Dengue

Spread by Aedes mosquitoes that bite during the day. Common in tropical and subtropical cities, peaking in the rainy season.

Symptoms

High fever, severe headache, muscle and joint pain, nausea, sometimes a rash. Most infections cause no symptoms at all. Severe complications are rare in travelers but more likely after a second infection.

Treatment

No specific treatment. Rest, fluids, and paracetamol for symptoms. Avoid aspirin and NSAIDs. See a doctor for any fever during or after travel.

Endemic regions

Tropical and subtropical regions worldwide — especially South and Southeast Asia, Latin America, and the Caribbean. Cases now also appear in southern Europe and the southern United States.

Prevention & prophylaxis

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Daytime mosquito protection

Aedes mosquitoes bite during the day, especially morning and late afternoon. Use DEET (20–50%) or picaridin (20%) on exposed skin, wear long sleeves and trousers, and consider permethrin-treated clothing in high-risk areas.

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Qdenga® — only for those previously infected

The dengue vaccine is recommended only for travelers ≥6 years with a documented previous dengue infection AND travel to a region with high ongoing transmission. Two doses, 3 months apart. Not recommended for first-time travelers, as protection is uneven across serotypes. The older vaccine, Dengvaxia®, is no longer used.

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Fever after travel — what to do

Any fever during or within weeks after travel should be checked by a doctor. Avoid aspirin and ibuprofen until dengue is ruled out — they can worsen bleeding risk. Use paracetamol for fever and pain.