What Is Dengue Fever?
A viral infection spread by Aedes mosquitoes, causing severe flu-like illness and potentially fatal haemorrhagic complications.
Pathogen: Dengue virus (DENV serotypes 1-4, Flavivirus family)
Type: Virus
Transmission
Bite of infected Aedes aegypti or Aedes albopictus mosquitoes, which bite predominantly during the day, especially in the early morning and late afternoon.
Vector: Aedes aegypti and Aedes albopictus mosquitoes (daytime biters, most active early morning and late afternoon)
Symptoms
Sudden high fever (40°C), severe headache, pain behind the eyes, muscle and joint pain ('breakbone fever'), nausea, vomiting, fatigue, and a skin rash appearing 2-5 days after fever onset. Severe dengue can cause plasma leakage, severe bleeding, organ impairment, and shock.
Incubation period: 4 – 14 days
Most commonly 4-7 days. Rarely exceeds 14 days.
Timeline: Fever lasts 2-7 days. The critical phase occurs around days 3-7 when fever drops — this is when severe dengue can develop. Most patients recover within 1-2 weeks.
Case fatality rate: Less than 1% with proper medical care. Severe dengue (dengue haemorrhagic fever/dengue shock syndrome) has a fatality rate of up to 5% with treatment, 20-50% without.
Diagnosis & Treatment
Diagnosis: NS1 antigen test (detectable in first 5 days), dengue IgM/IgG serology (from day 5 onwards), PCR for early detection. Full blood count showing dropping platelets and rising haematocrit suggests progression.
Treatment: No specific antiviral treatment. Supportive care includes rest, hydration (oral rehydration salts), and paracetamol for fever and pain. Avoid aspirin and ibuprofen as they increase bleeding risk. Severe dengue requires hospitalisation with intravenous fluid replacement and close monitoring.
Prevention
- DEET-based insect repellent applied during the day (20-50% concentration)
- Wear long sleeves and pants, especially in early morning and late afternoon
- Use air-conditioned or screened accommodation
- Remove standing water near accommodation (breeding sites)
- Picaridin or oil of lemon eucalyptus as alternative repellents
- Permethrin-treated clothing for high-risk areas
Post-Exposure
If you develop a high fever, severe headache, or pain behind the eyes within 2 weeks of travel to a dengue-endemic area, seek medical attention. Avoid aspirin and ibuprofen. Stay hydrated and monitor for warning signs of severe dengue: abdominal pain, persistent vomiting, bleeding gums, and lethargy.
Long-Term Effects
Post-dengue fatigue can persist for weeks to months. A second dengue infection with a different serotype carries higher risk of severe dengue due to antibody-dependent enhancement.
📋 Dengue is a nationally notifiable disease in Australia. The majority of cases are acquired overseas, with occasional local transmission in Far North Queensland.
Frequently Asked Questions
Can you get dengue in Bali?
Yes. Bali has year-round dengue transmission, with peak risk during the wet season (November to March). All tourist areas including Kuta, Seminyak, Ubud, and Canggu carry risk. There is no prophylactic medication — bite prevention with DEET repellent during the day is your main protection.
Is there a vaccine for dengue?
The Qdenga (TAK-003) vaccine was approved by the TGA in Australia in 2023 and is available through travel clinics. It is a two-dose vaccine given 3 months apart. It is recommended for travellers aged 6-65 heading to endemic areas, regardless of previous dengue infection. The older Dengvaxia vaccine is only for people with confirmed prior dengue infection.
What is the difference between dengue and severe dengue?
Classic dengue causes high fever, headache, muscle/joint pain, and rash but resolves within 1-2 weeks. Severe dengue (previously called dengue haemorrhagic fever) occurs in a small percentage of cases and involves plasma leakage, severe bleeding, organ damage, or shock. Warning signs include severe abdominal pain, persistent vomiting, rapid breathing, bleeding gums, and extreme fatigue. Severe dengue requires immediate hospitalisation.
Why should you avoid aspirin with dengue?
Aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen inhibit platelet function and can increase the risk of bleeding, which is already elevated in dengue due to low platelet counts. Use paracetamol only for fever and pain relief during a suspected dengue infection.
Can you get dengue twice?
Yes. There are four dengue serotypes (DENV-1 to DENV-4). Infection with one serotype provides lifelong immunity to that serotype but only short-term protection against the others. A second infection with a different serotype actually carries a higher risk of developing severe dengue due to a phenomenon called antibody-dependent enhancement.
When are dengue mosquitoes most active?
Aedes mosquitoes that transmit dengue bite primarily during the day, especially in the early morning (around sunrise) and late afternoon (before sunset). This is different from malaria mosquitoes which bite at night. You need to wear repellent during daylight hours in dengue-endemic areas.
How long does dengue fever last?
The acute illness typically lasts 5-7 days. Fever usually resolves within a week. However, fatigue and general malaise can persist for several weeks after the acute phase. The critical period is around days 3-7 when the fever drops — this is paradoxically when severe dengue can develop, so do not assume improvement when the fever breaks.
Is dengue a risk in Southeast Asia during the dry season?
Yes, dengue is transmitted year-round in most of Southeast Asia. While cases peak during and after the wet season, transmission continues during the dry season. Countries like Thailand, Vietnam, Indonesia, and the Philippines report dengue cases in every month of the year. Do not skip bite prevention measures because it is the dry season.
Sources & References
Last updated: April 2026