Dengue fever is the world's most common mosquito-borne viral illness, with WHO modeling estimating 390 million infections each year, of which approximately 96 million are symptomatic. The virus is transmitted by Aedes aegypti and Aedes albopictus mosquitoes biting during the day in tropical and subtropical regions.
Dengue fever (ICD-10: A90 dengue fever without warning signs; A91 dengue hemorrhagic fever / severe dengue) is an arboviral infection caused by one of four dengue virus serotypes (DENV-1, DENV-2, DENV-3, DENV-4), all single-stranded RNA flaviviruses. The virus is transmitted by day-biting Aedes aegypti and Aedes albopictus mosquitoes; humans are the principal reservoir in the urban transmission cycle that drives most outbreaks. After a 4-10 day incubation period, infection causes a self-limited febrile illness in most patients, with high fever, severe headache, retro-orbital pain, myalgia, arthralgia, maculopapular rash, and a characteristic platelet drop. The 2009 WHO classification recognizes three categories: dengue without warning signs, dengue with warning signs (abdominal pain, persistent vomiting, mucosal bleeding, lethargy, hepatomegaly), and severe dengue (plasma leakage with shock or respiratory distress, severe bleeding, or severe organ impairment).
The key symptoms of Dengue Fever are: Sudden onset of high fever (often 39-40°C) lasting 2-7 days after a 4-10 day incubation following an Aedes mosquito bite., Severe frontal or retro-orbital headache that worsens with eye movement., Diffuse myalgia and arthralgia — the classic 'break-bone fever' — affecting back, limbs, and joints., Maculopapular rash appearing day 3-5 of illness, often described as 'islands of white in a sea of red'., Mild bleeding manifestations: petechiae, gum bleeding, epistaxis, mild menstrual irregularity., Nausea, vomiting, abdominal discomfort, and reduced oral intake., Marked fatigue, anorexia, and altered taste that can persist for weeks after fever resolves..
Suspect dengue in any patient with sudden high fever and at least two of: severe headache, retro-orbital pain, myalgia, arthralgia, rash, mucosal bleeding, leukopenia, or thrombocytopenia, who has resided in or visited an active transmission area within the past two weeks. Concurrent testing for chikungunya, Zika, leptospirosis, malaria, and typhoid is essential in returning travelers because the differential is broad. Dengue NS1 antigen by ELISA or rapid lateral-flow test is highly sensitive in the first 5-7 days of illness; IgM antibody becomes positive 4-5 days after symptom onset and persists for 2-3 months; IgG is detectable from day 7 in primary infection (low titer) and earlier and at higher titer in secondary infection. RT-PCR is the most specific test but limited in availability outside reference laboratories. Daily complete blood count is the workhorse of clinical management — falling platelet count and rising hematocrit signal plasma leakage and the start of the critical phase. Liver enzymes, coagulation studies (PT, aPTT, fibrinogen), and serial vital signs (pulse rate, blood pressure, pulse pressure, capillary refill, urine output) drive fluid management. Imaging is reserved for evaluating effusion, ascites, or unusual presentations. Pediatric and obstetric cases warrant specialist input. The transition from febrile to critical phase around day 3-7 is the highest-risk period and warrants close monitoring or hospitalization in patients with warning signs.
Acute dengue without warning signs has an excellent prognosis: more than 99% of patients recover within 1-2 weeks. Mortality in severe dengue falls from over 20% without specific care to under 1% with adherence to WHO fluid management protocols. The critical phase around days 3-7 is the highest-risk period; once a patient has had 48 hours of stable hemodynamics and rising platelets, recovery is reliable. Long-term sequelae are uncommon; some patients report post-dengue fatigue syndrome with weakness, hair loss, and reduced exercise tolerance for weeks to a few months. Infection produces lifelong immunity to that serotype only; secondary infection with a different serotype carries the highest risk for severe disease. The widening adoption of TAK-003 (Qdenga) vaccine has the potential to change population-level outcomes over the next decade.
Infectious disease and pediatric specialist input is recommended for any patient with warning signs, severe dengue, pregnancy, or significant comorbidities. Critical care involvement is essential for dengue shock syndrome. Travel medicine clinics support vaccine decisions in eligible patients.
Find specialists →Acute fever resolves over 2-7 days. Critical phase lasts 24-48 hours after defervescence. Platelet count typically recovers over 5-10 days. Hematocrit normalizes over 2-3 days after the critical phase. Fatigue and reduced exercise tolerance may persist for 2-6 weeks during convalescence.
Rest during the acute and critical phases. Light walking once fever has resolved and warning signs have settled. Avoid strenuous exercise for at least 1-2 weeks during convalescence to allow full hematologic recovery. Athletes returning from dengue should have a normal CBC and clinician clearance before returning to high-intensity training.
Look for clinicians and hospitals familiar with WHO 2009 dengue case management, with established fluid management protocols and rapid access to NS1 and serology testing. In endemic regions, designated dengue care wards offer the best outcomes. Ensure pediatric and obstetric services are available for relevant patients.
Medically reviewed by AIHealz Medical Editorial Board · May 13, 2026
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