Rachael Herrell
Ninth
Grade
Miami
County
Veterinary
Medi Techs
Dr.
Lea Pugh
4-H
Veterinary
Science
Johnes
Disease
Johnes
Johnes,
otherwise known as Mycobacterium
paratuberculosis, is a contagious bacterial disease of the intestinal tract.
Some of the symptoms of this disease are decreased weight loss, scours,
decreased milk production, and the young are smaller than the other animals
their age. These symptoms might
lead the owner to an economic loss because of animals being culled.
This is a problem since Indiana’s surrounding states have tested 10%
positive for the disease. “Some
areas of the country test much higher infections rates, however in northern
dairy states like Minnesota, Wisconsin, Michigan, Ohio, Pennsylvania, and New
York, it is estimated that roughly 10% of dairy cattle are infected with
M. paratuberculosis,” stated by Johnes Information Center.
On October 23, 1894, Johnes was recognized as an infectious disease with
a unique etiology. The founder of
this remarkable discovery was H. Johne (Picture 1).
Most researchers have found that Johnes is
transmitted primarily through the feces of other infected animals.
This method of transmission is known as shedding.
Another way Johnes is transmitted is by the milk and colostrum, however
many victims are born with the Johnes disease.
The patients that are infected in the uterus are caused by the bacteria not having a cell wall therefore it can pass through the
membranes. The last known way of
transmission is through semen; this is also known as shedding. All of the large ranges of transmission are very common
despite the differences in the method.
Picture
1 H. Albert Johne First to Discover Johnes (Johnes)
There are a few ways of prevention for this dreaded disease (Picture 2). One of
the ways that is suggested by Dr. Laurie Denholm
“1. Purchasers of animals insist
on a written vendor statement that there has been no diagnosis or suspicion of
Johnes Disease on the property or in the herd for at least five years.
2. Purchasers of land to
obtain a written vendors declaration that Johnes Disease has not been known or
suspected on the property for five years or that the property has been
de-stocked for one year. 3.
All cases of ill-thrift or wasting to be fully investigated by the
farmer’s Veterinary Surgeon. 4.
Limit contact of deer with cattle and sheep 5. Monitor
progress of testing programs currently in progress.
6. Possible whole-herd blood
testing of stud stock.” (Fyffe, 1998) Although
these are good suggestions the only true way of prevention now is by burning the
animals. Johnes can become a
hardship that many sheep farmers in New South Wales are discovering.
This hardship has become a reality as testing has now become compulsory
in New South Wales. There is also another way of stopping the disease from
spreading further in the herd by using a vaccination to help prevent Johnes.
Picture
2 Computer Simulated Graph of Different Johnes Control Programs. (Johnes)
|
Vaccination
as a means to control paratuberculosis was the subject of many studies
in 1950’s. The young
scientific discipline of immunology brought its techniques to bear the
study of Johnes and in the 1960’s the vaccination was formed.
The vaccination that is used has a very high expense.
It also leaves a lump on the neck at the point of entry (picture
3). The lump begins as soon
as the needle has introduced the |
vaccination. This
lump will remain there until death, however even though it has had the
vaccination it still does shed the Johnes disease in its feces.
The vaccination just prolongs death not stops it.
Picture 3
Vaccination Site (Johnes)
One
of the signs of Johnes is diarrhea. In
cattle the disease affects the ileum which depreciates the animal of its
protein. Then the animal just
starts wasting away. Cattle dying from Johnes Disease usually have a thickened
intestinal tract and large internal lymph glands.
Johnes usually can be seen in sections of these tissues examined under
the microscope and isolated from them. The
mucosal surface is corrugated and granular in appearance (Picture 4).
The ileum isn’t thin and pliable as it should be, and it can not be
stretched to thinness. The inflammation makes the intestine not able to filter the
protein out into the bloodstream. The
lymph nodes that drain the ileum will be enlarged and lighter color than normal
(Picture 5) due to the influx of white blood cells. All other organs generally appear normal, but in advanced
Johnes disease, when animals have had diarrhea for over a week and shown marked
loss of weight, there may be noticeable loss of body fat (Picture 8)
Picture 4 J D
infected (top) and normal (bottom) Intestinal Mucosa (Johnes)
Picture
5 Lymph Nodes of JD Victim (Johnes) Picture 6 Bovine
Ileum Cord (Johnes)
Picture 7 Bovine Ileum (Johnes)
Picture 8 Guernsey with Johnes (Johnes)
To
have a safeguard against Johnes one should have compulsory testing every year. There are five main tests in the United States at this time.
