Solving the puzzle of chronic wasting disease: Veterinarian Beth Williams
by Alison MacaladyLARAMIE, WYOMING — Stacks of histopathologies — gray folders filled with the tissue of dead animals — litter the floor of Dr. Beth Williams’ office at the University of Wyoming’s State Veterinary Lab in Laramie. Crowded into the office with a computer and a microscope table, they leave little room for Williams herself.
The morbid artifacts belie Williams’ warm personality, but the cramped workspace, tucked in the back of the lab’s second-floor coffee room, hints at her humble style. Williams gives her colleagues as much credit as she gives herself for the work that has made her a leading expert on chronic wasting disease (CWD), the deer and elk disease that has sent shivers through the West’s hunting and ranching industries (HCN, 10/28/02: Deer, elk disease doesn't scare hunters).
Little is known about CWD and the rogue proteins called prions thought to cause it, or about the class of related diseases called transmissible spongiform encephalopathies (TSEs): mad cow in cattle, scrapie in sheep and Creutzfeldt-Jakob in humans. But after the mad cow outbreak in England was linked to over 130 cases of a variant of Creutzfeldt-Jakob disease in humans, fear that CWD might jump to cows or even people became palpable. That fear has not yet been justified, but CWD has put the brakes on the elk-ranching trade, and wildlife managers continue to worry about the disease ravaging wild populations.
In this climate of uncertainty, Williams’ work has provided some of the only clear answers about CWD, which has now been discovered in 12 states and two Canadian provinces.
Since they first diagnosed the disease in 1978, Williams and her colleagues have been studying its effects on cattle. In one experiment, five of 13 cows injected with CWD developed the disease. But cows fed food made from CWD-infected deer, and cows that simply share close quarters with infected deer, have so far remained healthy.
While it appears that cattle are highly unlikely to contract CWD, deer and elk herds are vulnerable. In September 2003, Williams and Colorado researcher Mike Miller published an article in the journal Nature, warning that CWD could spread rapidly among herds in the wild, especially where animal density is high. Williams believes that contamination in the environment — perhaps the feces and urine of infected animals — is an important factor in the disease’s spread.
Williams says she first "stumbled into" CWD work as a Colorado State University graduate student in the 1970s. At that point, no one knew why deer at a university research facility acted disoriented and eventually died, literally wasting away.
"We were confronted with deer that were dying before they should be," recalls Williams. "They were in captivity — were they stressed? Was it nutritional? Maybe there was a toxin in the environment? Trying to sort through all that, it was just a real mystery."
Williams noticed that the brains of infected deer were consistently speckled with holes. That led her to connect CWD with scrapie, the TSE that causes lesions in sheeps’ brains.
But Williams’ diagnosis went largely unnoticed outside the wildlife-science community. The lack of interest during the early years of her career stands in stark contrast to the hubbub swirling around CWD today.
"It’s been a bizarre transition," she says. The mad cow outbreak in England, and the discovery that eating contaminated beef can cause a variant form of Creutzfeldt-Jakob in humans, "put a lot of pressure on us — there were a lot of questions ... the issue (of CWD) related to humans is a good one, with no definite answers. There is still a mountain of work to do."
The discovery of mad cow disease in Washington last December only points to the importance of the work that Williams has already done. That has changed, and Williams’ work at the lab is now partially funded by McDonald’s and the National Cattlemen’s Beef Association.
CWD studies are low-tech and time-consuming, partly because there is no analytical test for prions in low concentrations or in soil and water. Scientists can’t measure directly how CWD makes its way through the environment; they have to wait for it to show up in an animal.
One of Williams’ latest experiments is designed to understand whether deer can get CWD by eating the feces of diseased animals. After pulling on black rubber overboots, Williams takes me to the Lab’s pastures to meet the experimental deer.
Wearing Wranglers and a sweater, her straight, waist-length hair parted down the middle, Williams looks the part of a Wyoming wildlife vet. Her affection for animals shows: She calls out to the "girls," and walks up to pet the four tame does on the nose and neck.
I approach the deer more cautiously, less comfortable touching the potentially infected animals. This is one of Williams’ biggest challenges as a CWD researcher: dealing with public anxiety about this poorly understood, devastating class of diseases.
"What does ‘unlikely’ mean?" Williams asks, referring to the possibility that CWD could jump to humans or cows. "That’s hard to quantify for people. Trying to talk to reporters, I say this is a gray area."
The way Williams sees it, explaining the amount of uncertainty in science is an essential part of her job.
"There’s a real need for scientists to get (their results) out of the lab," she says, "so that the public can understand that things are never black-and-white."