Dengue Fever in Children and Adolescents: A Comprehensive Guide to Understanding and Managing the Disease

WHO SEARO 2011 Dengue Severity Classification

Notes:

• DSS: DHF Grade III and IV represent Dengue Shock Syndrome (DSS).
• Plasma leakage: A hallmark of DHF, indicated by hemoconcentration, pleural effusion, or ascites.
• Spontaneous bleeding: Bleeding that occurs without any trauma or injury.
• Circulatory failure: Signs of inadequate blood flow to vital organs.
• Profound shock: Severe circulatory collapse with undetectable blood pressure.
• Expanded Dengue Syndrome (EDS): Atypical presentations of dengue involving severe organ dysfunction.

This table summarizes the WHO SEARO 2011 classification for dengue severity. It's a valuable tool for clinicians to assess dengue patients and guide treatment decisions. Remember that early recognition of warning signs and prompt management of complications is essential for improving patient outcomes.

---

Introduction

Dengue fever, a mosquito-borne viral illness caused by the dengue virus, is a significant public health concern in Thailand and other tropical regions. While most infections are asymptomatic or self-limiting, a subset of patients develop severe dengue, characterized by plasma leakage, bleeding, and organ dysfunction, which can be fatal. This comprehensive guide aims to equip healthcare professionals with the knowledge and tools to effectively diagnose, manage, and prevent dengue fever in children and adolescents.

Epidemiology of Dengue Fever in Thailand

• Endemic Disease: Dengue fever is endemic in Thailand, with yearly reported cases consistently exceeding 100,000, translating to an average of over 270 cases per day.
• Seasonal Peaks: Outbreaks typically peak during the rainy season (May-July).
• Affected Population: While the disease primarily affects school-aged children (5-14 years), infants, working-age adults, and individuals with underlying health conditions are also at risk.
• Mortality: Despite improved diagnostic and treatment strategies, Thailand's case fatality rate remains at 0.06-0.13%, highlighting the disease's severity and the need for continued vigilance.
• Challenges in Control: The widespread presence of Aedes mosquitoes, the primary vector, and a high proportion of asymptomatic infections (estimated at 80%) pose significant challenges to controlling dengue transmission.

---

Understanding the Disease Process

Pathogenesis

Although the exact mechanisms driving dengue pathogenesis are not fully elucidated, several key processes contribute to the clinical manifestations:

1. Increased Vascular Permeability:
   • The dengue virus infects and activates macrophages, which release cytokines and trigger the complement cascade.
   • This inflammatory response disrupts endothelial cell junctions, increasing vascular permeability and causing plasma leakage into the extravascular space.
   • This leakage leads to:
     • Pleural effusions: Fluid accumulation in the pleural space surrounding the lungs.
     • Ascites: Fluid buildup in the abdominal cavity.
     • Hemoconcentration: An increase in the concentration of red blood cells in the blood due to fluid loss.
     • Hypovolemic Shock (Dengue Shock Syndrome): Severe leakage can result in insufficient blood volume to maintain adequate circulation, leading to shock.
2. Thrombocytopenia:
   • Dengue virus infection directly suppresses platelet production in the bone marrow.
   • Additionally, immune-mediated destruction of platelets further contributes to the significant drop in platelet counts observed in dengue patients.
3. Coagulopathy:
   • Liver inflammation and endothelial injury in dengue infection activate the coagulation cascade, leading to a state of coagulopathy.
   • This is often reflected in laboratory tests as a prolonged activated partial thromboplastin time (APTT).

---

Clinical Classification of Dengue Infection

Dengue infections manifest with a wide spectrum of clinical presentations, classified into four categories:

1. Undifferentiated Fever (UF): around 80%
   • This category encompasses non-specific febrile illnesses resembling other viral infections.
   • UF is clinically indistinguishable from other common viral illnesses, making laboratory confirmation crucial for diagnosis.
2. Dengue Fever (DF):
   • This is the most common clinical presentation, particularly in older children and adults.
   • It is characterized by high fever, often accompanied by:
     • Headache (often severe)
     • Retro-orbital Pain: Pain behind the eyes.
     • Myalgia: Muscle aches and pains.
     • Arthralgia: Joint pain.
     • Facial Flushing: Redness of the face.
     • Rash: May be present in some cases.
   • While the symptoms of DF can be significant, it is generally self-limiting and resolves without specific treatment.
3. Dengue Hemorrhagic Fever (DHF):
   • DHF is a more severe form of dengue, usually progressing from an initial phase of DF.
   • Critical Phase: This phase is marked by evidence of plasma leakage, clinically manifested as:
     • Hemoconcentration: A significant increase in hematocrit.
     • Hepatomegaly: Enlarged liver.
     • Pleural Effusions: Fluid in the chest cavity.
     • Ascites: Fluid in the abdomen.
     • Bleeding: DHF is also characterized by a tendency to bleed easily, with varying degrees of severity.
   • Dengue Shock Syndrome (DSS): Severe plasma leakage can lead to circulatory collapse (shock) known as dengue shock syndrome. This is a life-threatening complication requiring immediate intervention.
4. Expanded Dengue Syndrome (EDS):
   • EDS refers to atypical manifestations involving various organ systems beyond the classic dengue symptoms.
   • Presentations can include:
     • Encephalitis: Inflammation of the brain.
     • Aseptic Meningitis: Inflammation of the meninges (membranes surrounding the brain and spinal cord).
     • Myocarditis: Inflammation of the heart muscle.
     • Hepatitis: Inflammation of the liver.
     • Acute Liver Failure: Severe liver dysfunction.
     • Renal Failure: Kidney dysfunction.

