Brucellosis in Cattle
Posted on July 01, 2009 by: WayCoolDogs
With the complete eradication of Brucellosis (Bangs Disease) in cattle within the United States, the achievement of the disease’s class-free status was announced on February 1, 2009, by the U.S. Department of Agriculture for the first time in 74-years even though Brucellosis in dogs is now spreading rapidly in the Central Plains. Plans are now being made for major efforts to eradicate the disease from the Greater Yellowstone Area, a Wyoming location where the disease is still present in free-ranging elk and bison populations. Future outbreaks of Brucellosis can still occur in cattle if the disease spreads from this specific source, which is why recognizing symptoms and causes of Brucellosis are still very much a priority for all cattlemen.
BRUCELLOSIS IN CATTLE
Brucellosis in cattle is primarily caused by contact, contaminated food or water, and contaminated excrement or infected material through the bacteria disease “Brucella bacteria”. Once a cow or bull acquires Brucellosis, they will remain carriers throughout their entire lives, so generally they are destroyed upon diagnosis of the disease. Brucellosis is considered an infectious disease of farm animals, and has primarily affected cattle and the American buffalo. It has also been known to transmit to humans through “Brucella abortus” with Brucellosis considered a dead-end disease when affecting horses, dogs, swine, and humans. While contained in these animals and in humans, the disease does not transmit to other animals as it does in cattle or bison.
Brucellosis in cattle primarily occurs in the female cow, whereas the male bull can be infected but does not spread the disease as readily. Brucellosis centers in the cow’s udder, uterus, and lymph nodes which are adjacent to the uterus, but in the bulls it centers in the testicles, seminal vesicles, ampullae, and epididymides where the bacteria produces a serious inflammation and may cause sterility. The results of the disease in the cow is usually self-aborting during the last third of pregnancy (fifth to eighth month), the afterbirth is retained, or the birth of weak calves if they survive. Yet many affected cows do not exhibit any of the clinical symptoms of Brucellosis, and give birth to normal healthy calves.
When the contaminated cow gives birth or aborts, the diseased organisms are shed by the millions through the afterbirth and fluids that result from calving or the abortion process. When the cattle consume these forages or clean their calves (or consume aborted fetuses) the disease is then spread inside the animal itself. Yet when the remains are on the drying hot ground and in the sunlight, the brucella bacteria is killed instantly.
As of now, there is no economical cure for Brucellosis in cattle except for the Strain-19 vaccine, a Brucellosis control program for U.S. cattle. The vaccine is a live vaccine which is known to stimulate the immune system once it enters the animal, allowing it to produce antibodies against the disease organism. This vaccine is known to allow a resistance to Brucellosis for years even though its detectable antibodies disappear within a couple of months. But cattle affected by the disease must be slaughtered at approved slaughter house facilities within a designated time frame of the diagnosis.
SYMPTOMS OF BRUCELLOSIS IN CATTLE
The primary symptoms of Brucellosis in cattle are infertility and weakness or death of the unborn or weakened calf. This is combined with a serious drop in the milk production of the cow and affected herd.
Cows who have Brucellosis usually will develop large swellings on their knees. But even though the general health of the cow is not in jeopardy, other symptoms consist of arthritic joints, a retained after-birth, spontaneous abortions, the inability of cows to conceive, or inflammation of the male sex organs in bulls. And as stated, the Brucellosis organism “Brucella” is typically present in the afterbirth and secretions of the uterus, and in aborted fetuses, which then spreads to the cow and to the entire herd. But the problem with symptoms of Brucellosis is that it mimics the symptoms of other diseases, so it may be difficult to prevent the disease from spreading throughout the entire herd without routine testings.
CONTROLLING BRUCELLOSIS IN CATTLE
Cattlemen vaccinate their dairy and nondairy heifers against Brucellosis from four to eight months of age to control the disease before the animal gets it. If the cattle are found to have the disease, they are slaughtered immediately to prevent the disease from spreading.
The diagnosis of Brucellosis in cattle is based on the presence of bacteriology or serology, where the B. abortus is removed or recovered from the cow’s placenta or in pure culture, from the lungs and stomach of the aborted fetus. In the cow, the infection is usually in the udder, supramammary lymph nodes or in throughout the reticuloendothelial system.
The standard diagnostic method of testing for Brucellosis in cattle is the serum agglutination test, which also tests for antibodies in the milk, plasma, semen, or whey, with the development of ELISA to further test the milk and serum. But sensitive supplemental testing can be used in cattle suspected of having Brucellosis but whose status is unclear. No practical treatment of affected cattle is available at this time, so detecting and preventing the disease before the cattle acquires it is a priority. Cattle herds are typically tested at regular intervals until negative results are found after two to three successive testings.
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