<prompt> Dengue haemorrhagic fever is diagnosed by -Acute onset of high fever, presence of petechiae, epistaxis platelet count2 lakhAcute onset of high fever, positive tourniquest test, epistaxis ormalena and malena and platelet count1.5lakhAcute onset high fever 2 to 7 days, associated with hemorrhagic manifestation e.g hemoptysis and platelet count less than 1.5lakhAcute onset of high fever, positive tourniquet test, bleeding gum and platelet count less than 1.0lakh  <response>: Dengue hemorrhagic fever is diagnosed by acute onset of fever ,hemorrhagic manifestation e.g.positive tourniquet test,platelet count 100,000 cellsmm3. Reference:Park;s textbook of preventive and social medicine,K.Park,23rd edition,page no:250. p 