---

Clinical Manifestations and Disease Progression

Dengue fever typically follows a characteristic three-phase course:

1. Febrile Phase (2-7 days):
   • This initial phase is marked by the sudden onset of high fever, often exceeding 38.5°C, which can last for 2-7 days.
   • Common accompanying symptoms include:
     • Headache (often severe)
     • Retro-orbital Pain: Pain behind the eyes.
     • Myalgia: Muscle aches and pains.
     • Arthralgia: Joint pain.
     • Vomiting
     • Anorexia (loss of appetite)
   • Dehydration Risk: Fever and vomiting can contribute to dehydration, especially in younger children.
   • Minor Bleeding: While major bleeding is more characteristic of the critical phase, minor bleeding, such as:
     • Petechiae: Small, red or purple spots on the skin caused by bleeding under the skin.
     • Epistaxis: Nosebleeds.
     • Gum Bleeding: Bleeding from the gums.May be observed during the febrile phase.
   • Positive Tourniquet Test: The Tourniquet test, which assesses capillary fragility, may be positive in this phase.
   • DF vs. DHF: It's important to note that differentiating between DF and DHF is not possible solely based on clinical presentation during the febrile phase.
2. Critical Phase (24-48 hours):
   • As the fever starts to subside, patients enter the critical phase, a period of heightened risk for severe complications.
   • Hallmark Features:
     • Significant Drop in Platelets: Platelet counts typically fall below 100,000 cells/mm3.
     • Rising Hematocrit (Hemoconcentration): Hematocrit increases by more than 20% from baseline, indicating plasma leakage.
     • Plasma Leakage Manifestations: The leakage of plasma into extravascular spaces leads to:
       • Pleural effusions
       • Ascites
       • Hypoalbuminemia: Low blood albumin levels.
     • Dengue Shock Syndrome (DSS): If plasma leakage is severe, patients can develop DSS, characterized by:
       • Restlessness
       • Cold Extremities
       • Weak, Rapid Pulse
       • Narrowing Pulse Pressure: The difference between systolic and diastolic blood pressure becomes smaller.
       • Hypotension: Low blood pressure.
     • Severe Bleeding: Major bleeding, such as gastrointestinal bleeding or hematuria, can also occur during this phase.
3. Recovery Phase (2-3 days):
   • The recovery phase signifies the cessation of plasma leakage, and fluid begins to return to the intravascular space.
   • Clinical Improvement:
     • Decreasing Hematocrit: Hematocrit levels start to decrease as fluid returns to the circulation.
     • Stabilizing Vital Signs: Pulse rate and blood pressure return towards normal.
     • Increased Urine Output: Kidney function improves, leading to increased urine production.
     • Returning Appetite: Appetite improves as the patient begins to feel better.
   • Convalescent Rash: A characteristic rash, often described as "white islands in a sea of red," and pruritus (itching) may appear.
   • Blood Count Recovery: Leukocyte and platelet counts gradually recover towards normal levels.
   • Fluid Overload Risk: If excessive fluids were administered during the critical phase, patients may experience fluid overload during the recovery phase.

---

Diagnosing Dengue Fever

Accurate and timely diagnosis is essential for effective management. Dengue diagnosis relies on a combination of clinical presentation and laboratory confirmation.

Clinical Evaluation

• History: A thorough history is essential, focusing on:
  • Exposure: Has the child traveled to or lived in a dengue-endemic area? Have there been recent local cases of dengue?
  • Symptom Onset and Progression: When did the fever and other symptoms begin? How have they progressed over time?
  • Previous Dengue Infection: Has the child had dengue fever before?
  • Underlying Medical Conditions: Does the child have any pre-existing health conditions?
  • Medications: Is the child taking any medications, including over-the-counter medications?
• Physical Examination:
  • Vital Signs: Assess temperature, heart rate, blood pressure, and respiratory rate.
  • General Appearance: Observe for signs of dehydration, lethargy, or restlessness.
  • Skin: Examine for rash, petechiae, or other bleeding manifestations.
  • Abdomen: Palpate for hepatomegaly (enlarged liver) or tenderness.
  • Neurological Examination: Assess mental status, reflexes, and cranial nerves.

