Dengue hemorrhagic fever is an immunopathologic disease; dengue virus–antibody immune complexes trigger release of vasoactive mediators by macrophages. The mediators increase vascular permeability, causing vascular leakage, hemorrhagic manifestations, hemoconcentration, and serous effusions, which can lead to circulatory collapse (ie, dengue shock syndrome).
Dengue hemorrhagic fever often begins with abrupt fever and headache and is initially indistinguishable from classic dengue. Warning signs that predict possible progression to severe dengue include
Circulatory collapse and multiorgan failure, called dengue shock syndrome, may develop rapidly 2 to 6 days after onset.
Bleeding tendencies manifest as follows:
Bronchopneumonia with or without bilateral pleural effusions is common. Myocarditis can occur.
Dengue hemorrhagic fever is suspected in children with World Health Organization–defined clinical criteria for the diagnosis:
Hemorrhagic manifestations include at least a positive tourniquet test and petechiae, purpura, ecchymoses, bleeding gums, hematemesis, or melena. The tourniquet test is done by inflating a blood pressure cuff to midway between the systolic and diastolic blood pressure for 15 minutes. The number of petechiae that form within a 2.5-cm diameter circle are counted; > 20 petechiae suggests capillary fragility.
Complete blood count, coagulation tests, urinalysis, liver tests, and dengue serologic tests should be done. Coagulation abnormalities include
There may be hypoproteinemia, mild proteinuria, and increases in aspartate aminotransferase (AST) levels.
Serological diagnosis can be made using the IgM capture enzyme-linked immunosorbent assay (MAC-ELISA). Combined with the dengue virus RNA amplification test, it can provide a diagnosis within the first 1 to 7 days of illness. The plaque reduction neutralization test (PRNT) is specific and sensitive. Titers in acute and convalescent phase serum samples can reliably establish dengue virus infection and may indicate the specific dengue virus type involved. The PRNT requires live dengue viruses for the test and is labor-intensive and expensive. Many laboratories are not able to do the PRNT.
Patients with World Health Organization-defined clinical criteria plus thrombocytopenia ( ≤ 100,000/mcL [≤ 100 x 10 9 /L]) or hemoconcentration (Hct increased by ≥ 20%) are presumed to have the disease (see the Centers for Disease Control and Prevention's Dengue Virus: Clinical Guidance ).
Patients with dengue hemorrhagic fever require intensive treatment to maintain euvolemia. Both hypovolemia (which can cause shock) and overhydration (which can cause acute respiratory distress syndrome) should be avoided. Urine output and the degree of hemoconcentration can be used to monitor intravascular volume.
No antivirals have been shown to improve outcome.
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