Introduction
Dengue fever is a mosquito-borne viral infection that poses a major public health threat, especially in tropical and subtropical regions. Caused by the dengue virus (DENV), which has four distinct serotypes (DENV-1 to DENV-4), dengue can lead to a wide spectrum of clinical presentations, ranging from a mild febrile illness to severe and potentially fatal forms like Dengue Hemorrhagic Fever (DHF) and Dengue Shock Syndrome (DSS). The World Health Organization (WHO) estimates that approximately 390 million dengue infections occur globally each year, with around 96 million manifesting clinically.
Effective management of dengue depends on early recognition, supportive care, and vigilant monitoring. This essay provides a comprehensive overview of dengue, including its transmission, clinical manifestations, diagnosis, and standardized treatment protocol.
Transmission and Epidemiology
Dengue is primarily transmitted through the bite of Aedes aegypti and Aedes albopictus mosquitoes, which are day-biting vectors. These mosquitoes breed in stagnant water and thrive in urban environments. Dengue outbreaks are more common during and after rainy seasons.
Once a mosquito feeds on an infected person, it becomes capable of transmitting the virus to others after an incubation period of about 8–12 days. Humans are the main reservoir of the virus, and infection with one serotype offers lifelong immunity to that serotype but not to others. Subsequent infections with different serotypes increase the risk of severe dengue due to a phenomenon known as antibody-dependent enhancement (ADE).
Clinical Presentation
Dengue infection has a broad clinical spectrum. The WHO classifies dengue into three categories:
1. Dengue Without Warning Signs
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High fever (sudden onset)
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Headache
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Retro-orbital pain
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Muscle and joint pain (“breakbone fever”)
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Rash
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Nausea and vomiting
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Leukopenia
2. Dengue With Warning Signs
These symptoms usually appear between 3 to 7 days after the onset of fever and indicate progression to severe dengue:
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Abdominal pain or tenderness
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Persistent vomiting
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Clinical fluid accumulation (ascites, pleural effusion)
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Mucosal bleeding
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Lethargy or restlessness
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Hepatomegaly
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Increase in hematocrit with rapid drop in platelet count
3. Severe Dengue
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Severe plasma leakage leading to shock (DSS)
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Severe bleeding (often internal)
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Organ impairment (liver, kidneys, heart)
Diagnosis
Timely and accurate diagnosis of dengue is crucial for effective treatment and prevention of complications. Diagnosis is based on clinical suspicion supported by laboratory tests:
a. Hematological Investigations
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Complete Blood Count (CBC): Look for leukopenia, thrombocytopenia (<100,000/mm³), and hemoconcentration (increased hematocrit).
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Platelet count: Drops significantly in moderate to severe cases.
b. Serological and Virological Tests
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NS1 Antigen Detection: Useful in the early phase (first 5 days of fever).
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IgM and IgG ELISA: IgM antibodies appear after 5 days, IgG indicates past infection.
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RT-PCR: Highly sensitive method to detect viral RNA, especially useful during the acute phase.
Treatment Protocol
There is no specific antiviral treatment for dengue. Management is primarily supportive, aimed at maintaining adequate fluid balance and monitoring for signs of complications. The WHO treatment protocol categorizes patients into three groups (A, B, and C) for tailored management.
Group A: Outpatient Management (No Warning Signs)
Criteria:
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Able to take oral fluids
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No warning signs
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Hemodynamically stable
Treatment:
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Oral rehydration: Encourage intake of fluids like oral rehydration salts (ORS), juices, soups, and water.
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Paracetamol: For fever and pain (avoid NSAIDs like aspirin or ibuprofen due to bleeding risk).
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Monitoring: Daily outpatient visits to check hematocrit and platelet count.
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Patient education: Teach warning signs and advise when to return to the hospital.
Group B: Inpatient Observation (Warning Signs Present)
Criteria:
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Presence of warning signs
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Co-existing conditions (e.g., pregnancy, diabetes)
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Inability to tolerate oral fluids
Treatment:
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IV fluid therapy: Begin with isotonic fluids (e.g., Ringer’s lactate or normal saline).
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Initial rate: 5–7 ml/kg/hr for 1–2 hours, then adjust based on response.
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Monitoring: Vital signs, urine output, hematocrit, and platelet count every 6 hours.
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Paracetamol only: Avoid anticoagulants or antiplatelet drugs.
Group C: Emergency Treatment (Severe Dengue)
Criteria:
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Severe plasma leakage (shock)
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Severe bleeding
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Organ dysfunction
Treatment:
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Rapid fluid resuscitation: Bolus of 10–20 ml/kg isotonic crystalloid solution over 15–30 minutes.
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If no improvement, switch to colloid solution (e.g., dextran or albumin).
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Blood transfusion: For significant bleeding or anemia.
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Oxygen therapy: For respiratory distress.
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ICU care: Required for close monitoring and organ support.
Monitoring and Supportive Care
a. Fluid Management
Dengue causes increased vascular permeability leading to plasma leakage. Overhydration can be as dangerous as underhydration. Therefore, fluid therapy must be individualized based on:
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Hematocrit levels
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Blood pressure
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Urine output
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Body weight
b. Platelet Transfusion
Routine platelet transfusion is not recommended unless:
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There is active bleeding
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Platelet count is <10,000/mm³
c. Nutritional Support
Patients should receive adequate nutrition once they can tolerate oral intake. Soft, easily digestible food is recommended.
Prevention and Control
a. Vector Control
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Eliminate mosquito breeding sites: Drain stagnant water from containers, tires, plant pots.
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Use of insecticide sprays, larvicides, and biological control (e.g., fish that eat larvae).
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Promote community-based sanitation campaigns.
b. Personal Protection
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Use of mosquito repellents
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Wearing long-sleeved clothes
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Installing mosquito nets and window screens
c. Vaccination
The Dengvaxia vaccine (CYD-TDV) is approved in some countries for individuals aged 9–45 years with a confirmed history of previous dengue infection. However, it is not universally recommended due to the risk of severe dengue in seronegative individuals.
d. Public Awareness
Education campaigns to inform communities about dengue symptoms, prevention, and when to seek medical care are vital to early detection and management.
Conclusion
Dengue remains a pressing global health concern with no specific antiviral cure. However, with early recognition, timely supportive care, and vigilant monitoring, most patients recover without complications. Implementation of WHO’s standardized treatment protocol—based on symptom severity—ensures optimal care and resource utilization. Prevention through vector control, vaccination (where applicable), and public awareness are key pillars in reducing the incidence and impact of dengue fever. As climate change and urbanization continue to influence the spread of mosquito-borne diseases, an integrated approach involving healthcare systems, governments, and communities is essential to combat dengue effectively.
Dr. Ramjee Bastola , NEPAL
