What is dengue fever and how serious is it?

Dengue is a viral infection transmitted by Aedes mosquitoes. Most people experience flu-like symptoms lasting 2-7 days. However, about 1 in 20 people develop severe dengue (previously called dengue hemorrhagic fever), which can cause internal bleeding, organ failure, and death if not treated promptly.

How does dengue spread?

Dengue spreads through bites from infected Aedes aegypti and Aedes albopictus mosquitoes. These mosquitoes bite primarily during the day, particularly in early morning and before dusk. Unlike malaria, dengue cannot spread directly from person to person - it requires mosquitoes as vectors.

What are the warning signs of severe dengue?

Warning signs typically appear 3-7 days after symptoms start and include severe abdominal pain, persistent vomiting, bleeding gums or nose, blood in vomit or stool, fatigue, restlessness, and rapid breathing. Severe dengue is a medical emergency requiring immediate hospitalization.

Can you get dengue more than once?

Yes, there are four dengue virus serotypes (DENV-1, DENV-2, DENV-3, DENV-4). Infection with one provides lifelong immunity to that serotype but only temporary partial immunity to the others. Subsequent infections with different serotypes increase the risk of developing severe dengue.

Is there a dengue vaccine?

Yes, dengue vaccines exist but have specific recommendations. Dengvaxia is approved for people aged 9-45 who live in endemic areas and have had a previous dengue infection. TAK-003 is approved in some countries. The vaccines are not recommended for people who have never had dengue due to increased risk of severe disease.

Where is dengue occurring now?

Dengue is endemic in over 100 countries in tropical and subtropical regions, including Southeast Asia, Latin America, Africa, and Pacific Islands. Climate change is expanding its range. Check the live outbreak data above for current dengue activity worldwide.

Dengue Fever

10 Active Outbreaks

Dengue is a mosquito-borne viral infection that causes flu-like illness and can develop into severe dengue, a potentially lethal complication. It is endemic in more than 100 countries, primarily in tropical and subtropical regions.

Countries Affected

929

Recent Cases (30d)

Active Outbreaks

17d ago

Last Updated

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What is Dengue Fever?

Dengue fever is one of the fastest-growing mosquito-borne diseases globally. Approximately half of the world's population is now at risk, with an estimated 390 million infections occurring each year. Climate change is expanding the range of Aedes mosquitoes that transmit the disease, bringing dengue to new regions.

Symptoms

High fever (104°F/40°C)
Severe headache
Pain behind the eyes
Severe joint and muscle pain (breakbone fever)
Rash (appears 2-5 days after fever)
Nausea and vomiting
Mild bleeding (nose, gums)

Transmission

Dengue is transmitted through bites from infected Aedes aegypti and Aedes albopictus mosquitoes. These mosquitoes become infected when they bite a person with dengue virus in their blood. The virus cannot spread directly between people.

Contagious Period: Not contagious person-to-person; infectious to mosquitoes from 1 day before fever onset through 5-7 days of illness

Prevention

Use mosquito repellent containing DEET, picaridin, or IR3535
Wear long-sleeved shirts and long pants
Use air conditioning or window/door screens
Remove standing water where mosquitoes breed
Use mosquito nets, especially during the day
Consider dengue vaccine if you live in endemic areas (consult healthcare provider)
Treat clothing and gear with permethrin

Live Dengue Fever Global Case Map

10 countries with reported activity. Updated from real-time surveillance data.

No reports

Yemen 2026-06-15

Active

This event envelope contains reports on dengue in Yemen.

Source: BEACON - View Full Report

64 0

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Expert Resources & References

Trusted information from leading health organizations

CDC

Official guidance from the U.S. Centers for Disease Control and Prevention

View CDC Resources →

WHO

Global disease surveillance and guidelines from the World Health Organization

View WHO Resources →

Research

Latest peer-reviewed research and clinical studies

View Research →

Medically Reviewed Content

Disease information on Virus Watcher is reviewed by our Chief Epidemiologist, a former CDC lead analyst for FluSight forecasting. Outbreak data is aggregated from verified sources including BEACON, ProMED, WHO, CDC, and 50+ national health agencies. This information is for educational purposes and should not replace professional medical advice.

Last reviewed: 2026-07-18

Frequently Asked Questions

Common questions about Dengue Fever answered by our epidemiology team

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