Dengue fever is a mosquito-borne flaviviral infection transmitted by Aedes aegypti and Aedes albopictus mosquitoes, with a characteristic triphasic clinical course (febrile → critical → convalescent). Approximately 60–80% of infections are asymptomatic; ≤5% of symptomatic cases progress to severe, life-threatening disease. [1-2] Early recognition of warning signs and judicious fluid management can reduce mortality by ≥20-fold. [1]
1. History
- Onset and timing: Abrupt onset of high-grade fever (≥38.5°C) after an incubation period of 5–7 days (range 3–10 days); fever lasts 2–7 days and may be biphasic [1-2]
- Cardinal symptoms: Severe headache, retro-orbital pain, bone/joint/muscle pain ("breakbone fever"), anorexia, nausea/vomiting [2-3]
- Rash: Transient facial erythema in first 24–48 hours; maculopapular or morbilliform eruption days 3–6 with islands of sparing [2]
- Travel history: Essential — dengue can be excluded if symptoms begin >2 weeks after leaving an endemic area; fever persisting >10 days argues against dengue [4]
- Prior dengue infection: Secondary infections carry significantly higher risk of severe disease (OR 2.26) [5]
- Important negatives: Cough and rhinitis are negatively associated with dengue and suggest alternative diagnoses [6-7]
2. Alarm Features
WHO warning signs (typically appear around defervescence, days 4–6): [1-3]
- Severe abdominal pain or tenderness
- Persistent vomiting (unable to tolerate oral fluids)
- Clinical fluid accumulation (ascites, pleural effusion, pericardial effusion) — highest positive predictive value for severe dengue (PPV up to 58%) [2]
- Mucosal bleeding (gums, nose, GI)
- Lethargy or restlessness
- Liver enlargement >2 cm
- Rising hematocrit concurrent with rapid platelet drop
- Postural hypotension
Severe dengue criteria: [2]
- Severe plasma leakage → shock (narrowing pulse pressure ≤20 mmHg, tachycardia, cold extremities, delayed cap refill) or respiratory distress from fluid accumulation
- Severe hemorrhage (hematemesis, melena, menorrhagia)
- Severe organ impairment: AST or ALT ≥1000 IU/L, encephalitis, myocarditis
Pearl: Patients may appear deceptively well during compensated shock — a rising diastolic BP with narrowing pulse pressure is an early sign before frank hypotension. [1][8]
3. Medications
- Antipyretic: Acetaminophen only for fever control [1][4]
- Contraindicated: Aspirin, NSAIDs (ibuprofen, naproxen) — increase bleeding risk [1][4]
- Avoid: Intramuscular injections (risk of large hematomas) [4]
- No proven benefit: Corticosteroids (potentially harmful except for autoimmune complications), antivirals, chloroquine, ivermectin [1-2]
- Prophylactic platelet transfusions are NOT beneficial and may contribute to fluid overload; transfuse only for clinically significant active bleeding with pRBCs or whole blood [1][9]
- Anticoagulants: Hold any anticoagulant medications during acute illness [1]
4. Diet
- Aggressive oral hydration is the cornerstone of outpatient management — oral rehydration solutions, water, juices, soups [1]
- Encourage small, frequent meals; anorexia is common
- No specific dietary triggers or restrictions beyond maintaining adequate caloric and fluid intake
- Avoid alcohol (hepatotoxicity risk given transaminitis)
5. Review of Systems
- Constitutional: Fever pattern, fatigue, malaise, weight loss
- HEENT: Retro-orbital pain, conjunctival injection, scleral suffusion, bleeding gums, epistaxis
- Skin: Rash (timing, distribution), petechiae, ecchymoses, pruritus (common in convalescence)
- GI: Abdominal pain (especially RUQ), nausea, vomiting, hematemesis, melena
- Respiratory: Dyspnea (pleural effusion), cough (argues against dengue)
- Neuro: Headache severity, lethargy, restlessness, altered mental status
