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January 23, 2003

Purdue, state test deer and elk for fatal disease

WEST LAFAYETTE, Ind. ‹ Purdue University and the state of Indiana have joined a federal effort to prevent spread of chronic wasting disease, a fatal illness that has been detected in wild and domestic deer and elk in 11 states, not including Indiana.

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This month, pathologists at the Indiana Animal Disease Diagnostic Laboratories (ADDL), based on the Purdue campus, began using a new machine to test tissue samples to determine whether deer or elk are infected with the disease. While no cases of chronic wasting disease (CWD) have been found in Indiana, seven cases were discovered since last November in northern Illinois. Wisconsin found the first cases east of the Mississippi River in February 2002.

"We have signed an agreement with the federal government to test samples from deer from Indiana and any other state that needs a diagnosis on possible CWD cases," said Randy White, Purdue associate professor and a veterinary pathologist with ADDL. "In Indiana, we need to be concerned because animals don't respect state boundary lines and CWD is very close to us in Illinois and Wisconsin."

Chronic wasting disease is a transmissible spongiform encephalopathy found only in cervids, the animal family that includes deer, elk, caribou and moose. It is similar to bovine spongiform encephalopathy (BSE), commonly referred to as mad cow disease. Though BSE has been linked to human illness in Great Britain, scientists so far have found no evidence that meat from CWD-infected animals can infect people, pets or other types of livestock.

However researchers don't yet know the origin of the illness or how it's transmitted, according to the U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS). The disease is believed to be caused by an abnormal type of protein called a prion (pree-on) that attacks the central nervous system, including the brain, killing cells. This eventually creates holes in the brain that give it a spongelike appearance.

"Although we have nothing to show that eating CWD-infected deer and elk is harmful to people, we can't say that it's okay or it's not okay to eat the meat," White said.

White and two laboratory technicians recently trained at the USDA National Veterinary Services Laboratory in Ames, Iowa, in the use of an automated and computerized CWD diagnostic machine. The Purdue lab now has the same type of equipment used by the national lab to test for chronic wasting disease. CWD was first recognized in 1967 as a clinical wasting disease in mule deer at a federal wildlife research facility in northern Colorado. It was identified as a transmissible spongiform encephalopathy in 1978.

In the mid-1980s, free-ranging deer and elk in adjacent areas of Colorado and Wyoming were diagnosed with the deadly illness, according to APHIS. Since that time, the national lab has handled all testing of suspected cases of chronic wasting disease.

White said that Purdue, along with other laboratories in Illinois, Minnesota, Michigan, Ohio, Texas and Arkansas, is now running tests for the disease. He said he expects that the ADDL at Purdue will receive samples from surrounding states and may receive some from national laboratory, so that diagnosis is timelier.

The diagnostic process takes six to seven hours. First tissue samples from the middle of the brain stem, called the obex, and from lymph nodes, are put on a slide and loaded into a machine called a decloaker. This machine will expose any prion antigens.

Next the slide is put into the staining machine, which can hold 20 slides, where a dye containing an antibody is placed on the tissue. Antibodies are molecules that detect a foreign disease-causing substance by binding to the antigens. If abnormal prions are present, that area of tissue will turn bright red. A pathologist must look at the tissues through a microscope to determine if abnormal prions are present.

"The State Board of Animal Health, the USDA and the Indiana Department of Natural Resources have instituted good programs to prevent the spread of CWD," White said. "People handling or eating deer and elk should take precautions, because many things about this disease are still unknown."

Anyone seeing a deer that appears ill should call the local Indiana Department of Natural Resources Fish and Wildlife Division office, which will handle the initial investigation. The symptoms of the disease include listlessness, staggering, emaciation, blank facial expression, excessive salivation, grinding of teeth, and increased drinking and urination.

According to APHIS, chronic wasting disease has been found in wild and farmed deer and elk in South Dakota, Wyoming, New Mexico, Nebraska, Colorado, Oklahoma, Kansas, Minnesota, Montana, Wisconsin and Illinois. The affected animals have been Rocky Mountain elk, mule deer, white-tailed deer and black-tailed deer. Indiana has a ban on imports of cervids that runs through May 1.

The National Wildlife Federation estimates that the rate of infection in areas where prion-diseased cervids have been found is approximately 1 percent in wild elk, 5 percent in wild mule deer and 10 percent to 12 percent in wild white-tailed deer.

Tests have been run placing domestic cattle, sheep and goats in research wildlife facilities that housed CWD-infected deer and elk. None of the domestic animals contracted the disease, according to the Animal and Plant Health Inspection Service.

Although no human cases of CWD have been found, experts offer the following advice:

  • Don't eat the eyes, brain, spinal cord, spleen, tonsils or lymph nodes of any deer or elk.

  • Don't eat any deer that appears sick.

  • Wear rubber or latex gloves when dressing carcasses.

  • Remove all meat from bones before cooking and eating.

  • Clean all equipment with a solution of half chlorine bleach and half water.

    NOTE TO JOURNALISTS: A publication-quality photograph of Randy White is available at ftp://ftp.purdue.edu/pub/uns/white.wasting.jpeg.

    Writer: Susan A. Steeves, (765) 496-7481, ssteeves@ purdue.edu

    Source: Randy White, (765) 494-7456, white@purdue.edu

    Related Web sites:

    Purdue University Department of Veterinary Pathobiology: https://www.vet.purdue.edu/vpb/index.htm

    Indiana Board of Animal Health: https://www.IN.gov/boah/

    Indiana CWD Information Site: https://www.deerhealth.in.gov

    Indiana Department of Natural Resources, CWD: https://www.in.gov/dnr/deerhealth/cwd.htm

    USDA Animal Plant Health Inspection Service: https://www.aphis.usda.gov

    PHOTOCAPTION:

    Purdue University veterinary pathologist Randy White operates new equipment that will diagnose chronic wasting disease in deer and elk at the Animal Disease Diagnostic Laboratory (ADDL). The state lab is now part of a federal program to identify and prevent the spread of the disease, which is fatal to infected animals. (Agricultural Communication photo/Tom Campbell)

    A publication-quality photograph is available at ftp://ftp.purdue.edu/pub/uns/white.wasting.jpeg.

    Purdue News Service: (765) 494-2096; purduenews@purdue.edu

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