Dengue Hemorrhagic Fever Symptoms . At first, symptoms of DHF may be mild, but they gradually worsen within a few days. The initial phase of dengue hemorrhagic fever is similar to that of dengue fever and other febrile viral illnesses. Pin on Infectious Disease Online (Cecelia Jensen) Some patients develop severe diarrhea that may also be bloody. DHF is a clinical syndrome defined by four key features Some patients with dengue fever go on to develop dengue hemorrhagic fever, a severe and sometimes fatal form of the disease. Dengue hemorrhagic fever is a serious complication of dengue infection, a viral infection transmitted to humans by mosquitoes. It is characterized by the sudden onset of fever and a vascular leak syndrome. The goal of treatment is to manage symptoms and keep the infection from becoming more severe. What is dengue and dengue haemorrhagic fever?? When do you ... ...