Penny Young, ASAS/ASAP Intern
The bovine tuberculosis (TB) outbreak traced to Jenner, Alberta late last year that set off a massive investigation involving over 60 farming operations finally has an end in sight. The investigation, overseen by the Canadian Food Inspection Agency (CFIA), has found no affected animals aside from the six identified in the index herd.
Using trace-back and trace-forward approaches, the CFIA identified and subsequently quarantined around 58 operations across Alberta and Saskatchewan. Testing of animals on these properties resulted in the selection of 18 properties for culling and testing procedures due to the presence of positive responders to the tuberculin test. These procedures resulted in the loss of around 10,000 mature cattle and most calves of the 18 farming operations, however it was found that no animals presented with tuberculosis in the enhanced post-mortem testing. In addition to routine searches for characteristic tuberculosis lesions, this testing included examination of tissue under microscope (looking to detect presence of Mycobacterium bovis), PCR, and tissue culture.
These findings have prompted decisions regarding the next phases of the investigation. Over 50 herds remain under quarantine as they received animals from the infected operation, and these herds will be subjected to screening tests. Only the responders will be slaughtered and given a post-mortem, and any herds that have no reactors will be released from quarantine. 16 herds have already been released, as they have been deemed a low enough risk. The decision of the CFIA not to do testing until fall will minimize risk of stressing pregnant cows and those who have recently calved, and also allows for movement of herds to summer pastures which should help to lessen the blow for those new herds identified in the continuing tracing procedures.
Farming operations with herds released from quarantine will be able to commence restocking after disinfection has occurred, although the official disinfection processes may have to wait until a period of warmer weather. Once these disinfection processes have been completed and verified, restocking can begin. New stock will be tested at six and 18 months on the property to ensure there has been no disease transmission and to confirm the efficacy of the cleaning and disinfection procedures.
The bovine TB outbreak was first identified by the USDA when it was found that a Canadian cow slaughtered in the US showed signs of tuberculosis infection. This cow was traced back to a property in Jenner, Alberta, and an investigation was launched by the CFIA. The same strain of TB was found in six cattle in that index herd, and no other infected animals were identified. The strain is one that has never been seen in Canada before, most recently being associated with bovine tuberculosis cases in Mexico. At the current time, it seems unlikely that the tuberculosis was from a wildlife source and passive surveillance of elk hunted near the affected area in Alberta has shown no sign of the disease.
The investigation now aims to determine potential sources of the disease by tracing back contacts with the index herd over the past five years.
Questions raised about outbreak management:
The difficulties associated with managing the investigation into the bovine tuberculosis outbreak have given rise to questions about how such an investigation should be prepared for. Dr. Ron Clarke wrote in the Canadian Cattlemen of how there were delays in testing during the investigation due to a shortage of tuberculin. He also questioned why the tuberculin test is still the primary screening process given the technological advances the industry has seen, and he stresses the need to prioritize research into blood tests or other chute side diagnostics. Cody Creelman interviewed for Alberta Farm Express suggested that perhaps regulatory protocols have not kept pace with the increases in size of farming operations, because the predesigned strategy for managing a bovine TB outbreak was inadequate in the face of the massive operations implicated in this case.
There has also been discussion about the inadequacies of compensation schemes. Although there are clear compensation schemes in place, many producers were frustrated by the delay in getting access to funds. This is particularly significant in this outbreak, because many of the operations affected were cow-calf producers who would have been selling off the calves during the quarantine period. As a result of the quarantine, they have had to keep animals on the property much longer than they normally would have, with inadequate provisions and a dearth of suitable facilities. Given the season, this was particularly hard to manage. Many have found it a struggle to pay for extra feed and other associated holding costs, and although government have announced compensation measures, earlier access to funds could have helped lighten the load.
Impact of the outbreak
While the chief CFIA veterinary officer says that there will be no trade implications due to the outbreak, there is no doubt that the economic impact for those involved will be significant. The federal government announced in November last year that it had earmarked $16.7 million for compensation through the AgriRecovery scheme, which should help manage those affected by the quarantine, as the CFIA compensation schemes mostly address those who have had their animals or other materials destroyed. It will also take quite some time for these herds to recover, even once properties are given the all clear for restocking.
To read more about the bovine tuberculosis outbreak, follow these links.
CFIA Official Releases:
Compensation and costs:
Dr. Ron Clarke on the outbreak: