Lyme Disease in Canada

Threats from ecological change to health and health systems are severe and worsening, leading the World Health Organization (WHO) to name climate change as the greatest threat to global health in the 21st century.1 Canada is warming at more than twice the global rate and the Canadian Arctic is warming at almost four times the global rate.2 Climate change is already harming the health of Canadians, increasing the frequency and intensity of extreme weather events,3 4 5 cases of heat stroke,6 7 cardiorespiratory issues 8 9 and Lyme disease from ticks that can now survive Canadian winters because our climate is warming. 10 11 The 2021 British Columbia heat dome was the deadliest weather event in Canadian history, with an estimated 619 heat-related deaths.12 More broadly, fossil fuel–related air pollution is estimated to be implicated in almost one-fifth of global deaths,13 and habitat losses are frequently placing human, vectors and hosts in novel contact, increasing the threat of future pandemics.