Dengue Fever
Dengue is a mosquito-borne viral infection causing high fever and joint pain, common in tropical destinations.
Dengue is a mosquito-borne viral infection causing high fever and joint pain, common in tropical destinations.
Also known as
Breakbone fever, Dengue haemorrhagic fever, DENV
Why travellers need to know
Dengue is present in over 100 countries and is spreading to new areas due to climate change. There's no widely available vaccine for travellers (Dengvaxia is only for people with prior infection) and no specific treatment. Prevention is entirely about avoiding mosquito bites: DEET repellent, long sleeves at dawn and dusk, and air-conditioned or screened accommodation. Unlike malaria mosquitoes, dengue-carrying Aedes mosquitoes bite during the day.
Real-world example
A week after returning from Bali, you develop a sudden high fever (40°C), severe headache behind the eyes, and aching joints so painful you can barely move. A blood test confirms dengue. There's no specific treatment; you rest, hydrate, and avoid ibuprofen (which can worsen bleeding risk). You recover in 10 days but feel fatigued for weeks.
Country-specific notes
🇹🇭 Thailand
Peak season: June-November; urban and rural risk
Thailand reports 50,000-100,000 dengue cases annually, peaking during the rainy season. Risk exists in both urban Bangkok and rural areas. Most tourist hotels have effective mosquito control, but outdoor activities during rain increase exposure.
🇧🇷 Brazil
Major outbreaks; over 1 million cases in recent years
Brazil experiences periodic large dengue outbreaks. All major cities including Rio and Sao Paulo have risk. Brazil began a Qdenga vaccination programme in 2024 but availability for visitors is limited.
Avoid ibuprofen and aspirin if you suspect dengue. These increase bleeding risk. Use paracetamol (acetaminophen) only for fever and pain.
🇻🇳 Vietnam
Vietnam has high year-round dengue transmission — the Aedes mosquito bites during daylight hours, not at dusk
Ho Chi Minh City and the Mekong Delta region consistently report high dengue caseloads. The rainy season (May–November) carries the highest risk, but transmission continues year-round. No specific antiviral treatment exists.
In Vietnam, apply DEET repellent during the day, not just at dusk — the Aedes aegypti mosquito that carries dengue is a daytime biter, unlike malaria mosquitoes.
Frequently asked questions
Can I get dengue more than once?
Yes. There are 4 dengue serotypes. Infection with one provides immunity to that serotype but not the others. A second infection with a different serotype carries a higher risk of severe dengue (dengue haemorrhagic fever).
How is dengue fever treated?
There is no specific antiviral for dengue. Treatment is supportive: rest, fluids, and paracetamol for fever. Ibuprofen and aspirin are contraindicated — they increase bleeding risk. Severe dengue requires hospitalisation with IV fluids and platelet monitoring. Most travellers recover in 7–10 days with good supportive care.
Your Nomedic record stores any previous dengue infections, which is critical information for doctors assessing severity if you contract a different serotype.