DHF and DSS usually occur in patients with previous exposure to dengue virus.
Hemorrhagic manifestations occur after defervescence of fever.
Vascular permeability increases.
Plasma extravasates into extravascular space, including pleural and abdominal cavities.
Bleeding tendency
Shock may ensue.
Disseminated intravascular coagulation (DIC) may develop.
Dengue fever, DHF, and DSS are all self-limited.
World Health Organization—required criteria for the diagnosis of DHF:
Fever
Bleeding evidenced by one of the following: Positive tourniquet test, petechiae, ecchymosis, purpura, GI tract bleeding, injection site bleeding
Increased vascular permeability and plasma leakage as evidenced by an elevated hematocrit (>20%), decreased hematocrit >20% after volume replacement or pleural effusions, ascites or hypoproteinemia
Thrombocytopenia (<100,000/mm 3 )
World Health Organization—required criteria for diagnosis of DSS:
All 4 criteria of DHF +
Rapid and weak pulse
Narrow pulse pressure or hypotension for age
Cold, clammy skin
Restlessness
ETIOLOGY
Occurs in tropical and subtropical regions: Asia, Africa, Central and South America, and the Caribbean
Caused by dengue virus serotypes 1–4
Transmitted by mosquitoes: Aedes aegypti and Aedes albopictus
Incubation period of 3–14 days
There is only transient and poor cross protection among the 4 serotypes