Disease Information for Dengue hemorrhagic fever: Definition

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  • Incubation 5-8 days; A distinct and virulent form of DENGUE [Dengue 1-4)characterized by thrombocytopenia and hemoconcentration and distinguished by a positive tourniquet test; When accompanied by circulatory failure and shock , it is called dengue shock syndrome; moderate hemorrhage and liver involvement; absent renal or encephalitis syndromes;---------------------------------------. DENGUE FEVER Dengue fever is the most common arboviral infection and, in the form of dengue hemorrhagic fever (DHF), annually causes hundreds of thousands of life-threatening infections in the tropics, principally in children; Four dengue virus serotypes are predominantly transmitted by the Aedes aegypti mosquitoes, which are present in most tropical urban areas of the world; In areas where transmission is endemic, dengue is principally a disease of childhood; Infections occur in almost 100% of children before 8 years of age; In the absence of previous immunity, when new virus strains are introduced, or among travelers from nonendemic areas, infections occur in all age groups; Classic dengue is a grippe-like, often biphasic illness associated with fever, muscle and joint pains, chills, headache, and lumbar back pain accompanied by anorexia, nausea, and vomiting; Facial flushing is characteristic, and in fair-skinned persons, a centrifugally spreading morbilliform rash may be detected late in the illness; Illness is self-limited and sometimes is complicated by minor hemorrhagic phenomena, such as epistaxis and minor gum, gastrointestinal, and vaginal mucosal bleeding; A positive tourniquet test, and lowered platelet, total leukocyte, and absolute monocyte and neutrophil counts reflect marrow suppression; The above self-limited hemorrhagic phenomena should be differentiated from the hemorrhagic-shock syndrome, which is characterized by thrombocytopenia, generalized bleeding, and evidence of increased vascular permeability (eg, hemoconcentration, pleural or abdominal effusions, or hypoalbuminemia); Advanced cases are called dengue shock syndrome (DSS), which is DHF plus narrow pulse pressure and hypotension, with a case fatality rate as high as 44%; Cross-immunity among the serotypes is limited, and sequential infection, particularly when dengue 2 virus causes the second infection, increases the risk for DHF/DSS; The onset of hypotension may be precipitous and typically occurs with defervescence; The interval of vascular instability may be as brief as 24 to 48 hours and reverses spontaneously; Sensitive clinical monitoring and supportive fluid, cardiovascular support, and the exclusion of aspirin reduce DHF mortality from 25% to less than 5%; -------------- [Rudolph"s Pediatrics 2002]--------------------

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