Animals > Animal Diseases > Bovine Tuberculosis  

Bovine Tuberculosis In Wild Animals

What is bovine tuberculosis?

Tuberculosis is a contagious disease caused by an infection in the lymph nodes which spreads 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. Bovine Tb is one of the most infectious forms of Tb and is reportable under the Health of Animals Act.

Another form of Tb called Avian Tb has also been known to affect cattle, pigs, and a few other animals, but is usually restricted to birds.

What are the signs of disease?

Sick animals may show general symptoms such as weakness, loss of appetite, weight loss, and a fluctuating fever.

Suspicious lesions might be apparent when an animal is being field-dressed. Tb lesions may be found in any organ or body cavity of diseased animals. In the early stages of the disease, lesions are difficult to find. In later stages, nodules or lumps may be found in the lungs and associated lymph nodes as well as in the lymph nodes of the head and intestinal tract.

What species are susceptible to Bovine Tb?

Bovine Tb can be transmitted from cattle to other farm animals, bison, and all of the deer species under certain conditions. Cattle are the usual host for this bacteria, but transmission can occur between wild deer.

How is Bovine Tb transmitted?

The most common means is by airborne transmission. Infected animals exhale bacteria through breathing, coughing and sneezing. Animals are more likely to infect each other when they share a common watering and feeding place.

Is Tb common in wild animals?

Bovine tuberculosis is not a naturally occurring disease in wild animals. It is thought that it was introduced into wildlife populations through contact with domestic animals. Although it is known that wild herds can become infected with Tb, results from specific hunter surveys in Manitoba and Alberta, and the capture and testing of wild animals for domestic and zoological purposes indicate that the disease is still not common in wild animals in Canada.

What does CFIA do to control Tb in wild animal population?

Responsibility for controlling disease rests with the agency that has legal jurisdiction over wildlife species. Animals within national parks, are a Parks Canada responsibility. Animals that are free roaming or on provincial crown land, are a provincial responsibility. Although the CFIA does not have a program specifically designed to control disease in wildlife populations it can provide information, advice, scientific and laboratory support to agencies which have jurisdiction over wild populations.

What are the alternatives\methods for controlling Tb in a wild animal population?

Realistically, there are limitations to what can be done. Fences have been used in some national parks to reduce the possibility of wildlife leaving the park. Farmers or ranchers can fence off hay bales\stacks to prevent wildlife from having access to hay, and to prevent contact with domestic livestock. Specific, targeted depopulation may also be considered.

Buffer zones have been tried to control disease outbreaks but have not found to be effective.

Can humans contract Bovine Tb from eating the meat of an infected animal?

It is unlikely that a person field-dressing or eating meat of an animal infected with bovine Tb could become infected. Hunters should practice sanitary precautions, including washing after field-dressing an animal. Hunters that suspect their kill of being infected should contact their provincial or federal agencies.

What does CFIA do when domestic cattle have been exposed to wild animals with the disease?

As a precautionary measure, cattle, bison, elk and deer are tested for Tb. If livestock has a positive reaction to the test, they are ordered destroyed and tissues are collected for laboratory examination.

Why are domestic animals infected with, or exposed to, Bovine Tb destroyed?

Canada follows a strict testing and eradication program in domestic animals. Because tuberculosis may have a long incubation period and does not always show up in tests, regulations require that all infected animals as well as all exposed susceptible animals be destroyed.

Are the farmer or producer compensated for animals that are destroyed?

Compensation may be awarded for farmed animals ordered destroyed under the provisions of the Health of Animals Act. Compensation is also awarded for disposal, transportation costs and kill fees charged by the abattoir.

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.

P0093E-02
March 2002