---

Laboratory Confirmation

• Virus Detection:
  • NS1 Antigen Detection: A rapid diagnostic test that is highly sensitive in the first 5 days of illness.
  • Reverse Transcription Polymerase Chain Reaction (RT-PCR): A highly sensitive and specific test for detecting dengue virus RNA, most accurate in the first 5 days of illness. However, it requires specialized laboratory facilities.
• Serology:
  • Immunoglobulin M (IgM) and Immunoglobulin G (IgG) Antibodies: These antibodies become detectable after 5-7 days of illness. Paired sera, collected at least 2 weeks apart, can demonstrate seroconversion, providing evidence of recent dengue infection.
  • Rapid Diagnostic Tests: Rapid tests combining NS1 antigen and IgM/IgG detection are available, offering rapid and convenient diagnosis.
• Complete Blood Count (CBC):
  • Leukopenia: Decreased white blood cell count.
  • Lymphocytosis: Increased lymphocyte count.
  • Thrombocytopenia: Decreased platelet count.
  • Hemoconcentration: Increased hematocrit (during the critical phase).
• Liver Function Tests (LFTs):
  • Elevated Transaminases: Aspartate transaminase (AST) and alanine transaminase (ALT) levels are often elevated, with AST typically higher than ALT.
• Other Laboratory Tests (as needed):
  • Electrolytes: Assess for hyponatremia (low sodium).
  • Renal Function Tests: Check blood urea nitrogen (BUN) and creatinine for signs of kidney dysfunction.
  • Coagulation Profile: Evaluate activated partial thromboplastin time (APTT) for coagulopathy.

The Tourniquet Test: A Bedside Assessment

The Tourniquet test, also known as the Rumpel-Leede test, is a simple bedside test to assess capillary fragility. While it can be helpful, it is not specific to dengue and should be interpreted in conjunction with other clinical and laboratory findings.

Procedure:

1. A blood pressure cuff is applied to the patient's arm and inflated to a pressure midway between the systolic and diastolic blood pressure.
2. The pressure is maintained for 5 minutes.
3. The number of petechiae (small, red or purple spots) that appear in a defined area (usually a square inch) is counted.

Interpretation:

• A positive Tourniquet test is defined as the presence of 10 or more petechiae per square inch.

Limitations:

• Specificity: A positive Tourniquet test can be seen in other conditions that cause capillary fragility.
• Sensitivity: The test's sensitivity varies with the stage of dengue illness, being less sensitive in the early stages and potentially falsely negative in patients with shock.
• Patient Factors: Obesity or extreme thinness can influence the test results.

---

Managing Dengue Fever: Outpatient vs. Inpatient Care

The management of dengue fever depends on the severity of the illness and the presence of warning signs.

Outpatient Management: Caring for Mild Dengue

Patients with mild dengue fever, typically those in the febrile phase without warning signs, can be managed as outpatients.

• Supportive Care:
  • Rest: Encourage adequate rest to promote recovery.
  • Oral Rehydration: Maintaining adequate hydration is crucial. Oral rehydration solutions (ORS), water, and fruit juices are recommended.
  • Fever Management: Acetaminophen (paracetamol) is the preferred antipyretic agent. The recommended dosage is 10-15 mg/kg/dose every 6 hours, with a maximum of 4 doses per day.
  • Avoidance of NSAIDs: Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and aspirin, should be avoided due to their potential to increase bleeding risk.
• Monitoring:
  • Warning Signs Education: Thoroughly educate patients and their caregivers about the warning signs of severe dengue (see below) and advise them to seek immediate medical attention if these develop.
  • Complete Blood Count (CBC) Monitoring: A baseline CBC should be obtained on day 3-4 of illness. If the WBC count is below 5,000 cells/mm3 and/or the platelet count is below 100,000-150,000 cells/mm3, daily CBC monitoring is recommended, and hospitalization should be considered.
• Mosquito Control:
  • Personal Protection:
    • Insect Repellents: Use insect repellents containing DEET or other effective ingredients.
    • Mosquito Nets: Sleep under insecticide-treated mosquito nets, especially during the day when Aedes mosquitoes are most active.
  • Environmental Control:
    • Eliminate Breeding Sites: Identify and eliminate potential mosquito breeding sites around the home, such as stagnant water in containers, tires, or flower pots.

Inpatient Management: When Hospitalization is Necessary

Hospitalization is indicated for patients with severe dengue or those who develop warning signs, suggesting potential for disease progression.

