The document discusses dengue hemorrhagic fever (DHF), which is a severe form of dengue infection spread by mosquitoes. It causes high fever, headaches, joint and muscle pain. In severe cases it can lead to bleeding, low blood pressure and shock. There are four types of dengue virus. Treatment involves rest, drinking oral rehydration solutions to replace lost fluids, and monitoring for complications like bleeding and shock. Prevention involves eliminating mosquito breeding sites and getting medical help for any bleeding symptoms.