Six more cattle herds to be tested in TB probe

Updated, Dec. 20 — Cattle from four more herds in British Columbia and two in Alberta are now being tested for bovine tuberculosis as officials probe the country’s latest domestic case of the disease.

The Canadian Food Inspection Agency on Monday reported the six herds are now under “movement controls” while TB testing is underway.

Other than their home provinces, which a CFIA representative released Dec. 20, no further information was immediately available on the locations of the six additional herds, nor on the numbers of cattle in those herds.

Testing began last month after a mature beef cow from a farm in B.C.’s southern Interior was confirmed Nov. 9 with bovine TB.

The cow — which in October was found to have TB-characteristic lesions at slaughter — remains the only animal found to be infected so far in this probe. Its home herd is also still under movement controls. No part of the animal entered the food chain, CFIA said previously.

CFIA’s investigation involves tracing the movements of the B.C. cow and its home herd, to try to identify the disease’s source as well as any potential spread. That means tracking the movement of animals to and from the infected herd during the past five years.

Any animals under CFIA-imposed movement controls are not allowed to be moved without the agency’s permission. Those controls remain in effect until all “testable” animals in the given herd have tested TB-negative.

If any animal under movement controls turns up positive for bovine TB, CFIA will then “follow established procedures for destruction” of those animals, and for compensating affected producers.

Testing is also still underway to identify the strain of TB bacterium in the infected B.C. cow, to see if it has any possible connections to previous bovine TB cases.

It’s not yet known how many more herds may need to be tested, nor how much time will be needed to complete the investigation, CFIA said.

CFIA in April formally closed its investigation on Canada’s most recent previous bovine TB outbreak, which began when a southern Alberta cow was confirmed with the disease in September 2016.

The resulting probe from that case led to the discovery of five more infected cattle and destruction of about 11,500 through trace-in and trace-out investigations. However, no source of infection was ever identified.

The strain of bacterium in the six infected cattle from the 2016 outbreak didn’t match any previously found in Canadian domestic animals, wildlife or people. It was found to be “closely related” to a strain originating from cattle in central Mexico in 1997.

CFIA has previously emphasized there is no risk to Canada’s food supply or to human health from this case.

Human exposure can only occur through the passage of fluids from an animal to an open skin sore, through “extended close contact” with an animal with active respiratory TB, or by drinking unpasteurized milk from an infected animal. — Glacier FarmMedia Network