They are the fecal culture, tissue morphology, agar gel immunodiffusion (AGID),
complement fixation, and the ELISA test. The
fecal culture has a specificity of 100% and sensitivity 50%in late clinically
and subclinical affected animals. Subclinical
animals shed intermittently or at levels below detection. The down side to this type of test is that it takes 8-16
weeks to obtain the results of the fecal culture, and it costs $10-$15 per test.
The next type of test is the tissue morphology.
This type of test has to be taken by laporatomy or at necropsy, but it is
very supportive of the diagnosis. The
third type of test is the AGID. It
is approximately 100% specific but lacks in subclinical cases (only 26%
detected). In clinically affected
cases, sensitivity is improved to 60-80%. Complement
fixation is similar to AGID, but this test is used for international
import/export testing. The last
type of test is the ELISA. It is
the newest test out. The USDA
finally approved this test in 1992. The
new ELISA test is superior to AGID and CF tests for detecting subclinical cases,
and its specificity is excellent at 99.7%.
This test is being recommended for screening herds and replacement
heifers and cows prior to purchase. In
comparison the ELISA and fecal culture (Picture 9) by far are the most accurate,
but the Elisa is more cost affective. Knowing
this one must also take into consideration that the eradication of the disease
might take a little longer due to the fact that the ELISA has a higher
sensitivity level during stage three Johnes.
The ELISA test is what we used for our herd.
Our herd results were all negative.
Picture 9
Comparing Accuracy of the ELISA (Yellow) and the Fecal
Culture (Red).
Notice the fecal detects early, but the Elisa conveys it until the
death. (Johnes)
In
conclusion the Johnes Disease must be dealt with before it gets out of hand like
other ailments that were not caught at an early stage.
Remember that problems always start small, but how they develop is the
way that they are dealt with. The
United States is still fortunate because other places such as New South Wales
are having an outbreak. “At least
320,000 sheep in 183 New South Wales flocks will be slaughtered [terminated] as
part of the campaign to eradicate Johnes Disease,” from Johnes Disease in
Australian Sheep. Through testing
and heavy culling along with as much prevention that is known we can help stop
this disease before there is an outbreak.
Scripture
Verse
Isaiah 40:11 He shall feed his flock like a shepherd: he shall gather the lambs with his arm, and carry them in his bosom, and shall gently lead those that are with young. Isaiah 40:11 (KJV)
This verse means to me that the Lord cares for each and every person as
an individual just like I care for each animal as an individual and no one
animal is more important than the other is.
The good shepherd does not ignore the problems, sicknesses, or concerns
of the individual person. I do not
neglect the individuals in my herd because they are sick, but I care for them
and try to comfort them to the best of my ability. It is my desire to give every animal the chance to live up to
it’s full potential.
References
Australian
Meat Technology. (1998)
Johnes Disease in Australian Sheep
(http://www.amt.com.au/archive/1997/08/Johnes%20disease%20in%20Australian%20sheep.htm)
Collins,
Michael T., DVM, PhD. (1997).
Johne’s Information Center
(http://www.vetmed.wisc.edu/pbs/johnes).
Madison: University of
Wisconsin,
Johne’s Information Center
Fyffe,
Jeff. BVSc, MRCVs, MACVSc. Johnes Disease
(http://www.bloodlines.undaware.com.au/vetdoc14.html).
Bendigo: McIvor Road
Veterinary Center
Scarratt,
W. Kent. (1980). What’s New
with Johnes Disease
(gopher://gopher.ext.vt.edu/00/.docs/aps/aps-471).
Regional College of Veterinary Medicine
Williamson,
Dr. Lisa. Johnes Disease (Paratuberculosis)
(http://128.192.20.19/LAM/LM000155.HTML#Johnes
Disease
(Paratuberculosis))
