http://www.aphis.usda.gov/oa/pubs/fsfmdvac.html
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March 2001 Foot-and-Mouth Disease Foot-and-mouth disease (FMD) is a severe, highly infectious viral disease
of cloven-hooved animals. Although not usually fatal, it causes
suffering and vastly reduces animalsí commercial value by reducing their
weight and milk output. Cattle, swine, sheep, goats, and deer are
highly susceptible and can exhibit signs of infection after an incubation
period of only 1 to 8 days; however, the incubation period may last longer
and in sheep and goats it may go undetected altogether. Clinical signs
include fever and blister-like lesions followed by erosions on the tongue and
lips; in the mouth, muzzle, and snout; on the teats; between the hooves; and
around the digits. FMD is widely believed to be the most economically devastating livestock
disease in the world, and if it were introduced into the United States, which
is FMD-free, it could cause billions of dollars in losses to the U.S.
economy. Although the disease is not a risk to humans, people who have
worked around or been near infected animals can carry and spread the virus
via their cars, clothing, shoes, and even through their respiratory tracts. The FMD Vaccine Vaccines are used to produce or stimulate immunity against a particular
disease. FMD vaccines are killed virus preparations that are pure,
safe, and effective, and they are available to the United States through the
North American Foot-and-Mouth Vaccine Bank. Mexico and Canada are also
members of the Vaccine Bank. There are seven different types and more than 60 subtypes of FMD virus,
and there is no universal vaccine against the disease. Vaccines for FMD
must match to the type and subtype present in the affected area. The
North American FMD Vaccine Bank stores different types of concentrated,
inactivated FMD virus antigen at ultralow temperatures over liquid
nitrogen. In this state, several types of antigen can be kept
indefinitely and formulated into vaccine rapidly should an FMD outbreak
occur. FMD antigen is produced by first growing the virus in cell cultures;
filtering the virus harvest to remove debris; and inactivating it using a chemical
such as binary ethyleneimine. The resulting antigen is then
concentrated, purified, and stored in a cold, secure holding facility.
The North American FMD Vaccine Bank stores several FMD antigens, which are
sent overseas when a specific vaccine needs to be formulated. The Bank
can obtain hundreds of thousands of doses of FMD vaccine within days.
Animals that receive the vaccine usually develop some degree of protection
against clinical signs of FMD within 7 to 8 days. The North American Foot-and-Mouth
Disease Vaccine Bank The North American FMD Vaccine Bank is housed at the Department of
Agriculture's (USDA) Foreign Animal Disease Diagnostic Laboratory (FADDL) at
Plum Island Animal Disease Center. The Center, located 11/2 miles off
the coast of Long Island, New York, is the only place in the United States
where scientists can conduct research and diagnostic work on highly
contagious exotic animal diseases such as FMD. Currently, the
facilities on Plum Island operate at a biosafety-3 level, which indicates
that they are designed, constructed, and operated to prevent the escape of
microorganisms from the laboratory into the environment. Scientists at FADDL monitor FMD outbreaks around the world and stock the
North American Vaccine Bank with antigens for the most active serotypes or
strains of the virus. If necessary, these scientists can isolate and
identify an FMD serotype from a field sample in as little as four days.
With this information, FADDL scientists would know what vaccine type to order
from an overseas supplier, and if it were not in stock, the supplier could
use the isolate to create a new vaccine. FADDL scientists also test
currently available vaccines. Their testing has helped ensure that FMD
vaccines are not contaminated with other microorganisms and that they do not
produce adverse local or systemic reactions following administration. Reasons to Vaccinate Emergency vaccination can play an important supporting role in the control
of FMD outbreaks in FMD-free countries such as the United States.
