Animals > Animal Diseases > Bovine Tuberculosis  

Bovine Tuberculosis

What is bovine tuberculosis?

Tuberculosis is a contagious disease caused by an infection in the lymph nodes which is then spread to other organs like the lungs. This disease affects practically all mammals, and before control measures were adopted, was one of the major diseases of man and domestic animals.

What are the signs of disease?

Generally, enlarged lesions in lymph nodes or other tissues examined post-mortem can indicate the presence of the disease. In some instances, the disease only becomes apparent when it reaches an advanced stage. However, the disease organisms can lie dormant in the host for its lifetime without causing a progressive disease.

Nevertheless, if the disease is progressive, the general signs are weakness, loss of appetite, weight-loss and fluctuating fever. When the lungs are extensively diseased, there can be an intermittent, hacking cough.

How is this disease spread?

Tuberculous cattle with open lung lesions throw micro-droplets of the disease agent into the air by coughing. Adult cattle are infected by the inhalation of air-borne dust particles to which the disease agent attaches itself as well as contaminated feed and water facilities. Young calves may be infected by drinking unpasteurized infected milk.

Certain scenarios can create a considerable risk of transmission and introduction of tuberculosis into other herds. The movement of infected animals from one herd to another with subsequent extended close contact can increase this risk.

Can bovine tuberculosis be spread to humans?

Bovine tuberculosis may produce infection in humans. Owners and handlers of infected cattle are at risk. Anyone who may have come in direct contact with infected animals should seek medical advice. Quarantining of the premises ensures that no other humans can come in direct contact with the infected cattle or premises.

How is bovine tuberculosis controlled in Canada?

Bovine tuberculosis is a reportable disease in Canada. When it is reported, the Canadian Food Inspection Agency (CFIA) follows a strict testing and eradication program. Regulations require that all infected animals as well as all exposed susceptible animals be destroyed. This is the only proven way to eliminate the disease.

Because 95 percent of all commercial animals slaughtered are sent to a federal abattoir, the CFIA uses an abattoir surveillance system which looks primarily for tuberculosis-like lesions in the lymph nodes of slaughtered animals.

When a farm has been declared infected, it is immediately put under quarantine and the provincial health department in the area of the known infection is alerted.

Are owners of cattle ordered destroyed compensated by the federal government?

Owners can be compensated up to the maximum amount established under the Health of Animals Act.

What measures are taken for cleaning and disinfecting a farm?

The owner is responsible for cleaning and disinfection of infected premises. Cleaning and disinfection can be carried out only after all the animals ordered destroyed have left the premises. Once a CFIA inspector has confirmed that the premises have been cleaned and disinfected, the quarantine can be lifted. The owner must wait 30 days before the premises can be restocked. Replacement animals will be tested at specified intervals for a period of up to four years. If the owner waits one year before restocking, no testing will be required.

What can owners do to ensure their cattle do not have tuberculosis?

There is no preventative treatment to protect animals from becoming infected with tuberculosis. Cattle buyers can require that animals be tested before purchasing. However, this does not provide 100 percent guarantee. Some infected livestock seem to be in prime condition, showing no evidence of infection until they are slaughtered. In some instances, the disease organisms lie dormant within the host's body for its lifetime, both in animals and in humans, without causing progressive disease.

How to get more information?

Contact your Canadian Food Inspection Agency Area Office:

You can find your local Canadian Food Inspection Agency District Office on the CFIA Web site or by consulting the blue pages of your local phone directory.

P0092E-00
May 2000