The meeting's speakers and attendees were carefully selected
to represent various sides of this issue so that pertinent questions
and concerns could be addressed. Following an introduction by
Dr. Ferraro, Dr. Bennie Osburn, the Dean of the UC Davis School
of Veterinary Medicine, discussed the veterinary school's role
in addressing emerging viral diseases. Dr. Fred Murphy, former
Dean of the UC Davis School of Veterinary Medicine and former
Director for the Center for Infectious Diseases, Centers for
Disease Control, discussed the global status of emerging infectious
diseases.
The USDA's agricultural research arm was represented by Dr. Geoff
Letchworth, the Research Leader for the Arthropod Borne Animal
Disease Research Laboratory in Wyoming. He explained the disease
and discussed its current research status. Dr. Dana Nelson of
the USDA's Animal and Plant Health Inspection Service (APHIS)
for California and Nevada, and Dr. Richard Breitmeyer of the
CDFA, outlined the regulatory response that could be expected
should any viral encephalitis outbreak occur within California.
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Speakers at the West Nile fever meeting conducting
a panel discussion. (left to right) Dr. Richard Breitmeyer-CDFA,
Dr. Dana Nelson-USDA, Dr. John Edman-UC Davis Center for Vector
Borne Disease, Dr. Geoff Letchworth-USDA, Dr. Michele Jay-State
of CA Public Health Vet., Dr. Sharon Hietala-CA Animal Health
and Food Safety Lab., Dr. Bernard Salick-Sandstone Farm and Ms.
Amy Mann-American Horse Council. |
California Animal Health and Food Safety Laboratory (CAHFS)
spokesperson Dr. Sharon Hietala discussed the strategies for
dealing with emerging equine viruses in California, including
the sentinel chicken program for the early detection of arboviruses
(those transmitted by mosquitoes). This disease warning system
has been used for many years within California to indicate the
presence of dangerous infectious disease agents. Officials maintain
flocks of chickens and test them every other week to detect antibodies
to various diseases to which the chickens have been naturally
exposed. Dr. Hietala also discussed the many diagnostic services
available to California horsemen through the CAHFS service.
The public health perspective was represented by Dr. John Edman,
Director of the UC Davis Center for Vector Borne Disease, and
Dr. Michele Jay, Public Health Veterinarian for the State of
California. They discussed the importance of identifying an outbreak
of the virus early on so that proper control measures could be
adopted. Early detection is accomplished by increasing surveillance
through the sentinel chicken flocks and by collecting mosquitoes
and testing for a much larger range of viruses to include the
flaviviruses. Any sample that tests positive for St. Louis encephalitis
needs to be further tested for West Nile virus.
Ms. Amy Mann, the Director of Health and Regulatory Affairs for
the American Horse Council, represented the horse industry's
point of view. She clearly stated horse owner's concerns regarding
 regulatory
issues such as possible restrictions on the international movement
of horses, the need for interaction and coordination between
regulatory agencies, and the proper dissemination of accurate
information to the public. She also decried the lack of federal
funding to the USDA for research and disease control of diseases
affecting the equine industry. Ms. Mann clearly made the point
that if the West Nile virus did not have the potential to infect
humans, there would be no national governmental interest in this
disease. She urged all horsemen to lobby their local Congressional
representatives on this issue.
Helen Scott-Orr, the Executive Director of Research, Advisory
and Education for the New South Wales Department of Agriculture
in Australia, explained concerns regarding the international
movement of horses to and from areas where West Nile fever was
identified. Considering the large number of people and horses
that are expected to attend the Olympic Games this summer in
Australia, it is reasonable to expect regulators to institute
any and all measures necessary to protect public health and safety.
Animals from any areas experiencing a contagious disease outbreak
will most likely be denied travel to Australia.
 Dr. Bernard Salick
of Sandstone Farm, represented the show horse owner's point of
view. He raises Holsteiners that compete at World Class levels
in jumping and dressage. His farm in Thousand Oaks, California
has been designated as this year's quarantine area for the US
horses competing in the Olympic Games. He discussed the monetary
investment owners have in top quality competitive horses and
how infectious diseases affect breeding, sales and showing of
these animals. He shared his passion for infectious disease research
and stated that because there is no worldwide standard for equine
disease control, UC Davis and the Bernard and Gloria Salick Equine
Viral Disease Laboratory have the power to set a standard, starting
with West Nile fever.
