Current and future temperature suitability for autochthonous transmission of malaria in Canada.

BACKGROUND

Malaria continues to be one of the most significant infectious diseases in terms of morbidity and mortality. In many parts of North America, including parts of southern Canada, competent malaria vectors Anopheles quadrimaculatus and Anopheles freeborni are present. With climate change, Canada may be increasingly suitable for transmission of the malaria parasite Plasmodium spp. The objective of this study was to identify the geographic locations in Canada where, and the frequency with which, temperature conditions may be suitable for autochthonous transmission of Plasmodium vivax and Plasmodium falciparum under current and projected climate.

METHODS

Temperature and duration thresholds from historic Plasmodium spp. transmission studies were applied on gridded historical and projected data to compute yearly frequencies of suitable conditions in Canada.

RESULTS

The resulting yearly frequencies from 2000 to 2023 show rising trends for both Plasmodium species, with surges reaching 34% of the Canadian population temporarily living under suitable temperature conditions for Plasmodium falciparum, and 56% for Plasmodium vivax. Projected populations percentages vary significantly with the Plasmodium species, climate change scenario, and climate model considered.

CONCLUSION

Our results underscore the increasing risk of autochthonous transmission of malaria in Canada due to climate change.