This document discusses dengue hemorrhagic fever (DHF), a severe mosquito-borne viral illness characterized by increased vascular permeability, hypovolemia, and abnormal blood clotting. It is caused by any of four dengue virus serotypes and transmitted by the Aedes aegypti mosquito. DHF symptoms include high fever, bleeding, and plasma leakage that can lead to shock. Treatment focuses on fluid replacement and management of bleeding and shock. Prevention emphasizes eliminating mosquito breeding sites and using protective measures against mosquito bites.