OAHN Wildlife Project: Bovine tuberculosis surveillance – retroactive and now (in progress)

Project Lead: Dr. Larissa Nituch

Collaborator:  Dr. Claire Jardine

Project Proposal

Bovine tuberculosis (bTb) is a devastating human zoonosis that, despite its name, infects a number of ungulate species, rodents, carnivores such as cats and coyotes, and some bird species. Caused by Mycobacterium bovis, Canada has been considered free of bTb except in two small pockets of wildlife, the cervids in Riding Mountain National park and wood bison in and around Wood Buffalo National Park. Recently, two outbreaks have occurred in western Canada from unknown sources; the scope of the 2024 outbreak is still being determined, the outbreak in 2017 took approximately 2 years to resolve. Countries with endemic bTb regularly see human infections from food animals, and the disease can be difficult to treat as it is resistant to standard tuberculosis treatments. Michigan has seen sustained transmission within a bTb management zone, which is a small area of Michigan where less than 2% of the wild whitetail are infected with bTb. Nonetheless, these deer pose risk to hunters and indigenous communities, domestic livestock and pets who may contact wildlife. Indeed, the Animal Health Laboratory at the University of Guelph has the CWHC perform all wild cervid necropsies as bTb suspects due to perceived risk of spread from Michigan.

The Ministry of Natural Resources (MNR) have banked lymph node samples from hunter shot CWD surveillance. Every year, risk modelling determines where CWD surveillance occurs, but generally areas close to known CWD positive areas are sampled (such as close to the Michigan border). We propose to test a subset of these banked samples at 5, 10 and 15 years, as well as samples from the upcoming fall hunt. We would aim for 100 samples at each time period of retropharyngeal lymph node and lung tissue, or if RPLN is not available hilar lymph nodes. Samples will be tested at the Animal Health Centre by PCR. It is valuable to know that this disease is not present and has not been present, in case range expansion from Michigan or Manitoba occurs or an outbreak in domestic animals occurs, such as the outbreaks in AB and SK. The AB source was never determined and so far the SK outbreak seems to be an independent introduction unrelated to AB.

https://inspection.canada.ca/en/animal-health/terrestrial-animals/diseases/reportable/bovine-tuberculosis/fact-sheet-wildlife

https://www.purdue.edu/fnr/extension/bovine-tb/#:~:text=Both%20Michigan%20and%20Minnesota%20have,a%20wild%20deer%20in%20Minnesota