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Dr. James MacLachlan, Director of the Bernard and Gloria Salick
Equine Viral Disease Laboratory, discussed the current status
of equine virology research. He stated his goal was not to create
hysteria regarding West Nile fever, but instead, to put a group
together to address the important issues. He said the equine
viral disease laboratory would hold the high ground scientifically
and offer a research resource to those investigating the disease.
The laboratory will also train the next generation of veterinary
scientists to be prepared for emerging equine viral diseases.
He concluded by moderating a panel discussion for questions and
answers. |
Dr. James MacLachlan, Director of the Bernard
and Gloria Salick Equine Viral Disease Laboratory. |
The first step in dealing with this issue is to identify what
we know -- to differentiate between fact and fiction -- which
was the purpose of this meeting. Once the facts are laid out,
the next step is to identify what we need to know. The million
dollar question is can West Nile fever be transmitted from horse
to horse or from horse to other animals and humans? If it can
be transmitted, then regulatory agencies throughout the world
are justified in establishing quarantine procedures. If it turns
out the horse is a dead-end host (can not transmit the disease
to others), then quarantine procedures are not necessary and
researchers can concentrate on diagnostics and treatment.
Dr. Letchworth is currently investigating this question in Colorado
and holds the key to handling this disease. This study is on
the fast track and he plans to have more information by the end
of this year. He is working in a biosecurity level 3 laboratory,
one of very few that are certified to conduct this type of research
-- this laboratory is able to safely contain live infected mosquitoes
for research. UC Davis does not have this kind of research laboratory
for equine viruses; however, the campus is currently discussing
developing a biosecurity level 3 laboratory for horses because
of the increase in emerging viruses. The Bernard and Gloria Salick
Equine Viral Disease Laboratory was developed to combat these
diseases through research and is collaborating with scientists
in South Africa who have experience with West Nile fever and
have banked infected sera (blood) available for research.
Do we want to develop a vaccine? Scientists could easily and
quickly develop a vaccine for West Nile fever, but there are
some things to consider. With some diseases, immunoenhancement
occurs where the first exposure to the virus causes a mild immune
response, but the second or third exposure results in a much
more severe reaction. A vaccine could also cause this complication
and until the disease is further investigated, immunoenhancement
remains a risk with vaccination.
In addition, once a horse is vaccinated, would scientists be
able to differentiate between actual disease and mere exposure/previous
vaccination? If quarantine regulations are instituted, a vaccinated
horse may test positive for the disease and would not be allowed
to travel in non-infected areas.
What should we do right now? Increase surveillance and research!
Dr. Fred Murphy stated "We have to be prepared for a diverse
set of risks for the future. A strong research base is the key
for action -- without research, we have no keys to move forward."
The sentinel chicken flocks will provide an early warning of
a West Nile fever outbreak and Dr. Letchworth's research in the
biosecurity level 3 laboratory will shed some light on how this
disease spreads.
What should we do to prepare for an outbreak this summer? Eliminate
standing water to prevent mosquito breeding areas and use mosquito
repellent sprays on your horses. Limit outdoor exposure during
periods of peak mosquito activity, especially after dusk. Watch
for any large bird die offs in your area and report it to local
CDFA officials (see inset for contacts). Also watch for signs
of encephalitic disease in your horses such as depression, dementia,
head pressing, and weakness or ataxia in the hind limbs. The
disease can easily be mistaken for equine protozoal myelitis
(EPM), herpes virus or rabies so consult your local and state
veterinarians.
Dr. Gregory Ferraro, Center for Equine Health
Director, hosted the West Nile fever meeting. |
Although we won't know if West Nile fever will be a problem again
until the summer, it is prudent to plan for a possible outbreak.
Now that the virus has been introduced to the United States,
it's likely that it is here to stay and sooner or later, it will
emerge. Other countries will most likely play it safe and set
quarantine regulations which will affect the international movement
of horses. The Center for Equine Health and the Bernard and Gloria
Salick Equine Viral Disease Laboratory are working together with
researchers, regulatory officials and practicing veterinarians
to educate and inform the horse-owning public so that if West
Nile fever rears its ugly head, we will have a plan of action
to fight it. |
One major new disease a year emerges in humans. Dr. Ferraro stated,
"Today's disease is West Nile fever; tomorrow, it could
be something else," and the CEH and the Bernard and Gloria
Salick Equine Viral Disease Laboratory plan to be prepared to
meet the challenge.
Udavis part 1|2000AAEP update
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ERC
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CEH Prepares for West
Nile Virus Outbreak (Part2)