cattle and sheep herds were reported.
Two free-grazing cattle herds in northeastern Greece, near the
Turkish border, were struck by the disease in July 2000, and
surrounding cattle, goat and swine herds were destroyed. In the
fall, Turkish governmental authorities requested more than $43
million in international aid to curtail livestock smuggling in its
eastern and southeastern regions and stop the introduction of FMD
and its potential spread into Europe. South American countries
were hit by infection in late summer 2000, said Dr. Coats. Paraguay
was struck first in early August, followed by outbreaks in Uruguay
and Colombia. Argentinean officials blamed their country's outbreak
on cattle smuggled from Paraguay. An Argentinean newspaper reported
that as many as 20,000 head were illegally smuggled in from
Paraguay. When a Brazilian dairy was hit by the disease, the
Brazil's minister of agriculture reported that he suspected
bioterrorism, as the virus was of a different strain than the one
detected in Paraguay and Argentina. (FMD virus has as many as seven
types and 70 differing strains.) "Argentina is the world's
fourth-largest cattle-production country, and producers had planned
to expand their exports by $5 billion in 2000. Brazil is the
world's largest exporter of beef. Both countries lost their
marketing opportunities when FMD hit the countries," said Dr.
Coats. "When infection spread to
Uruguay, the military shut down all human and animal movement and
dropped food into the restricted area from helicopters," said Dr.
Logan, who visited the country last fall. "Animals in the affected
area were euthanized and buried within 24 hours, which stopped the
spread of disease. Uruguayan officials and producers had prepared
for such an outbreak ahead of time by setting up funds to pay
producers for their livestock losses." FMD also wreaked havoc
in South Africa in summer 2000, when viral-contaminated wastefood
was off-loaded from a foreign vessel and fed to swine. "This
situation mirrored the scenario for the tabletop emergency disease
exercise in November, conducted cooperatively by the U.S., Canada
and Mexico," said Dr. Coats. "In the simulated outbreak, a South
Texas producer collected contaminated wastefood from a foreign ship
and fed it to his pigs. Within two weeks, routine livestock
marketing and movement could have spread the disease across Texas
and into several states and Canada. We estimated it would have
cost $50 million to eradicate the disease just in Hidalgo County."
"We're monitoring the movement of FMD closely. Buffer zones and
existing prevention efforts seem to have failed, as one after
another, countries are hit by the disease," said Dr. Coats. "Foreign
animal diseases, like FMD, are the 'gift that keeps on giving,' as
demonstrated by the 2001 resurgence of infection in Taiwan, after
the country lost nearly all of its swine herds in l997 outbreaks."
"This most recent FMD outbreak affecting Great
Britain was initially detected by a veterinarian inspecting pigs at
a slaughter plant in a town northeast of London. Since then, cases
have been disclosed throughout Great Britain, which has about
157,000 livestock farms," commented Dr. Coats. He said British
authorities believe the virus may have been introduced through the
feeding of contaminated wastefood to swine. Sheep on a nearby farm
were exposed and may have spread infection to as many as 25,000
animals when they were hauled to three markets.
"Livestock shows in Great Britain have been
cancelled, and animal parks and zoos have been closed. Horse events
also have been postponed, even though equine are not susceptible to
the disease. Fears are that the virus could be carried and spread
either by the horses' hooves or by the vehicles used to transport
the animals," commented Dr. Coats. He said French authorities are
destroying more than 47,000 British sheep that were recently
imported. He pointed out that, in Germany, authorities are taking
precautions, destroying susceptible animals that were recently
shipped in from Great Britain. In the Netherlands, more than 4,300
susceptible livestock and deer have been killed on farms that have
links to Great Britain. Livestock markets in the Netherlands also
are being closed for a week, he said. "Worldwide, nearly two-thirds
of the FMD outbreaks are attributed to the introduction and feeding
of contaminated meat, meat products or garbage to animals," said Dr.
Logan. She said about a quarter of infection is spread by airborne
transmission, and about 10 percent is comprised of infected
livestock importations or contaminated objects and people."
"The FMD situation is a lot like watching a hurricane develop. We
can't pinpoint its next landfall, but we know its direction. We must
be prepared to take action immediately if the virus is introduced
into the U.S.
--or Texas," said Dr. Logan. |
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Below is a fact sheet regarding the
German-imported cattle currently quarantined
in Texas. You may have heard media reports, and I wanted to ensure
you had accurate, timely information to help dispel any rumors!
