Merial Canada

March 22, 2005 17:03 ET

Equine West Nile Virus Remains Unpredictable Threat to Horses; Spring is the Best Time to Vaccinate Horses against West Nile Virus


NEWS RELEASE TRANSMITTED BY CCNMatthews

FOR: MERIAL CANADA

MARCH 22, 2005 - 17:03 ET

Equine West Nile Virus Remains Unpredictable Threat to
Horses; Spring is the Best Time to Vaccinate Horses
against West Nile Virus

BAIE D'URFE, Quebec--(CCNMatthews - Mar 22, 2005) -

Of the approximately 800,000 horses throughout Canada, all are at risk
for contracting West Nile Virus (WNV), since the disease is endemic to
North America. Due to the unpredictability of the disease, the American
Association of Equine Practitioners (AAEP) recommends that all horses in
North America be immunized against West Nile Virus.

"The best time to vaccinate horses is right now, during the spring
months, before the onset of mosquito season," says Normand Plourde,
Technical Services Veterinarian, Merial Canada. "It is also important to
make sure previously vaccinated horses get their annual booster shot
before mosquitoes become more prevalent in the summer."

Equine WNV is a serious, life-threatening and often debilitating disease
for horses. The death rate for horses with clinical signs of WNV
infection is approximately 33 percent. Forty percent of horses that
contracted the neurological form of WNV disease and survived have
displayed residual effects such as gait and behavioral abnormalities,
according to the AAEP.

Risk of exposure and geographic distribution of WNV vary from year to
year with changes in distribution of insect vectors and reservoirs of
the virus. The AAEP recommends an annual booster after the primary
series of vaccinations. In endemic areas, booster as required or
warranted due to local conditions conducive to disease risk.

"In 2004, Merial Canada launched a new WNV vaccine that uses the most
advanced vaccine technology available," Plourde says. "RECOMBITEK®
Equine West Nile Virus vaccine is a recombinant vector-virus vaccine
that provides fast-acting and long-lasting protection against WNV."

Research studies show that the new vaccine protects 90 percent of horses
against WNV viremia one year after a primary vaccination series of two
injections.(1) In a separate study, eight of nine horses were protected
from WNV with the vaccine in just 26 days following a single
injection.(1) The vaccine can be used to booster any previously
vaccinated horses. It is also safe for foals.(1)

"West Nile Virus should not be taken lightly," Plourde warns. "Taking
action today to protect horses through vaccination is much easier and
less expensive than providing treatment later for horses that contract
this disease."

Merial is a world-leading, innovation-driven animal health company,
providing a comprehensive range of products to enhance the health,
well-being and performance of a wide range of animals. Merial employs
approximately 6,000 people and operates in more than 150 countries
worldwide. Its 2004 sales were in excess of $1.8 billion. Merial Limited
is a joint venture between Merck & Co. and sanofi-aventis. For more
information, please see www.merial.com.

®RECOMBITEK is a registered trademark of Merial Limited.

(1)Data on file

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