1. Department of Veterinary Microbiology and Parasitology, School of Veterinary Medicine, Louisiana State University,
1
and
2. Conservation and Production Research Laboratory, USDA, Agricultural Research Service, Bushland,
2
3. Department of Veterinary Science, LSU Agricultural Center, Baton Rouge,
3
Louisiana;
4. Texas Veterinary Diagnostic Laboratory, Amarillo,
4
and
5. National Animal Disease Center, Ames, Iowa
5
6. Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station,
6
Texas; and