Thank you. Should you get media requests, we will be glad to
handle them, if you'll refer them to me at 1-800-550-8242, ext. 710.
Thanks!
Carla Everett
Public Information
Texas Animal Health Commission
Questions & Answers Regarding German-Imported Cattle
Q: When were the
German cattle imported into the U.S.?
Twenty-nine
animals were imported legally into Texas between February 1996 and
September l997. Eight others went to Colorado, one to California,
one to Illinois. At the same time, two head were imported from
Belgium to Minnesota. Four of the animals in Texas have been
destroyed and tested, with negative results for BSE. Three other of
the imports died of causes not related to BSE, leaving 22
German-imported cattle currently in Texas. The eight in
Colorado and the one animal in California also have been destroyed
and tested, with negative results for BSE.
Q: When were the
cattle placed under quarantine--and why?
In l997, Belgium
had its first case of BSE, believed to have been the result of
feeding contaminated feed. It was also determined at that time that
contaminated feed was being moved throughout the European Union, and
the U.S. stopped allowing the importation of cattle and meat
products from the EU. All EU cattle in Texas were located, and the
Texas Animal Health Commission, in cooperation with the USDA in
Texas, in March l997, placed quarantines on these animals. Likewise,
state veterinary officials placed quarantines on the European
imports shipped to Colorado, California and Illinois.
Q: Has Germany had
any cases of BSE?
According to the
OIE--the Office Internationale Epizooties--in Paris, France, which
keeps the reportable disease data for purposes of international
trade, Germany had a BSE-positive animal in l992. IT IS IMPORTANT TO
NOTE THAT THIS WAS AN IMPORTED ANIMAL FROM GREAT BRITAIN.
Three more animals imported to Germany were positive in l994, and
two imported animals in l997. Not until November 2000 did
Germany have domestic cattle affected by the disease. Forty-seven
domestic animals in Germany have tested positive. Germany, like
other EU countries, are testing slaughter animals for the disease.
Q: What will
happen to the 21 German-imported cattle in Texas?
The animals have
been held under quarantine, while the cattle industry-spearheaded by
the National Cattlemen's Beef Association -- raised funds to augment
the federal indemnity of $2,000 per animal. A professional appraiser
has determined the fair market value of the animals. None of the
animals have shown any signs of BSE. Funding from the industry
has been secured, and the animals will be euthanized. Brain
tissue from each animal will be collected for testing at the
National Veterinary Services Laboratory in Ames, Iowa. The carcasses
of the animals will be incinerated, and the meat will not enter the
food chain.
Q: What about the
offspring from these animals?
The offspring have
not been restricted, as there is no evidence of vertical
transmission from asymptomatic animals to calves.
Q: Are there other
imported cattle in the U.S that are at risk?
Currently under
quarantine are four animals from the Great Britain in Vermont, and
the two from Belgium in Minnesota. No signs of BSE or positive test
results have been found in any imported animals. Furthermore, all
import records have been double-checked by the USDA to ensure there
are no other high-risk imported animals in the U.S.
Q: Weren't there a
number of animals imported from the UK?
Yes, prior to the
ban on UK cattle and meat products in l989. The USDA traced 496 head
of cattle from Great Britain that were imported to the US between
l981 and l989. No signs of BSE or positive test results were found
in these animals.
Q: What countries
have been affected by BSE?
According to OIE
reports:
Great Britain has had the lion's share of cases, with 174,648 cases
in 34,810 herds, as of Jan. 29, 01. Of these, 60 percent were in
dairy herds.
Belgium--imported and domestic animals--23 cases total.
Denmark-- 1 imported case in l992, 1 domestic in 2001.
France--264 cases--imported and domestic animals.
Italy--2 cases, imported and domestic animals.
Liechtenstein--2 domestic cases.
Luxembourg--1 domestic case.
Netherlands--9 cases, domestic.
Portugal--509 domestic and imported cases.
Spain--34 cases.
Switzerland--367 cases, domestic and imported.
