Dengue

Definition

Dengue is an acute mosquito-borne viral infection caused by any of the four serotypes of dengue virus (DENV-1 to DENV-4), characterized by high fever, severe myalgia, rash, and in severe cases, plasma leakage, hemorrhage, and shock.

Epidemiology

• Endemic in tropical and subtropical regions worldwide, particularly Southeast Asia, South America, and the Caribbean
• Transmitted primarily by Aedes aegypti and Aedes albopictus mosquitoes
• Incidence has increased globally over the past decades
• Affects all age groups, but children may present more severe forms in endemic areas
• Secondary infection with a different serotype increases risk of severe dengue

Etiology

• Caused by dengue virus, a positive-sense single-stranded RNA virus of the Flaviviridae family
• Four serotypes: DENV-1, DENV-2, DENV-3, DENV-4
• Transmission via bite of infected female Aedes mosquitoes
• Risk factors: living in endemic area, previous dengue infection, lack of mosquito control, poor sanitation

Pathophysiology

• Virus infects dendritic cells, macrophages, and hepatocytes after mosquito bite
• Immune response leads to cytokine release and endothelial activation
• Capillary permeability increases, causing plasma leakage, hemoconcentration, and hypotension
• Thrombocytopenia and coagulopathy result from bone marrow suppression and immune-mediated platelet destruction
• Secondary infection may trigger antibody-dependent enhancement, increasing risk of severe disease