Criteria for Hospitalization:

Hospitalize a child with suspected or confirmed dengue if ANY of the following are present:

1. Inability to Tolerate Oral Intake: Inability to eat or drink, persistent vomiting (more than 3 episodes per day), severe abdominal pain, profound weakness, or fainting spells.
2. Significant Bleeding: Vomiting blood, bloody stools, excessive menstrual bleeding, or any other clinically significant bleeding.
3. Hypotension or Dengue Shock Syndrome: Low blood pressure, narrow pulse pressure (less than 20 mmHg), or a diagnosis of Dengue Shock Syndrome (DSS).
4. Hemoconcentration: A hematocrit greater than 42% in girls or greater than 45% in boys, or an increase in hematocrit of 20% or more from baseline.
5. Severe Thrombocytopenia: Platelet count less than 100,000 cells/mm3.
6. Elevated Liver Enzymes: Aspartate transaminase (AST) or alanine transaminase (ALT) levels greater than 500 units/L.
7. Organ Dysfunction: Evidence of kidney, heart, or neurological dysfunction, such as decreased urine output, irregular heartbeat, or altered mental status.
8. High-Risk Groups: Hospitalization should be strongly considered for patients in the following high-risk groups:
   • Infants (less than 1 year old)
   • Elderly patients
   • Pregnant women
   • Obese patients (BMI > 30 kg/m2 )
   • Patients with underlying blood disorders: G6PD deficiency, thalassemia, other hemoglobinopathies.
   • Patients with congenital heart disease
   • Patients with chronic medical conditions: Diabetes, hypertension, asthma, heart disease, severe kidney disease, liver cirrhosis.
   • Patients taking corticosteroids or NSAIDs
9. Inability to Follow Up as an Outpatient: Patients who lack reliable access to medical care or are unable to comply with outpatient management recommendations should be hospitalized.

Warning Signs (Red Flags): Indicators of Potential Severe Dengue

Patients and their caregivers should be educated about the following warning signs, which require immediate medical attention:

• Worsening Symptoms Despite Fever Resolution: If the fever subsides but the child's overall condition deteriorates (increased weakness, restlessness, lethargy, etc.), seek immediate medical attention.
• Persistent Vomiting: More than 3 episodes of vomiting in a day.
• Signs of Circulatory Compromise: Dizziness, feeling faint, cold extremities, or any alteration in mental status.
• Decreased Urine Output: Little or no urine passed in 4-6 hours.
• Abnormal Bleeding: Any unusual bleeding, especially from mucous membranes (nosebleeds, black stools, vomiting blood, irregular or heavy menstrual periods, blood in urine) or dark brown/black urine, which can indicate blood breakdown.

Specific Management Strategies for Inpatients

Fluid Management

• Goal: Maintain adequate circulatory volume and prevent or treat shock.
• Fluid Choices:
  • Isotonic Crystalloids: 0.9% sodium chloride (normal saline) with or without 5% dextrose is the preferred initial fluid for most patients. Balanced crystalloids (e.g., Plasma-Lyte, Sterofundin) can also be used.
  • Colloids: Human albumin (5%) is the preferred colloid, especially in cases of severe leakage or shock. Fresh frozen plasma (FFP) can be considered in patients with coagulopathy.
  • Dextran-40: Can be used cautiously in specific situations (e.g., massive pleural effusions), but monitor for renal impairment and coagulopathy.
  • Avoid Hypotonic Fluids: Hypotonic fluids (e.g., 0.45% saline) can exacerbate hyponatremia, a common complication in dengue.
• Fluid Rates and Volumes:
  • Initial Bolus: 10-20 ml/kg of isotonic crystalloids over 15-30 minutes for patients with signs of shock.
  • Maintenance Fluids: Adjust based on urine output, clinical response, and hematocrit.
  • Fluid Challenges: For patients with uncertain fluid status, consider fluid challenges (small boluses of fluid) to assess responsiveness.
• Monitoring:
  • Vital Signs: Monitor heart rate, blood pressure, respiratory rate, and oxygen saturation frequently.
  • Urine Output: Maintain urine output of at least 0.5-1 ml/kg/hour.
  • Hematocrit: Monitor hematocrit levels to assess for hemoconcentration and guide fluid therapy.

Bleeding Management

• Minor Bleeding:
  • Local Pressure: Apply direct pressure to the bleeding site (e.g., nasal packing for epistaxis).
  • Tranexamic Acid: An antifibrinolytic agent that can help reduce bleeding, available in oral and intravenous formulations.
  • Oral Contraceptives (for menorrhagia): Can help regulate heavy menstrual bleeding.
  • Platelet Transfusion: Consider platelet transfusion if platelets are below 10,000 cells/mm3 with active bleeding that doesn't respond to the above measures, or if platelets are below 50,000 cells/mm3 before invasive procedures.
• Major Bleeding:
  • Packed Red Blood Cells: Transfuse packed red blood cells to restore oxygen-carrying capacity and stabilize blood pressure.
  • Platelets: Transfuse platelets to improve clotting function.
  • Fresh Frozen Plasma (FFP): Provide clotting factors to address coagulopathy.
  • Cryoprecipitate: Rich in fibrinogen, which is essential for clot formation.
  • Massive Transfusion Protocol: For patients with massive bleeding, consider a massive transfusion protocol, which involves transfusing packed red blood cells, platelets, and FFP in a specific ratio (e.g., 1:1:1).
  • Tranexamic Acid (IV): Can be used for severe bleeding, especially mucosal bleeding (e.g., gastrointestinal bleeding).
  • Recombinant Activated Factor VII: A clotting factor that can be used for life-threatening bleeding unresponsive to other measures. It's typically used under the guidance of a hematologist.