Prepared by the Texas Animal Health Commission
1-800-550-8242 |
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Recently, I disseminated a fact sheet regarding
cattle imported to Texas from Germany prior the l997 ban on animals
and meat products from Europe, due to BSE and/or questionable feed
practices. I wanted to update you on this situation and am
forwarding this media advisory issued yesterday by Diane Oswald of
the College of Veterinary Medicine:
MEDIA ADVISORY FROM College of Veterinary Medicine, TX A&M
University
German Imported Cattle
Sixteen cattle imported from Germany in 1996, before diagnosis of
Bovine Spongiform Encephalopathy (BSE) in that country, will be
transported to the College of Veterinary Medicine at Texas A&M
University on Thursday, April 5, where they will be euthanized for
subsequent testing of BSE. The animals will be processed in a
restricted area.
Brain tissue from each animal will be sent to the National
Veterinary Services Laboratory in Ames, Iowa for BSE testing.
These actions are precautionary measures monitored by United State
Department of Agriculture veterinarians as part of the National BSE
Surveillance Program. None of these animals has shown any sign of
BSE, commonly known as "mad cow" disease.
"The quarantine and testing of imported cattle has been in place for
a number of years as a precautionary measure against BSE," said H.
Richard Adams, Dean of the College of Veterinary Medicine at Texas
A&M.
Although there has been nationwide BSE testing for nearly a decade,
the disease has not been diagnosed in any U. S. cattle. Strict
preventative measures, such as those being used with the cattle
imported from Germany into Texas, are in effect to ensure public
safety.
The carcasses of the animals will be incinerated and none of the
meat will enter the food chain. BSE is not a highly contagious
disease, and can only be transmitted by ingestion.
The USDA has banned the importation of cattle from countries where
BSE has occurred since 1989, and from countries that have feeding
practices that put animals at risk for exposure to the disease.
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For info, contact Carla Everett, information officer, at
1-800-550-8242, ext.
710, or
ceverett@tahc.state.tx.us
NEWS RELEASE
Texas Animal Health Commission
Box l2966 *Austin, Texas 78711 *(800) 550-8242* FAX (512) 719-0719
Linda Logan, DVM, PhD* Executive Director
For Immediate Release--
First Cases of Anthrax in 2001 Reported in
Uvalde and Val Verde Counties;
Producers in Area Urged to Vaccinate
Two cases of anthrax have been confirmed in deer from Uvalde and Val
Verde Counties in Southwest Texas, and livestock health officials
are urging producers in the area to consult their private veterinary
practitioners about vaccinating livestock against this disease that
resurfaces periodically. Many long-time ranchers in the area have
experienced sporadic outbreaks and routinely inoculate their
livestock against this disease that is weather-dependent and can
develop during warm spring and summer months.
"Anthrax is caused by Bacillus anthracis, a spore-forming bacteria.
The disease often occurs after we have periods of wet, cool weather
followed by a several weeks of hot and dry conditions," explained
Dr. Dan Baca, a veterinary epidemiologist with the Texas Animal
Health Commission (TAHC), the state's livestock health regulatory
agency. "When livestock graze in an affected pasture, they can
ingest the spores that are on the grass or ground. Historically,
most of Texas' cases each year occur in a triangle bounded by
Uvalde, Ozona and Eagle Pass."
The triangular area takes in portions of Crockett, Val Verde,
Sutton, Edwards, Kinney, Uvalde and Maverick counties. However, if
conditions are right, cases could
occur anywhere in Texas, stated Dr. Baca. In l997, cases were
confirmed in Edwards, Val Verde, Terrell, Webb, Starr and Uvalde
counties. An anthrax case in l997 also was confirmed in Parker
County, in north Texas.
Dr. Baca said ranches with confirmed cases are quarantined until at
least 10 days after all livestock are vaccinated, and after proper
disposal of all carcasses. "By halting the movement of animals, any
livestock exposed or incubating the disease will not spread
infection to other ranches," he said. "It's not unusual for one
premise to have livestock losses, while livestock on an adjacent
ranch remain healthy."
Anthrax is a reportable disease in Texas. While laboratory tests,
conducted by the Texas Veterinary Medical Diagnostic Laboratory in
College Station, are needed to confirm infection, Dr. Baca said that
suspected cases also are to be reported to the TAHC at
1-800-550-8242. A veterinarian is available to take calls 24 hours a
day. If outbreaks occur in dairy animals, Dr. Baca advised producers
to call the TAHC immediately for assistance to prevent potential
human exposure through milk products.
Signs of the disease in livestock and deer can include sudden death,
rapid bloating of the carcass, and blood oozing from body openings.
