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Emergency And Acute Medicine – Dengue Fever
Basic Overview
Dengue fever results from infection with the dengue virus and represents the most common mosquito-borne viral illness worldwide. Severe disease forms include dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), which are believed to arise from a poorly understood immunopathologic response, most often in patients with prior dengue exposure. Hemorrhagic manifestations typically appear after the fever subsides. Increased vascular permeability leads to plasma leakage into extravascular spaces such as the pleural and abdominal cavities, resulting in bleeding tendencies and potential shock. Disseminated intravascular coagulation may occur. Dengue fever, DHF, and DSS are -limited illnesses.
World Health Organization Diagnostic Criteria
For dengue hemorrhagic fever, required findings include fever; bleeding manifestations such as a positive tourniquet test, petechiae, ecchymoses, purpura, gastrointestinal or injection-site bleeding; evidence of increased vascular permeability with plasma leakage demonstrated by elevated hematocrit greater than 20%, a hematocrit decrease greater than 20% after volume replacement, pleural effusions, ascites, or hypoproteinemia; and thrombocytopenia with platelet count below 100,000/mm³.
Dengue shock syndrome requires all criteria for DHF plus rapid and weak pulse, narrow pulse pressure or age-specific hypotension, cold clammy skin, and restlessness.
Etiology And Transmission
Dengue occurs predominantly in tropical and subtropical regions including Asia, Africa, Central and South America, and the Caribbean. It is caused by dengue virus serotypes 1 through 4 and transmitted by Aedes mosquitoes, primarily Aedes aegypti and Aedes albopictus. The incubation period ranges from 3 to 14 days. Immunity is serotype-specific, with only transient and incomplete cross-protection among serotypes.
Clinical Features
Fever typically begins abruptly, often reaching 39°C or higher, lasting 2–7 days, and may follow a biphasic “saddleback” pattern. Headache, particularly frontal or retro-orbital, is common. A generalized maculopapular rash occurs in about half of patients at fever onset, later becoming diffusely erythematous with areas of fading and possible desquamation. After defervescence, scattered petechiae may appear on the trunk, extensor surfaces, and axillae, sparing the palms and soles.
Musculoskeletal complaints include myalgias, arthralgias, and severe lumbar back pain. Gastrointestinal symptoms include anorexia, nausea, vomiting, abdominal pain, altered taste, hepatomegaly, ascites, and gastrointestinal bleeding. Additional findings may include epistaxis, gingival bleeding, hemoptysis, hypotension, narrowed pulse pressure, and retro-orbital pain.
Essential Evaluation
Diagnosis is primarily clinical and should be suspected in endemic areas or in patients with relevant travel history.
Diagnostic Studies And Interpretation
Laboratory findings commonly include thrombocytopenia and elevated hematocrit on complete blood count. Electrolyte testing may reveal hyponatremia and elevated blood urea nitrogen. Liver function tests often show elevated AST. Coagulation studies may demonstrate prolonged INR, PT, and PTT with low fibrinogen and elevated D-dimer. Viral isolation or detection of dengue-specific antibodies via hemagglutination inhibition assay is available only in limited laboratories. Chest radiography may show pleural effusions.
The tourniquet test is performed by inflating a blood pressure cuff to the midpoint between systolic and diastolic pressure; the appearance of three or more petechiae per square centimeter constitutes a positive test.
Differential Considerations
The differential diagnosis includes nonspecific viral illnesses, influenza, rubella, measles, malaria, Rocky Mountain spotted fever, typhoid fever, Kawasaki disease, scarlet fever, erythema infectiosum, infectious mononucleosis, roseola infantum, secondary syphilis, enterovirus infection, West Nile virus, HIV, leptospirosis, chikungunya fever, toxic shock syndrome, hepatitis, appendicitis, and meningitis.
Initial Management And Stabilization
Establish intravenous access and administer crystalloid fluids for hypotension. Provide supplemental oxygen and close monitoring for unstable patients.
Emergency Department Care
Management is supportive. Provide intravenous fluids, acetaminophen for fever, and analgesics for pain. Platelet transfusion is reserved for severe thrombocytopenia. Treat disseminated intravascular coagulation if present.
Pediatric Considerations
Neonatal dengue may occur via vertical transmission if maternal infection occurs within 0–8 days before delivery. Infants may develop DHF or DSS due to passive maternal immunity. Severe dengue forms are most common in children aged 7–12 years.
Disposition And Follow-Up
Intensive care admission is required for hypotension, disseminated intravascular coagulation, thrombocytopenia, or hemoconcentration. Hospital admission is recommended for patients 15 years or younger, those with prior dengue exposure, or when reliable follow-up cannot be ensured. Discharge may be considered if close follow-up is guaranteed, oral intake is tolerated, and pain is controlled.
Key Clinical Insights And Common Errors
Always consider dengue in patients presenting with fever and rash after travel to endemic regions. Chikungunya fever is an important emerging infection with overlapping features and should be included in the differential, particularly in travelers from Asia and Africa.
