August 15, 2007


 New building to advance study of tuberculosis in cattle, wildlife

Posted Aug. 1, 2007 

Two veterinarians who study tuberculosis can't wait to move their research into the new high-containment large animal facility at the National Centers for Animal Health in Ames, Iowa.

Even before the dedication, Drs. Mitchell V. Palmer and W. Ray Waters relocated some white-tailed deer to the premises so the animals could acclimate—and help showcase the special cervid rooms.

The veterinary medical officers work for the U.S. Department of Agriculture, which began tuberculosis research in 1992 to respond to an increasing prevalence of the disease in cattle. Dr. Palmer said the main objectives are to improve diagnostic tests for Mycobacterium bovis, to explore the immunopathogenesis of the infection, and to develop vaccines. The researchers study tuberculosis in cattle and white-tailed deer as well as elk, reindeer, and raccoons.

The program to eradicate tuberculosis in cattle dates to 1917, Dr. Palmer said. Prior to the pasteurization of milk, M bovis accounted for about 25 percent of the cases of tuberculosis in humans.

"A big motivation for the tuberculosis eradication program was public health," Dr. Palmer said.

Now, tuberculosis in cattle poses problems for domestic and international trade. In the 1990s, the United States began importing more cattle from Mexico, where M bovis is not uncommon. The USDA also found wildlife reservoirs in white-tailed deer in Michigan and possibly Minnesota.

"Wildlife reservoirs, when they're present, are extremely difficult to eliminate," Dr. Palmer said.

Researchers have started their work by trying to develop a blood test for tuberculosis to replace the skin test. Simultaneously, they are developing vaccines that the USDA could administer to cattle and wildlife in select areas. Dr. Palmer said vaccinating wildlife creates challenges, particularly in terms of safety when delivering oral vaccines in bait.

"You're putting a vaccine out into the environment," he said. "Species that you may not intend to be vaccinated will be exposed to this vaccine."

Studying tuberculosis also creates challenges because it is infectious to humans and many other animal species. Researchers must study M bovis at facilities that meet standards for biosafety level 3—agriculture and that can house research animals much larger than mice.

The facility where the researchers have been working dates back about 50 years. While the building can house large animals, the designers had no idea that the USDA would be studying wildlife. The researchers have had to retrofit, remodel, and rig up housing for the white-tailed deer.

The architects of the new high-containment large animal facility designed rooms specifically to accommodate the behavior of wildlife, including the flighty nature of deer. The facilities will allow researchers to handle animals more safely. Plus, the new building provides enough space for additional animals in evaluations of diagnostics and vaccines.

Dr. Waters said the facility also offers benefits for researchers who study brucellosis in cattle, bison, elk, and feral swine. For example, the building features large rooms for studies involving bison, which have a tendency to be aggressive—particularly after calving.

"The gates are configured so you can move the bison without actually getting in there with them," Dr. Waters said.

He said the new facility is safer in terms of containment, too, partly because it is one big building rather than several smaller ones.

Dr. Waters gave tours during the dedication of the new building, and he said all the stakeholders found the facility to be rather impressive.

"It is a world-class facility," he said. "It's the new gold standard for a BSL-3—Ag large animal facility."