What kind of test? [Archive] - The Michigan Sportsman Forums

Fierkej

02-15-2002, 08:39 AM

Marty,

The following is a joint publication by MI DNR, MSU and MI Department of Community Health which explains, in great detail, our testing procedures for bovine tuberculosis in wild deer, elk and carnivores.

Testing for Bovine Tuberculosis in Michigan’s Wildlife

By Melinda Raths, RLWDL MDNR; Elaine Carlson, MDNR;
Kelly Butler, MSU AHDL; and Dale Berry, MDCH

Wildlife personnel with the MI Department of Natural Resources (MDNR) have been examining harvested deer submitted by hunters for over 50 years. This activity has been an important source of biological data on the status and health of the deer herd. With the discovery of bovine tuberculosis (TB) in wild deer, a disease surveillance and monitoring program was necessary. The voluntary check of deer by hunters has facilitated this effort.
The process starts at field check stations, located throughout the state, mostly at MDNR offices. During rifle deer season in November there are additional check stations on southbound lanes of major highways, at the Mackinac Bridge, and at other field locations convenient to the hunter. Cooperation from owners of meat processing plants, taxidermy shops, and other businesses that cater to deer hunters has also had a positive impact on the disease surveillance effort.
At a check station, hunters are asked several questions about the date and location of kill and check station personnel record biological data. The age of the deer is determined by examining tooth replacement and wear patterns. Antler development is measured on all adult bucks by taking beam diameters and counting the number of points. The presence or absence of lactation is noted for all does. A visual check of the chest cavity for the presence of nodules or abnormal tissues is made. Unusual coat color or other diseases and anomalies are noted. Hunters are offered a Management Cooperators patch for any deer brought to these check stations.
Hunters are also asked if they want to submit the deer head for bovine TB testing. If agreed, check station personnel will cut off the head an inch or so behind the ears, remove antlers, if desired by the hunter, and attach a TB tag that includes the hunters’ name, address, and phone number and the date and location of kill. The hunter receives the tear off portion on the TB tag with an identification number and will be contacted after the test results are completed. If a hunter chooses to leave a deer carcass intact for any reason, TB tags are completed at the check stations but given to the hunter to turn in with the deer head at a later date. Skinned and de-antlered skulls may still be examined for bovine TB. Hunters have also submitted for testing entire deer carcasses that exhibit visible lesions suggestive of bovine TB. In this case, the hunter receives a free replacement deer license at the checkstation. Also, there is a mandatory check for all hunter harvested and road-killed elk. Every elk head is submitted for TB testing and follows the same procedures as the deer heads.
After the heads are collected at check stations they are brought to the MDNR's Rose Lake Wildlife Disease Laboratory (RLWDL). Trucks deliver loads of heads throughout the year, but during the peak time, from mid-November to mid-December, several truckloads arrive daily. In 2000, the most heads received in one day was about 3,500!
The heads are unloaded and removed from bags. The teeth in each deer or elk head are re-examined to make sure the correct age and sex have been recorded on the TB tag that is attached. Once examined, the numbered tag is clipped from the head, leaving an identical number still attached. The heads are put back in bags and reloaded into trucks. Whole deer carcasses and/or abnormal tissues that are submitted are examined by one of the veterinarians or the pathologist who makes notes about lesions found in the deer.
Carnivores and omnivores are also occasionally received at the MDNR's RLWDL and the age and sex are recorded on the TB tags. The deer and elk heads, deer carcasses and carnivore/omnivore carcasses are driven to Michigan State University's Animal Health Diagnostic Laboratory (MSU's AHDL) for examination. All table surfaces and the necropsy room at RLWDL are disinfected with a tuberculocide.
While the heads are being processed at the MDNR's RLWDL, the tags that have been clipped are put into a disinfectant bath. They are then rinsed and dried, which prepares them to be handled by personnel in order for all information to be entered into a database. This is a long, but important part of the process. It takes several people several hours to enter the data when dealing with tags from a couple thousand deer. All information previously recorded by field personnel is entered into the database so that the hunter may be contacted with the results of the TB test.
The location of where the deer was taken is important in order to keep track of how many deer have been tested in each county and also to locate exactly where the positive deer have come from. This information is displayed in maps that are handed out at meetings and to the public. Most of the TB-related maps are created at the MDNR's RLWDL, including the positive deer map, carnivores tested map, and the all animals positive map.
Once the heads arrive at MSU's AHDL they are again unloaded from the trucks and taken into the necropsy room via carts used specifically for tuberculosis suspect cases. The heads are examined by trained necropsy personnel under the supervision of, and in cooperation with, several veterinary pathologists. All surfaces in the lab with which the heads and carnivores/omnivores may come in contact are covered with disposable plastic protectors prior to use.