- GU: Urine output (oliguria = shock), hematuria, menorrhagia
- MSK: Myalgia, arthralgia severity
6. Collateral History and Family History
- Household/neighborhood contacts with dengue in the past week (AOR 3.59 for dengue diagnosis) [7]
- Prior dengue infection in patient or family members (secondary infection risk)
- Travel companions with similar symptoms
- Living conditions: standing water, mosquito exposure, use of bed nets/repellents
- Pregnancy status — pregnant women with dengue should always be hospitalized [1]
7. Risk Factors
Risk factors for progression to severe disease: [2][5]
- Secondary DENV infection (especially with longer interval since prior infection; OR 2.26)
- Age extremes: Young children (increased vascular permeability) and older adults (≥60 years, comorbidities)
- Female sex (OR 1.13 in adults)
- Comorbidities: Diabetes (OR 4.38), renal disease (OR 4.67), hypertension (OR 2.19), cardiovascular disease (OR 2.79)
- DENV serotype 2 (particularly in children)
- Poor glycemic control (HbA1c >7%) independently increases risk [5]
8. Differential Diagnosis
The differential is broad during the febrile phase: [2][4]
- Malaria — must be excluded in any febrile traveler from endemic areas; thick/thin smear or rapid diagnostic test
- Chikungunya — prominent arthralgia (often symmetric, small joints), similar rash; co-circulates with dengue
- Zika virus — milder fever, conjunctivitis, less myalgia
- Typhoid fever — stepwise fever, relative bradycardia, rose spots; blood cultures diagnostic
- Leptospirosis — conjunctival suffusion, jaundice, renal failure; exposure to contaminated water
- Rickettsial diseases — eschar, centripetal rash
- Measles/rubella — coryza, Koplik spots, lymphadenopathy
- Acute HIV seroconversion — pharyngitis, lymphadenopathy, mucocutaneous ulcers
- Viral hemorrhagic fevers — travel to specific endemic zones, higher mortality
Distinguishing features for dengue: Leukopenia + thrombocytopenia + elevated transaminases + low CRP + absence of cough/rhinitis is highly predictive. [4][6][10]
9. Past Medical History
- Prior dengue infections (serotype if known) — critical for risk stratification
- Diabetes, hypertension, renal disease, cardiovascular disease [5]
- Chronic liver disease (increased bleeding risk)
- Immunosuppression or immunocompromising conditions
- Current medications (especially anticoagulants, antiplatelets, NSAIDs)
- Vaccination history (Dengvaxia — only for seropositive individuals aged 9–16 in endemic areas) [3]
- Pregnancy status
10. Physical Exam
- Vitals: High-grade fever, tachycardia; monitor for narrowing pulse pressure (≤20 mmHg = decompensated shock), postural hypotension [8]
- Skin: Maculopapular rash with islands of sparing, petechiae, ecchymoses, facial flushing
- Tourniquet test: Inflate BP cuff midway between systolic and diastolic for 5 minutes → ≥20 petechiae per 1-inch square = positive (sensitivity ~90% for early dengue) [4]
- Eyes: Conjunctival injection, scleral suffusion
- Oropharynx: Injected, bleeding gums
- Abdomen: RUQ tenderness, hepatomegaly (>2 cm below costal margin = warning sign), ascites
- Lungs: Decreased breath sounds at bases (pleural effusion)
- Extremities: Capillary refill time (>2 seconds = poor perfusion), cool/mottled extremities in shock
- Neuro: Mental status (lethargy, restlessness)
11. Lab Studies
12. Imaging
- Chest X-ray: Pleural effusions (right-sided more common), may show fluid overload
- Abdominal ultrasound: Ascites, gallbladder wall thickening (pericholecystic fluid), hepatomegaly, pleural effusions — useful for detecting subclinical plasma leakage [3]
- CT/MRI: Generally unnecessary; consider for atypical presentations (encephalitis, intracranial hemorrhage)
- Echocardiography: If myocarditis or pericardial effusion suspected
