Mosquitoes on the Move: How Climate Change Is Transforming Global Travel Health Risks

By Sherilyn Houle (expanded with additional research and commentary by Destinations Travel Clinic)

Climate change is no longer a distant environmental issue — it’s an urgent global health concern that’s reshaping the landscape of infectious diseases and travel medicine. Rising temperatures, shifting rainfall patterns, and expanding habitats for insects are accelerating the spread of vector-borne diseases such as malaria, dengue, chikungunya, yellow fever, Japanese encephalitis, Zika virus, West Nile virus, and Lyme disease.

For travellers, this means destinations once considered low-risk are now experiencing new disease threats. Understanding these changes — and preparing with expert, pharmacist-led pre-travel consultations — has never been more important.

Climate Change and Vector Expansion

Common vectors include mosquitoes, ticks, sandflies, midges, and blackflies. Climate factors such as temperature, humidity, and precipitation directly influence how these vectors breed, survive, and transmit infections.

• Mosquitoes and temperature: Most are ectothermic (cold-blooded), relying on environmental heat for survival. Their biting frequency and reproduction increase with warmer temperatures — up to an optimal limit (around 29°C for Aedes aegypti and 25°C for Anopheles). Beyond those thresholds, survival declines.
• Water and humidity: Many vectors require standing water or specific moisture conditions to reproduce. Increased rainfall and flooding create ideal breeding grounds, while drought may drive mosquitoes to urban areas seeking water storage containers.
• Pathogen replication: Higher temperatures accelerate viral and parasitic replication inside vectors, increasing the likelihood of transmission.

According to the World Health Organization (WHO), over 700,000 people die annually from vector-borne diseases. Climate modelling shows that by 2050, billions more people will be at risk, as vector habitats expand into Europe, North America, and higher altitudes in Africa, Asia, and South America.

For example:

• Aedes aegypti, the mosquito responsible for dengue and Zika, is now established as far north as southern Europe, the U.S. Midwest, and parts of southern Canada.
• Ixodes scapularis, the tick that carries Lyme disease, has spread across much of Ontario, Quebec, and the Prairies, compared to its limited presence 20 years ago.
• Culex mosquitoes transmitting West Nile virus now appear earlier in the year and remain active longer into the fall.

Changing Patterns of Travel Health Risk

As global travel resumes post-pandemic, travellers must be aware that disease maps and historical risk data are no longer static. Formerly “safe” destinations may now have new vector-borne risks.

For example:

• Malaria remains endemic in sub-Saharan Africa, but cases have emerged in areas once malaria-free, such as the Horn of Africa and southern Asia.
• Dengue has surged globally, with the Pan American Health Organization reporting over 8 million cases in 2024, the highest ever recorded.
• Tick-borne encephalitis is rising in parts of central and northern Europe, driven by milder winters and longer tick activity seasons.

Updated Resources for Travel Health Professionals and Travellers

Healthcare professionals and travellers should always consult current, country-specific epidemiologic data before departure. Reliable sources include:

• TravelHealthPro (UK) – outbreak surveillance and vector maps
• Government of Canada Travel Health Advisories
• CDC Travelers’ Health (USA)
• Subscription-based tools such as Shoreland Travax, Tropimed, and TravelCare

Tip: Always cross-reference your travel health advice with the Köppen Climate Classification system to understand seasonal risks at your destination.

Prevention: Vaccines, Medications, and Expert Counselling

At Destinations Travel Clinic, we offer personalized, evidence-based protection plans for all major vector-borne diseases. Preventive measures available in Canada include:

• Vaccines: Yellow fever, Japanese encephalitis, and (soon in some regions) dengue.
• Antimalarials: Atovaquone-proguanil, doxycycline, or mefloquine — prescribed based on region, resistance, and traveller profile.
• Emerging prevention: New malaria vaccines (RTS,S and R21/Matrix-M) have been WHO-endorsed, expected to reduce childhood mortality and may become relevant for travellers by 2026–2027.

Each consultation at DTC includes:

1. Review of your destination-specific risk (region, elevation, season, urban vs. rural).
2. Advice on bite avoidance, including DEET or icaridin-based repellents, insecticide-treated clothing, and bed nets.
3. Counselling on sun protection, hydration, and heat-related illness, as global warming amplifies multiple health risks for travellers.

Vector Avoidance and Repellents

• Preferred agents: DEET (20–30%) and icaridin (20%) remain first-line.
• Permethrin-treated clothing provides an additional 70–90% reduction in bites.
• Natural oils and bracelets should not be used as sole protection when disease risk exists.
• Even domestic travel within Canada now warrants repellent use due to Lyme disease and West Nile virus risks.

Summary: Why Climate-Smart Travel Medicine Matters

Climate change has transformed global disease maps. Staying informed and protected requires regular updates, expert travel consultations, and awareness of evolving health trends.

At Destinations Travel Clinic, our team helps you travel confidently — with the right vaccines, medications, and prevention strategies tailored to your itinerary and health profile.

Your destination may be changing. Your travel protection should, too.

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Disclaimer: The medical information on this site is provided as an information resource only and is not to be used or relied upon for any diagnostic or treatment purposes. This information does not substitute for professional diagnosis and treatment. Please do not initiate, modify, or discontinue any treatment, medication, or supplement solely based on this information. Always seek the advice of your healthcare provider first. Full Disclaimer.