Basic Overview
Dengue fever results from infection with the dengue virus and represents the most common mosquito-borne viral illness worldwide. Severe disease forms include dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), which are believed to arise from a poorly understood immunopathologic response, most often in patients with prior dengue exposure. Hemorrhagic manifestations typically appear after the fever subsides. Increased vascular permeability leads to plasma leakage into extravascular spaces such as the pleural and abdominal cavities, resulting in bleeding tendencies and potential shock. Disseminated intravascular coagulation may occur. Dengue fever, DHF, and DSS are -limited illnesses.
World Health Organization Diagnostic Criteria
For dengue hemorrhagic fever, required findings include fever; bleeding manifestations such as a positive tourniquet test, petechiae, ecchymoses, purpura, gastrointestinal or injection-site bleeding; evidence of increased vascular permeability with plasma leakage demonstrated by elevated hematocrit greater than 20%, a hematocrit decrease greater than 20% after volume replacement, pleural effusions, ascites, or hypoproteinemia; and thrombocytopenia with platelet count below 100,000/mm³.
Dengue shock syndrome requires all criteria for DHF plus rapid and weak pulse, narrow pulse pressure or age-specific hypotension, cold clammy skin, and restlessness.
Etiology And Transmission
Dengue occurs predominantly in tropical and subtropical regions including Asia, Africa, Central and South America, and the Caribbean. It is caused by dengue virus serotypes 1 through 4 and transmitted by Aedes mosquitoes, primarily Aedes aegypti and Aedes albopictus. The incubation period ranges from 3 to 14 days. Immunity is serotype-specific, with only transient and incomplete cross-protection among serotypes.
Clinical Features
Fever typically begins abruptly, often reaching 39°C or higher, lasting 2–7 days, and may follow a biphasic “saddleback” pattern. Headache, particularly frontal or retro-orbital, is common. A generalized maculopapular rash occurs in about half of patients at fever onset, later becoming diffusely erythematous with areas of fading and possible desquamation. After defervescence, scattered petechiae may appear on the trunk, extensor surfaces, and axillae, sparing the palms and soles.
Musculoskeletal complaints include myalgias, arthralgias, and severe lumbar back pain. Gastrointestinal symptoms include anorexia, nausea, vomiting, abdominal pain, altered taste, hepatomegaly, ascites, and gastrointestinal bleeding. Additional findings may include epistaxis, gingival bleeding, hemoptysis, hypotension, narrowed pulse pressure, and retro-orbital pain.
Essential Evaluation
Diagnosis is primarily clinical and should be suspected in endemic areas or in patients with relevant travel history.
Diagnostic Studies And Interpretation
Laboratory findings commonly include thrombocytopenia and elevated hematocrit on complete blood count. Electrolyte testing may reveal hyponatremia and elevated blood urea nitrogen. Liver function tests often show elevated AST. Coagulation studies may demonstrate prolonged INR, PT, and PTT with low fibrinogen and elevated D-dimer. Viral isolation or detection of dengue-specific antibodies via hemagglutination inhibition assay is available only in limited laboratories. Chest radiography may show pleural effusions.
The tourniquet test is performed by inflating a blood pressure cuff to the midpoint between systolic and diastolic pressure; the appearance of three or more petechiae per square centimeter constitutes a positive test.
Differential Considerations
The differential diagnosis includes nonspecific viral illnesses, influenza, rubella, measles, malaria, Rocky Mountain spotted fever, typhoid fever, Kawasaki disease, scarlet fever, erythema infectiosum, infectious mononucleosis, roseola infantum, secondary syphilis, enterovirus infection, West Nile virus, HIV, leptospirosis, chikungunya fever, toxic shock syndrome, hepatitis, appendicitis, and meningitis.
Initial Management And Stabilization
Establish intravenous access and administer crystalloid fluids for hypotension. Provide supplemental oxygen and close monitoring for unstable patients.
Emergency Department Care
Management is supportive. Provide intravenous fluids, acetaminophen for fever, and analgesics for pain. Platelet transfusion is reserved for severe thrombocytopenia. Treat disseminated intravascular coagulation if present.
Pediatric Considerations
Neonatal dengue may occur via vertical transmission if maternal infection occurs within 0–8 days before delivery. Infants may develop DHF or DSS due to passive maternal immunity. Severe dengue forms are most common in children aged 7–12 years.
Disposition And Follow-Up
Intensive care admission is required for hypotension, disseminated intravascular coagulation, thrombocytopenia, or hemoconcentration. Hospital admission is recommended for patients 15 years or younger, those with prior dengue exposure, or when reliable follow-up cannot be ensured. Discharge may be considered if close follow-up is guaranteed, oral intake is tolerated, and pain is controlled.
Key Clinical Insights And Common Errors
Always consider dengue in patients presenting with fever and rash after travel to endemic regions. Chikungunya fever is an important emerging infection with overlapping features and should be included in the differential, particularly in travelers from Asia and Africa.
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