Dengue Fever

Dengue is a viral infection caused by one of four dengue virus serotypes. It is transmitted primarily by *Aedes aegypti* and *Aedes albopictus* mosquitoes. A person’s travel or residence in an area with dengue transmission is therefore central to the assessment, not a minor historical detail. The dangerous feature of dengue is increased vascular permeability. Immune-mediated endothelial dysfunction makes the vessel wall temporarily more porous, allowing plasma to move into surrounding tissues. The patient may then lose effective circulating volume even without obvious external bleeding. As intravascular volume falls, tissue perfusion can deteriorate and fluid may accumulate in spaces such as the abdomen or pleural cavity. This mechanism explains a high-yield laboratory pattern: a rising hematocrit occurring at the same time as a falling platelet count. The hematocrit rises because plasma is leaving the vascular compartment; the platelet decline reflects the evolving illness. Neither value should be interpreted alone. The trend, the patient’s perfusion, urine output, bleeding assessment, and respiratory status determine urgency. For the practical nurse, dengue is not a “fever and low platelets” problem. It is a condition...