Comment from Dr. Charles Thoen

My main concern is Mexican cattle that are entering the USA. A report from USDA indicates that 75% of the M. bovis slaughter cases were of foreign orign during 2003 to 2008. I feel this is a very important finding and one of major concern since this may represent only a "tip of the iceberg" as many young tuberculous cattle may not have gross lesions detected at slaughter and specimens would not have been submitted for laboratory examination! The number of M.bovis-infected cattle of foreign orign may be as much as 100 times or more greater than that reported in NASS Agriculture Statistics. Therfore, more stringent regulations should be enforced immediately. I feel strongly that the tuberculin skin tests (CFT and CCT) that are available and in use in the US are adequate to eliminate M.bovis-infection in cattle. More than 95% of the TB in cattle in US has been eliminated by use of the CFT. I strongly feel that additional hands-on training of accredited veterinarians is needed to emphasize the importance of good technique and response evaluation. Also, I believe that a greater emphasis perhaps needs to be placed on interpretation of results especially in cattle herds in which M. bovis has been identified in a traceback from slaughter. While some research work could be conducted to evaluate "new" tests, I am not optimistic about identifying reliable new tests with improved sensitivity for field use in the near future. Moreover, I am of the opinion that serologic assays may be of only limited value. I do not support any major changes in the regulations regarding the handling or quarantine of herds in which M. bovis has been diagnosed. What is being done is necessary in order to eliminate spread of M.bovis! I think what your organization is doing is appropriate. I hope you find my comments helpful. Best regards. Charles