Travel-related dengue, Zika and chikungunya in Canada, 2024

Dengue, Zika and chikungunya are vector-borne diseases (VBD) spread by mosquitoes that people living in Canada may encounter during travel abroad ^{Footnote 1}. These diseases are not currently endemic in Canada and are not reportable and/or nationally notifiable; yet hundreds of travelers returning from endemic regions are diagnosed in Canada each year ^{Footnote 2Footnote 3}.

Laboratory-based surveillance uses routine laboratory requisition and testing data to identify and monitor disease activity.

Laboratory-based surveillance uses routine laboratory requisition and testing data to identify and monitor disease activity. The Retro 3 feasibility pilot ^{Footnote 4} applied this approach to retrospectively analyze travel-related dengue, Zika and chikungunya in Canada from 2012 to 2023 ^{Footnote 3}, now updated through 2024. Results reflect testing conducted at the National Microbiology Laboratory (NML) only, including confirmatory serology for all provinces and territories and molecular testing for all except British Columbia, Alberta, Ontario and Québec, and underestimate the total disease burden ^{Footnote a}.

Dengue

A total of 120 laboratory-based cases of travel-related dengue ^{Footnote b} were identified among persons tested for dengue at the NML in 2024:

• 17% increase versus 2023
• 47% were women
• 43% were aged 55+ years

Zika

A total of one laboratory-based case of travel-related Zika ^{Footnote d} was identified among persons tested for Zika at the NML in 2024:

• 67% decrease in laboratory-based cases versus 2023
• 56% decrease in persons tested versus 2023

Chikungunya

A total of 57 laboratory-based cases of travel-related chikungunya ^{Footnote f} were identified among persons tested for chikungunya at the NML in 2024:

• >500% increase versus 2023
• 57% were women
• 44% were aged 35–54 years

Pregnancy

In 2024, individuals with reported pregnancy accounted for 6% of all persons tested, down from 20% in 2023 and an average of 31% from 2019 to 2023^{Footnote h}. This included 1% among those tested for dengue, down from 11% in 2023 and an average of 20% from 2019 to 2023; 36% for Zika, down from 41% in 2023 and an average of 47% from 2019 to 2023; and 0% for chikungunya, down from 24% in 2023 and an average of 7% from 2019 to 2023.

Travel^{Footnote i}

While travel history data were available for nearly 90% of persons tested between 2012 and 2023, encompassing destinations spread over 180 countries across all seven continents, complete travel history was recorded for approximately 40% of persons tested in 2024. The Latin America and Caribbean region emerged as the most common travel destination linked to laboratory-based cases of dengue and chikungunya in 2024, followed by South-Eastern Asia for dengue and Sub-Saharan Africa for chikungunya.

Key Results from 2024

• A total of 120 dengue, 1 Zika and 57 chikungunya laboratory-based travel-related cases were identified among a total of 752 persons tested^{Footnote j} for one or more of these diseases at the NML in 2024 ^{Footnote c}.
• Disease patterns closely reflected global trends and those observed in countries of travel destination.
• Compared to the 2019–2023 average, dengue laboratory-based cases in 2024 showed higher proportions aged 55+ (43% versus 20%) and men (53% versus 31%). For chikungunya, most 2024 cases occurred among adults aged 35–54 (44%), and women (57%); previous years had few cases for meaningful comparison.
• No dengue or chikungunya laboratory-based cases in 2024 were identified among individuals with reported pregnancy, compared to an average of 28% for dengue from 2019 to 2023, and only one case for chikungunya during the same period^{Footnote h}.

Conclusion

In 2024, results from a pilot laboratory-based surveillance study revealed a marked increase in identified laboratory-based travel-related cases of dengue and chikungunya. Laboratory data can be leveraged for epidemiological analyses, offering timely insights to support surveillance of evolving trends and inform public health response.

Public Health Agency of Canada, BCCDC Public Health Laboratory, Alberta Precision Laboratories, Public Health Ontario Laboratory. Travel-related dengue, Zika, and chikungunya in Canada, 2024: Update to results from a feasibility pilot study on laboratory-based surveillance. Can Commun Dis Rep 2025;51(9):374.