Information you hope you’ll never need about Tuberculosis, brucellosis and Bibersteinia trehalosi
January 11, 2018
Diseases such as tuberculosis and brucellosis are rare in U.S. cattle herds. Thanks to cooperative eradication protocols that started in 1917 and 1954 respectively, these bacterial diseases are almost a thing of the past. The keyword being "almost." As rare and controlled as they have become, outbreaks of these diseases still occur, as complete eradication has proven an elusive feat.
An outbreak of either one could have the potential to cause widespread devastation. All things considered, these are diseases ranchers should be aware of, having an understanding of the signs and symptoms as well as a solid protocol for prevention and treatment of suspect animals.
How They Spread
Both tuberculosis (TB) and brucellosis are contagious bacterial diseases that can affect a wide variety of wild and domestic animals, including cattle. TB is transmitted through the saliva and airborne particles from the respiratory tracts of infected animals, while Brucellosis is a slightly different beast. Transmission of Brucellosis occurs when healthy animals come into direct contact with the birthing tissues and fluids or other bodily fluids (i.e. milk, blood, urine, and semen) of infected animals.
In the United States, the most common introductions of TB into a previously TB-free herd are through the purchase of infected cattle or contact with infected wildlife. The same is true of brucellosis.
What They Look Like
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TB is all but impossible to diagnose early on because the clinical signs are not visible until the infection is in advanced stages. By that time, symptoms resemble that of pneumonia, including a low-grade fever, lethargy, loss of appetite, and a wet cough.
Brucellosis manifests itself in reproductive issue. Abortion, still birth, and infertility are often the first indicators of the disease. Other than that, infected animals typically show no signs of infection.
What to Do with Suspect Animals
Suspect animals should be isolated from the rest of the herd immediately for further examination and proper diagnosis by a veterinarian.
Since there is no cure for either disease, suspect animals that test positive for either disease are slaughtered. In some cases of infection, depopulation of the entire herd may apply. If depopulation is not practical, the herd can regularly be tested, slaughtering only those that test positive.
The Best Prevention
Prevention is the best medicine and the best prevention in the case of these two diseases is continued vigilance and good animal husbandry. While vaccination protocols exist for brucellosis (the Bangs vaccine given to heifers), there is no vaccine available for TB.
According the United States Department of Agriculture (USDS) Animal and Plant Health Inspection Service (APHIS), following these best practices will help keep cattle free from infection:
- Have your livestock tested for TB and, if possible, keep a closed herd and raise your own replacement stock.
- Buy your animals from an accredited TB-free herd, test the new animals prior to purchase, and finally, isolate them for 60 days and retest before commingling them with your herd.
- Restrict or eliminate all contact between your herd and other herds.
- Clean with a disinfectant any trailers or facilities that have housed newly purchased animals or animals that did not originate from your herd.
- Keep on-farm visitors away from your herd whenever possible. This includes milk haulers, feed delivery personnel, and anyone who may have contact with other herds.
- Make sure your fences are in good condition to separate your herd from wildlife. If the wildlife in your area is affected by TB, contact the U.S. Department of Agriculture (USDA) Wildlife Services office in your State for advice on reducing wildlife contact with your herd.
Another One to Watch
Bibersteinia trehalosi is an emerging pathogen that ranchers need to have on their radar. Initially seen in sheep and goats, this close relative of Mannheimia hemolytica has made the jump from small ruminants to cattle within recent years. It first presented in dairy calves in California. From there it made its way to adult dairy cattle, to stocker backgrounder type cattle, then to feed yards, and finally adult cattle on pasture.
Bibersteinia trehalosi is present in wild populations of ruminants such as elk, white tail deer, and bighorn sheep. The disease tends to be more prevalent in the fall and winter, possibly due to the wildlife coming in to eat hay when forage is limited during the dormant season.
Unlike most diseases, Biberseinia trehalosi seems to hit heavier unstressed cattle the hardest.
"In adult cattle, from the time that you first think they maybe look a little bit off until they're dead is 12 to 18 hours. This thing kills cows very, very quickly," said Dr. Victor Cortese, Director of Cattle-Equine Immunology Biologics for Zoetis.
If caught early, infected cows will have high fevers, ranging upwards of 106 to 108 degrees. However, when they are hot the cows actually look good, making Biberstenia hard to catch early on. If it is caught early it can be treated with a cephalosporin, the only antibiotic shown to effectively combat the disease.
What more commonly happens is discovery of one dead cow, followed by another a week later, then a few more a few days later. By that time, "you're on the front end of a hurricane," according to Cortese.
"It will routinely, if it is a hotter strain, lose 10 to 15 percent of the herd," said Dr. Cortese.
According to Cotese, extremely compromised lungs and full rumens upon post mortem inspection are good indications of a Bibersteinia trehalosi infection. The cows die so fast that they don't have time to go off feed.
"The reason this thing is so fast is it doesn't come from the nose to the lungs. It comes from the blood stream to the lungs," said Cortese.
There are currently no vaccines on the market against Biberstenia trehalosi. However, there is a group of researchers that have developed a challenge model to look at protecting against it. While autogenous vaccines have not worked well, there are some Pasteurella vaccines on the market that will cross protect against this fast-moving bacteria. Newport Laboratories has also been successful in developing “custom” vaccines for particular herds that have been affected by the bacteria.