---

Managing Dengue-Related Complications

1. Acute Kidney Injury (AKI)

• Pathophysiology: AKI in dengue can be caused by:
  • Decreased Renal Perfusion: Shock, cytokine storm, or intra-abdominal hypertension (IAH) can reduce blood flow to the kidneys.
  • Direct Viral Invasion: The dengue virus can directly infect kidney cells.
  • Immune-Mediated Glomerulonephritis: The immune response to dengue infection can cause inflammation of the kidneys.
• Diagnosis: Use the Kidney Disease: Improving Global Outcomes (KDIGO) 2012 criteria to diagnose and stage AKI.
• Management:
  • Optimize Fluid Balance: Ensure adequate hydration and maintain urine output greater than 0.5-1 ml/kg/hour.
  • Hemodynamic Support: Treat shock aggressively to restore blood pressure and improve kidney perfusion.
  • Address Intra-Abdominal Hypertension (IAH): If present, relieve IAH with abdominal paracentesis.
  • Avoid Nephrotoxic Medications: Avoid medications known to harm the kidneys.
  • Monitor Closely: Monitor urine output and creatinine levels closely.
  • Nephrology Consultation: Consult a pediatric nephrologist for worsening AKI or stage 2 AKI or higher.
  • Renal Replacement Therapy: In severe cases, renal replacement therapy (dialysis) may be necessary to support kidney function.

2. Intravascular Volume Overload

• Causes: Volume overload can occur due to:
  • Excessive Fluid Administration: Overly aggressive fluid resuscitation can lead to fluid overload.
  • Delayed Colloid Use: Using colloids (e.g., albumin) late in the course of treatment can cause fluid to shift back into the intravascular space, leading to overload.
  • Inappropriate Blood Product Transfusions: Transfusing excessive amounts of blood products can contribute to volume overload.
  • Underlying Cardiopulmonary or Renal Disease: Patients with pre-existing heart, lung, or kidney conditions are more susceptible to volume overload.
• Management:
  • Reduce or Discontinue IV Fluids: If signs of volume overload are present, reduce or stop intravenous fluid administration.
  • Low-Dose Diuretics: In some cases, low-dose furosemide (a diuretic) can be used to remove excess fluid. However, use diuretics cautiously, as they can worsen shock if not used judiciously.
  • Fluid Restriction: Restrict oral fluid intake if necessary.

3. Hemophagocytic Lymphohistiocytosis (HLH)

• Pathophysiology: HLH is a rare but serious complication of dengue. It involves an overactivation of the immune system, leading to uncontrolled inflammation and damage to organs.
• Clinical Features:
  • Prolonged high fever.
  • Hepatosplenomegaly (enlarged liver and spleen).
  • Lymphadenopathy (enlarged lymph nodes).
  • Bicytopenia or pancytopenia (low counts of two or more blood cell types).
  • Severe or persistent shock.
• Diagnosis: Based on clinical and laboratory criteria, including fever, splenomegaly, cytopenia, hypertriglyceridemia, hypofibrinogenemia, hyperferritinemia, hemophagocytosis in bone marrow, low NK cell activity, and elevated sCD25 levels.
• Management:
  • Intensive Care: Patients with HLH require intensive care monitoring and support.
  • Immunosuppression: Treatment involves immunosuppressive therapy to control the overactive immune response. This typically includes:
    • Corticosteroids: High-dose corticosteroids (e.g., methylprednisolone, dexamethasone) are the mainstay of treatment.
    • Intravenous Immunoglobulin (IVIG): May be used in addition to corticosteroids.
    • Etoposide: A chemotherapy drug that may be used in severe cases, but its use is often limited in dengue due to concerns about myelosuppression (suppression of bone marrow function).

