Questions and Answers on current status: Bovine Tuberculosis investigation – Western Canada
What is the current state of the investigation and what are the next steps?
The Canadian Food Inspection Agency (CFIA) is continuing to make progress in its bovine TB investigation in response to the detection of the disease in an Alberta cow in September 2016.
The CFIA has depopulated the infected herd and the highest risk herds that co-mingled with the infected herd. Six cases of bovine TB were confirmed in the index herd.
The CFIA has also identified animals that left the infected herd in the last five years (trace-out animals) so that the trace-out animals could be destroyed and their herds could be quarantined and tested. The testing for trace-out animals is largely complete with no additional cases to date.
The on-farm testing of trace-in herds (approximately 15,000 animals) is complete. Premises will continue to be released from quarantine as laboratory and post-mortem examination results are received. Trace-in herds are tested to determine if they were the source of infection but it is possible that the source will not be found.
Will the trace-in farms have to undergo CFIA approved cleaning and disinfection?
Only premises that have been declared infected are required to undergo CFIA-approved cleaning and disinfection (C&D), which includes a 45-day waiting period of warmer temperatures.
Once a trace-in herd has been tested and no bovine TB is detected, the quarantine is removed and the farm can resume normal operations.
In addition, parts of the community pastures where the infected animals had spent time will also require C&D.
Will the premises where the infected herd and those that co-mingled with the infected herd resided require testing after restocking?
Once these premises have been restocked, the Agency will test the new herds after six and 18 months. The post-restocking testing provides an additional level of confidence about the effectiveness of the C&D and any residual risk with the affected premises.
What are the specific additional elements examined during the enhanced post-mortem?
The enhanced post-mortem involves the taking of tissue samples for further testing in a CFIA laboratory. Three additional tests designed to detect the tuberculosis bacteria will be conducted on these tissues:
- The tissue samples will be examined under a microscope to try and detect the presence tuberculosis bacteria.
- Samples will also undergo a polymerase chain reaction (PCR) test which searches for DNA from tuberculosis bacteria.
- The final test is the tissue culture test where the laboratory attempts to grow the bacteria. The culture test takes approximately 12 to 14 weeks to complete.
Can you confirm that the six TB positive cases are related?
Test results confirm that the six cows that tested positive all have the same strain of TB.
What is the source of these cases of TB? Is it possible it could come from wild elk in the region?
The investigation is ongoing. Genetic analysis has shown that the bovine TB organism from the infected cows is not the same as any strains detected in Canadian domestic livestock or wildlife or humans to date. All six currently confirmed positive cows have the same strain of TB. This strain of TB identified in these confirmed cows is closely related to a strain first found in cattle in Central Mexico in 1997.
Based on this information, it is unlikely that wildlife is the source of this outbreak.The source of an infection can be difficult to identify, especially with cases that occur far from places where bovine TB is known to be present in wild animals.
The priority area for the CFIA investigation is domestic livestock as disease management in wildlife is under provincial jurisdiction. The Agency is working with the provincial governments of Alberta and Saskatchewan to ensure that any risks associated with TB in wildlife in the area of the infected farming operation are included in the investigation. The Agency will work with provincial authorities to determine appropriate surveillance and testing activities of wildlife in the proximity of the infected premises going forward.
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