- Imaging is most useful during the critical phase to assess extent of plasma leakage
13. Special Tests
Diagnostic confirmation: [2][11]
- RT-PCR (NAAT): Preferred method; detects viral RNA in first 7 days; identifies serotype [2]
- NS1 antigen: Detectable days 1–7 (sensitivity comparable to PCR in primary infection, lower in secondary); rapid test available [2][11]
- Dengue IgM: Detectable from day 4 to ~12 weeks; positive result suggests recent infection [2][11]
- Dengue IgG: Rises by day 7 in primary infection; rapid early rise in secondary infection; cross-reacts with other flaviviruses (Zika, West Nile) [11]
- Tourniquet test: Bedside screening tool; high sensitivity (~90%) for early dengue [4]
- PRNT (plaque reduction neutralization test): Reference standard for specificity; available at CDC/public health labs [11]
Pearl: Combine NS1 antigen + IgM for optimal sensitivity across the illness timeline. A negative rapid test does not exclude dengue — sensitivity is only ~62%. [7]
14. ECG
- Obtain ECG if myocarditis is suspected (chest pain, new heart failure, arrhythmia)
- Findings may include: sinus bradycardia (convalescent phase), ST-T wave changes, low voltage (pericardial effusion), arrhythmias
- Myocarditis is an uncommon but recognized complication of severe dengue [1][3]
15. Assessment
WHO 2009 Classification (guides triage and management): [1-3]
- Dengue without warning signs: Fever + ≥2 of: nausea/vomiting, rash, aches/pains, positive tourniquet test, leukopenia — >90% of cases; self-limiting
- Dengue with warning signs: Any warning sign present (see Alarm Features) — requires hospitalization and close monitoring
- Severe dengue: Shock, severe hemorrhage, or severe organ impairment — requires ICU-level care
The critical period is at defervescence (typically days 4–7). A patient who appears to be "improving" with resolution of fever may actually be entering the most dangerous phase. [1-2]
Atypical presentations include isolated encephalitis, hepatitis, myocarditis, pancreatitis, and acute kidney injury. [1][3]
16. Treatment Plan
Initial stabilization
- ABCs; IV access if warning signs or severe disease
- Assess volume status, mental status, and perfusion
Outpatient (Group A — no warning signs, no comorbidities): [1-2][9]
- Acetaminophen for fever (avoid NSAIDs/aspirin)
- Aggressive oral hydration (ORS, water, juices)
- Daily clinic follow-up with CBC (hematocrit + platelets) until 24–48 hours after defervescence [9]
- Mosquito avoidance (repellent, bed nets) to prevent community transmission [1]
Inpatient (Group B — warning signs or comorbidities): [1-2]
- IV isotonic crystalloids (Ringer's lactate or NS 0.9%) — minimum volume to maintain perfusion and urine output ≥0.5 mL/kg/hr
- IV fluids typically needed only 24–48 hours during the critical phase [1]
- Serial hematocrit and platelet monitoring q4–6h during critical phase
- Monitor for fluid overload as plasma leakage resolves
ICU (Group C — severe dengue/shock): [1][4][9]
- Fluid resuscitation: Isotonic crystalloid bolus 10–20 mL/kg/hr; reassess after each bolus
- Colloids reserved for profound shock or failure to respond to crystalloids [4][9]
- Blood products: pRBCs or whole blood for active hemorrhage; FFP/cryoprecipitate per coagulation profile [9]
- No prophylactic platelet transfusions [1][9]
- Vasopressors/inotropes if refractory shock [9]
- Renal replacement therapy if indicated
Fluid management pearls: [1]
- Limit IV fluids during the febrile phase
- Use ideal body weight for calculations in obese patients
- Discontinue IV fluids promptly when leakage subsides to prevent iatrogenic overload
- Reassess vitals after every fluid rate change
17. Disposition
Admit: [1][3-4][9]
- Any WHO warning sign present
