October 2015
From the State Vet's Office

Is Cattle TB Catching Fire Again?

The west is on fire, the stock market is falling and bovine tuberculosis will not go away.

I don’t much like reality TV shows. Reality is often just too stressful. Maybe that’s the attraction to those TV shows. People want to know that everybody else’s lives are also stressful. Give me a good Westernor comedyof something that doesn’t even resemble reality. Watching the evening news is enough reality for me. As I write this article, I just heard them say that one of the wildfires in Washington may burn until snow arrives. The stock market has seen the biggest correction since 2008. There is one thing that pretty much doesn’t get any airtime on the national news, although it has been reported in local papers and on the news in Texas and Michigan. That news is that animal agriculture officials are dealing with bovine tuberculosis, also known as cattle TB.

Alabama became bovine tuberculosis free back in 1981. We continued to have reasonably strict cattle TB import regulation for a long time after that. But, as most states became bovine tuberculosis free, everybody sort of relaxed their import requirements. Over the past few years, there has been a nagging refusal by this disease to go quietly into the night. Mostly found in dairy cattle, but occasionally beef cattle and Mexican roping steers, some states have once again tightened their import regulations. We have not gone to that length, but, at this point, we have our antennas up and one eyebrow raised as we remain aware that we cannot just go to sleep and forget about cattle TB.

In 2015, there have only been four cases of cattle TB confirmed, in spite of strict trace back and investigation of possible exposed cattle. Back in January, there were two dairy cows in Texas confirmed positive. In April, there was a dairy cow from Michigan found positive. Then, in late July, a beef animal from a small herd in Michigan tested positive. For a program that began about a hundred years ago as the State-Federal Cooperative Bovine Tuberculosis Eradication Program, I would say that has been pretty successful. Could you imagine if they developed a strep throat eradication program and a hundred years from now we had only four cases in a year? That would certainly be considered a success. But a friend of mine once corrected me when I said it was something like comparing apples and oranges, he said my comparison was actually more like comparing apples to washing machines.

I suppose the comparison between cattle TB and human strep throat, so far as eradicating the disease, would be kind of a stretch. Actually, for many years, the cattle TB program focused on test and slaughter. We could not, nor would we want to, test and slaughter humans who had strep throat. I think I had it a time or two when I was a kid. Anyway, in the 1960s, surveillance for cattle TB at slaughter facilities became a key component of the program.

Interestingly, the eradication program, begun in 1917 with the appropriation of $1 million, was a result of the human medical community, the veterinary community and the cattle industry pressuring the government to do something about the disease. I can’t really say since we sometimes forget how some of these diseases affected humans and livestock. The fact is that most of us can’t really remember when diseases like TB and brucellosis were wreaking havoc on cattle, with other livestock also affected. In addition, there was the public health threat as humans were frequently affected by these diseases.

If you research it, you will find cattle TB is not a huge deal in most developed countries. Yet in many underdeveloped countries, the disease is still a formidable threat to cattle and humans. One common way disease is transferred among cattle is when calves nurse infected mothers. Raw or unpasteurized cow’s milk is a common source of human infection. Other ways cattle TB is transferred between animals is common feed and water troughs. Research has shown that Mycobacteria bovis, the causative agent of the disease, can survive for over two weeks in stagnant water. And while cattle and swine are the most susceptible species for bovine tuberculosis, many other species can become infected. That became quite a problem several years ago in Michigan when the disease got pretty well-established in the wild deer population. Then it became a viscous circle of cattle infecting deer and deer infecting cattle.

Cattle TB can affect many different systems in the body. It could be inhaled and mostly cause problems in the lungs. It could be swallowed and cause problems in the intestinal tract. It can even infiltrate the uterus and mammary tissue. Unfortunately, there are really no signs of the disease early in the infection. Later, the disease will likely cause the cow to waste away as well as develop a cough or wheeze if the respiratory tract is involved.

We still have a few herds in the state that maintain TB Free Accreditation. That means they do a complete herd test every year. However, our main source of surveillance is at harvest, when cattle go to slaughter. Our state meat inspectors and veterinary medical officers are aware and on the lookout for anything that may look like tuberculosis.

We generally have the ability to trace animals from the processing plant to farm-of-origin in case we need to perform herd tests. There are other situations when testing cattle from an exposed herd could be a little difficult … or at least take a lot more work than might be necessary if feeder calves were properly identified. Imagine a situation where a stocker buyer is buying black and red calves and baldies. He may end up with 300 black baldies with no identification. Then we find out one of the black baldies he bought originated from an exposed herd and must be tested. Instead of finding the single calf that came from the exposed herd, we would have to test all 300. You can expect, somewhere down the road, we will probably have to tag feeder calves so they can be traced in such a situation.

Not long ago, one of the local morning news programs was at the scene of a fire they had reported on the 10 o’clock news the night before. Everyone thought the fire was out and went home about midnight. The next morning, the reporter stood in front of a completely burned structure. The problem was that there was a smoldering hot spot that had not been noticed before the firemen went home. We are trying to make sure we don’t let smoldering bovine tuberculosis catch fire again.

 

 

Dr. Tony Frazier is the State Veterinarian for Alabama. You can contact him at 334-240-7253.