Q: Can’t TB be treated?
A: Infected people can be treated for TB and in the vast majority of cases the treatment is successful. The course of treatment takes 6 to 9 months and is, therefore, expensive. Treatment of infected cattle is not feasible.
Q: How safe is our food?
A: Pasteurization kills disease pathogens meaning that pasteurized milk is completely safe for all consumers. The USDA meat inspection system examines carcasses and looks for any type of problem that would impact the health of consumers. When combined with proper handling and cooking, our meat supply is also safe for all consumers.
Q: How reliable is the TB test?
A: Tests are evaluated for their sensitivity (having a low rate of false negative responses) and their specificity (having a low rate of false positive responses). In diagnosing TB, no test is perfect. A test that has high sensitivity, like the caudal fold test (CFT), is used as a screening test, and is followed up with a test that has a higher specificity (gamma interferon or comparative cervical test, CCT). When an animal responds on both of these tests, it is taken and sacrificed and the tissues and lymph nodes examined. Samples from these will be tested for genetic markers (PCR) of M. bovis and cultures will be done to see if lab personnel can grow the bacteria from tissue samples. If either of these last two tests is positive, the animal is called infected, and therefore the herd is called infected.
CFT has been the standard screening test for many years. Its sensitivity is only around 80 percent meaning that approximately 20 percent of infected animals will go undetected. The specificity of the CFT is about 95 percent meaning that 2-5 percent of the time it will yield a false positive result. The desire and effort within the scientific community has been to have a screening test with a higher sensitivity and higher specificity and research in developing other tests is ongoing.
Q: If I’m a cattle producer what should I do?
A: Michigan State University Extension recommends taking the following measures to reduce the risk of transmission of TB to your herd:
- Wildlife control. Wildlife can be vectors of diseases, that is, they can carry diseases to cattle. This is not just the case with TB but also with other diseases as well. Cattle producers, no matter where they are located, should develop measures to protect feed, water and housing areas from wildlife and should use all legal means to control the numbers of wild animals in the area of their farm. Talk with your Department of Natural Resources Officer to learn more about the legal means available to you.
- Herd health. Cattle producers need to support the health of their herd through every means possible and lower the potential exposure to all disease pathogens because one disease may impair immune response to another disease, making them more susceptible. This includes having a clean and dry environment for all cattle, particularly at calving, managing the stocking rate to keep aerosol and manure exposure lower, reducing the mixing of cattle of different ages and from different herds, and reducing the exposure of cattle to blood from other cattle. The latter may mean that you and your veterinarian commit to single use of examination sleeves and needles, and reduced use of bulls. In addition cattle should be fed diets that meet their nutritional and immune system needs including proper balancing for minerals and vitamins. Additionally, vaccination is an important tool to strengthen the immune response to certain viruses and bacteria. An animal whose health is compromised by one disease is more susceptible to other diseases.
- Work with your veterinarian. Managing cattle herd health should always be a partnership with your veterinarian in which together you evaluate the weaknesses and breakdowns in herd health and together plan ways to strengthen your herd health program.
- Always properly identify animals. Whenever an infected animal is found, the first question is what other animals have been exposed. Tracing the movements of an animal and being able to determine other exposed animals will help control contagious diseases faster with fewer animals needing to be killed. That requires that all animals that move be identified and that good records be kept of animals and where they went or where they came from. Therefore, it goes beyond simply complying with regulations to having records that can be provided if and when necessary.