"After talking with several ranchers, we're assuming a number of
suspected cases occur each year, but are not reported," he said.
To prevent contaminating the ground with anthrax spores which can
remain dormant
for years, Dr. Baca said TAHC regulations require that the property
or livestock owner thoroughly burn carcasses of animals that may
have died from anthrax. The animal's bedding, manure and the
surrounding soil also should be burned. This keeps predators or wild
pigs, coyotes or dogs from being exposed to the disease. Because
anthrax strikes during dry periods, he said carcass disposal can
pose its own dangers, so precautions must be taken to keep the fires
from 'getting out of hand.' To avoid spreading spores, he said the
TAHC recommends that carcasses be burned where they lay.
Dr. Baca also advised producers to wear long sleeves and gloves when
handling the carcasses or when working or vaccinating livestock to
avoid contaminating any sores or scratches on arms or hands. General
sanitation procedures should be followed after handling livestock,
and equipment used on the animals should be disinfected. Pets should
be kept away from dead carcasses. Bones of dead animals may also
pose a disease threat. Healthy animals should be moved from
anthrax-contaminated areas.
"It is possible for ranchers to contract a skin form of anthrax, so
if any wounds appear to be infected, see your physician for
appropriate antibiotic treatment," he said.
"Although movies and popular mythology portay anthrax as an
invariably fatal human disease threat, the often fatal pulmonary
form of the disease is nearly non-existent in
developed countries. Producers may want to talk with their physician
or contact the Texas Department of Health if they have human health
questions."
"Hunters often ask about anthrax, and by the time hunting season
starts, cool weather usually puts an end to any cases," said Dr.
Baca. "However, my best advice always is to shoot only
healthy-looking animals. By the time an animal displays signs of
anthrax that can include staggering, trembling or convulsions, death
is inevitable."
Dr. Baca said several steps need to be taken when anthrax occurs:
1. Properly dispose of animal carcasses by burning to prevent
exposure to other
animals, such as predators or dogs. Remove healthy livestock from
the area.
2. Vaccinate livestock if cases occur in the surrounding areas.
Because the anthrax vaccine is a "live" vaccine, it should not be
administered concurrently with antibiotics. Vaccinated animals are
to be withheld from slaughter for two months.
3. Restrict movement of livestock from an affected premise until
animals can develop immunity through vaccination. |
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NEWS
RELEASE
Texas Animal Health Commission
Box l2966 *Austin, Texas 78711 *(800) 550-8242* FAX (512) 719-0719
Linda Logan, DVM, PhD* Executive Director
For info, contact Carla Everett, information officer, at
1-800-550-8242,
ext. 710, or
ceverett@tahc.state.tx.us
For Immediate
Release--February 7, 2002
Vaccinate Horses NOW for Maximum Protection
Against Mosquito-Borne Diseases
Despite blustery
days now and again, spring is just around the corner, and animal
health officials are urging owners to protect their equids,
including horses, mules and donkeys against several mosquito-borne
diseases before "bug" season starts.
"Vaccines are available to protect equids against both equine
encephalitis, better known as "sleeping sickness" and West Nile
Virus (WNV). However, the shots are no value if they aren't
given prior to disease exposure," said veterinarian Terry Conger,
state epidemiologist for the Texas Animal Health Commission (TAHC),
the state's livestock health regulatory agency. "These
vaccines require two doses, administered several weeks apart, and
full protection doesn't develop until four to six weeks after the
second dose. Realistically, then, it can take up to 10 weeks
for the horse to be disease-resistant. That's why it's so important
to start the round of vaccinations now."
Dr. Conger noted that cases of "sleeping sickness," or equine
encephalitis, occur sporadically in Texas equids, and on rare
occasions, humans contract the mosquito-borne infection. Transmitted
by mosquitoes that have fed on diseased birds, Eastern Equine
Encephalitis (EEE) and Western Equine
Encephalitis (WEE) causes swelling of the brain, resulting in
staggering, convulsions, and fever. Although horses do not
transmit the disease to humans, equids are "sentinel animals," or
indicators that infected mosquitoes are in a specific area.
"Veterinarians can administer an effective 'two-way' vaccine to
protect equids against EEE and WEE," said Dr. Irby, TAHC equine
specialist. "Two injections, 30 days apart, are required, and the
animal will need a 'booster shot' annually or biannually."