Vaccination can help contain the disease quickly if it is used strategically
to create barriers between infected zones and disease-free zones. If USDA officials were to determine that FMD vaccinations should be
administered to U.S. livestock in response to an FMD outbreak, USDA officials
would collaborate with State and local officials to determine vaccination
zones, and they would work together to inform livestock producers and the
general public of the necessary quarantines and vaccination procedures. Reasons Not to Vaccinate Although there are FMD vaccines available, they are not currently used in
this country because the United States has been free of the disease since
1929. There is no need to vaccinate against a disease that no animals
have, especially when strict import restrictions are in place. USDA's
Animal and Plant Health Inspection Service (APHIS) imposes import
prohibitions on live ruminants and swine and their products on all
FMD-affected countries. In response to the FMD outbreak among some
European Union (EU) member countries in early 2001, APHIS has temporarily
restricted the importation of live ruminants and swine and their products
from all EU member states. If an outbreak occurred here, USDA's first
response would be to take swift measures to contain and eradicate the
disease. USDA has several reservations about implementing a vaccination
program. First, for animals to maintain immunity to FMD, annual
re-vaccination is required. This would be a costly investment and would
require considerable effort on the part of animal health technicians,
producers, veterinarians, and others involved in the livestock
industry. There is also a risk of the disease spreading outside of
vaccination zones. For example, vaccine teams could carry the virus
from an infected farm to a clean farm if they do not follow proper sanitary
procedures. In addition, once the vaccination program starts, the
United States might be lulled into a false sense of security. The vaccine
does not protect animals against FMD infection; it is designed to protect
animals from developing the clinical symptoms of the disease. This
means that if a vaccinated animal encountered the disease in circulation, the
animal could harbor the virus for several months or years in its upper
respiratory tract. Members of the public who do not realize this might
allow vaccinated animals to come into contact with unvaccinated animals,
including deer and other wildlife, and the vaccinated animals may spread the disease.
Finally, if an FMD vaccination program were implemented in the United
States, our country's international trade status would be compromised.
Countries that vaccinate for FMD cannot claim FMD-free status, so U.S.
livestock exports would face many new restrictions. This could cost
U.S. producers millions, if not billions, of dollars. The Office
International des Epizooties' current International Animal Health Code
requires FMD-free countries such as the United States to undergo a 3-month waiting
period between the time they have slaughtered their last vaccinated animals
and the time they can claim FMD-free status, assuming ongoing surveillance
and serological testing have demonstrated the countryís freedom from FMD
viral activity. In the event that vast numbers of animals were to be
vaccinated or if re-vaccinations were needed, our country could wait years
before regaining FMD-free status. Summary USDA currently maintains a variety of FMD antigens, which could be swiftly
finished and deployed as vaccine if officials determined this to be an
appropriate response to an FMD outbreak. There are drawbacks to using
the vaccine, including its potentially devastating impact on export markets,
so USDA's first response to an outbreak would be one of "stamping out"ófreezing
animal movement and eradicating the disease immediately. USDA scientists at Plum Island Animal Disease Center continue to develop
and experiment with novel biotechnology to improve the FMD vaccine. Additional Information For more information about the FMD vaccine, contact: The APHIS Emergency Operations Center The U.S. Department of Agriculture (USDA) prohibits discrimination in all
its programs and activities on the basis of race, color, national origin,
sex, religion, age, disability, political beliefs, sexual orientation, or
marital or family status. (Not all prohibited bases apply to all
programs.) Persons with disabilities who require alternative means for
communication of program information (Braille, large print, audiotape, etc.)
should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write USDA, Director, Office of
Civil Rights, Room 326-W, Whitten Building, 1400 Independence Avenue,
SW, Washington, DC 20250-9410 or call (202)720-5964 (voice and TDD).
USDA is an equal opportunity provider and employer. |
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ALL
INFORMATION, DATA, AND MATERIAL CONTAINED, PRESENTED, OR PROVIDED HERE IS FOR
GENERAL INFORMATION PURPOSES ONLY AND IS NOT TO BE CONSTRUED AS REFLECTING
THE KNOWLEDGE OR OPINIONS OF THE PUBLISHER, AND IS NOT TO BE CONSTRUED OR
INTENDED AS PROVIDING MEDICAL OR LEGAL ADVICE. THE DECISION WHETHER OR
NOT TO VACCINATE IS AN IMPORTANT AND COMPLEX ISSUE AND SHOULD BE MADE BY YOU,
AND YOU ALONE, IN CONSULTATION WITH YOUR HEALTH CARE PROVIDER. |