The chikungunya outbreak in the western hemisphere accounted for well over 1 million autochthonous, or locally transmitted cases in 40 countries in the Americas in 2014, including the United States.

Image/Perry-Castañeda Library

North of the border in Canada, while no local transmission of chikungunya was reported, the number of imported cases was by far the largest yearly number of chikungunya cases ever documented in the country.

According to the Public Health Agency of Canada, since the first confirmed case with travel to the Caribbean was identified in a Québec resident who had visited Martinique in mid-January 2014 and returned to Canada in early February, as of December 9, 2014, 320 confirmed and 159 probable cases (lgM positive, confirmatory testing pending) have been identified in Canada by laboratory testing among travelers returning from affected areas in both the Americas and the Asia-Pacific region (The majority of cases with documented travel histories had traveled to the Caribbean).

Health authorities say this is likely an underestimate due to missed diagnoses and undetected cases of mild disease.

Chikungunya is not nationally notifiable in Canada, but the number of cases identified by diagnostic testing requested at NML provides an indication of how many Canadians are affected by the virus. In previous years, case numbers ranged from one to twenty cases a year from approximately 200 submissions for testing.

The breakdown by province is as follows: Quebec-114, Ontario-165, Alberta-14 and British Columbia-14, Manitoba-7, Saskatchewan, New Brunswick and Newfoundland all had < 5 cases each.

Health officials note that no local transmission of chikungunya virus has yet occurred in Canada likely due to the absence of the primary mosquito vectors—Aedes aegypti and Aedes albopictus.

The increase in chikungunya cases in Canada in 2014 merits increased awareness among travelers and clinicians of the risks from vector-borne diseases and how to prevent infection.