Risk Assessment: Emergence and Vector-borne Transmission of Zika Virus in Québec

  • Zika virus emerged in the Americas in 2015 and has since expanded its geographical range significantly. Currently, the virus is transmitted locally in 35 countries of the Caribbean, Central America and South America.

  • Zika virus infection is benign: 70 to 80% of patients have no symptoms, whereas 20% have a fever and rash accompanied by arthralgia and myalgia, conjunctivitis, headache, retro-orbital pain and fatigue.

  • Zika virus infection can cause neurological complications, including Guillain-Barré syndrome.

  • Zika virus infection during pregnancy causes congenital defects, including newborn microcephaly.

  • Zika virus infection is transmitted by mosquitoes of the genus Aedes: in America, Ae. aegypti is the primary vector and Ae. albopictus is a potential vector. These vectors are currently absent in Québec.

  • Zika virus needs a threshold temperature between 22°C and 26°C for 15 days for replication in Ae. aegypti, and above 27°C for one week for replication in Ae. albopictus. Québec's current summer temperatures are unlikely to allow for an extrinsic incubation period.

  • Therefore, the current risk of vector-borne transmission of Zika virus in Québec is negligible.

  • The medium-term risk of Zika virus emergence and vector-borne transmission in Québec is assessed as low. However, the presence of favourable conditions warrants concerns about long-term Zika virus emergence and vector-borne transmission for the following reasons: 

    • Since humans are reservoirs of the virus, travellers coming from countries where Zika virus is endemic could carry it to Québec by airplane;

    • Established populations of the Ae. albopictus mosquito vector have been documented in American states bordering Québec;

    • The southern Québec climate could be favourable to Ae. albopictus introduction;

  • There is a possibility for a point-source introduction of adult mosquito vectors and Zika virus in the province.

  • The Institut national de santé publique du Québec (INSPQ) [Québec’s public health institute] is continuing scientific monitoring of the topics and additional questions raised in this risk assessment.

  • Recommendations are to:

    • Develop a plan for sustainable entomological surveillance that would expand entomological surveillance objectives;

    • Add Zika virus infection to the notifiable diseases list and to the human case surveillance lists of doctors and laboratories;

    • Conduct studies on the capacity of Ae. albopictus to survive in the southern Québec climate.



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