Dengue haemorrhagic fever and dengue shock syndrome
Typical cases of DHF are characterized by high fever, haemorrhagic phenomena, hepatomegaly, and often circulatory failure. Moderate to marked thrombocytopenia with concurrent haemoconcentration are distinctive clinical laboratory findings. The major pathophysiologic changes that determine the severity of the disease in DHF and differentiate it from DF are abnormal haemostasis and leakage of plasma as manifested by thrombocytopenia and rising haematocrit.
DHF commonly begins with a sudden rise in temperature which is accompanied by facial flush and other non-specific constitutional symptoms resembling dengue fever, such as anorexia, vomiting, headache, and muscle or joint pains.
Some DHF patients complain of sore throat, and an injected pharynx may be found on examination. Epigastric discomfort, tenderness at the right costal margin, and generalized abdominal pain are common. The temperature is typically high and in most cases continues for two to seven days, then falls to a normal or subnormal level. Occasionally the temperature may be as high as 40oC, and febrile convulsions may occur.
The most common haemorrhagic phenomenon is a positive tourniquet test. Easy bruising and bleeding at venipuncture sites are present in most cases. Fine petechiae scattered on the extremities, axillae, face and soft palate may be seen during the early febrile phase. A confluent petechial rash with characteristic small, round areas of normal skin is sometimes seen in convalescence after the temperature has returned to normal. A maculopapular or rubella-type rash may be observed early or late in the disease. Epistaxis and gum bleeding are less common. Mild gastrointestinal haemorrhage is occasionally observed. Haematuria is rarely observed.