Dengue Fever: What Travellers Need to Know

Dengue is one of the most common travel-related illnesses globally and cases have been rising sharply. In 2026, the CDC issued a global dengue advisory covering over a dozen countries simultaneously. Most travellers have heard of it but don't know much about it — here's what's actually useful to know.

What dengue actually is

Dengue is a viral infection spread by Aedes aegypti mosquitoes. Unlike malaria mosquitoes, which bite at night, Aedes mosquitoes are daytime biters — peak activity is in the early morning and late afternoon. This catches people off guard. You're more likely to get bitten on a beach or in a café garden than while sleeping.

Most people who get dengue have a fairly miserable week — high fever, intense headache, pain behind the eyes, joint and muscle aches, rash. It's sometimes called breakbone fever, which gives you a sense of how it feels. The majority of cases resolve on their own. But a minority progress to severe dengue, which involves plasma leakage, bleeding, and organ involvement. This is a medical emergency.

Where the risk is highest right now

Dengue is endemic across much of tropical Asia, Latin America, and parts of Africa. Southeast Asia — Thailand, Vietnam, Indonesia, the Philippines — has persistent year-round transmission, with higher peaks during and after monsoon season. Latin America has seen significant outbreaks in 2025 and 2026, particularly Brazil, Colombia, and Peru. Mauritius, Réunion, and parts of the Caribbean have also had elevated activity recently.

Urban areas are not lower risk. Dengue thrives in cities because Aedes mosquitoes breed in small containers of standing water — flower pots, gutters, discarded tyres. Bangkok, Jakarta, and Ho Chi Minh City all have significant dengue burden.

Is there a vaccine

There is, but it's complicated. Dengvaxia is approved in some countries but is only recommended for people who have already had dengue at least once — giving it to someone with no prior dengue infection can increase the risk of severe disease on subsequent infection. A second vaccine, Qdenga, has a different profile and can be given regardless of prior infection status. It's available in some European countries and parts of Asia.

Whether a dengue vaccine makes sense for your trip depends on your destination, the duration, and your travel style. It's worth asking your travel clinic specifically about it rather than waiting for them to bring it up.

How to actually protect yourself

DEET-based repellent at 30-50% concentration, applied to exposed skin, is the most effective option. Reapply every few hours. Wear long sleeves and trousers during peak biting hours if you're in a high-risk area. Air conditioning and window screens help because the mosquitoes prefer outdoor environments. These aren't perfect but they substantially reduce your exposure.

If you develop a sudden high fever within two weeks of returning from a dengue-risk destination, tell your doctor where you've been. Dengue won't show up on a standard blood test unless they're specifically looking for it.