Dengue Fever: The Fastest-Spreading Tropical Disease

Dengue reached a record in 2024: more than 14.6 million cases and over 12,000 deaths reported to WHO, according to the WHO dengue fact sheet. 2026 has been quieter, but the virus keeps turning up in new places. PandemicAlarm rates dengue's global situation at severity 3/5. Not because any single outbreak threatens pandemic-scale catastrophe, but because its range keeps growing and countermeasures remain limited.

About half the world's population now lives at risk of dengue. WHO estimates 100 to 400 million infections every year, most never diagnosed, and says the disease is endemic in more than 100 countries and spreading into the European and Eastern Mediterranean regions.

Where is dengue now?

ECDC's September 2026 overview counted over 2 million cases and over 1,000 deaths worldwide since January, fewer than in the same period of 2025. Quieter is not quiet.

Americas: 1,658,783 cases up to the week ending 30 August, per PAHO data cited by ECDC. That is 57% below 2025 and 64% below the five-year average. Brazil reported 1,294,963, followed by Colombia (79,304) and Bolivia (58,628).
Asia: Viet Nam had 115,967 cases by 6 September, Sri Lanka 100,127 by 27 September and Cambodia 85,920, with 104 deaths.
Africa: 4,170 cases by 30 August, led by Mali and Kenya, almost certainly an undercount.
Europe: as at 14 October, Italy had 70 locally acquired cases and France 6, per ECDC's week 42 threats report.

Bangladesh shows how fast a season can turn. WHO counted 267,680 cases and 1,333 deaths there between January and 30 October 2023, which WHO called the largest dengue outbreak ever reported in the country.

Why is a second dengue infection more dangerous?

Four related dengue viruses, called serotypes, circulate. Recovering from one does not reliably protect you against the others, and WHO says people infected a second time are at greater risk of severe dengue.

Most infections are mild or silent. CDC's Yellow Book estimates 40% to 80% cause no symptoms, and up to 5% of people who do get sick develop severe disease. Where several serotypes circulate at once, a whole population can be primed for second infections.

Why is dengue spreading to new places?

WHO lists rising temperatures, high rainfall and humidity among the factors behind its spread. Aedes aegypti, the main carrier, thrives in warm cities, while Europe's local outbreaks rely on Aedes albopictus, the tiger mosquito.

Europe's trend is not smooth. ECDC's table of locally acquired cases records 213 in Italy and 83 in France in 2024, then 4 and 29 in 2025. Italy is back up to 70 this year. Our explainer on geographic spread shows why new territory matters more than raw counts.

Is there a dengue vaccine?

Yes, but not one most travelers can use. Qdenga (Takeda) received WHO prequalification on 10 May 2024, and WHO recommends it for children aged 6 to 16 in high-transmission areas. CDC says it is not available in the US, and UK advisers recommend it only for people who have had dengue before.

Dengvaxia has been discontinued. Brazil approved a single-dose vaccine, Butantan-DV, in late 2025, but the Ministry of Health suspended its use on 8 June 2026 after two deaths among vaccinated people.

How do you protect yourself?

By avoiding mosquito bites. WHO notes that Aedes mosquitoes bite mainly in daylight, so bed nets alone won't protect you. Use DEET or picaridin repellent, cover up, and empty anything holding standing water.

Our guide to mosquito-borne disease prevention covers permethrin and repellent strengths, and disease risks by region shows where dengue is seasonal. CDC's global dengue travel notice, updated 2 October 2026, calls it a year-round risk in many parts of the world.

What should you watch for?

Symptoms usually start 4 to 10 days after a bite and include high fever, severe headache, pain behind the eyes, muscle and joint pain, nausea and rash, according to WHO. Use paracetamol (acetaminophen) for pain and fever. Avoid ibuprofen and aspirin, which increase bleeding risk.

The dangerous phase often begins as the fever goes away. Severe abdominal pain, persistent vomiting, bleeding gums or nose, and restlessness are warning signs that need care immediately, WHO says.

FAQ

Can you get dengue more than once?

Yes. Four dengue serotypes circulate, and infection with one does not reliably protect against the others. WHO says people infected a second time are at greater risk of severe dengue, so a past case is a reason for more caution, not less, when you travel to an area with dengue.

Is dengue contagious between people?

Not through everyday contact. Dengue spreads mainly through the bites of infected Aedes mosquitoes, which pick up the virus from an infected person and pass it on. That is why a sick person in an area with Aedes mosquitoes should avoid bites, to stop local mosquitoes spreading it further.

Can you catch dengue in Europe?

Yes, though cases are still uncommon. As at 14 October 2026, ECDC had recorded 70 locally acquired cases in Italy and 6 in France this year, in people who caught it locally rather than abroad. ECDC tracks these cases weekly through the summer and autumn transmission season.