4. Acute Intravascular Hemolysis

• Risk Factors:
  • Thalassemia: A genetic blood disorder that affects hemoglobin production.
  • G6PD Deficiency: A genetic enzyme deficiency that makes red blood cells more susceptible to damage.
  • Other Hereditary Hemolytic Disorders: Conditions that cause red blood cells to break down prematurely.
• Clinical Features:
  • Exacerbation of anemia.
  • Jaundice (yellowing of the skin and eyes).
  • Hemoglobinuria (dark urine due to the presence of hemoglobin).
• Management:
  • Hospitalization: All children with thalassemia, G6PD deficiency, or other hereditary hemolytic disorders who develop dengue fever should be hospitalized, even during the febrile phase.
  • Monitor Hematocrit Carefully: The presence of hemolysis can make hematocrit levels unreliable for assessing plasma leakage. Rely on clinical signs and other laboratory findings to guide fluid management.
  • Urine Analysis: Check urine for blood to detect hemoglobinuria, which can indicate the need for more aggressive hydration.
  • Blood Transfusions: Packed red blood cell transfusions may be needed to address anemia.
  • Avoid Repeated Transfusions in Thalassemia: In thalassemia, repeated blood transfusions within a short period can increase the risk of iron overload and other complications.
  • Assess for Plasma Leakage Clinically: Use physical examination (e.g., assessing for pleural effusions) and chest X-rays to evaluate for plasma leakage if hematocrit is unreliable.
  • Discontinue Iron Chelation: If the patient is on iron chelation therapy (for thalassemia), discontinue it during dengue infection.
  • Consider Co-Infection: Children with thalassemia or other hemolytic disorders who have had a splenectomy (removal of the spleen) or have splenic dysfunction are at increased risk for serious bacterial infections. Consider co-infection with encapsulated bacteria and administer empirical antibiotics as needed.

5. Intra-Abdominal Hypertension (IAH)

• Pathophysiology: IAH is defined as an elevation of pressure within the abdominal cavity. It can occur in dengue due to:
  • Ascites: Fluid buildup in the abdomen due to plasma leakage.
  • Organomegaly: Enlargement of abdominal organs, such as the liver or spleen.
• Consequences: IAH can compress blood vessels and organs, leading to:
  • Respiratory Distress: Reduced chest wall compliance and difficulty breathing.
  • Decreased Kidney Function: Reduced blood flow to the kidneys.
  • Bowel Ischemia: Reduced blood flow to the intestines.
• Diagnosis:
  • Clinical Suspicion: Consider IAH in patients with abdominal distention, increased abdominal girth, or a tense abdomen.
  • Bladder Pressure Measurement: Measure intra-abdominal pressure by measuring bladder pressure via a Foley catheter.
  • IAH: Intra-abdominal pressure of 10 mmHg or higher.
  • Abdominal Compartment Syndrome (ACS): A more severe form of IAH, defined as intra-abdominal pressure of 20 mmHg or higher, or 10 mmHg or higher with evidence of organ dysfunction.
• Management:
  • Conservative Measures:
    • Optimize Abdominal Wall Compliance: Use sedation, analgesia, and muscle relaxants for intubated patients. Avoid head elevation and position the patient in reverse Trendelenburg (head lower than feet).
    • Evacuate Intra-luminal Content: Consider nasogastric tube or rectal tube decompression to remove gas and fluid from the gastrointestinal tract. Use these measures cautiously to avoid inducing bleeding.
    • Correct Positive Fluid Balance: Reduce or discontinue intravenous fluids, consider colloids, and manage any underlying causes of fluid retention.
  • Invasive Measures (for ACS):
    • Abdominal Paracentesis: Drain fluid from the abdominal cavity using ultrasound guidance to minimize the risk of organ injury. Ensure adequate correction of coagulopathy before the procedure.

6. Neurological Complications

• Types: Neurological complications in dengue can include:
  • Dengue Encephalopathy: Altered mental status (confusion, lethargy, coma) secondary to shock, organ failure, or metabolic disturbances. CSF examination is typically normal.
  • Dengue Encephalitis: Inflammation of the brain caused by direct viral invasion or immune-mediated mechanisms. Patients may present with altered mental status, seizures, and focal neurological deficits. Evidence of dengue infection (antibodies, antigen, or viral RNA) may be found in the CSF.
  • Other Neurological Syndromes: Less common but potentially serious neurological complications include:
    • Acute Disseminated Encephalomyelitis (ADEM): An inflammatory demyelinating disease of the brain and spinal cord.
    • Acute Childhood Myositis: Inflammation of the muscles.
    • Stroke: Ischemic or hemorrhagic stroke.
    • Guillain-Barré Syndrome (GBS): An autoimmune disorder that affects the peripheral nerves.
• Risk Factors:
  • Young Age: Young children are at higher risk of neurological complications.
  • Dengue Virus Serotype: Infection with DEN-2 or DEN-3 serotypes is associated with a higher risk of neurological complications.
• Diagnosis:
  • Clinical Evaluation: A thorough neurological examination is essential to identify focal deficits, altered mental status, or other neurological signs.
  • CSF Examination: Lumbar puncture to obtain cerebrospinal fluid (CSF) for analysis. CSF findings in encephalitis may include elevated protein, increased white blood cell count, and the presence of dengue virus antibodies, antigen, or RNA.
  • Brain Imaging: Computed tomography (CT) or magnetic resonance imaging (MRI) of the brain may be performed to assess for structural abnormalities or inflammation.
• Management:
  • Supportive Care: Supportive care is the mainstay of management for most neurological complications.
  • Intensive Care Monitoring: Close monitoring in an intensive care unit (ICU) is often necessary, especially for patients with altered mental status, seizures, or signs of increased intracranial pressure.
  • Neurology Consultation: Consult a pediatric neurologist for evaluation and management.
  • Specific Treatments: Specific treatments may be indicated depending on the type of neurological complication:
    • Seizure Control: Anti-seizure medications (e.g., phenytoin, levetiracetam) may be needed to control seizures.
    • Management of Brain Edema: If brain swelling is present, measures to reduce intracranial pressure may be necessary, such as head elevation, hyperventilation, and medications (e.g., mannitol).
    • Immunomodulatory Therapy: For immune-mediated neurological complications (e.g., ADEM, GBS), immunomodulatory therapies, such as corticosteroids or IVIG, may be used.