- Severe dengue (shock, severe hemorrhage, organ impairment)
- Platelets <100,000/μL (highest risk for DHF) [4]
- Significant comorbidities (diabetes, renal disease, hypertension, cardiovascular disease)
- Inability to tolerate oral fluids
- Pregnancy (always hospitalize) [1]
- Difficult social circumstances or inability to follow up daily
ICU admission
- Dengue shock syndrome (compensated or decompensated)
- Severe hemorrhage requiring transfusion
- Severe organ impairment (AST/ALT ≥1000, encephalitis, myocarditis)
Discharge criteria
- Afebrile for ≥24–48 hours without antipyretics
- Improving clinical status with adequate oral intake
- Rising platelet trend
- Stable or declining hematocrit
- No warning signs
- Adequate urine output
18. Follow Up / Return Precautions
Follow-up
- Outpatients require daily in-person evaluation with CBC until 24–48 hours post-defervescence [9]
- Post-discharge follow-up within 48–72 hours with repeat CBC
- Convalescent fatigue and depression may persist for weeks
Return immediately for: [1]
- Severe abdominal pain
- Persistent vomiting or inability to drink
- Bleeding from any site (gums, nose, vomiting blood, black stools, heavy menstrual bleeding)
- Dizziness, lightheadedness, or fainting (especially on standing)
- Difficulty breathing
- Decreased urine output
- Confusion, excessive drowsiness, or irritability
- Cold or clammy extremities
Patient counseling
- The most dangerous period is when the fever breaks (days 4–7) — do not assume improvement
- Use mosquito repellent and bed nets for at least 1 week after symptom onset to prevent transmission
- Avoid aspirin/NSAIDs for at least 2 weeks
- Expected recovery: most patients recover fully within 2–4 weeks, though fatigue may linger
Images
References
1. Dengue. — Liliana Sánchez-González, Laura E. Adams, and Gabriela Paz-Bailey CDC Yellow Book. 2025.
2. Dengue. — Paz-Bailey G, Adams LE, Deen J, Anderson KB, Katzelnick LC. Lancet. 2024.
3. Dengue Vaccine: Recommendations of the Advisory Committee on Immunization Practices, United States, 2021. — Paz-Bailey G, Adams L, Wong JM, et al. MMWR. Recommendations and Reports : Morbidity and Mortality Weekly Report. Recommendations and Reports. 2021.
4. Dengue in Travelers. — Wilder-Smith A, Schwartz E. The New England Journal of Medicine. 2005.
5. Risk Predictors of Progression to Severe Disease During the Febrile Phase of Dengue: A Systematic Review and Meta-Analysis. — Sangkaew S, Ming D, Boonyasiri A, et al. The Lancet. Infectious Diseases. 2021.
6. Early Diagnostic Indicators of Dengue Versus Other Febrile Illnesses in Asia and Latin America (IDAMS Study): A Multicentre, Prospective, Observational Study. — Rosenberger KD, Phung Khanh L, Tobian F, et al. The Lancet. Global Health. 2023.
7. Rapid Testing Requires Clinical Evaluation for Accurate Diagnosis of Dengue Disease: A Passive Surveillance Study in Southern Malaysia. — Ngim CF, Husain SMT, Hassan SS, et al. PLoS Neglected Tropical Diseases. 2021.
8. Job Aid for Reviewing Clinical Medical Records for Dengue Cases. — Joshua Wong MD, Parmi Suchdev MD MPH United States Centers for Disease Control and Prevention (2024). 2024.
9. Dengue. — Simmons CP, Farrar JJ, Nguyen vV, Wills B. The New England Journal of Medicine. 2012.
10. Clinical Features and Dynamic Ordinary Laboratory Tests Differentiating Dengue Fever From Other Febrile Illnesses in Children. — Chen CH, Huang YC, Kuo KC, Li CC. Journal of Microbiology, Immunology, and Infection = Wei Mian Yu Gan Ran Za Zhi. 2018.
11. Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2024 Update by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM). — Miller JM, Binnicker MJ, Campbell S, et al. Clinical Infectious Diseases : An Official Publication of the Infectious Diseases Society of America. 2024.