An Overview of Early Anthrax Outbreaks in Northern Canada: Field Reports of the Health of Animals Branch, Agriculture Canada, 1962–71

Between 1962 and 1971, six outbreaks of anthrax occurred in the bison herds of the Northwest Territories and northern Alberta. In response, the federal Health of Animals Branch dispatched staff veterinarians to oversee carcass disposal operations and later to take part in bison depopulation and vaccination programs. Recently, a collection of documents from that agency concerning the outbreaks was discovered in the federal archives. The collection includes field reports from the veterinarians that provide valuable, detailed, first-person accounts of the outbreaks and later programs, information which has generally been lacking in the published literature. The reports identify at least 1102 bison that died of anthrax during the six outbreaks, dozens more than reported previously. They also indicate that the disease spread into Wood Buffalo National Park in 1963, rather than in 1964, as reported previously. A minimum of 598 healthy bison were also killed in depopulation programs aimed at preventing the spread of anthrax into the Park, even though anthrax carcasses had already been discovered within the Park and the targeted regions would be repopulated within weeks. Coverage and revaccination rates were low throughout the vaccination program, and a further 828 bison died during the vaccine roundups.