Questions and Answers on initial phase: Bovine Tuberculosis investigation – Alberta and Saskatchewan

The information in the following pages reflect the current status of the investigation:

The Investigation

What is the mandate of the Canadian Food Inspection Agency (CFIA) in this animal disease situation?

The CFIA has a mandate for controlling certain diseases in animals, especially those diseases that can be transmitted to humans. This may include investigation, movement restrictions, quarantines and the humane depopulation of animals at risk of being diseased. These activities maintain the health of Canada's cattle population as well as integrity of Canada's international zoosanitary status and market access.

The CFIA may pay compensation for all animals ordered destroyed, other things ordered destroyed such as contaminated feed or animal products and for the disposal costs of animals ordered destroyed.

In all cases where federally regulated diseases are suspected or confirmed, the goal is to minimize disruptions to producers while taking appropriate control measures. These measures are critical for protecting the health of Canadian animals and for maintaining market access for Canadian producers.

Why is it important to eradicate bovine TB?

Canada's bovine TB program began in 1923. The program has been successfully progressing to reduce the incidence of bovine TB similar to the bovine brucellosis program, which resulted in complete eradication of that disease in 1985. Bovine TB in domestic cattle in Canada is extremely rare, with occasional cases occurring years apart (the last case was seen in 2011, the one prior to that in 2008).

The disease has virtually been eliminated in wildlife in Manitoba, and in northern Alberta it has been assessed as posing an extremely low risk for transmission to cattle.

By contrast, the United States continue to have multiple cases of bovine tuberculosis in multiple states each year. Canada is very close to complete eradication of bovine tuberculosis and will continue to pursue this goal, which has taken many years and resources to attain.

For more information on the history of bovine TB in Canada, consult the CFIA's website.

What is the focus of the investigation?

The focus is to halt the spread of the disease and eradicate it by:

  • Carrying out the humane depopulation, further examination and testing of all animals that are at high risk of being infected with the disease
  • Identifying and testing of all animals that may have been exposed to the disease (contact and trace-out herds)

When does the CFIA estimate that the quarantines will be lifted?

A quarantine will be lifted when a premises is determined to be free of bovine TB. This determination is based on a scientific evaluation of the risk.

Given the nature of the disease and the requirement to trace animal movements over a five year period, it is expected that the investigation will identify additional animals that have had contact with the infected herd, and require additional quarantines, for some time.

When does the CFIA estimate that testing of the animals under quarantine will be complete?

The full testing process can take up to 14 weeks.

Animals are first tested at the premises. Two tests are conducted – a blood test and a caudal fold test – during which a small amount of tuberculin is injected under the skin of the animal. A reaction is an indication of the presence of the disease but it is not a guarantee. In a disease-free livestock population, between 1% and 3% of animals may react due to exposure to other types of TB (such as avian tuberculosis) or even without any exposure to tuberculosis.

Animals that react to either the tuberculin or the blood test are humanely slaughtered and subject to post-mortem examination. A detailed post-mortem examination is then conducted on the animal to look for visible signs of TB infection, such as lesions in the lungs and lymph nodes. However, it is also possible for animals to be infected without any visible lesions.

Tissue samples are taken from lesions and normal tissues for additional testing at CFIA's laboratory. Tissue samples are incubated and cultured to enable the growth of the bovine TB bacteria. The test is positive if growth of the bacteria is confirmed.

The culture test takes 8 to 12 weeks to complete.

An animal may be declared positive on the basis of the results of:

  • the post-mortem exam; and
  • histopathology (an examination of tissue sections that detects the presence of tuberculosis bacteria); and
  • the polymerase chain reaction (PCR) test (which tests the DNA of the bacteria to identify the species and strain of mycobacteria); or
  • the culture test.

An animal will be considered negative for bovine TB when the culture test is negative.

Further information outlining the testing process and timeline is available on CFIA's website.

What is required for a quarantine to be lifted?

The time required will be affected by factors, such as how many animals have to have tissues cultured and the availability of slaughter capacity for destruction and disposal.

Each additional premise that is declared infected will extend the quarantines to a new set of contact and trace-out animals.

A herd can be released from quarantine under direction from the CFIA, when all reactors from a herd have tested negative for bovine TB, and an epidemiological evaluation has been completed. An infected premise would also require cleaning and disinfection activities to be completed.

What measures are taken for cleaning and disinfecting a farm?

The owner is responsible for the 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 the cleaning and disinfection is completed and verified by the CFIA, including a 45-day waiting period of warmer temperatures, these producers will be allowed to restock. Restocked cattle will be required to be tested at 6 and 18 months after entry onto the premises. This helps ensure the effectiveness of the cleaning and disinfection.

If no cleaning and disinfection is performed, then a two year vacant period is required before the premises is no longer considered infected and can be restocked.

Why have so many farms and cattle been quarantined if the disease has only been found in six animals?

In line with our current TB policy, we expand the quarantines based on findings from the trace-out activities. Where animals are found to have had contact with the infected herd over the course of the past five years, these animals will also have to be quarantined and tested for bovine TB.

How can a herd be declared infected without any confirmed test results?

Under Section 22 of the Health of Animals Act, where the CFIA suspects or determines that a disease exists on a premises and could spread or that animals or things entering the premises could become affected, that premises may be declared infected.

An infected place declaration applies to all of the susceptible animals in the infected premises. Based on the updated disease risk evaluation, the CFIA determined that the degree of contact between the animals from 18 premises all pose the same risk of exposure to the 6 confirmed cases and make up the infected herd.