7. Acute Hepatitis and Pediatric Acute Liver Failure (PALF)

• Pathophysiology: Liver involvement is common in dengue fever, and a small percentage of children can develop severe hepatitis or even acute liver failure.
• Clinical Features:
  • Acute Hepatitis:
    • Elevated liver enzymes (AST and ALT).
    • Jaundice (yellowing of the skin and eyes).
    • Fatigue.
    • Nausea and vomiting.
  • PALF:
    • Rapidly progressive liver dysfunction.
    • Encephalopathy (altered mental status).
    • Coagulopathy (bleeding problems).
• Diagnosis:
  • Acute Hepatitis: Diagnosis is based on elevated liver enzymes.
  • PALF: Diagnosis is based on clinical and laboratory criteria, including:
    • Age: 0-18 years.
    • No pre-existing liver disease.
    • Acute onset of symptoms (less than 8 weeks).
    • Severe liver dysfunction (elevated AST/ALT, bilirubin, and INR).
    • Hepatic encephalopathy.
• Management:
  • Supportive Care: Supportive care measures include:
    • Intravenous fluids to maintain hydration.
    • Blood glucose monitoring and management.
    • Nutritional support.
    • Management of complications, such as bleeding.
  • Transfer to Tertiary Care: Children with suspected PALF should be transferred to a tertiary care facility with experience in managing liver failure.
  • ICU Admission: Children with severe hepatitis or PALF often require intensive care monitoring and support.
  • Multidisciplinary Management: A multidisciplinary team, including gastroenterologists, hepatologists, intensivists, and other specialists, should be involved in the child's care.
  • Specific Therapies:
    • N-Acetylcysteine (NAC): NAC is an antioxidant that may help protect the liver from damage.
    • Liver Support Therapies: In specialized centers, liver support therapies, such as:
      • Single-Pass Albumin Dialysis (SPAD)
      • High-Volume Therapeutic Plasma Exchange (HV-TPE)
      • Hemoperfusion/Adsorptive TherapiesMay be used to bridge patients to liver transplantation or allow for liver regeneration.
  • Liver Transplantation: Liver transplantation is the definitive treatment for PALF, but it is a complex procedure with associated risks and benefits that must be carefully considered.

8. Cytokine Storm

• Pathophysiology: In some cases, the immune response to dengue infection can become dysregulated, leading to a massive release of cytokines (signaling molecules) that cause widespread inflammation and damage to organs.
• Clinical Features:
  • High fever.
  • Low diastolic blood pressure.
  • Tachycardia (rapid heart rate).
  • Wide pulse pressure (large difference between systolic and diastolic pressure).
  • Signs of severe plasma leakage, such as pleural effusions, pulmonary edema, and generalized edema.
• Diagnosis: Diagnosis is based on clinical suspicion and supportive laboratory findings, including elevated levels of inflammatory markers (e.g., ferritin, C-reactive protein).
• Management:
  • Supportive Care: Provide intensive supportive care, including fluid management, oxygen therapy, and mechanical ventilation if necessary.
  • Antibiotics: Consider broad-spectrum antibiotics initially, as it can be difficult to differentiate cytokine storm from bacterial sepsis.
  • Hemodynamic Monitoring: Closely monitor the child's hemodynamic status (blood pressure, heart rate, cardiac output) using echocardiography or other monitoring techniques.
  • Vasopressors and Inotropes: Use vasopressors (medications that constrict blood vessels) and inotropes (medications that increase the force of heart contractions) to support blood pressure and circulation.
  • Immunomodulatory Therapies:
    • Intravenous Immunoglobulin (IVIG): May help to modulate the immune response and reduce inflammation.
    • Corticosteroids: High-dose corticosteroids may be considered in severe cases, but their use is controversial due to potential side effects.
  • Extracorporeal Blood Purification: In experienced centers, extracorporeal blood purification techniques (e.g., hemoperfusion, cytokine adsorption) may be used to remove inflammatory mediators from the blood.

