FREE ESSAY ON BOVINE TB

BOVINE TB

Bovine Tuberculosis
Mycobacterium bovis (Bovine Tuberculosis) (or cattle Tuberculosis) was first discovered
by Columella (Louis Junius Moderatus Columella) which was born in Cadiz, Spain and
resided in Northern Italy when he discovered the bovine Tuberculosis in the year 14 A D.
In 1882 Robert Koch discovered that the connection between human and animal Tuberculosis
actually were established. When Koch realized that children were becoming infected from
contaminated cow's milk most nations brought out legal instruments designed to remove
chronically infected animals and take a look at the public health aspect of the problem.

The Disease
Mycobacterium bovis is the bacterium that causes bovine Tuberculosis. It manifests itself
in livestock (especially in cattle and hogs) and it has also affected wild life such as
White Tailed Deer, Bear, Coyotes, Raccoons, and Bobcat in the northeastern part of the
Lower Peninsula of Michigan. From 1995 to 1999 17,721 deer from six counties (Alpena,
Montmorency, Oscoda, Alcona, Presque Ile, and Otsego) in Michigan were taken and examined
and to date only 228 deer, 1 bear, 5 coyotes, 2 raccoons, and 1 bobcat have tested
positive for bovine Tuberculosis. In the same area there was also 3 herds of cattle
infected with the disease. This disease is also known all over the country and the world
from Australia to New Zealand to the United Kingdom. The most likely way to spread the
disease in the wild is the bobcat, coyotes, raccoons, 
and bear eating the lungs and lymph nodes of infected animals.
There are three main types of bovine Tuberculosis: human (Mycobacterium
Tuberculosis)which can affect humans and can be transmitted to dogs, cats, cattle, hogs,
goats, sheep, and most any other mammal on earth, bovine (Mycobacterium bovis) which
affects animals and can be transmitted to humans (but it is very rare that this may
happen), avian (Mycobacterium avian complex) which primarily effect only birds but in
some cases there has been some cases in which 
cattle and hogs have been infected with the avian Tuberculosis. The two-mammalian types
are more closely related to each other then the avian type. The disease's presence in
humans has been reduced as a result in the eradication program, advances in sanitation
and hygiene, the discovery of effective drugs, and pasteurization of milk. There is
another minor type of bovine Tuberculosis, which is as microti (Mycobacterium Microti)
which affects rodents.
Mycobacterium Tuberculosis is the most host specific of the three major types of
Tuberculosis, rarely being transmitted to other birds (Mycobacterium avian), or mammals
(Mycobacterium bovis). Bovine Tuberculosis is the most infectious type of Tuberculosis it
infects most warm-blooded animals to include humans. 
Condition
Bovine Tuberculosis can only live for only a few weeks out side of the host's body
because it can not handle the exposure of the heat, direct sunlight, or extremely dry
conditions. Bovine Tuberculosis will survive longer under cool to cold, moist, and dark
conditions. The only place the Mycobacterium will grow (outside of the host) is on a
culture plate, where the bacteria will multiply at a very slow rate of about every 20
hours or so. As time goes on, bovine Tuberculosis is a disease that take many months or
may take many years to develop or may lie dormant in the 
host's body for a lifetime. If the disease does not become dormant, in wildlife and in
livestock it 
will leave multiple tan or yellow lumps on the rib cage or yellow lesions on the lungs
about the size of a pea. 
Transmission
Bovine Tuberculosis is a chronic, highly contagious and infectious disease caused by
several 
bacteria of the Mycobacterium family (tubercles) which it first affects the respiratory
system and the lymph nodes and may be found in any organ or body cavity. There are
several different ways for animals to contract the disease; one is airborne exposure from
coughing and sneezing, (which is the most frequent way to contract the disease) which the
risk is much higher in enclosed areas, such as barns. Another way to be infected is the
consumption of contaminated food, water, or milk, from infected animals rubbing on a post
or wire and another animal rubs against the same 
area, also using infected cattle trailers or transport vehicles, and avoid interaction
and contact with other herds.
Eradication Program
The most effective way to handle the problem of bovine Tuberculosis in humans is to
eradicate it in livestock. The eradication program began in 1917, the cooperative
state-federal Tuberculosis eradication program, which was administered by the U.S.
Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS). All
