State's only CWD detection lab ramps up as deer season looms


 

September 28, 2019

MADISON - As deer hunting season gets underway, the only lab in Wisconsin that detects chronic wasting disease is also preparing itself for its annual busy spell.

For about six weeks around Thanksgiving and Christmas each year, pathology sciences supervisor Dan Barr, three full-time employees, about 10 short-term staff and a rotating team of specialists chip in to keep the lab operating 16 hours a day by performing diagnostic tests on thousands of deer samples, The Capital Times reports.

What they're looking for at their facility on the University of Wisconsin-Madison campus is evidence of CWD, a fatal wildlife disease that has affected 56 of the state's 72 counties, per the Department of Natural Resources. But only 36 counties have had at least one CWD-positive result and most are concentrated in southern Wisconsin.

The Wisconsin Veterinary Diagnostic Laboratory's busy season coincides with the deer hunt, which began with archery and crossbow in mid-September and picks up during the gun hunt, which kicks off this year on Nov. 23.

For now, the lab's in preparation mode, a time that has involved moving into a bigger room on the building's third floor a space, at 2,100 square feet, that's nearly three times the size of the old one, a 742-square foot room that had been used to perform CWD diagnostics tests since 2006.

The increased capacity, Barr said, means the lab was able to purchase two extra $10,000 biosafety cabinets, where workers prepare tissues for sampling, thus creating four more workstations for the additional temporary employees they're seeking to hire.

"We were definitely living outside of our means in terms of being able to do this," Barr said in a recent interview.

Barr, who's served as pathology sciences supervisor for 11 years, began working in the lab's old facility on Mineral Point Road in 2002, meaning he was involved in the Department of Natural Resources' first collection of CWD samples in the state. The first CWD positive deer were detected that year.

Already, the lab is working to advertise the job openings and recruit and interview temporary workers ahead of the November and December rush-period.

Last year, during the six-week time frame, the lab tested around 17,000 deer of the approximately 211,000 that were killed in Wisconsin, or around 8%, Barr said. Of those, 1,063 tested positive for CWD, a record high.

The disease, caused by abnormal proteins called prions, affects deer, elk and other animals and targets their brain and spinal cord, per the federal Centers for Disease Control and Prevention. It is spread through contact between animals including nose-to-nose touching as well as food or drinking water in the environment.

An infected animal could exhibit weight loss, drooling, a lack of fear around people and other signs. At this point, it's unclear whether the disease could be passed to people, although the Centers for Disease Control and Prevention notes studies "suggest that it is important to prevent human exposures to CWD."

To perform the tests, DNR wildlife biologists and technicians work with hunters to acquire the samples from deer by cutting open the animals' throats to expose the two retropharyngeal lymph nodes, which are then removed, cut in half and put into pre-labeled containers.

From there, samples are sent to the lab, where they are either frozen or spend time in a preservative to firm up the tissues, before being cut and prepped for testing. The lab performs two types of tests on samples: an immunohistochemistry test, or IHC, which takes about a week, and the Enzyme-Linked Immunosorbent Assay test, or "ELISA," which takes about a day.

For the IHC, the lymph nodes and obex, or part of the brain stem, are targeted and embedded in molten wax, which is left to harden. They're then shaved down to a thin slice the thickness of one cell, transferred to a slide, stained in order to detect CWD and examined under a microscope.

But for the ELISA test, tissue is submitted to the lab after being frozen by the DNR. Two hundred milligrams of tissue from the outer cortex is then put into a small grinding tube, which takes the semi-solid tissue piece and "turns it into a protein shake," Barr said, that can be pipetted without clogging and examined.

It's the ELISA test that the lab used to test all 17,000 deer tissue samples last year, Barr said. The temporary workers that are brought on perform the majority of the sample preparation, such as cutting the frozen lymph nodes to the proper size.

In addition to CWD testing, the lab also uses its chemistry toxicology equipment to investigate other animals' deaths as requested by pet owners, farmers and others.

About 40% of the lab's funding comes from tax dollars, while the remaining 60% comes from its service fee, Barr said. For each test the lab does, he added, officials levy charges against a submitting agency, veterinarian and others who submit samples for testing.

The lab, he noted, charges the DNR around $20 per animal sample submitted. In all, according to the DNR, the agency paid $347,556 to the lab between July 1, 2018, and June 30, 2019, to cover CWD testing costs.

The fees currently are inflated between 60% and 70% to cover the lab's expenses, Barr said. If the lab was fully funded through state tax dollars, he said the service fee would "decrease significantly" for those who submit samples for testing.

Barr said he's previously requested additional state funding, including under former Gov. Scott Walker, but nothing came of the efforts.

Asked if he was hopeful that would change under Gov. Tony Evers' administration, Barr said: "No, essentially we're out in left field. Most people don't even know that we exist. They think the DNR does the testing. So we're basically in the shadows, performing the tests."

State and federal regulations, he said, prevent other labs from getting involved in the testing process and lessening the overall workload. In order to do so, he said sites need accreditation from the American Association for Veterinary Laboratory Diagnosticians and the National Animal Health Laboratory Network.

In Wisconsin, Walker in 2018 proposed emergency rules to limit the spread of deer carcasses and implement additional fencing requirements. The former provision was rejected by lawmakers and never went into effect, while the latter provision expired in the spring after the DNR failed to release a permanent rule on the matter.

This session, the state directed the DNR to use $100,000 for CWD research targeted at improving deer management practices in the state. Separately, Democratic state Rep. Katrina Shankland has recently floated three bills to direct $2 million toward additional CWD research, allocate $2 million for deer carcass waste bins and free up $200,000 for extra kiosks where hunters can drop off deer samples for testing.

On adding more kiosks, Barr said extras would help increase sample representation throughout the state.

"The more animals that we test across a more broad geographic location, the better idea we have of distribution and prevalence," he said.

Associated Press