The CFIA does not make these decisions lightly and is fully aware of the difficulties this presents for affected producers.

Why is the CFIA being so aggressive in its investigation of bovine TB in Canada?

Bovine TB is a chronic infectious disease affecting livestock, wildlife, and humans. It is a reportable disease in Canada and has been subject to a mandatory national eradication program since 1923. Canada uses a range of science-based, internationally recognized measures aimed at detecting infection in livestock and preventing its transmission. Although this has virtually eliminated the disease, isolated cases do still occur. The near complete elimination of bovine TB from Canada has had significant benefits for public health, animal health and ensures Canadian beef producers can continue to export their products.

For more information on the history of bovine TB in Canada, consult the CFIA's website.

What would be the impacts if more animals test positive in the course of this investigation?

The impacts of new positive cases would vary, depending on the location of the animal.

If a positive animal is found on an already- infected premises, there is no additional impact to the investigation or trade.

If a positive animal is found on premises not declared infected, the premises would be added to the infected herd and new tracing activities would begin. This tracing would lead to additional quarantines and testing. No additional impacts on trade would be expected.

The Disease

Does bovine TB pose a risk to other animals or humans?

Generally, findings of bovine TB in animals do not pose a threat to the health of the public in the Canadian context. This is due to the extremely low prevalence of the disease in Canada. Individuals who have extended, close contact with an infected animal while it is alive are at risk of contracting the disease.

There is no information to suggest that there is any elevated human health risks at this point related to this unique strain.

For more information about human health risks, please contact the provincial public health authorities.

While lying dormant, is tuberculosis contagious?

The bacteria associated with the disease may lie dormant in an animal for years without causing clinical signs or progressive disease symptoms. Prolonged contact with such animals may result in disease transmission.

Definitions

What do we define as a premises?

A premises is a single geographic location where a group of animals, regulated under the Health of Animals Act, is located.

What do we define as a herd?

A herd is considered to be all the animals that have intermingled for a significant amount of time at any location. Some cattle may have resided at more than one premises.

How do we define an infected herd?

An infected herd is considered a herd in which one or more infected animals have been identified.

What do we define as contact herd?

A contact herd consists of animals identified to have had some contact with animals from the infected herd.

How do we define a trace-out animal?

A trace-out animal is an animal that came from an infected herd or infected premises.

What do we define as a trace-out herd?

A trace-out herd consists of a herd in which a trace-out animal has resided.

Testing and Process

What is the source of these cases of bovine 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 cow is not the same as any strains detected in Canadian domestic livestock or wildlife or humans to date. The strain of TB in the confirmed case is closely related to a strain originating from 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 are included in the investigation.

Should we expect more quarantines?

Yes. The Agency is working with producers to trace the movements of all animals at risk of having been exposed to, or been the source of, bovine TB.

This may include herds that have provided animals to, or received animals from, the infected herd in the past five years. These tracing activities require significant time to complete and the CFIA will continue to identify additional premises to be quarantined. Given the scope and the complexity of this investigation, the number of quarantines required is expected to increase significantly.

What is involved in tracing activities?

When investigating an animal disease, the CFIA traces the movement of animals that have entered or left quarantined premises in the past five years.

Trace-in activities identify animals that were introduced to a herd and may have been the source of bovine TB.

Trace-out activities find animals at risk of having been exposed to bovine TB on an infected farm but which may have since been moved away from that farm.

Does the absence of lesions during the post-mortem exam mean an animal is free from tuberculosis?

No. It is possible for animals to be infected without any visible lesions. While it is possible to confirm bovine TB at various stages of testing, only the results of a culture test can confirm that an animal is negative for the disease.

An animal may be declared positive on the basis of the results of:

  • the post-mortem exam; and
  • histopathology (an examination of tissue sections that detects the presence of tuberculosis bacteria); and
  • the polymerase chain reaction (PCR) test (which tests the DNA of the bacteria to identify the species and strain of mycobacteria); or
  • the culture test.

An animal will only be considered negative for bovine TB when the culture test is negative. The full testing process may take up to 14 weeks.

Slaughter

What is the inspection process for animals that go for slaughter?

For animals sent to slaughter, there are inspections before slaughter and after slaughter to ensure any animal entering the food chain is inspected for diseases such as bovine TB. The post-mortem examination is always in place at federal and provincial establishments, even when there is not a bovine TB investigation ongoing.

Animals that showed a reaction to initial TB testing are subject to enhanced post-mortem examination, as required by the testing process. The CFIA ensures that meat going into the food chain is safe for human consumption.

Food safety is a top priority for the CFIA. We work every day, in collaboration with the food industry, to keep our food safe to eat. Our system is built on international standards and is supported by science.

Food safety is also the responsibility of everyone. Therefore, if you are locally butchering/hunting your own animals, ensure meat products are appropriately cooked prior to consuming.

When depopulation is deemed necessary, are all warm-blooded mammals (horses, dogs, cats, etc.) on the property also depopulated?

The first step is to take a look at which animals are in danger of having or getting TB. Some animals—such as house cats or lap dogs—are low risk and may not need to be depopulated. While others —such as horses, swine, goats and alpacas —are higher risk.

Decision on susceptible animals will be made on a case-by-case basis as per the risk determination.

A risk evaluation on premises declared infected is done in all circumstances.

The CFIA completed the risk evaluations on domestic animals currently under quarantine. These animals were considered low-risk and will not be depopulated.

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