Each head is visually (grossly) examined. Specific lymph nodes sectioned for inspection in each head include lymph nodes near the temple, behind the lower jaw, and the lymph nodes at the base of jaw near the vertebrae. Those heads with no lesions in these lymph nodes or elsewhere are discarded into lined carts for incineration. The same lymph nodes along with the lymph nodes throughout the body (thoracic and abdominal) are examined in the carnivores/omnivores. All surfaces potentially touched by any tuberculosis suspect case at MSU's AHDL are disinfected thoroughly with an anti-mycobacterial cleanser (one that specifically kills tuberculosis bacteria).
Deer or elk heads that have gross evidence of tuberculosis (pus within a single lymph node) undergo further testing. All tissues from the carnivores/omnivores, however, are examined histologically and are cultured regardless of whether or not anything is found on gross examination. Lymph nodes from the grossly suspect heads are collected in separate containers for both histologic and microbiologic (culture) evaluations. Currently, suspect tissues are being sent to the Michigan Department of Community Health (MDCH) TB lab for culture work. The histologic evaluation of tissues collected from suspect deer or elk is performed by a veterinary pathologist at MSU’s AHDL. Tissues examined histologically are prepared with both routine stains and stains that specifically highlight mycobacteria, the type of bacteria responsible for tuberculosis. Reports of any lesions identified by MSU pathologists are sent directly to the MDNR's RLWDL.
At this time the personnel at the MDNR's RLWDL can send post cards to hunters who have submitted deer or elk that had negative TB results. This typically takes seven to ten days after the deer is submitted to the MDNR. Letters are sent to hunters whose deer or elk had suspicious looking lymph nodes explaining that further testing will be needed. Results are then pending until further notification from the MDCH. Hunters are encouraged not to eat the meat if a deer tests positive.
The MDCH receives suspicious tissue specimens from deer, elk, and carnivores/omnivores from MSU's AHDL. These must be accompanied by a test request form indicating the animal's identification number, the type of tissue specimen and the county of origin. The first step in a microbiologic examination is to examine the specimen visually for areas in which the tissue might be dead or which look suspicious. These areas are removed and prepared for testing by cutting into small pieces. The small pieces of tissue are placed in a strongly alkaline solution containing sodium hydroxide. This will kill other bacteria and fungi which might be present and which might inhibit the growth of the tuberculosis bacteria (Mycobacterium bovis). This solution can be used on Mycobacterium (M.) because these bacteria contain a waxy material which protects them from the strong alkaline solution. After 20 minutes, the chemical reaction is stopped with a buffer and a portion of the treated tissue is placed on a microscope slide and stained so that any Mycobacterium which are present in the tissue can be seen using a microscope. The bacteria will look like very small red rods and are called acid-fast bacilli. The remaining specimen is transferred to culture (growth) media which will allow any acid-fast bacilli which are present to multiply. A report showing the results of the microscopic examination is sent by FAX to MSU's AHDL and the MDNR's RLWDL within twenty-four hours of when the tissues were received at the MDCH. Positive test results are also sent to the United States Department of Agriculture.
Over the next two months, culture media is examined regularly looking for growth typical of M. bovis. This normally appears in about 10-14 days. The growth is tested using genetic probes to determine whether the culture contains M. tuberculosis complex, of which M. bovis is a member. Additional biochemical testing will be performed to confirm the final identification. The biochemical testing requires two to three weeks to complete. Therefore, it requires three to five weeks to determine if a specimen contains M. bovis. DNA testing (fingerprinting) may be done to determine if the M. bovis found in one deer is related to the M. bovis found in another deer. This type of DNA testing requires another two to three weeks to complete. The testing protocol used at the MDCH is designed to provide accurate and rapid testing results using modern methods and a computerized electronic reporting system.
These agencies have been working cooperatively on bovine tuberculosis surveillance and eradication since 1994 when the first TB positive deer was found. The Bovine TB Eradication Project involves an outstanding effort and long hours by all people involved. To date over 66,617 deer have been tested since 1994, with almost 26,000 being tested in 2000 alone.
Currently, planning for the construction of the new Michigan Domestic and Wild Animal Diagnostic Center is underway with completion expected in 2003. This new lab will help combine the efforts of the MDNR's RLWDL and MSU's AHDL. Heads will no longer have to be transported from one facility to the other. Also, it will provide the much needed space for processing the growing number of deer heads that are received each year.

If you are interested in reading more about testing procedures done primarily on cattle you can visit the following site:

http://www.bovinetb.com/SubPage.asp?sec=1&LinkID=71

This site lists several testing methods used for bovine tb testing.