"Another form of sleeping sickness, Venezuelan Equine Encephalitis
(VEE), is a foreign animal disease that originated in South America.
In l971, a VEE outbreak swept northward through Mexico, threatening
horses in the southern U.S. In two years, due to an all-out
effort, more than 2.8
million animals in l9 states were vaccinated against VEE," Dr. Irby
said. "On rare occasions, VEE cases still creep into southern
Mexico, and if it should move north, it would threaten American
animals. Therefore, as an added precaution, equids in South Texas
should receive a three-way vaccine that protects not only against
EEE and WEE, but also VEE."
Although it has yet to be diagnosed in Texas, another
mosquito-borne, encephalitic disease causing concern is West Nile
Virus (WNV). Dr. Irby said WNV was unheard of in the US until
l999 in New York, where seven persons died from the infection and at
least 25 equids were infected. In
2000, the virus had spread to 12 states, and by year's end
2001, the disease impacted 27 states, including Louisiana and
Arkansas. At least 564 equids tested positive for the disease
in 2001, reported Dr. Irby.
Epidemiologists are still uncertain how or when an infected person,
bird or mosquito entered the country, initiating the bird-mosquito
WNV disease cycle in the US. First isolated in1937 in the West Nile
District of Uganda, the disease now has widespread distribution,
including Africa, Europe, the
Middle East, and West and Central Asia, As the virus has moved
across the U.S., the U.S. Department of Agriculture changed WNV's
designation from a "foreign animal disease," to an "emerging
disease."
"Texas is particularly vulnerable to the introduction of WNV,
because major migratory routes for birds pass over a large portion
of east Texas. This summer, we may find that the disease is brought
into the state by infected birds," commented Dr. Irby. He
pointed out that at least 17 species of
mosquitoes can be involved in the disease cycle.
"Many horses infected with WNV won't appear to be ill, while, others
become debilitated and too weak to rise," he said. "About 20
percent of the horses infected with WNV in 2001 either died or were
euthanized because they were so ill."
"Late last summer, a WNV vaccine was approved for equids, and like
many other encephalitic vaccines, two injections are needed. For WNV
vaccine, the injections must be three to six weeks apart. The
timing of vaccination is crucial, as demonstrated in Florida last
year, where 267,000 doses of vaccine were made available.
Eighty-six equine that became infected had received only one dose of
vaccine. Seventeen other stricken animals received their second dose
of vaccine less than three weeks prior to becoming infected," he
explained. "Since immunity may not develop for four to six
weeks after the second dose, owners should have their animals
vaccinated now, so they'll be protected by the time mosquito season
begins this spring."
Dr. Irby reminded owners to reduce mosquito populations by draining
stagnant water from birdbaths, flowerpots, troughs and other
containers, and by keeping pools properly chlorinated. Insect
repellents and insecticides should be used only according to
directions, he said, and
owners may want to stable their animals at night, to provide added
protection.
"WNV is a 'zoonotic disease,' one that also can affect human
health," commented Dr. Conger. "Species other than horses, humans
and birds are susceptible to the disease, and it has been
demonstrated in other states that canines can contract the
infection. No vaccine has been approved for dogs, but this
information may be useful in an epidemiological investigation of a
potential WNV introduction."
The Texas Department of Health (TDH) also is conducting disease
surveillance, for testing mosquitoes, dead crows, blue jays and
hawks. To submit a dead crow, blue jay or hawk for laboratory
examination, call your regional Texas Department of Health office or
the Texas Department of Health in Austin at 1-512-458-7255.
TAHC field personnel are collecting blood samples from equids
involved in regulatory disease programs, and the agency operates a
24-hour hotline at 1-800-550-8242 for taking reports of unusual
signs of disease in livestock, such as:
1. staggering,
falling, or inability to rise
2. illness affecting a large percentage of animals
3. sudden death loss
4. blistering around an animal's lips, teats or hooves
5. unusual ticks or maggots
"Only the first
three of the disease signs apply to encephalitic diseases, but the
other two--blistering and ticks--should be kept in mind, as they
could be signs of other very serious disease situations," said Dr.
Irby. "TAHC and USDA veterinarians will work with private
veterinary practitioners and producers at no charge to help diagnose
foreign or emerging diseases. The earlier we can make a
diagnosis, the sooner we can take appropriate measures to control or
stop the spread of a disease." |
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