Bovine tuberculosis in livestock

Overview

Bovine tuberculosis (bTB) is a bacterial disease associated with infections of Mycobacterium bovis (M. bovis), a species in the M. tuberculosis complex. The disease mostly affects cattle but can become established in other species. In some countries, specific wildlife species can maintain infections and pose risk of re-infecting cattle.

This is a federally reportable disease and all cases must be reported to the CFIA. Bovine TB is also a provincially notifiable animal disease. See below for How to report suspected or confirmed cases.

In countries with eradication programs such as Canada, advanced bTB is rare. Most cases are detected at an early stage when infection typically consists of few or small lesions in the lungs or lymph nodes associated with the respiratory system.

Clinical signs

In Canada, few bTB infections progress to the point of presenting clinical signs. But when progressive disease does occur, the general signs are:

• weakness
• loss of appetite
• weight-loss
• fluctuating fever

When the lungs are extensively diseased, there can be an intermittent, hacking cough.

For more information on the disease, see Bovine tuberculosis fact sheet (CFIA).

How to report

Bovine tuberculosis is a provincially notifiable disease under Alberta's Animal Health Act and must be monitored. It is also a reportable disease under the federal Health of Animals Act and all cases must be reported to the Canadian Food Inspection Agency.

All suspected or confirmed cases must be reported to the Office of the Chief Provincial Veterinarian (OCPV) within 24 hours:

Hours: 8:15 am to 4:30 pm (open Monday to Friday, closed statutory holidays)

Phone: 780-427-3448
Toll free: 310-0000 before the phone number (in Alberta)
Fax: 780-415-0810

Where it's found

In fall 2016, M. bovis was detected in a beef cow from southeastern Alberta. The CFIA immediately initiated a livestock investigation program and confirmed 6 cases of bTB in a single herd. After testing 34,000 animals on over 145 farms in Western Canada, the CFIA did not identify a source of infection for the index herd. Nor did it find evidence of the spread of infection to any animals, including wildlife, outside the index herd. In April 2018, the investigation was closed. For more information, visit the CFIA website: Bovine tuberculosis investigation in Western Canada.

Today, surveillance and testing for bTB in livestock still occurs in Alberta on a regular basis. No cases have been detected in the province since 2016. See confirmed cases of regulated animal diseases in Alberta.

The risk of bTB infection in wildlife in Canada is low. However, in summer 2017 the CFIA worked with the Alberta government and provincial wildlife agencies to develop a plan for bTB surveillance of wildlife. For more information on bTB and wildlife, see Wildlife diseases in Alberta.

Risk to humans

Bovine tuberculosis is a zoonotic disease (transmitted between animals and humans). It does not pose a threat to public health due in part to the extremely low prevalence of the disease in Canada.

Although human cases of bTB are rare, humans may be at greater risk of acquiring the bacteria as a result of:

• extended close contact with an animal with active respiratory TB
• consuming unpasteurized milk or milk products from an infected cow

For more information on the risk of human exposure, see Bovine tuberculosis fact sheet (CFIA).