cattle herds were 
tested, and all of the cattle that tested positive for bovine Tuberculosis were sent to
the slaughterhouse. After the animals were slaughtered the premises were cleaned and
disinfected after the animals were removed. As a result of the eradication program, the
rate of infected cattle were reduced by approximately 5% to currently less than 0.02%.
The human Tuberculosis also was reduced significantly. The recent surge of human
Tuberculosis is due M. Tuberculosis. Today, there is a very low rate of bovine
Tuberculosis cases in humans.
State or Federal meat inspectors check the glands and organs of cattle and hogs and in
some 
cases wildlife for signs of bovine Tuberculosis. If these inspectors find any lesions or
other signs 
of bovine Tuberculosis, tissue samples are taken and sent to APHIS, National Veterinarian
Services Laboratories in Aimes, IA, for confirmation. If the laboratory confirms that the
lesions are a result of bovine Tuberculosis, an attempt to track down the livestock from
where it originally came from and to find the herd that the infected cattle were
affiliated with, then a Tuberculin PPD (Purified Protein Derivative) (Bovine) test will
be administered to all of the herd. If the herd is infected with bovine Tuberculosis the
rest of the herd will be taken to the 
slaughterhouse to be destroyed. If the whole herd can not be eliminated it is held under
quarantine and tested repeatedly until all evidence of infection is eliminated.
Veterinarians also try to find out the date that the herd was probably infected. Then
they try to trace all cattle that moved into or out of the affected herd and try to find
out where the infection probably started and where it might have gone and where it might
be going. 
Testing
A skin test is the most reliable way to identify bovine Tuberculosis in cattle. If cattle
have been infected or exposed to bovine Tuberculosis a reaction will occur at the test
site on the skin. (So far to date there is no effective vaccine or medications for
treatment for wild animals). If a reaction does occur an additional test is required to
identify which type of Tuberculosis that the animal is infected with. Once the type is
identified you would use a sterile liquid containing protein derivatives from a heat
killed Mycobacterium bovis (Strain AN 5), which is grown on a 
synthetic medium. If the test resulted in the bovine Tuberculosis you would use the
Tuberculin PPD (Purified Protein Derivative) (Bovine). 
Retesting
Retesting may only be done at least 60 days after the last injection of Tuberculin PPD
was 
administered. This applies to either the intradermal caudal fold test or a comparative
test was completed. 
Dosage and Administration 
Use the single intradermal test (skin test). Give a single intradermal 0.1-ml injection
of Tuberculin PPD (bovine) (The vaccine should be stored between 2 and 8 degrees Celsius,
but do not freeze and keep it out of the light). The caudal fold (stomach or abdominal
area) is where the Injection will be administered. Clean the area thoroughly with
Betadine or an iodine 
solution where the injection will take place, for sterilization, prior to injection. 
Government actions
In order to protect the human population, the Government has introduced the following
actions:
(1) Heat treatment of milk (Pasteurization).
(2) Inspection of carcasses at slaughterhouses.
(3) Reduce the population of infected animals.
Summary
It is highly unlikely (less then 1%) the humans will contract bovine Tuberculosis from
animals, but there is always the possibility of transmission of the disease. If you do
come in contact with an animal that has bovine Tuberculosis you will need to get in
contact your state or federal inspectors to have the animal eradicated.
References
"Cattle: Tuberculin PPD (Bovine)", available at:
www.csl.com.au/vet_div/cattle/c_tbculs.htm visited 14 Oct 99
"Cattle: Bovine Tuberculosis", available at:
www.csl.com.au/vet_div_cattle/c_t_bonv.htm visited 14 Oct 99
"Animal Disease Control Programs", available at:
www.state.oh.us/agr/animal/animal2c.htm visited 14 Oct 99
Wayne Cunningham, 13 Aug 98, "Colorado Department of Agriculture", available at:
www.state.co.us/animals/livestock%20disease/tb.htm visited 20 Oct 99
"Bovine Tuberculosis", 20 May 99, available at
www.irlgov.ie/daff/9851.htm visited 20 Oct 99
"Tuberculosis in cattle and humans-detailed information", available at:
www.maff.gov.uk/animalh/tb/public/sheeta2.htm visited 22 Oct 99
J. Flerke, Aug 98, "Bovine Tuberculosis in Michigan", available at:
www.dnr.state.mi.us/wildlife/division/roselake/…/brochure%20for%20web.htm visited
14 Oct 99
Susan E. Aiello, B.S., D.V.M., E.L.S. "Merck Veterinarian Manual" 1998