9. Co-Infections

• Prevalence: Co-infections with other pathogens, both bacterial and viral, are relatively common in dengue fever, occurring in approximately 10% of cases.
• Common Co-Infections: The most common co-infections include:
  • Bacterial:
    • Enteric fever (typhoid fever)
    • Leptospirosis
    • Scrub typhus
    • Pneumonia (bacterial)
  • Viral:
    • Viral hepatitis (A, B, C)
    • Chikungunya
    • Zika virus
    • COVID-19
• Clinical Significance:
  • Co-infections can complicate the diagnosis and management of dengue.
  • They can worsen disease severity and increase the risk of complications and mortality.
• Diagnosis:
  • Maintain a high index of suspicion for co-infections, especially in patients with:
    • Atypical presentations
    • Severe or prolonged illness
    • Unexplained laboratory abnormalities
  • Perform specific diagnostic tests based on the suspected co-infection, such as:
    • Blood cultures: To detect bacterial infections.
    • Serology: To detect antibodies against specific pathogens (e.g., leptospirosis, scrub typhus).
    • Malaria smears: To identify malaria parasites.
    • Molecular testing (PCR): To detect viral RNA (e.g., for hepatitis viruses, chikungunya, Zika, COVID-19).
• Management:
  • Treat both dengue and the co-infection simultaneously.
  • Specific treatment approaches depend on the co-infecting pathogen.

---

Preventing Dengue Fever: A Multifaceted Approach

Preventing dengue fever requires a multi-pronged strategy that involves personal protection, mosquito control, and community education.

Personal Protection

• Insect Repellents: Use insect repellents containing DEET or other effective ingredients on exposed skin.
• Mosquito Nets: Sleep under insecticide-treated mosquito nets, particularly during the day when Aedes mosquitoes are most active.
• Protective Clothing: Wear long-sleeved shirts and long pants when outdoors, especially in areas where mosquitoes are prevalent.

Mosquito Control

• Eliminate Breeding Sites: The most effective way to reduce mosquito populations is to eliminate their breeding sites. This involves:
  • Removing stagnant water from containers around the home (e.g., flower pots, tires, buckets).
  • Covering water storage containers tightly.
  • Regularly cleaning gutters and drains.
  • Using larvicides (chemicals that kill mosquito larvae) in water sources that cannot be drained.
• Community-Wide Efforts: Effective mosquito control often requires community-wide efforts, involving:
  • Public education campaigns to raise awareness about dengue prevention.
  • Organized clean-up drives to remove breeding sites.
  • Insecticide spraying programs conducted by public health authorities.

Dengue Vaccines: A Promising Tool for Prevention

Two dengue vaccines are currently available:

1. Dengvaxia™:
   • Type: Live-attenuated chimeric yellow fever dengue vaccine.
   • Schedule: 3 doses (0, 6, and 12 months).
   • Indications: Approved for individuals aged 6-45 years who have had a previous dengue infection (confirmed by serology or history).
   • Efficacy: Higher efficacy in individuals with prior dengue infection.
2. Qdenga™:
   • Type: Live-attenuated dengue2-dengue vaccine.
   • Schedule: 2 doses (0 and 3 months).
   • Indications: Approved for individuals aged 4-60 years.
   • Efficacy: Effective in both individuals with and without prior dengue infection.
   • Serotype Coverage: Demonstrates high efficacy against the DEN-2 serotype, which is prevalent in Thailand.

---

Recommendations for Dengue Vaccine Use:

• Previously Infected Individuals: Vaccinate individuals who have had a previous dengue infection after at least 6 months of recovery. Either vaccine can be used.
• Seronegative Individuals: For individuals without prior dengue infection, Qdenga™ is recommended.
• Complete Vaccination: If possible, complete the vaccination schedule with the same vaccine type. Switching between vaccines may be considered if necessary.
• Booster Doses: Currently, no booster doses are recommended for either vaccine.

Referral Guidelines

Appropriate and timely referral is crucial for patients with severe dengue or those who develop complications.

• Level 1 (Village Health Volunteer): Refer all suspected cases of dengue to a higher level of care.
• Level 2 (Community Hospital): Refer the following cases:
  • DHF grade III or higher
  • Expanded dengue syndrome
  • High-risk groups: Infants, pregnant women, obese patients, patients with underlying medical conditions (e.g., G6PD deficiency, thalassemia)
  • Patients with significant bleeding and limited access to blood products
• Level 3 (General Hospital): Refer the following cases:
  • Shock requiring vasopressors without advanced hemodynamic monitoring
  • Severe organ involvement or failure (e.g., HLH, PALF, AKI)
  • Severe leakage requiring human albumin after Dextran-40 >15-20 ml/kg

---

Conclusion

Dengue fever is a complex and potentially life-threatening illness that requires vigilance, prompt diagnosis, and appropriate management. Understanding the disease's pathogenesis, clinical presentations, diagnostic approaches, and management strategies is essential for healthcare professionals caring for children and adolescents. Adhering to evidence-based guidelines, recognizing warning signs, and collaborating with specialists are crucial for optimizing patient outcomes and minimizing the impact of dengue fever. Prevention efforts, including personal protection, mosquito control, and vaccination, play a vital role in reducing the burden of this significant public health threat.