For more than a decade, Department of Natural Resources wildlife workers have been checking deer and elk heads at the agency's Wildlife Disease Laboratory, looking for evidence of bovine tuberculosis (TB) in the animals' lymph nodes.

The DNR began analyzing the heads in 1995, the year after TB was confirmed in a free-ranging whitetail in the northeastern Lower Peninsula. Since the program started, the DNR has examined more than 115,000 deer heads, mostly collected from hunters who took the animals from within the TB zone, as well as elsewhere, as the agency investigated the extent of the disease.

In 1998, the DNR also started looking for evidence of chronic wasting disease (CWD), an always fatal neurological disorder that had begun showing up in cervids, mostly in western states and Canadian provinces.

"At that time we weren't overly concerned that the disease was here in the state, but we started looking," said Dr. Steve Schmitt, DNR veterinarian. "In 2002, we became more concerned when Wisconsin announced they had it. Michigan is not that much different than Wisconsin; high deer densities, lots of captive cervid facilities, and plenty of feeding and baiting."

Today, everything has changed. After a case of CWD was confirmed in a privately owned deer enclosure in Kent County in August, looking for the disease has become "Job No. 1" at the Diagnostic Center for Population and Animal Health at Michigan State University (MSU), where the Wildlife Division's Animal Health Team is located. The team moved into the facility in 2003 from the Rose Lake headquarters, where it had been since 1957. The $58 million, 152,500-square-foot facility at MSU is a state-of-the-art animal laboratory.

In recent years, the DNR has checked about 1,500 heads annually for CWD. So far this year, workers have already surpassed that number and plans to check a minimum of 8,000 heads, hoping they will not find what they are looking for.

Heads from deer, killed by hunters, taken under disease-control permits, or even collected from fresh roadkills, have been arriving at the DNR Wildlife Disease Laboratory almost daily, coming in by truck from collection points at DNR field offices across the state. Crews of Wildlife Disease Laboratory staff, with assistance from other wildlife-health professionals, spend time almost every day in the bio-secure laboratory, looking for evidence of the disease.

It's a different process than the TB testing. When looking for TB, the staff looks for abscesses in the lymph nodes.

"With CWD, you can't see anything," Dr. Schmitt said. "We're using the same lymph nodes, but you can't tell a positive from a negative just by looking."

Instead, technicians remove 200 milligrams from the cortex of the medial retropharyngeal lymph node, put it in a container, and then send it elsewhere in the lab, where a scientist runs an automated

test. The material changes color if prions, the mutated proteins that cause CWD, are present.

When the three-hour test turns up a suspect, as it did in August with the infected deer from the private facility in Kent County, the test is repeated. If a second test comes back positive, the sample is sent to the United States Department of Agriculture (USDA) National Animal Disease Center in Ames, Iowa, where the diagnosis can be confirmed.

"At peak times, we get about 15 people on the floor working on heads, our staff and some people from the USDA," Dr. Schmitt said. "They bring in wildlife disease biologists from around the country and have them here for a two-week period. They've got 44 of them in 44 states; they use this as a training exercise."

It works out well for both the USDA and the DNR. Scientists from the USDA have an opportunity to spend some time working in a state-of-the-art facility, while getting a taste of what might happen if they are ever called upon to react to an outbreak of a dangerous animal disease. The DNR gets manpower from the USDA for its CWD-testing program at no cost to the agency.

The sampling takes place in what Dr. Schmitt refers to as the BL3 (Biological Level 3) necropsy room.

"It's an airtight room with negative air pressure," he explained. "Even if all the doors were opened, the infectious agent could not get out. It would be sucked out of the room through the filtration system. It protects the individual working in the lab and makes sure the 'bug' won't get out of the room and into the environment.

"Technicians wear Tyvek® suits, gloves, eye protection, and respirators. They shower out. Nothing that is on the floor comes back out, other than the staff. Anthrax could be worked on in this lab. Everything that comes into this building for necropsy or testing is incinerated at 1,800 degrees. That will kill anything."

Dr. Schmitt said the DNR is working in the largest animal necropsy facility in North America, and possibly the world.

"When this place was built, we were working on TB, but looking to the future," Dr. Schmitt said. "There are probably other diseases we'll be seeing that we're not even aware of yet. We were looking at what we needed 10 years or more down the road."

And although taking tissue samples from deer heads has been a big part of Dr. Schmitt's job since August, the crew was just getting started then. The crew worked seven days a week during the firearms deer season in November.